xpath.c

/*
 * xpath.c: XML Path Language implementation
 *          XPath is a language for addressing parts of an XML document,
 *          designed to be used by both XSLT and XPointer
 *
 * Reference: W3C Recommendation 16 November 1999
 *     http://www.w3.org/TR/1999/REC-xpath-19991116
 * Public reference:
 *     http://www.w3.org/TR/xpath
 *
 * See Copyright for the status of this software
 *
 * Author: Daniel Veillard
 */

/* To avoid EBCDIC trouble when parsing on zOS */
#if defined(__MVS__)
#pragma convert("ISO8859-1")
#endif

#define IN_LIBXML
#include "libxml.h"

#include <limits.h>
#include <string.h>
#include <stddef.h>
#include <math.h>
#include <float.h>
#include <ctype.h>

#include <libxml/xmlmemory.h>
#include <libxml/tree.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>
#include <libxml/parserInternals.h>
#include <libxml/hash.h>
#ifdef LIBXML_DEBUG_ENABLED
#include <libxml/debugXML.h>
#endif
#include <libxml/xmlerror.h>
#include <libxml/threads.h>
#ifdef LIBXML_PATTERN_ENABLED
#include <libxml/pattern.h>
#endif

#include "private/buf.h"
#include "private/error.h"
#include "private/memory.h"
#include "private/xpath.h"

/* Disabled for now */
#if 0
#ifdef LIBXML_PATTERN_ENABLED
#define XPATH_STREAMING
#endif
#endif

/**
 * Use the Timsort algorithm provided in timsort.h to sort
 * nodeset as this is a great improvement over the old Shell sort
 * used in xmlXPathNodeSetSort()
 */
#define WITH_TIM_SORT

/*
* If defined, this will use xmlXPathCmpNodesExt() instead of
* xmlXPathCmpNodes(). The new function is optimized comparison of
* non-element nodes; actually it will speed up comparison only if
* xmlXPathOrderDocElems() was called in order to index the elements of
* a tree in document order; Libxslt does such an indexing, thus it will
* benefit from this optimization.
*/
#define XP_OPTIMIZED_NON_ELEM_COMPARISON

/*
* If defined, this will optimize expressions like "key('foo', 'val')[b][1]"
* in a way, that it stop evaluation at the first node.
*/
#define XP_OPTIMIZED_FILTER_FIRST

/*
 * when compiling an XPath expression we arbitrary limit the maximum
 * number of step operation in the compiled expression. 1000000 is
 * an insanely large value which should never be reached under normal
 * circumstances
 */
#define XPATH_MAX_STEPS 1000000

/*
 * when evaluating an XPath expression we arbitrary limit the maximum
 * number of object allowed to be pushed on the stack. 1000000 is
 * an insanely large value which should never be reached under normal
 * circumstances
 */
#define XPATH_MAX_STACK_DEPTH 1000000

/*
 * when evaluating an XPath expression nodesets are created and we
 * arbitrary limit the maximum length of those node set. 10000000 is
 * an insanely large value which should never be reached under normal
 * circumstances, one would first need to construct an in memory tree
 * with more than 10 millions nodes.
 */
#define XPATH_MAX_NODESET_LENGTH 10000000

/*
 * Maximum amount of nested functions calls when parsing or evaluating
 * expressions
 */
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
#define XPATH_MAX_RECURSION_DEPTH 500
#elif defined(_WIN32)
/* Windows typically limits stack size to 1MB. */
#define XPATH_MAX_RECURSION_DEPTH 1000
#else
#define XPATH_MAX_RECURSION_DEPTH 5000
#endif

/*
 * TODO:
 * There are a few spots where some tests are done which depend upon ascii
 * data.  These should be enhanced for full UTF8 support (see particularly
 * any use of the macros IS_ASCII_CHARACTER and IS_ASCII_DIGIT)
 */

#if defined(LIBXML_XPATH_ENABLED)

static void
xmlXPathNameFunction(xmlXPathParserContextPtr ctxt, int nargs);

static const struct {
    const char *name;
    xmlXPathFunction func;
} xmlXPathStandardFunctions[] = {
    { "boolean", xmlXPathBooleanFunction },
    { "ceiling", xmlXPathCeilingFunction },
    { "count", xmlXPathCountFunction },
    { "concat", xmlXPathConcatFunction },
    { "contains", xmlXPathContainsFunction },
    { "id", xmlXPathIdFunction },
    { "false", xmlXPathFalseFunction },
    { "floor", xmlXPathFloorFunction },
    { "last", xmlXPathLastFunction },
    { "lang", xmlXPathLangFunction },
    { "local-name", xmlXPathLocalNameFunction },
    { "not", xmlXPathNotFunction },
    { "name", xmlXPathNameFunction },
    { "namespace-uri", xmlXPathNamespaceURIFunction },
    { "normalize-space", xmlXPathNormalizeFunction },
    { "number", xmlXPathNumberFunction },
    { "position", xmlXPathPositionFunction },
    { "round", xmlXPathRoundFunction },
    { "string", xmlXPathStringFunction },
    { "string-length", xmlXPathStringLengthFunction },
    { "starts-with", xmlXPathStartsWithFunction },
    { "substring", xmlXPathSubstringFunction },
    { "substring-before", xmlXPathSubstringBeforeFunction },
    { "substring-after", xmlXPathSubstringAfterFunction },
    { "sum", xmlXPathSumFunction },
    { "true", xmlXPathTrueFunction },
    { "translate", xmlXPathTranslateFunction }
};

#define NUM_STANDARD_FUNCTIONS \
    (sizeof(xmlXPathStandardFunctions) / sizeof(xmlXPathStandardFunctions[0]))

#define SF_HASH_SIZE 64

static unsigned char xmlXPathSFHash[SF_HASH_SIZE];

double xmlXPathNAN = 0.0;
double xmlXPathPINF = 0.0;
double xmlXPathNINF = 0.0;

/**
 * @deprecated Alias for xmlInitParser().
 */
void
xmlXPathInit(void) {
    xmlInitParser();
}

ATTRIBUTE_NO_SANITIZE_INTEGER
static unsigned
xmlXPathSFComputeHash(const xmlChar *name) {
    unsigned hashValue = 5381;
    const xmlChar *ptr;

    for (ptr = name; *ptr; ptr++)
        hashValue = hashValue * 33 + *ptr;

    return(hashValue);
}

/**
 * Initialize the XPath environment
 */
ATTRIBUTE_NO_SANITIZE("float-divide-by-zero")
void
xmlInitXPathInternal(void) {
    size_t i;

#if defined(NAN) && defined(INFINITY)
    xmlXPathNAN = NAN;
    xmlXPathPINF = INFINITY;
    xmlXPathNINF = -INFINITY;
#else
    /* MSVC doesn't allow division by zero in constant expressions. */
    double zero = 0.0;
    xmlXPathNAN = 0.0 / zero;
    xmlXPathPINF = 1.0 / zero;
    xmlXPathNINF = -xmlXPathPINF;
#endif

    /*
     * Initialize hash table for standard functions
     */

    for (i = 0; i < SF_HASH_SIZE; i++)
        xmlXPathSFHash[i] = UCHAR_MAX;

    for (i = 0; i < NUM_STANDARD_FUNCTIONS; i++) {
        const char *name = xmlXPathStandardFunctions[i].name;
        int bucketIndex = xmlXPathSFComputeHash(BAD_CAST name) % SF_HASH_SIZE;

        while (xmlXPathSFHash[bucketIndex] != UCHAR_MAX) {
            bucketIndex += 1;
            if (bucketIndex >= SF_HASH_SIZE)
                bucketIndex = 0;
        }

        xmlXPathSFHash[bucketIndex] = i;
    }
}

/************************************************************************
 *									*
 *			Floating point stuff				*
 *									*
 ************************************************************************/

/**
 * Checks whether a double is a NaN.
 *
 * @param val  a double value
 * @returns 1 if the value is a NaN, 0 otherwise
 */
int
xmlXPathIsNaN(double val) {
#ifdef isnan
    return isnan(val);
#else
    return !(val == val);
#endif
}

/**
 * Checks whether a double is an infinity.
 *
 * @param val  a double value
 * @returns 1 if the value is +Infinite, -1 if -Infinite, 0 otherwise
 */
int
xmlXPathIsInf(double val) {
#ifdef isinf
    return isinf(val) ? (val > 0 ? 1 : -1) : 0;
#else
    if (val >= xmlXPathPINF)
        return 1;
    if (val <= -xmlXPathPINF)
        return -1;
    return 0;
#endif
}

/*
 * TODO: when compatibility allows remove all "fake node libxslt" strings
 *       the test should just be name[0] = ' '
 */

static const xmlNs xmlXPathXMLNamespaceStruct = {
    NULL,
    XML_NAMESPACE_DECL,
    XML_XML_NAMESPACE,
    BAD_CAST "xml",
    NULL,
    NULL
};
static const xmlNs *const xmlXPathXMLNamespace = &xmlXPathXMLNamespaceStruct;

static void
xmlXPathNodeSetClear(xmlNodeSetPtr set, int hasNsNodes);

#define XML_NODE_SORT_VALUE(n) XML_PTR_TO_INT((n)->content)

#ifdef XP_OPTIMIZED_NON_ELEM_COMPARISON

/**
 * Compare two nodes w.r.t document order.
 * This one is optimized for handling of non-element nodes.
 *
 * @param node1  the first node
 * @param node2  the second node
 * @returns -2 in case of error 1 if first point < second point, 0 if
 *         it's the same node, -1 otherwise
 */
static int
xmlXPathCmpNodesExt(xmlNodePtr node1, xmlNodePtr node2) {
    int depth1, depth2;
    int misc = 0, precedence1 = 0, precedence2 = 0;
    xmlNodePtr miscNode1 = NULL, miscNode2 = NULL;
    xmlNodePtr cur, root;
    XML_INTPTR_T l1, l2;

    if ((node1 == NULL) || (node2 == NULL))
	return(-2);

    if (node1 == node2)
	return(0);

    /*
     * a couple of optimizations which will avoid computations in most cases
     */
    switch (node1->type) {
	case XML_ELEMENT_NODE:
	    if (node2->type == XML_ELEMENT_NODE) {
		if ((0 > XML_NODE_SORT_VALUE(node1)) &&
		    (0 > XML_NODE_SORT_VALUE(node2)) &&
		    (node1->doc == node2->doc))
		{
		    l1 = -XML_NODE_SORT_VALUE(node1);
		    l2 = -XML_NODE_SORT_VALUE(node2);
		    if (l1 < l2)
			return(1);
		    if (l1 > l2)
			return(-1);
		} else
		    goto turtle_comparison;
	    }
	    break;
	case XML_ATTRIBUTE_NODE:
	    precedence1 = 1; /* element is owner */
	    miscNode1 = node1;
	    node1 = node1->parent;
	    misc = 1;
	    break;
	case XML_TEXT_NODE:
	case XML_CDATA_SECTION_NODE:
	case XML_COMMENT_NODE:
	case XML_PI_NODE: {
	    miscNode1 = node1;
	    /*
	    * Find nearest element node.
	    */
	    if (node1->prev != NULL) {
		do {
		    node1 = node1->prev;
		    if (node1->type == XML_ELEMENT_NODE) {
			precedence1 = 3; /* element in prev-sibl axis */
			break;
		    }
		    if (node1->prev == NULL) {
			precedence1 = 2; /* element is parent */
			/*
			* URGENT TODO: Are there any cases, where the
			* parent of such a node is not an element node?
			*/
			node1 = node1->parent;
			break;
		    }
		} while (1);
	    } else {
		precedence1 = 2; /* element is parent */
		node1 = node1->parent;
	    }
	    if ((node1 == NULL) || (node1->type != XML_ELEMENT_NODE) ||
		(0 <= XML_NODE_SORT_VALUE(node1))) {
		/*
		* Fallback for whatever case.
		*/
		node1 = miscNode1;
		precedence1 = 0;
	    } else
		misc = 1;
	}
	    break;
	case XML_NAMESPACE_DECL:
	    /*
	    * TODO: why do we return 1 for namespace nodes?
	    */
	    return(1);
	default:
	    break;
    }
    switch (node2->type) {
	case XML_ELEMENT_NODE:
	    break;
	case XML_ATTRIBUTE_NODE:
	    precedence2 = 1; /* element is owner */
	    miscNode2 = node2;
	    node2 = node2->parent;
	    misc = 1;
	    break;
	case XML_TEXT_NODE:
	case XML_CDATA_SECTION_NODE:
	case XML_COMMENT_NODE:
	case XML_PI_NODE: {
	    miscNode2 = node2;
	    if (node2->prev != NULL) {
		do {
		    node2 = node2->prev;
		    if (node2->type == XML_ELEMENT_NODE) {
			precedence2 = 3; /* element in prev-sibl axis */
			break;
		    }
		    if (node2->prev == NULL) {
			precedence2 = 2; /* element is parent */
			node2 = node2->parent;
			break;
		    }
		} while (1);
	    } else {
		precedence2 = 2; /* element is parent */
		node2 = node2->parent;
	    }
	    if ((node2 == NULL) || (node2->type != XML_ELEMENT_NODE) ||
		(0 <= XML_NODE_SORT_VALUE(node2)))
	    {
		node2 = miscNode2;
		precedence2 = 0;
	    } else
		misc = 1;
	}
	    break;
	case XML_NAMESPACE_DECL:
	    return(1);
	default:
	    break;
    }
    if (misc) {
	if (node1 == node2) {
	    if (precedence1 == precedence2) {
		/*
		* The ugly case; but normally there aren't many
		* adjacent non-element nodes around.
		*/
		cur = miscNode2->prev;
		while (cur != NULL) {
		    if (cur == miscNode1)
			return(1);
		    if (cur->type == XML_ELEMENT_NODE)
			return(-1);
		    cur = cur->prev;
		}
		return (-1);
	    } else {
		/*
		* Evaluate based on higher precedence wrt to the element.
		* TODO: This assumes attributes are sorted before content.
		*   Is this 100% correct?
		*/
		if (precedence1 < precedence2)
		    return(1);
		else
		    return(-1);
	    }
	}
	/*
	* Special case: One of the helper-elements is contained by the other.
	* <foo>
	*   <node2>
	*     <node1>Text-1(precedence1 == 2)</node1>
	*   </node2>
	*   Text-6(precedence2 == 3)
	* </foo>
	*/
	if ((precedence2 == 3) && (precedence1 > 1)) {
	    cur = node1->parent;
	    while (cur) {
		if (cur == node2)
		    return(1);
		cur = cur->parent;
	    }
	}
	if ((precedence1 == 3) && (precedence2 > 1)) {
	    cur = node2->parent;
	    while (cur) {
		if (cur == node1)
		    return(-1);
		cur = cur->parent;
	    }
	}
    }

    /*
     * Speedup using document order if available.
     */
    if ((node1->type == XML_ELEMENT_NODE) &&
	(node2->type == XML_ELEMENT_NODE) &&
	(0 > XML_NODE_SORT_VALUE(node1)) &&
	(0 > XML_NODE_SORT_VALUE(node2)) &&
	(node1->doc == node2->doc)) {

	l1 = -XML_NODE_SORT_VALUE(node1);
	l2 = -XML_NODE_SORT_VALUE(node2);
	if (l1 < l2)
	    return(1);
	if (l1 > l2)
	    return(-1);
    }

turtle_comparison:

    if (node1 == node2->prev)
	return(1);
    if (node1 == node2->next)
	return(-1);
    /*
     * compute depth to root
     */
    for (depth2 = 0, cur = node2; cur->parent != NULL; cur = cur->parent) {
	if (cur->parent == node1)
	    return(1);
	depth2++;
    }
    root = cur;
    for (depth1 = 0, cur = node1; cur->parent != NULL; cur = cur->parent) {
	if (cur->parent == node2)
	    return(-1);
	depth1++;
    }
    /*
     * Distinct document (or distinct entities :-( ) case.
     */
    if (root != cur) {
	return(-2);
    }
    /*
     * get the nearest common ancestor.
     */
    while (depth1 > depth2) {
	depth1--;
	node1 = node1->parent;
    }
    while (depth2 > depth1) {
	depth2--;
	node2 = node2->parent;
    }
    while (node1->parent != node2->parent) {
	node1 = node1->parent;
	node2 = node2->parent;
	/* should not happen but just in case ... */
	if ((node1 == NULL) || (node2 == NULL))
	    return(-2);
    }
    /*
     * Find who's first.
     */
    if (node1 == node2->prev)
	return(1);
    if (node1 == node2->next)
	return(-1);
    /*
     * Speedup using document order if available.
     */
    if ((node1->type == XML_ELEMENT_NODE) &&
	(node2->type == XML_ELEMENT_NODE) &&
	(0 > XML_NODE_SORT_VALUE(node1)) &&
	(0 > XML_NODE_SORT_VALUE(node2)) &&
	(node1->doc == node2->doc)) {

	l1 = -XML_NODE_SORT_VALUE(node1);
	l2 = -XML_NODE_SORT_VALUE(node2);
	if (l1 < l2)
	    return(1);
	if (l1 > l2)
	    return(-1);
    }

    for (cur = node1->next;cur != NULL;cur = cur->next)
	if (cur == node2)
	    return(1);
    return(-1); /* assume there is no sibling list corruption */
}
#endif /* XP_OPTIMIZED_NON_ELEM_COMPARISON */

/*
 * Wrapper for the Timsort algorithm from timsort.h
 */
#ifdef WITH_TIM_SORT
#define SORT_NAME libxml_domnode
#define SORT_TYPE xmlNodePtr
/**
 * Comparison function for the Timsort implementation
 *
 * @param x  a node
 * @param y  another node
 * @returns -2 in case of error -1 if first point < second point, 0 if
 *         it's the same node, +1 otherwise
 */
static
int wrap_cmp( xmlNodePtr x, xmlNodePtr y );
#ifdef XP_OPTIMIZED_NON_ELEM_COMPARISON
    static int wrap_cmp( xmlNodePtr x, xmlNodePtr y )
    {
        int res = xmlXPathCmpNodesExt(x, y);
        return res == -2 ? res : -res;
    }
#else
    static int wrap_cmp( xmlNodePtr x, xmlNodePtr y )
    {
        int res = xmlXPathCmpNodes(x, y);
        return res == -2 ? res : -res;
    }
#endif
#define SORT_CMP(x, y)  (wrap_cmp(x, y))
#include "timsort.h"
#endif /* WITH_TIM_SORT */

/************************************************************************
 *									*
 *			Error handling routines				*
 *									*
 ************************************************************************/

/**
 * Macro to raise an XPath error and return NULL.
 *
 * @param X  the error code
 */
#define XP_ERRORNULL(X)							\
    { xmlXPathErr(ctxt, X); return(NULL); }

/*
 * The array xmlXPathErrorMessages corresponds to the enum xmlXPathError
 */
static const char* const xmlXPathErrorMessages[] = {
    "Ok\n",
    "Number encoding\n",
    "Unfinished literal\n",
    "Start of literal\n",
    "Expected $ for variable reference\n",
    "Undefined variable\n",
    "Invalid predicate\n",
    "Invalid expression\n",
    "Missing closing curly brace\n",
    "Unregistered function\n",
    "Invalid operand\n",
    "Invalid type\n",
    "Invalid number of arguments\n",
    "Invalid context size\n",
    "Invalid context position\n",
    "Memory allocation error\n",
    "Syntax error\n",
    "Resource error\n",
    "Sub resource error\n",
    "Undefined namespace prefix\n",
    "Encoding error\n",
    "Char out of XML range\n",
    "Invalid or incomplete context\n",
    "Stack usage error\n",
    "Forbidden variable\n",
    "Operation limit exceeded\n",
    "Recursion limit exceeded\n",
    "?? Unknown error ??\n"	/* Must be last in the list! */
};
#define MAXERRNO ((int)(sizeof(xmlXPathErrorMessages) /	\
		   sizeof(xmlXPathErrorMessages[0])) - 1)
/**
 * Handle a memory allocation failure.
 *
 * @param ctxt  an XPath context
 */
void
xmlXPathErrMemory(xmlXPathContextPtr ctxt)
{
    if (ctxt == NULL)
        return;
    xmlRaiseMemoryError(ctxt->error, NULL, ctxt->userData, XML_FROM_XPATH,
                        &ctxt->lastError);
}

/**
 * Handle a memory allocation failure.
 *
 * @param ctxt  an XPath parser context
 */
void
xmlXPathPErrMemory(xmlXPathParserContextPtr ctxt)
{
    if (ctxt == NULL)
        return;
    ctxt->error = XPATH_MEMORY_ERROR;
    xmlXPathErrMemory(ctxt->context);
}

/**
 * Handle an XPath error
 *
 * @param ctxt  a XPath parser context
 * @param code  the error code
 */
void
xmlXPathErr(xmlXPathParserContextPtr ctxt, int code)
{
    xmlStructuredErrorFunc schannel = NULL;
    xmlGenericErrorFunc channel = NULL;
    void *data = NULL;
    xmlNodePtr node = NULL;
    int res;

    if (ctxt == NULL)
        return;
    if ((code < 0) || (code > MAXERRNO))
	code = MAXERRNO;
    /* Only report the first error */
    if (ctxt->error != 0)
        return;

    ctxt->error = code;

    if (ctxt->context != NULL) {
        xmlErrorPtr err = &ctxt->context->lastError;

        /* Don't overwrite memory error. */
        if (err->code == XML_ERR_NO_MEMORY)
            return;

        /* cleanup current last error */
        xmlResetError(err);

        err->domain = XML_FROM_XPATH;
        err->code = code + XML_XPATH_EXPRESSION_OK - XPATH_EXPRESSION_OK;
        err->level = XML_ERR_ERROR;
        if (ctxt->base != NULL) {
            err->str1 = (char *) xmlStrdup(ctxt->base);
            if (err->str1 == NULL) {
                xmlXPathPErrMemory(ctxt);
                return;
            }
        }
        err->int1 = ctxt->cur - ctxt->base;
        err->node = ctxt->context->debugNode;

        schannel = ctxt->context->error;
        data = ctxt->context->userData;
        node = ctxt->context->debugNode;
    }

    if (schannel == NULL) {
        channel = xmlGenericError;
        data = xmlGenericErrorContext;
    }

    res = xmlRaiseError(schannel, channel, data, NULL, node, XML_FROM_XPATH,
                        code + XML_XPATH_EXPRESSION_OK - XPATH_EXPRESSION_OK,
                        XML_ERR_ERROR, NULL, 0,
                        (const char *) ctxt->base, NULL, NULL,
                        ctxt->cur - ctxt->base, 0,
                        "%s", xmlXPathErrorMessages[code]);
    if (res < 0)
        xmlXPathPErrMemory(ctxt);
}

/**
 * Formats an error message.
 *
 * @param ctxt  the XPath Parser context
 * @param file  the file name
 * @param line  the line number
 * @param no  the error number
 */
void
xmlXPatherror(xmlXPathParserContextPtr ctxt, const char *file ATTRIBUTE_UNUSED,
              int line ATTRIBUTE_UNUSED, int no) {
    xmlXPathErr(ctxt, no);
}

/**
 * Adds opCount to the running total of operations and returns -1 if the
 * operation limit is exceeded. Returns 0 otherwise.
 *
 * @param ctxt  the XPath Parser context
 * @param opCount  the number of operations to be added
 */
static int
xmlXPathCheckOpLimit(xmlXPathParserContextPtr ctxt, unsigned long opCount) {
    xmlXPathContextPtr xpctxt = ctxt->context;

    if ((opCount > xpctxt->opLimit) ||
        (xpctxt->opCount > xpctxt->opLimit - opCount)) {
        xpctxt->opCount = xpctxt->opLimit;
        xmlXPathErr(ctxt, XPATH_OP_LIMIT_EXCEEDED);
        return(-1);
    }

    xpctxt->opCount += opCount;
    return(0);
}

#define OP_LIMIT_EXCEEDED(ctxt, n) \
    ((ctxt->context->opLimit != 0) && (xmlXPathCheckOpLimit(ctxt, n) < 0))

/************************************************************************
 *									*
 *			Parser Types					*
 *									*
 ************************************************************************/

/*
 * Types are private:
 */

typedef enum {
    XPATH_OP_END=0,
    XPATH_OP_AND,
    XPATH_OP_OR,
    XPATH_OP_EQUAL,
    XPATH_OP_CMP,
    XPATH_OP_PLUS,
    XPATH_OP_MULT,
    XPATH_OP_UNION,
    XPATH_OP_ROOT,
    XPATH_OP_NODE,
    XPATH_OP_COLLECT,
    XPATH_OP_VALUE, /* 11 */
    XPATH_OP_VARIABLE,
    XPATH_OP_FUNCTION,
    XPATH_OP_ARG,
    XPATH_OP_PREDICATE,
    XPATH_OP_FILTER, /* 16 */
    XPATH_OP_SORT /* 17 */
} xmlXPathOp;

typedef enum {
    AXIS_ANCESTOR = 1,
    AXIS_ANCESTOR_OR_SELF,
    AXIS_ATTRIBUTE,
    AXIS_CHILD,
    AXIS_DESCENDANT,
    AXIS_DESCENDANT_OR_SELF,
    AXIS_FOLLOWING,
    AXIS_FOLLOWING_SIBLING,
    AXIS_NAMESPACE,
    AXIS_PARENT,
    AXIS_PRECEDING,
    AXIS_PRECEDING_SIBLING,
    AXIS_SELF
} xmlXPathAxisVal;

typedef enum {
    NODE_TEST_NONE = 0,
    NODE_TEST_TYPE = 1,
    NODE_TEST_PI = 2,
    NODE_TEST_ALL = 3,
    NODE_TEST_NS = 4,
    NODE_TEST_NAME = 5
} xmlXPathTestVal;

typedef enum {
    NODE_TYPE_NODE = 0,
    NODE_TYPE_COMMENT = XML_COMMENT_NODE,
    NODE_TYPE_TEXT = XML_TEXT_NODE,
    NODE_TYPE_PI = XML_PI_NODE
} xmlXPathTypeVal;

typedef struct _xmlXPathStepOp xmlXPathStepOp;
typedef xmlXPathStepOp *xmlXPathStepOpPtr;
struct _xmlXPathStepOp {
    xmlXPathOp op;		/* The identifier of the operation */
    int ch1;			/* First child */
    int ch2;			/* Second child */
    int value;
    int value2;
    int value3;
    void *value4;
    void *value5;
    xmlXPathFunction cache;
    void *cacheURI;
};

struct _xmlXPathCompExpr {
    int nbStep;			/* Number of steps in this expression */
    int maxStep;		/* Maximum number of steps allocated */
    xmlXPathStepOp *steps;	/* ops for computation of this expression */
    int last;			/* index of last step in expression */
    xmlChar *expr;		/* the expression being computed */
    xmlDictPtr dict;		/* the dictionary to use if any */
#ifdef XPATH_STREAMING
    xmlPatternPtr stream;
#endif
};

/************************************************************************
 *									*
 *			Forward declarations				*
 *									*
 ************************************************************************/

static void
xmlXPathReleaseObject(xmlXPathContextPtr ctxt, xmlXPathObjectPtr obj);
static int
xmlXPathCompOpEvalFirst(xmlXPathParserContextPtr ctxt,
                        xmlXPathStepOpPtr op, xmlNodePtr *first);
static int
xmlXPathCompOpEvalToBoolean(xmlXPathParserContextPtr ctxt,
			    xmlXPathStepOpPtr op,
			    int isPredicate);
static void
xmlXPathFreeObjectEntry(void *obj, const xmlChar *name);

/************************************************************************
 *									*
 *			Parser Type functions				*
 *									*
 ************************************************************************/

/**
 * Create a new Xpath component
 *
 * @returns the newly allocated xmlXPathCompExprPtr or NULL in case of error
 */
static xmlXPathCompExprPtr
xmlXPathNewCompExpr(void) {
    xmlXPathCompExprPtr cur;

    cur = (xmlXPathCompExprPtr) xmlMalloc(sizeof(xmlXPathCompExpr));
    if (cur == NULL)
	return(NULL);
    memset(cur, 0, sizeof(xmlXPathCompExpr));
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
    cur->maxStep = 1;
#else
    cur->maxStep = 10;
#endif
    cur->nbStep = 0;
    cur->steps = (xmlXPathStepOp *) xmlMalloc(cur->maxStep *
	                                   sizeof(xmlXPathStepOp));
    if (cur->steps == NULL) {
	xmlFree(cur);
	return(NULL);
    }
    memset(cur->steps, 0, cur->maxStep * sizeof(xmlXPathStepOp));
    cur->last = -1;
    return(cur);
}

/**
 * Free up the memory allocated by `comp`
 *
 * @param comp  an XPATH comp
 */
void
xmlXPathFreeCompExpr(xmlXPathCompExprPtr comp)
{
    xmlXPathStepOpPtr op;
    int i;

    if (comp == NULL)
        return;
    if (comp->dict == NULL) {
	for (i = 0; i < comp->nbStep; i++) {
	    op = &comp->steps[i];
	    if (op->value4 != NULL) {
		if (op->op == XPATH_OP_VALUE)
		    xmlXPathFreeObject(op->value4);
		else
		    xmlFree(op->value4);
	    }
	    if (op->value5 != NULL)
		xmlFree(op->value5);
	}
    } else {
	for (i = 0; i < comp->nbStep; i++) {
	    op = &comp->steps[i];
	    if (op->value4 != NULL) {
		if (op->op == XPATH_OP_VALUE)
		    xmlXPathFreeObject(op->value4);
	    }
	}
        xmlDictFree(comp->dict);
    }
    if (comp->steps != NULL) {
        xmlFree(comp->steps);
    }
#ifdef XPATH_STREAMING
    if (comp->stream != NULL) {
        xmlFreePatternList(comp->stream);
    }
#endif
    if (comp->expr != NULL) {
        xmlFree(comp->expr);
    }

    xmlFree(comp);
}

/**
 * Add a step to an XPath Compiled Expression
 *
 * @param ctxt  XPath parser context
 * @param ch1  first child index
 * @param ch2  second child index
 * @param op  an op
 * @param value  the first int value
 * @param value2  the second int value
 * @param value3  the third int value
 * @param value4  the first string value
 * @param value5  the second string value
 * @returns -1 in case of failure, the index otherwise
 */
static int
xmlXPathCompExprAdd(xmlXPathParserContextPtr ctxt, int ch1, int ch2,
   xmlXPathOp op, int value,
   int value2, int value3, void *value4, void *value5) {
    xmlXPathCompExprPtr comp = ctxt->comp;
    if (comp->nbStep >= comp->maxStep) {
	xmlXPathStepOp *real;
        int newSize;

        newSize = xmlGrowCapacity(comp->maxStep, sizeof(real[0]),
                                  10, XPATH_MAX_STEPS);
        if (newSize < 0) {
	    xmlXPathPErrMemory(ctxt);
	    return(-1);
        }
	real = xmlRealloc(comp->steps, newSize * sizeof(real[0]));
	if (real == NULL) {
	    xmlXPathPErrMemory(ctxt);
	    return(-1);
	}
	comp->steps = real;
	comp->maxStep = newSize;
    }
    comp->last = comp->nbStep;
    comp->steps[comp->nbStep].ch1 = ch1;
    comp->steps[comp->nbStep].ch2 = ch2;
    comp->steps[comp->nbStep].op = op;
    comp->steps[comp->nbStep].value = value;
    comp->steps[comp->nbStep].value2 = value2;
    comp->steps[comp->nbStep].value3 = value3;
    if ((comp->dict != NULL) &&
        ((op == XPATH_OP_FUNCTION) || (op == XPATH_OP_VARIABLE) ||
	 (op == XPATH_OP_COLLECT))) {
        if (value4 != NULL) {
	    comp->steps[comp->nbStep].value4 = (xmlChar *)
	        (void *)xmlDictLookup(comp->dict, value4, -1);
	    xmlFree(value4);
	} else
	    comp->steps[comp->nbStep].value4 = NULL;
        if (value5 != NULL) {
	    comp->steps[comp->nbStep].value5 = (xmlChar *)
	        (void *)xmlDictLookup(comp->dict, value5, -1);
	    xmlFree(value5);
	} else
	    comp->steps[comp->nbStep].value5 = NULL;
    } else {
	comp->steps[comp->nbStep].value4 = value4;
	comp->steps[comp->nbStep].value5 = value5;
    }
    comp->steps[comp->nbStep].cache = NULL;
    return(comp->nbStep++);
}

#define PUSH_FULL_EXPR(op, op1, op2, val, val2, val3, val4, val5)	\
    xmlXPathCompExprAdd(ctxt, (op1), (op2),			\
	                (op), (val), (val2), (val3), (val4), (val5))
#define PUSH_LONG_EXPR(op, val, val2, val3, val4, val5)			\
    xmlXPathCompExprAdd(ctxt, ctxt->comp->last, -1,		\
	                (op), (val), (val2), (val3), (val4), (val5))

#define PUSH_LEAVE_EXPR(op, val, val2)					\
xmlXPathCompExprAdd(ctxt, -1, -1, (op), (val), (val2), 0 ,NULL ,NULL)

#define PUSH_UNARY_EXPR(op, ch, val, val2)				\
xmlXPathCompExprAdd(ctxt, (ch), -1, (op), (val), (val2), 0 ,NULL ,NULL)

#define PUSH_BINARY_EXPR(op, ch1, ch2, val, val2)			\
xmlXPathCompExprAdd(ctxt, (ch1), (ch2), (op),			\
			(val), (val2), 0 ,NULL ,NULL)

/************************************************************************
 *									*
 *		XPath object cache structures				*
 *									*
 ************************************************************************/

/* #define XP_DEFAULT_CACHE_ON */

typedef struct _xmlXPathContextCache xmlXPathContextCache;
typedef xmlXPathContextCache *xmlXPathContextCachePtr;
struct _xmlXPathContextCache {
    xmlXPathObjectPtr nodesetObjs;  /* stringval points to next */
    xmlXPathObjectPtr miscObjs;     /* stringval points to next */
    int numNodeset;
    int maxNodeset;
    int numMisc;
    int maxMisc;
};

/************************************************************************
 *									*
 *		Debugging related functions				*
 *									*
 ************************************************************************/

#ifdef LIBXML_DEBUG_ENABLED
static void
xmlXPathDebugDumpNode(FILE *output, xmlNodePtr cur, int depth) {
    int i;
    char shift[100];

    for (i = 0;((i < depth) && (i < 25));i++)
        shift[2 * i] = shift[2 * i + 1] = ' ';
    shift[2 * i] = shift[2 * i + 1] = 0;
    if (cur == NULL) {
	fprintf(output, "%s", shift);
	fprintf(output, "Node is NULL !\n");
	return;

    }

    if ((cur->type == XML_DOCUMENT_NODE) ||
	     (cur->type == XML_HTML_DOCUMENT_NODE)) {
	fprintf(output, "%s", shift);
	fprintf(output, " /\n");
    } else if (cur->type == XML_ATTRIBUTE_NODE)
	xmlDebugDumpAttr(output, (xmlAttrPtr)cur, depth);
    else
	xmlDebugDumpOneNode(output, cur, depth);
}
static void
xmlXPathDebugDumpNodeList(FILE *output, xmlNodePtr cur, int depth) {
    xmlNodePtr tmp;
    int i;
    char shift[100];

    for (i = 0;((i < depth) && (i < 25));i++)
        shift[2 * i] = shift[2 * i + 1] = ' ';
    shift[2 * i] = shift[2 * i + 1] = 0;
    if (cur == NULL) {
	fprintf(output, "%s", shift);
	fprintf(output, "Node is NULL !\n");
	return;

    }

    while (cur != NULL) {
	tmp = cur;
	cur = cur->next;
	xmlDebugDumpOneNode(output, tmp, depth);
    }
}

static void
xmlXPathDebugDumpNodeSet(FILE *output, xmlNodeSetPtr cur, int depth) {
    int i;
    char shift[100];

    for (i = 0;((i < depth) && (i < 25));i++)
        shift[2 * i] = shift[2 * i + 1] = ' ';
    shift[2 * i] = shift[2 * i + 1] = 0;

    if (cur == NULL) {
	fprintf(output, "%s", shift);
	fprintf(output, "NodeSet is NULL !\n");
	return;

    }

    if (cur != NULL) {
	fprintf(output, "Set contains %d nodes:\n", cur->nodeNr);
	for (i = 0;i < cur->nodeNr;i++) {
	    fprintf(output, "%s", shift);
	    fprintf(output, "%d", i + 1);
	    xmlXPathDebugDumpNode(output, cur->nodeTab[i], depth + 1);
	}
    }
}

static void
xmlXPathDebugDumpValueTree(FILE *output, xmlNodeSetPtr cur, int depth) {
    int i;
    char shift[100];

    for (i = 0;((i < depth) && (i < 25));i++)
        shift[2 * i] = shift[2 * i + 1] = ' ';
    shift[2 * i] = shift[2 * i + 1] = 0;

    if ((cur == NULL) || (cur->nodeNr == 0) || (cur->nodeTab[0] == NULL)) {
	fprintf(output, "%s", shift);
	fprintf(output, "Value Tree is NULL !\n");
	return;

    }

    fprintf(output, "%s", shift);
    fprintf(output, "%d", i + 1);
    xmlXPathDebugDumpNodeList(output, cur->nodeTab[0]->children, depth + 1);
}

/**
 * Dump the content of the object for debugging purposes
 *
 * @param output  the FILE * to dump the output
 * @param cur  the object to inspect
 * @param depth  indentation level
 */
void
xmlXPathDebugDumpObject(FILE *output, xmlXPathObjectPtr cur, int depth) {
    int i;
    char shift[100];

    if (output == NULL) return;

    for (i = 0;((i < depth) && (i < 25));i++)
        shift[2 * i] = shift[2 * i + 1] = ' ';
    shift[2 * i] = shift[2 * i + 1] = 0;


    fprintf(output, "%s", shift);

    if (cur == NULL) {
        fprintf(output, "Object is empty (NULL)\n");
	return;
    }
    switch(cur->type) {
        case XPATH_UNDEFINED:
	    fprintf(output, "Object is uninitialized\n");
	    break;
        case XPATH_NODESET:
	    fprintf(output, "Object is a Node Set :\n");
	    xmlXPathDebugDumpNodeSet(output, cur->nodesetval, depth);
	    break;
	case XPATH_XSLT_TREE:
	    fprintf(output, "Object is an XSLT value tree :\n");
	    xmlXPathDebugDumpValueTree(output, cur->nodesetval, depth);
	    break;
        case XPATH_BOOLEAN:
	    fprintf(output, "Object is a Boolean : ");
	    if (cur->boolval) fprintf(output, "true\n");
	    else fprintf(output, "false\n");
	    break;
        case XPATH_NUMBER:
	    switch (xmlXPathIsInf(cur->floatval)) {
	    case 1:
		fprintf(output, "Object is a number : Infinity\n");
		break;
	    case -1:
		fprintf(output, "Object is a number : -Infinity\n");
		break;
	    default:
		if (xmlXPathIsNaN(cur->floatval)) {
		    fprintf(output, "Object is a number : NaN\n");
		} else if (cur->floatval == 0) {
                    /* Omit sign for negative zero. */
		    fprintf(output, "Object is a number : 0\n");
		} else {
		    fprintf(output, "Object is a number : %0g\n", cur->floatval);
		}
	    }
	    break;
        case XPATH_STRING:
	    fprintf(output, "Object is a string : ");
	    xmlDebugDumpString(output, cur->stringval);
	    fprintf(output, "\n");
	    break;
	case XPATH_USERS:
	    fprintf(output, "Object is user defined\n");
	    break;
    }
}

static void
xmlXPathDebugDumpStepOp(FILE *output, xmlXPathCompExprPtr comp,
	                     xmlXPathStepOpPtr op, int depth) {
    int i;
    char shift[100];

    for (i = 0;((i < depth) && (i < 25));i++)
        shift[2 * i] = shift[2 * i + 1] = ' ';
    shift[2 * i] = shift[2 * i + 1] = 0;

    fprintf(output, "%s", shift);
    if (op == NULL) {
	fprintf(output, "Step is NULL\n");
	return;
    }
    switch (op->op) {
        case XPATH_OP_END:
	    fprintf(output, "END"); break;
        case XPATH_OP_AND:
	    fprintf(output, "AND"); break;
        case XPATH_OP_OR:
	    fprintf(output, "OR"); break;
        case XPATH_OP_EQUAL:
	     if (op->value)
		 fprintf(output, "EQUAL =");
	     else
		 fprintf(output, "EQUAL !=");
	     break;
        case XPATH_OP_CMP:
	     if (op->value)
		 fprintf(output, "CMP <");
	     else
		 fprintf(output, "CMP >");
	     if (!op->value2)
		 fprintf(output, "=");
	     break;
        case XPATH_OP_PLUS:
	     if (op->value == 0)
		 fprintf(output, "PLUS -");
	     else if (op->value == 1)
		 fprintf(output, "PLUS +");
	     else if (op->value == 2)
		 fprintf(output, "PLUS unary -");
	     else if (op->value == 3)
		 fprintf(output, "PLUS unary - -");
	     break;
        case XPATH_OP_MULT:
	     if (op->value == 0)
		 fprintf(output, "MULT *");
	     else if (op->value == 1)
		 fprintf(output, "MULT div");
	     else
		 fprintf(output, "MULT mod");
	     break;
        case XPATH_OP_UNION:
	     fprintf(output, "UNION"); break;
        case XPATH_OP_ROOT:
	     fprintf(output, "ROOT"); break;
        case XPATH_OP_NODE:
	     fprintf(output, "NODE"); break;
        case XPATH_OP_SORT:
	     fprintf(output, "SORT"); break;
        case XPATH_OP_COLLECT: {
	    xmlXPathAxisVal axis = (xmlXPathAxisVal)op->value;
	    xmlXPathTestVal test = (xmlXPathTestVal)op->value2;
	    xmlXPathTypeVal type = (xmlXPathTypeVal)op->value3;
	    const xmlChar *prefix = op->value4;
	    const xmlChar *name = op->value5;

	    fprintf(output, "COLLECT ");
	    switch (axis) {
		case AXIS_ANCESTOR:
		    fprintf(output, " 'ancestors' "); break;
		case AXIS_ANCESTOR_OR_SELF:
		    fprintf(output, " 'ancestors-or-self' "); break;
		case AXIS_ATTRIBUTE:
		    fprintf(output, " 'attributes' "); break;
		case AXIS_CHILD:
		    fprintf(output, " 'child' "); break;
		case AXIS_DESCENDANT:
		    fprintf(output, " 'descendant' "); break;
		case AXIS_DESCENDANT_OR_SELF:
		    fprintf(output, " 'descendant-or-self' "); break;
		case AXIS_FOLLOWING:
		    fprintf(output, " 'following' "); break;
		case AXIS_FOLLOWING_SIBLING:
		    fprintf(output, " 'following-siblings' "); break;
		case AXIS_NAMESPACE:
		    fprintf(output, " 'namespace' "); break;
		case AXIS_PARENT:
		    fprintf(output, " 'parent' "); break;
		case AXIS_PRECEDING:
		    fprintf(output, " 'preceding' "); break;
		case AXIS_PRECEDING_SIBLING:
		    fprintf(output, " 'preceding-sibling' "); break;
		case AXIS_SELF:
		    fprintf(output, " 'self' "); break;
	    }
	    switch (test) {
                case NODE_TEST_NONE:
		    fprintf(output, "'none' "); break;
                case NODE_TEST_TYPE:
		    fprintf(output, "'type' "); break;
                case NODE_TEST_PI:
		    fprintf(output, "'PI' "); break;
                case NODE_TEST_ALL:
		    fprintf(output, "'all' "); break;
                case NODE_TEST_NS:
		    fprintf(output, "'namespace' "); break;
                case NODE_TEST_NAME:
		    fprintf(output, "'name' "); break;
	    }
	    switch (type) {
                case NODE_TYPE_NODE:
		    fprintf(output, "'node' "); break;
                case NODE_TYPE_COMMENT:
		    fprintf(output, "'comment' "); break;
                case NODE_TYPE_TEXT:
		    fprintf(output, "'text' "); break;
                case NODE_TYPE_PI:
		    fprintf(output, "'PI' "); break;
	    }
	    if (prefix != NULL)
		fprintf(output, "%s:", prefix);
	    if (name != NULL)
		fprintf(output, "%s", (const char *) name);
	    break;

        }
	case XPATH_OP_VALUE: {
	    xmlXPathObjectPtr object = (xmlXPathObjectPtr) op->value4;

	    fprintf(output, "ELEM ");
	    xmlXPathDebugDumpObject(output, object, 0);
	    goto finish;
	}
	case XPATH_OP_VARIABLE: {
	    const xmlChar *prefix = op->value5;
	    const xmlChar *name = op->value4;

	    if (prefix != NULL)
		fprintf(output, "VARIABLE %s:%s", prefix, name);
	    else
		fprintf(output, "VARIABLE %s", name);
	    break;
	}
	case XPATH_OP_FUNCTION: {
	    int nbargs = op->value;
	    const xmlChar *prefix = op->value5;
	    const xmlChar *name = op->value4;

	    if (prefix != NULL)
		fprintf(output, "FUNCTION %s:%s(%d args)",
			prefix, name, nbargs);
	    else
		fprintf(output, "FUNCTION %s(%d args)", name, nbargs);
	    break;
	}
        case XPATH_OP_ARG: fprintf(output, "ARG"); break;
        case XPATH_OP_PREDICATE: fprintf(output, "PREDICATE"); break;
        case XPATH_OP_FILTER: fprintf(output, "FILTER"); break;
	default:
        fprintf(output, "UNKNOWN %d\n", op->op); return;
    }
    fprintf(output, "\n");
finish:
    /* OP_VALUE has invalid ch1. */
    if (op->op == XPATH_OP_VALUE)
        return;

    if (op->ch1 >= 0)
	xmlXPathDebugDumpStepOp(output, comp, &comp->steps[op->ch1], depth + 1);
    if (op->ch2 >= 0)
	xmlXPathDebugDumpStepOp(output, comp, &comp->steps[op->ch2], depth + 1);
}

/**
 * Dumps the tree of the compiled XPath expression.
 *
 * @param output  the FILE * for the output
 * @param comp  the precompiled XPath expression
 * @param depth  the indentation level.
 */
void
xmlXPathDebugDumpCompExpr(FILE *output, xmlXPathCompExprPtr comp,
	                  int depth) {
    int i;
    char shift[100];

    if ((output == NULL) || (comp == NULL)) return;

    for (i = 0;((i < depth) && (i < 25));i++)
        shift[2 * i] = shift[2 * i + 1] = ' ';
    shift[2 * i] = shift[2 * i + 1] = 0;

    fprintf(output, "%s", shift);

#ifdef XPATH_STREAMING
    if (comp->stream) {
        fprintf(output, "Streaming Expression\n");
    } else
#endif
    {
        fprintf(output, "Compiled Expression : %d elements\n",
                comp->nbStep);
        i = comp->last;
        xmlXPathDebugDumpStepOp(output, comp, &comp->steps[i], depth + 1);
    }
}

#endif /* LIBXML_DEBUG_ENABLED */

/************************************************************************
 *									*
 *			XPath object caching				*
 *									*
 ************************************************************************/

/**
 * Create a new object cache
 *
 * @returns the xmlXPathCache just allocated.
 */
static xmlXPathContextCachePtr
xmlXPathNewCache(void)
{
    xmlXPathContextCachePtr ret;

    ret = (xmlXPathContextCachePtr) xmlMalloc(sizeof(xmlXPathContextCache));
    if (ret == NULL)
	return(NULL);
    memset(ret, 0 , sizeof(xmlXPathContextCache));
    ret->maxNodeset = 100;
    ret->maxMisc = 100;
    return(ret);
}

static void
xmlXPathCacheFreeObjectList(xmlXPathObjectPtr list)
{
    while (list != NULL) {
        xmlXPathObjectPtr next;

        next = (void *) list->stringval;

	if (list->nodesetval != NULL) {
	    if (list->nodesetval->nodeTab != NULL)
		xmlFree(list->nodesetval->nodeTab);
	    xmlFree(list->nodesetval);
	}
	xmlFree(list);

        list = next;
    }
}

static void
xmlXPathFreeCache(xmlXPathContextCachePtr cache)
{
    if (cache == NULL)
	return;
    if (cache->nodesetObjs)
	xmlXPathCacheFreeObjectList(cache->nodesetObjs);
    if (cache->miscObjs)
	xmlXPathCacheFreeObjectList(cache->miscObjs);
    xmlFree(cache);
}

/**
 * Creates/frees an object cache on the XPath context.
 * If activates XPath objects (xmlXPathObject) will be cached internally
 * to be reused.
 *
 * `options` must be set to 0 to enable XPath object caching.
 * Other values for `options` have currently no effect.
 *
 * `value` sets the maximum number of XPath objects to be cached per slot.
 * There are two slots for node-set and misc objects.
 * Use <0 for the default number (100).
 *
 * @param ctxt  the XPath context
 * @param active  enables/disables (creates/frees) the cache
 * @param value  a value with semantics dependent on `options`
 * @param options  options (currently only the value 0 is used)
 * @returns 0 if the setting succeeded, and -1 on API or internal errors.
 */
int
xmlXPathContextSetCache(xmlXPathContextPtr ctxt,
			int active,
			int value,
			int options)
{
    if (ctxt == NULL)
	return(-1);
    if (active) {
	xmlXPathContextCachePtr cache;

	if (ctxt->cache == NULL) {
	    ctxt->cache = xmlXPathNewCache();
	    if (ctxt->cache == NULL) {
                xmlXPathErrMemory(ctxt);
		return(-1);
            }
	}
	cache = (xmlXPathContextCachePtr) ctxt->cache;
	if (options == 0) {
	    if (value < 0)
		value = 100;
	    cache->maxNodeset = value;
	    cache->maxMisc = value;
	}
    } else if (ctxt->cache != NULL) {
	xmlXPathFreeCache((xmlXPathContextCachePtr) ctxt->cache);
	ctxt->cache = NULL;
    }
    return(0);
}

/**
 * This is the cached version of xmlXPathWrapNodeSet().
 * Wrap the Nodeset `val` in a new xmlXPathObjectPtr
 *
 * In case of error the node set is destroyed and NULL is returned.
 * @param pctxt  the XPath context
 * @param val  the NodePtr value
 * @returns the created or reused object.
 */
static xmlXPathObjectPtr
xmlXPathCacheWrapNodeSet(xmlXPathParserContextPtr pctxt, xmlNodeSetPtr val)
{
    xmlXPathObjectPtr ret;
    xmlXPathContextPtr ctxt = pctxt->context;

    if ((ctxt != NULL) && (ctxt->cache != NULL)) {
	xmlXPathContextCachePtr cache =
	    (xmlXPathContextCachePtr) ctxt->cache;

	if (cache->miscObjs != NULL) {
	    ret = cache->miscObjs;
            cache->miscObjs = (void *) ret->stringval;
            cache->numMisc -= 1;
            ret->stringval = NULL;
	    ret->type = XPATH_NODESET;
	    ret->nodesetval = val;
	    return(ret);
	}
    }

    ret = xmlXPathWrapNodeSet(val);
    if (ret == NULL)
        xmlXPathPErrMemory(pctxt);
    return(ret);
}

/**
 * This is the cached version of xmlXPathWrapString().
 * Wraps the `val` string into an XPath object.
 *
 * @param pctxt  the XPath context
 * @param val  the xmlChar * value
 * @returns the created or reused object.
 */
static xmlXPathObjectPtr
xmlXPathCacheWrapString(xmlXPathParserContextPtr pctxt, xmlChar *val)
{
    xmlXPathObjectPtr ret;
    xmlXPathContextPtr ctxt = pctxt->context;

    if ((ctxt != NULL) && (ctxt->cache != NULL)) {
	xmlXPathContextCachePtr cache = (xmlXPathContextCachePtr) ctxt->cache;

	if (cache->miscObjs != NULL) {
	    ret = cache->miscObjs;
            cache->miscObjs = (void *) ret->stringval;
            cache->numMisc -= 1;
	    ret->type = XPATH_STRING;
	    ret->stringval = val;
	    return(ret);
	}
    }

    ret = xmlXPathWrapString(val);
    if (ret == NULL)
        xmlXPathPErrMemory(pctxt);
    return(ret);
}

/**
 * This is the cached version of xmlXPathNewNodeSet().
 * Acquire an xmlXPathObjectPtr of type NodeSet and initialize
 * it with the single Node `val`
 *
 * @param pctxt  the XPath context
 * @param val  the NodePtr value
 * @returns the created or reused object.
 */
static xmlXPathObjectPtr
xmlXPathCacheNewNodeSet(xmlXPathParserContextPtr pctxt, xmlNodePtr val)
{
    xmlXPathObjectPtr ret;
    xmlXPathContextPtr ctxt = pctxt->context;

    if ((ctxt != NULL) && (ctxt->cache != NULL)) {
	xmlXPathContextCachePtr cache = (xmlXPathContextCachePtr) ctxt->cache;

	if (cache->nodesetObjs != NULL) {
	    /*
	    * Use the nodeset-cache.
	    */
	    ret = cache->nodesetObjs;
            cache->nodesetObjs = (void *) ret->stringval;
            cache->numNodeset -= 1;
            ret->stringval = NULL;
	    ret->type = XPATH_NODESET;
	    ret->boolval = 0;
	    if (val) {
		if ((ret->nodesetval->nodeMax == 0) ||
		    (val->type == XML_NAMESPACE_DECL))
		{
		    if (xmlXPathNodeSetAddUnique(ret->nodesetval, val) < 0)
                        xmlXPathPErrMemory(pctxt);
		} else {
		    ret->nodesetval->nodeTab[0] = val;
		    ret->nodesetval->nodeNr = 1;
		}
	    }
	    return(ret);
	} else if (cache->miscObjs != NULL) {
            xmlNodeSetPtr set;
	    /*
	    * Fallback to misc-cache.
	    */

	    set = xmlXPathNodeSetCreate(val);
	    if (set == NULL) {
                xmlXPathPErrMemory(pctxt);
		return(NULL);
	    }

	    ret = cache->miscObjs;
            cache->miscObjs = (void *) ret->stringval;
            cache->numMisc -= 1;
            ret->stringval = NULL;
	    ret->type = XPATH_NODESET;
	    ret->boolval = 0;
	    ret->nodesetval = set;
	    return(ret);
	}
    }
    ret = xmlXPathNewNodeSet(val);
    if (ret == NULL)
        xmlXPathPErrMemory(pctxt);
    return(ret);
}

/**
 * This is the cached version of xmlXPathNewString().
 * Acquire an xmlXPathObjectPtr of type string and of value `val`
 *
 * @param pctxt  the XPath context
 * @param val  the xmlChar * value
 * @returns the created or reused object.
 */
static xmlXPathObjectPtr
xmlXPathCacheNewString(xmlXPathParserContextPtr pctxt, const xmlChar *val)
{
    xmlXPathObjectPtr ret;
    xmlXPathContextPtr ctxt = pctxt->context;

    if ((ctxt != NULL) && (ctxt->cache != NULL)) {
	xmlXPathContextCachePtr cache = (xmlXPathContextCachePtr) ctxt->cache;

	if (cache->miscObjs != NULL) {
            xmlChar *copy;

            if (val == NULL)
                val = BAD_CAST "";
            copy = xmlStrdup(val);
            if (copy == NULL) {
                xmlXPathPErrMemory(pctxt);
                return(NULL);
            }

	    ret = cache->miscObjs;
            cache->miscObjs = (void *) ret->stringval;
            cache->numMisc -= 1;
	    ret->type = XPATH_STRING;
            ret->stringval = copy;
	    return(ret);
	}
    }

    ret = xmlXPathNewString(val);
    if (ret == NULL)
        xmlXPathPErrMemory(pctxt);
    return(ret);
}

/**
 * This is the cached version of xmlXPathNewCString().
 * Acquire an xmlXPathObjectPtr of type string and of value `val`
 *
 * @param pctxt  the XPath context
 * @param val  the char * value
 * @returns the created or reused object.
 */
static xmlXPathObjectPtr
xmlXPathCacheNewCString(xmlXPathParserContextPtr pctxt, const char *val)
{
    return xmlXPathCacheNewString(pctxt, BAD_CAST val);
}

/**
 * This is the cached version of xmlXPathNewBoolean().
 * Acquires an xmlXPathObjectPtr of type boolean and of value `val`
 *
 * @param pctxt  the XPath context
 * @param val  the boolean value
 * @returns the created or reused object.
 */
static xmlXPathObjectPtr
xmlXPathCacheNewBoolean(xmlXPathParserContextPtr pctxt, int val)
{
    xmlXPathObjectPtr ret;
    xmlXPathContextPtr ctxt = pctxt->context;

    if ((ctxt != NULL) && (ctxt->cache != NULL)) {
	xmlXPathContextCachePtr cache = (xmlXPathContextCachePtr) ctxt->cache;

	if (cache->miscObjs != NULL) {
	    ret = cache->miscObjs;
            cache->miscObjs = (void *) ret->stringval;
            cache->numMisc -= 1;
            ret->stringval = NULL;
	    ret->type = XPATH_BOOLEAN;
	    ret->boolval = (val != 0);
	    return(ret);
	}
    }

    ret = xmlXPathNewBoolean(val);
    if (ret == NULL)
        xmlXPathPErrMemory(pctxt);
    return(ret);
}

/**
 * This is the cached version of xmlXPathNewFloat().
 * Acquires an xmlXPathObjectPtr of type double and of value `val`
 *
 * @param pctxt  the XPath context
 * @param val  the double value
 * @returns the created or reused object.
 */
static xmlXPathObjectPtr
xmlXPathCacheNewFloat(xmlXPathParserContextPtr pctxt, double val)
{
    xmlXPathObjectPtr ret;
    xmlXPathContextPtr ctxt = pctxt->context;

    if ((ctxt != NULL) && (ctxt->cache != NULL)) {
	xmlXPathContextCachePtr cache = (xmlXPathContextCachePtr) ctxt->cache;

	if (cache->miscObjs != NULL) {
	    ret = cache->miscObjs;
            cache->miscObjs = (void *) ret->stringval;
            cache->numMisc -= 1;
            ret->stringval = NULL;
	    ret->type = XPATH_NUMBER;
	    ret->floatval = val;
	    return(ret);
	}
    }

    ret = xmlXPathNewFloat(val);
    if (ret == NULL)
        xmlXPathPErrMemory(pctxt);
    return(ret);
}

/**
 * This is the cached version of xmlXPathObjectCopy().
 * Acquire a copy of a given object
 *
 * @param pctxt  the XPath context
 * @param val  the original object
 * @returns a created or reused created object.
 */
static xmlXPathObjectPtr
xmlXPathCacheObjectCopy(xmlXPathParserContextPtr pctxt, xmlXPathObjectPtr val)
{
    xmlXPathObjectPtr ret;
    xmlXPathContextPtr ctxt = pctxt->context;

    if (val == NULL)
	return(NULL);

    if ((ctxt != NULL) && (ctxt->cache != NULL)) {
	switch (val->type) {
            case XPATH_NODESET: {
                xmlNodeSetPtr set;

                set = xmlXPathNodeSetMerge(NULL, val->nodesetval);
                if (set == NULL) {
                    xmlXPathPErrMemory(pctxt);
                    return(NULL);
                }
                return(xmlXPathCacheWrapNodeSet(pctxt, set));
            }
	    case XPATH_STRING:
		return(xmlXPathCacheNewString(pctxt, val->stringval));
	    case XPATH_BOOLEAN:
		return(xmlXPathCacheNewBoolean(pctxt, val->boolval));
	    case XPATH_NUMBER:
		return(xmlXPathCacheNewFloat(pctxt, val->floatval));
	    default:
		break;
	}
    }
    ret = xmlXPathObjectCopy(val);
    if (ret == NULL)
        xmlXPathPErrMemory(pctxt);
    return(ret);
}

/************************************************************************
 *									*
 *		Parser stacks related functions and macros		*
 *									*
 ************************************************************************/

/**
 * Converts an XPath object to its number value
 *
 * @param ctxt  parser context
 * @param val  an XPath object
 * @returns the number value
 */
static double
xmlXPathCastToNumberInternal(xmlXPathParserContextPtr ctxt,
                             xmlXPathObjectPtr val) {
    double ret = 0.0;

    if (val == NULL)
	return(xmlXPathNAN);
    switch (val->type) {
    case XPATH_UNDEFINED:
	ret = xmlXPathNAN;
	break;
    case XPATH_NODESET:
    case XPATH_XSLT_TREE: {
        xmlChar *str;

	str = xmlXPathCastNodeSetToString(val->nodesetval);
        if (str == NULL) {
            xmlXPathPErrMemory(ctxt);
            ret = xmlXPathNAN;
        } else {
	    ret = xmlXPathCastStringToNumber(str);
            xmlFree(str);
        }
	break;
    }
    case XPATH_STRING:
	ret = xmlXPathCastStringToNumber(val->stringval);
	break;
    case XPATH_NUMBER:
	ret = val->floatval;
	break;
    case XPATH_BOOLEAN:
	ret = xmlXPathCastBooleanToNumber(val->boolval);
	break;
    case XPATH_USERS:
	/* TODO */
	ret = xmlXPathNAN;
	break;
    }
    return(ret);
}

/**
 * Pops the top XPath object from the value stack
 *
 * @param ctxt  an XPath evaluation context
 * @returns the XPath object just removed
 */
xmlXPathObjectPtr
xmlXPathValuePop(xmlXPathParserContextPtr ctxt)
{
    xmlXPathObjectPtr ret;

    if ((ctxt == NULL) || (ctxt->valueNr <= 0))
        return (NULL);

    ctxt->valueNr--;
    if (ctxt->valueNr > 0)
        ctxt->value = ctxt->valueTab[ctxt->valueNr - 1];
    else
        ctxt->value = NULL;
    ret = ctxt->valueTab[ctxt->valueNr];
    ctxt->valueTab[ctxt->valueNr] = NULL;
    return (ret);
}

/**
 * Pushes a new XPath object on top of the value stack. If value is NULL,
 * a memory error is recorded in the parser context.
 *
 * The object is destroyed in case of error.
 * @param ctxt  an XPath evaluation context
 * @param value  the XPath object
 * @returns the number of items on the value stack, or -1 in case of error.
 */
int
xmlXPathValuePush(xmlXPathParserContextPtr ctxt, xmlXPathObjectPtr value)
{
    if (ctxt == NULL) return(-1);
    if (value == NULL) {
        /*
         * A NULL value typically indicates that a memory allocation failed.
         */
        xmlXPathPErrMemory(ctxt);
        return(-1);
    }
    if (ctxt->valueNr >= ctxt->valueMax) {
        xmlXPathObjectPtr *tmp;
        int newSize;

        newSize = xmlGrowCapacity(ctxt->valueMax, sizeof(tmp[0]),
                                  10, XPATH_MAX_STACK_DEPTH);
        if (newSize < 0) {
            xmlXPathPErrMemory(ctxt);
            xmlXPathFreeObject(value);
            return (-1);
        }
        tmp = xmlRealloc(ctxt->valueTab, newSize * sizeof(tmp[0]));
        if (tmp == NULL) {
            xmlXPathPErrMemory(ctxt);
            xmlXPathFreeObject(value);
            return (-1);
        }
	ctxt->valueTab = tmp;
        ctxt->valueMax = newSize;
    }
    ctxt->valueTab[ctxt->valueNr] = value;
    ctxt->value = value;
    return (ctxt->valueNr++);
}

/**
 * Pops a boolean from the stack, handling conversion if needed.
 * Check error with xmlXPathCheckError.
 *
 * @param ctxt  an XPath parser context
 * @returns the boolean
 */
int
xmlXPathPopBoolean (xmlXPathParserContextPtr ctxt) {
    xmlXPathObjectPtr obj;
    int ret;

    obj = xmlXPathValuePop(ctxt);
    if (obj == NULL) {
	xmlXPathSetError(ctxt, XPATH_INVALID_OPERAND);
	return(0);
    }
    if (obj->type != XPATH_BOOLEAN)
	ret = xmlXPathCastToBoolean(obj);
    else
        ret = obj->boolval;
    xmlXPathReleaseObject(ctxt->context, obj);
    return(ret);
}

/**
 * Pops a number from the stack, handling conversion if needed.
 * Check error with xmlXPathCheckError.
 *
 * @param ctxt  an XPath parser context
 * @returns the number
 */
double
xmlXPathPopNumber (xmlXPathParserContextPtr ctxt) {
    xmlXPathObjectPtr obj;
    double ret;

    obj = xmlXPathValuePop(ctxt);
    if (obj == NULL) {
	xmlXPathSetError(ctxt, XPATH_INVALID_OPERAND);
	return(0);
    }
    if (obj->type != XPATH_NUMBER)
	ret = xmlXPathCastToNumberInternal(ctxt, obj);
    else
        ret = obj->floatval;
    xmlXPathReleaseObject(ctxt->context, obj);
    return(ret);
}

/**
 * Pops a string from the stack, handling conversion if needed.
 * Check error with xmlXPathCheckError.
 *
 * @param ctxt  an XPath parser context
 * @returns the string
 */
xmlChar *
xmlXPathPopString (xmlXPathParserContextPtr ctxt) {
    xmlXPathObjectPtr obj;
    xmlChar * ret;

    obj = xmlXPathValuePop(ctxt);
    if (obj == NULL) {
	xmlXPathSetError(ctxt, XPATH_INVALID_OPERAND);
	return(NULL);
    }
    ret = xmlXPathCastToString(obj);
    if (ret == NULL)
        xmlXPathPErrMemory(ctxt);
    xmlXPathReleaseObject(ctxt->context, obj);
    return(ret);
}

/**
 * Pops a node-set from the stack, handling conversion if needed.
 * Check error with xmlXPathCheckError.
 *
 * @param ctxt  an XPath parser context
 * @returns the node-set
 */
xmlNodeSetPtr
xmlXPathPopNodeSet (xmlXPathParserContextPtr ctxt) {
    xmlXPathObjectPtr obj;
    xmlNodeSetPtr ret;

    if (ctxt == NULL) return(NULL);
    if (ctxt->value == NULL) {
	xmlXPathSetError(ctxt, XPATH_INVALID_OPERAND);
	return(NULL);
    }
    if (!xmlXPathStackIsNodeSet(ctxt)) {
	xmlXPathSetTypeError(ctxt);
	return(NULL);
    }
    obj = xmlXPathValuePop(ctxt);
    ret = obj->nodesetval;
    obj->nodesetval = NULL;
    xmlXPathReleaseObject(ctxt->context, obj);
    return(ret);
}

/**
 * Pops an external object from the stack, handling conversion if needed.
 * Check error with xmlXPathCheckError.
 *
 * @param ctxt  an XPath parser context
 * @returns the object
 */
void *
xmlXPathPopExternal (xmlXPathParserContextPtr ctxt) {
    xmlXPathObjectPtr obj;
    void * ret;

    if ((ctxt == NULL) || (ctxt->value == NULL)) {
	xmlXPathSetError(ctxt, XPATH_INVALID_OPERAND);
	return(NULL);
    }
    if (ctxt->value->type != XPATH_USERS) {
	xmlXPathSetTypeError(ctxt);
	return(NULL);
    }
    obj = xmlXPathValuePop(ctxt);
    ret = obj->user;
    obj->user = NULL;
    xmlXPathReleaseObject(ctxt->context, obj);
    return(ret);
}

/*
 * Macros for accessing the content. Those should be used only by the parser,
 * and not exported.
 *
 * Dirty macros, i.e. one need to make assumption on the context to use them
 *
 *   CUR_PTR return the current pointer to the xmlChar to be parsed.
 *   CUR     returns the current xmlChar value, i.e. a 8 bit value
 *           in ISO-Latin or UTF-8.
 *           This should be used internally by the parser
 *           only to compare to ASCII values otherwise it would break when
 *           running with UTF-8 encoding.
 *   NXT(n)  returns the n'th next xmlChar. Same as CUR is should be used only
 *           to compare on ASCII based substring.
 *   SKIP(n) Skip n xmlChar, and must also be used only to skip ASCII defined
 *           strings within the parser.
 *   CURRENT Returns the current char value, with the full decoding of
 *           UTF-8 if we are using this mode. It returns an int.
 *   NEXT    Skip to the next character, this does the proper decoding
 *           in UTF-8 mode. It also pop-up unfinished entities on the fly.
 *           It returns the pointer to the current xmlChar.
 */

#define CUR (*ctxt->cur)
#define SKIP(val) ctxt->cur += (val)
#define NXT(val) ctxt->cur[(val)]
#define CUR_PTR ctxt->cur
#define CUR_CHAR(l) xmlXPathCurrentChar(ctxt, &l)

#define COPY_BUF(b, i, v)						\
    if (v < 0x80) b[i++] = v;						\
    else i += xmlCopyCharMultiByte(&b[i],v)

#define NEXTL(l)  ctxt->cur += l

#define SKIP_BLANKS							\
    while (IS_BLANK_CH(*(ctxt->cur))) NEXT

#define CURRENT (*ctxt->cur)
#define NEXT ((*ctxt->cur) ?  ctxt->cur++: ctxt->cur)


#ifndef DBL_DIG
#define DBL_DIG 16
#endif
#ifndef DBL_EPSILON
#define DBL_EPSILON 1E-9
#endif

#define UPPER_DOUBLE 1E9
#define LOWER_DOUBLE 1E-5
#define	LOWER_DOUBLE_EXP 5

#define INTEGER_DIGITS DBL_DIG
#define FRACTION_DIGITS (DBL_DIG + 1 + (LOWER_DOUBLE_EXP))
#define EXPONENT_DIGITS (3 + 2)

/**
 * Convert the number into a string representation.
 *
 * @param number  number to format
 * @param buffer  output buffer
 * @param buffersize  size of output buffer
 */
static void
xmlXPathFormatNumber(double number, char buffer[], int buffersize)
{
    switch (xmlXPathIsInf(number)) {
    case 1:
	if (buffersize > (int)sizeof("Infinity"))
	    snprintf(buffer, buffersize, "Infinity");
	break;
    case -1:
	if (buffersize > (int)sizeof("-Infinity"))
	    snprintf(buffer, buffersize, "-Infinity");
	break;
    default:
	if (xmlXPathIsNaN(number)) {
	    if (buffersize > (int)sizeof("NaN"))
		snprintf(buffer, buffersize, "NaN");
	} else if (number == 0) {
            /* Omit sign for negative zero. */
	    snprintf(buffer, buffersize, "0");
	} else if ((number > INT_MIN) && (number < INT_MAX) &&
                   (number == (int) number)) {
	    char work[30];
	    char *ptr, *cur;
	    int value = (int) number;

            ptr = &buffer[0];
	    if (value == 0) {
		*ptr++ = '0';
	    } else {
		snprintf(work, 29, "%d", value);
		cur = &work[0];
		while ((*cur) && (ptr - buffer < buffersize)) {
		    *ptr++ = *cur++;
		}
	    }
	    if (ptr - buffer < buffersize) {
		*ptr = 0;
	    } else if (buffersize > 0) {
		ptr--;
		*ptr = 0;
	    }
	} else {
	    /*
	      For the dimension of work,
	          DBL_DIG is number of significant digits
		  EXPONENT is only needed for "scientific notation"
	          3 is sign, decimal point, and terminating zero
		  LOWER_DOUBLE_EXP is max number of leading zeroes in fraction
	      Note that this dimension is slightly (a few characters)
	      larger than actually necessary.
	    */
	    char work[DBL_DIG + EXPONENT_DIGITS + 3 + LOWER_DOUBLE_EXP];
	    int integer_place, fraction_place;
	    char *ptr;
	    char *after_fraction;
	    double absolute_value;
	    int size;

	    absolute_value = fabs(number);

	    /*
	     * First choose format - scientific or regular floating point.
	     * In either case, result is in work, and after_fraction points
	     * just past the fractional part.
	    */
	    if ( ((absolute_value > UPPER_DOUBLE) ||
		  (absolute_value < LOWER_DOUBLE)) &&
		 (absolute_value != 0.0) ) {
		/* Use scientific notation */
		integer_place = DBL_DIG + EXPONENT_DIGITS + 1;
		fraction_place = DBL_DIG - 1;
		size = snprintf(work, sizeof(work),"%*.*e",
			 integer_place, fraction_place, number);
		while ((size > 0) && (work[size] != 'e')) size--;

	    }
	    else {
		/* Use regular notation */
		if (absolute_value > 0.0) {
		    integer_place = (int)log10(absolute_value);
		    if (integer_place > 0)
		        fraction_place = DBL_DIG - integer_place - 1;
		    else
		        fraction_place = DBL_DIG - integer_place;
		} else {
		    fraction_place = 1;
		}
		size = snprintf(work, sizeof(work), "%0.*f",
				fraction_place, number);
	    }

	    /* Remove leading spaces sometimes inserted by snprintf */
	    while (work[0] == ' ') {
	        for (ptr = &work[0];(ptr[0] = ptr[1]);ptr++);
		size--;
	    }

	    /* Remove fractional trailing zeroes */
	    after_fraction = work + size;
	    ptr = after_fraction;
	    while (*(--ptr) == '0')
		;
	    if (*ptr != '.')
	        ptr++;
	    while ((*ptr++ = *after_fraction++) != 0);

	    /* Finally copy result back to caller */
	    size = strlen(work) + 1;
	    if (size > buffersize) {
		work[buffersize - 1] = 0;
		size = buffersize;
	    }
	    memmove(buffer, work, size);
	}
	break;
    }
}


/************************************************************************
 *									*
 *			Routines to handle NodeSets			*
 *									*
 ************************************************************************/

/**
 * Call this routine to speed up XPath computation on static documents.
 * This stamps all the element nodes with the document order
 * Like for line information, the order is kept in the element->content
 * field, the value stored is actually - the node number (starting at -1)
 * to be able to differentiate from line numbers.
 *
 * @param doc  an input document
 * @returns the number of elements found in the document or -1 in case
 *    of error.
 */
long
xmlXPathOrderDocElems(xmlDocPtr doc) {
    XML_INTPTR_T count = 0;
    xmlNodePtr cur;

    if (doc == NULL)
	return(-1);
    cur = doc->children;
    while (cur != NULL) {
	if (cur->type == XML_ELEMENT_NODE) {
            count += 1;
            cur->content = XML_INT_TO_PTR(-count);
	    if (cur->children != NULL) {
		cur = cur->children;
		continue;
	    }
	}
	if (cur->next != NULL) {
	    cur = cur->next;
	    continue;
	}
	do {
	    cur = cur->parent;
	    if (cur == NULL)
		break;
	    if (cur == (xmlNodePtr) doc) {
		cur = NULL;
		break;
	    }
	    if (cur->next != NULL) {
		cur = cur->next;
		break;
	    }
	} while (cur != NULL);
    }
    return(count);
}

/**
 * Compare two nodes w.r.t document order
 *
 * @param node1  the first node
 * @param node2  the second node
 * @returns -2 in case of error 1 if first point < second point, 0 if
 *         it's the same node, -1 otherwise
 */
int
xmlXPathCmpNodes(xmlNodePtr node1, xmlNodePtr node2) {
    int depth1, depth2;
    int attr1 = 0, attr2 = 0;
    xmlNodePtr attrNode1 = NULL, attrNode2 = NULL;
    xmlNodePtr cur, root;

    if ((node1 == NULL) || (node2 == NULL))
	return(-2);
    /*
     * a couple of optimizations which will avoid computations in most cases
     */
    if (node1 == node2)		/* trivial case */
	return(0);
    if (node1->type == XML_ATTRIBUTE_NODE) {
	attr1 = 1;
	attrNode1 = node1;
	node1 = node1->parent;
    }
    if (node2->type == XML_ATTRIBUTE_NODE) {
	attr2 = 1;
	attrNode2 = node2;
	node2 = node2->parent;
    }
    if (node1 == node2) {
	if (attr1 == attr2) {
	    /* not required, but we keep attributes in order */
	    if (attr1 != 0) {
	        cur = attrNode2->prev;
		while (cur != NULL) {
		    if (cur == attrNode1)
		        return (1);
		    cur = cur->prev;
		}
		return (-1);
	    }
	    return(0);
	}
	if (attr2 == 1)
	    return(1);
	return(-1);
    }
    if ((node1->type == XML_NAMESPACE_DECL) ||
        (node2->type == XML_NAMESPACE_DECL))
	return(1);
    if (node1 == node2->prev)
	return(1);
    if (node1 == node2->next)
	return(-1);

    /*
     * Speedup using document order if available.
     */
    if ((node1->type == XML_ELEMENT_NODE) &&
	(node2->type == XML_ELEMENT_NODE) &&
	(0 > XML_NODE_SORT_VALUE(node1)) &&
	(0 > XML_NODE_SORT_VALUE(node2)) &&
	(node1->doc == node2->doc)) {
	XML_INTPTR_T l1, l2;

	l1 = -XML_NODE_SORT_VALUE(node1);
	l2 = -XML_NODE_SORT_VALUE(node2);
	if (l1 < l2)
	    return(1);
	if (l1 > l2)
	    return(-1);
    }

    /*
     * compute depth to root
     */
    for (depth2 = 0, cur = node2;cur->parent != NULL;cur = cur->parent) {
	if (cur->parent == node1)
	    return(1);
	depth2++;
    }
    root = cur;
    for (depth1 = 0, cur = node1;cur->parent != NULL;cur = cur->parent) {
	if (cur->parent == node2)
	    return(-1);
	depth1++;
    }
    /*
     * Distinct document (or distinct entities :-( ) case.
     */
    if (root != cur) {
	return(-2);
    }
    /*
     * get the nearest common ancestor.
     */
    while (depth1 > depth2) {
	depth1--;
	node1 = node1->parent;
    }
    while (depth2 > depth1) {
	depth2--;
	node2 = node2->parent;
    }
    while (node1->parent != node2->parent) {
	node1 = node1->parent;
	node2 = node2->parent;
	/* should not happen but just in case ... */
	if ((node1 == NULL) || (node2 == NULL))
	    return(-2);
    }
    /*
     * Find who's first.
     */
    if (node1 == node2->prev)
	return(1);
    if (node1 == node2->next)
	return(-1);
    /*
     * Speedup using document order if available.
     */
    if ((node1->type == XML_ELEMENT_NODE) &&
	(node2->type == XML_ELEMENT_NODE) &&
	(0 > XML_NODE_SORT_VALUE(node1)) &&
	(0 > XML_NODE_SORT_VALUE(node2)) &&
	(node1->doc == node2->doc)) {
	XML_INTPTR_T l1, l2;

	l1 = -XML_NODE_SORT_VALUE(node1);
	l2 = -XML_NODE_SORT_VALUE(node2);
	if (l1 < l2)
	    return(1);
	if (l1 > l2)
	    return(-1);
    }

    for (cur = node1->next;cur != NULL;cur = cur->next)
	if (cur == node2)
	    return(1);
    return(-1); /* assume there is no sibling list corruption */
}

/**
 * Sort the node set in document order
 *
 * @param set  the node set
 */
void
xmlXPathNodeSetSort(xmlNodeSetPtr set) {
#ifndef WITH_TIM_SORT
    int i, j, incr, len;
    xmlNodePtr tmp;
#endif

    if (set == NULL)
	return;

#ifndef WITH_TIM_SORT
    /*
     * Use the old Shell's sort implementation to sort the node-set
     * Timsort ought to be quite faster
     */
    len = set->nodeNr;
    for (incr = len / 2; incr > 0; incr /= 2) {
	for (i = incr; i < len; i++) {
	    j = i - incr;
	    while (j >= 0) {
#ifdef XP_OPTIMIZED_NON_ELEM_COMPARISON
		if (xmlXPathCmpNodesExt(set->nodeTab[j],
			set->nodeTab[j + incr]) == -1)
#else
		if (xmlXPathCmpNodes(set->nodeTab[j],
			set->nodeTab[j + incr]) == -1)
#endif
		{
		    tmp = set->nodeTab[j];
		    set->nodeTab[j] = set->nodeTab[j + incr];
		    set->nodeTab[j + incr] = tmp;
		    j -= incr;
		} else
		    break;
	    }
	}
    }
#else /* WITH_TIM_SORT */
    libxml_domnode_tim_sort(set->nodeTab, set->nodeNr);
#endif /* WITH_TIM_SORT */
}

#define XML_NODESET_DEFAULT	10
/**
 * Namespace node in libxml don't match the XPath semantic. In a node set
 * the namespace nodes are duplicated and the next pointer is set to the
 * parent node in the XPath semantic.
 *
 * @param node  the parent node of the namespace XPath node
 * @param ns  the libxml namespace declaration node.
 * @returns the newly created object.
 */
static xmlNodePtr
xmlXPathNodeSetDupNs(xmlNodePtr node, xmlNsPtr ns) {
    xmlNsPtr cur;

    if ((ns == NULL) || (ns->type != XML_NAMESPACE_DECL))
	return(NULL);
    if ((node == NULL) || (node->type == XML_NAMESPACE_DECL))
	return((xmlNodePtr) ns);

    /*
     * Allocate a new Namespace and fill the fields.
     */
    cur = (xmlNsPtr) xmlMalloc(sizeof(xmlNs));
    if (cur == NULL)
	return(NULL);
    memset(cur, 0, sizeof(xmlNs));
    cur->type = XML_NAMESPACE_DECL;
    if (ns->href != NULL) {
	cur->href = xmlStrdup(ns->href);
        if (cur->href == NULL) {
            xmlFree(cur);
            return(NULL);
        }
    }
    if (ns->prefix != NULL) {
	cur->prefix = xmlStrdup(ns->prefix);
        if (cur->prefix == NULL) {
            xmlFree((xmlChar *) cur->href);
            xmlFree(cur);
            return(NULL);
        }
    }
    cur->next = (xmlNsPtr) node;
    return((xmlNodePtr) cur);
}

/**
 * Namespace nodes in libxml don't match the XPath semantic. In a node set
 * the namespace nodes are duplicated and the next pointer is set to the
 * parent node in the XPath semantic. Check if such a node needs to be freed
 *
 * @param ns  the XPath namespace node found in a nodeset.
 */
void
xmlXPathNodeSetFreeNs(xmlNsPtr ns) {
    if ((ns == NULL) || (ns->type != XML_NAMESPACE_DECL))
	return;

    if ((ns->next != NULL) && (ns->next->type != XML_NAMESPACE_DECL)) {
	if (ns->href != NULL)
	    xmlFree((xmlChar *)ns->href);
	if (ns->prefix != NULL)
	    xmlFree((xmlChar *)ns->prefix);
	xmlFree(ns);
    }
}

/**
 * Create a new xmlNodeSetPtr of type double and of value `val`
 *
 * @param val  an initial xmlNodePtr, or NULL
 * @returns the newly created object.
 */
xmlNodeSetPtr
xmlXPathNodeSetCreate(xmlNodePtr val) {
    xmlNodeSetPtr ret;

    ret = (xmlNodeSetPtr) xmlMalloc(sizeof(xmlNodeSet));
    if (ret == NULL)
	return(NULL);
    memset(ret, 0 , sizeof(xmlNodeSet));
    if (val != NULL) {
        ret->nodeTab = (xmlNodePtr *) xmlMalloc(XML_NODESET_DEFAULT *
					     sizeof(xmlNodePtr));
	if (ret->nodeTab == NULL) {
	    xmlFree(ret);
	    return(NULL);
	}
	memset(ret->nodeTab, 0 ,
	       XML_NODESET_DEFAULT * sizeof(xmlNodePtr));
        ret->nodeMax = XML_NODESET_DEFAULT;
	if (val->type == XML_NAMESPACE_DECL) {
	    xmlNsPtr ns = (xmlNsPtr) val;
            xmlNodePtr nsNode = xmlXPathNodeSetDupNs((xmlNodePtr) ns->next, ns);

            if (nsNode == NULL) {
                xmlXPathFreeNodeSet(ret);
                return(NULL);
            }
	    ret->nodeTab[ret->nodeNr++] = nsNode;
	} else
	    ret->nodeTab[ret->nodeNr++] = val;
    }
    return(ret);
}

/**
 * checks whether `cur` contains `val`
 *
 * @param cur  the node-set
 * @param val  the node
 * @returns true (1) if `cur` contains `val`, false (0) otherwise
 */
int
xmlXPathNodeSetContains (xmlNodeSetPtr cur, xmlNodePtr val) {
    int i;

    if ((cur == NULL) || (val == NULL)) return(0);
    if (val->type == XML_NAMESPACE_DECL) {
	for (i = 0; i < cur->nodeNr; i++) {
	    if (cur->nodeTab[i]->type == XML_NAMESPACE_DECL) {
		xmlNsPtr ns1, ns2;

		ns1 = (xmlNsPtr) val;
		ns2 = (xmlNsPtr) cur->nodeTab[i];
		if (ns1 == ns2)
		    return(1);
		if ((ns1->next != NULL) && (ns2->next == ns1->next) &&
	            (xmlStrEqual(ns1->prefix, ns2->prefix)))
		    return(1);
	    }
	}
    } else {
	for (i = 0; i < cur->nodeNr; i++) {
	    if (cur->nodeTab[i] == val)
		return(1);
	}
    }
    return(0);
}

static int
xmlXPathNodeSetGrow(xmlNodeSetPtr cur) {
    xmlNodePtr *temp;
    int newSize;

    newSize = xmlGrowCapacity(cur->nodeMax, sizeof(temp[0]),
                              XML_NODESET_DEFAULT, XPATH_MAX_NODESET_LENGTH);
    if (newSize < 0)
        return(-1);
    temp = xmlRealloc(cur->nodeTab, newSize * sizeof(temp[0]));
    if (temp == NULL)
        return(-1);
    cur->nodeMax = newSize;
    cur->nodeTab = temp;

    return(0);
}

/**
 * add a new namespace node to an existing NodeSet
 *
 * @param cur  the initial node set
 * @param node  the hosting node
 * @param ns  a the namespace node
 * @returns 0 in case of success and -1 in case of error
 */
int
xmlXPathNodeSetAddNs(xmlNodeSetPtr cur, xmlNodePtr node, xmlNsPtr ns) {
    int i;
    xmlNodePtr nsNode;

    if ((cur == NULL) || (ns == NULL) || (node == NULL) ||
        (ns->type != XML_NAMESPACE_DECL) ||
	(node->type != XML_ELEMENT_NODE))
	return(-1);

    /* @@ with_ns to check whether namespace nodes should be looked at @@ */
    /*
     * prevent duplicates
     */
    for (i = 0;i < cur->nodeNr;i++) {
        if ((cur->nodeTab[i] != NULL) &&
	    (cur->nodeTab[i]->type == XML_NAMESPACE_DECL) &&
	    (((xmlNsPtr)cur->nodeTab[i])->next == (xmlNsPtr) node) &&
	    (xmlStrEqual(ns->prefix, ((xmlNsPtr)cur->nodeTab[i])->prefix)))
	    return(0);
    }

    /*
     * grow the nodeTab if needed
     */
    if (cur->nodeNr >= cur->nodeMax) {
        if (xmlXPathNodeSetGrow(cur) < 0)
            return(-1);
    }
    nsNode = xmlXPathNodeSetDupNs(node, ns);
    if(nsNode == NULL)
        return(-1);
    cur->nodeTab[cur->nodeNr++] = nsNode;
    return(0);
}

/**
 * add a new xmlNodePtr to an existing NodeSet
 *
 * @param cur  the initial node set
 * @param val  a new xmlNodePtr
 * @returns 0 in case of success, and -1 in case of error
 */
int
xmlXPathNodeSetAdd(xmlNodeSetPtr cur, xmlNodePtr val) {
    int i;

    if ((cur == NULL) || (val == NULL)) return(-1);

    /* @@ with_ns to check whether namespace nodes should be looked at @@ */
    /*
     * prevent duplicates
     */
    for (i = 0;i < cur->nodeNr;i++)
        if (cur->nodeTab[i] == val) return(0);

    /*
     * grow the nodeTab if needed
     */
    if (cur->nodeNr >= cur->nodeMax) {
        if (xmlXPathNodeSetGrow(cur) < 0)
            return(-1);
    }

    if (val->type == XML_NAMESPACE_DECL) {
	xmlNsPtr ns = (xmlNsPtr) val;
        xmlNodePtr nsNode = xmlXPathNodeSetDupNs((xmlNodePtr) ns->next, ns);

        if (nsNode == NULL)
            return(-1);
	cur->nodeTab[cur->nodeNr++] = nsNode;
    } else
	cur->nodeTab[cur->nodeNr++] = val;
    return(0);
}

/**
 * add a new xmlNodePtr to an existing NodeSet, optimized version
 * when we are sure the node is not already in the set.
 *
 * @param cur  the initial node set
 * @param val  a new xmlNodePtr
 * @returns 0 in case of success and -1 in case of failure
 */
int
xmlXPathNodeSetAddUnique(xmlNodeSetPtr cur, xmlNodePtr val) {
    if ((cur == NULL) || (val == NULL)) return(-1);

    /* @@ with_ns to check whether namespace nodes should be looked at @@ */
    /*
     * grow the nodeTab if needed
     */
    if (cur->nodeNr >= cur->nodeMax) {
        if (xmlXPathNodeSetGrow(cur) < 0)
            return(-1);
    }

    if (val->type == XML_NAMESPACE_DECL) {
	xmlNsPtr ns = (xmlNsPtr) val;
        xmlNodePtr nsNode = xmlXPathNodeSetDupNs((xmlNodePtr) ns->next, ns);

        if (nsNode == NULL)
            return(-1);
	cur->nodeTab[cur->nodeNr++] = nsNode;
    } else
	cur->nodeTab[cur->nodeNr++] = val;
    return(0);
}

/**
 * Merges two nodesets, all nodes from `val2` are added to `val1`
 * if `val1` is NULL, a new set is created and copied from `val2`
 *
 * Frees `val1` in case of error.
 * @param val1  the first NodeSet or NULL
 * @param val2  the second NodeSet
 * @returns `val1` once extended or NULL in case of error.
 */
xmlNodeSetPtr
xmlXPathNodeSetMerge(xmlNodeSetPtr val1, xmlNodeSetPtr val2) {
    int i, j, initNr, skip;
    xmlNodePtr n1, n2;

    if (val1 == NULL) {
	val1 = xmlXPathNodeSetCreate(NULL);
        if (val1 == NULL)
            return (NULL);
    }
    if (val2 == NULL)
        return(val1);

    /* @@ with_ns to check whether namespace nodes should be looked at @@ */
    initNr = val1->nodeNr;

    for (i = 0;i < val2->nodeNr;i++) {
	n2 = val2->nodeTab[i];
	/*
	 * check against duplicates
	 */
	skip = 0;
	for (j = 0; j < initNr; j++) {
	    n1 = val1->nodeTab[j];
	    if (n1 == n2) {
		skip = 1;
		break;
	    } else if ((n1->type == XML_NAMESPACE_DECL) &&
		       (n2->type == XML_NAMESPACE_DECL)) {
		if ((((xmlNsPtr) n1)->next == ((xmlNsPtr) n2)->next) &&
		    (xmlStrEqual(((xmlNsPtr) n1)->prefix,
			((xmlNsPtr) n2)->prefix)))
		{
		    skip = 1;
		    break;
		}
	    }
	}
	if (skip)
	    continue;

	/*
	 * grow the nodeTab if needed
	 */
        if (val1->nodeNr >= val1->nodeMax) {
            if (xmlXPathNodeSetGrow(val1) < 0)
                goto error;
        }
	if (n2->type == XML_NAMESPACE_DECL) {
	    xmlNsPtr ns = (xmlNsPtr) n2;
            xmlNodePtr nsNode = xmlXPathNodeSetDupNs((xmlNodePtr) ns->next, ns);

            if (nsNode == NULL)
                goto error;
	    val1->nodeTab[val1->nodeNr++] = nsNode;
	} else
	    val1->nodeTab[val1->nodeNr++] = n2;
    }

    return(val1);

error:
    xmlXPathFreeNodeSet(val1);
    return(NULL);
}


/**
 * Merges two nodesets, all nodes from `set2` are added to `set1`.
 * Checks for duplicate nodes. Clears set2.
 *
 * Frees `set1` in case of error.
 * @param set1  the first NodeSet or NULL
 * @param set2  the second NodeSet
 * @returns `set1` once extended or NULL in case of error.
 */
static xmlNodeSetPtr
xmlXPathNodeSetMergeAndClear(xmlNodeSetPtr set1, xmlNodeSetPtr set2)
{
    {
	int i, j, initNbSet1;
	xmlNodePtr n1, n2;

	initNbSet1 = set1->nodeNr;
	for (i = 0;i < set2->nodeNr;i++) {
	    n2 = set2->nodeTab[i];
	    /*
	    * Skip duplicates.
	    */
	    for (j = 0; j < initNbSet1; j++) {
		n1 = set1->nodeTab[j];
		if (n1 == n2) {
		    goto skip_node;
		} else if ((n1->type == XML_NAMESPACE_DECL) &&
		    (n2->type == XML_NAMESPACE_DECL))
		{
		    if ((((xmlNsPtr) n1)->next == ((xmlNsPtr) n2)->next) &&
			(xmlStrEqual(((xmlNsPtr) n1)->prefix,
			((xmlNsPtr) n2)->prefix)))
		    {
			/*
			* Free the namespace node.
			*/
			xmlXPathNodeSetFreeNs((xmlNsPtr) n2);
			goto skip_node;
		    }
		}
	    }
	    /*
	    * grow the nodeTab if needed
	    */
            if (set1->nodeNr >= set1->nodeMax) {
                if (xmlXPathNodeSetGrow(set1) < 0)
                    goto error;
            }
	    set1->nodeTab[set1->nodeNr++] = n2;
skip_node:
            set2->nodeTab[i] = NULL;
	}
    }
    set2->nodeNr = 0;
    return(set1);

error:
    xmlXPathFreeNodeSet(set1);
    xmlXPathNodeSetClear(set2, 1);
    return(NULL);
}

/**
 * Merges two nodesets, all nodes from `set2` are added to `set1`.
 * Doesn't check for duplicate nodes. Clears set2.
 *
 * Frees `set1` in case of error.
 * @param set1  the first NodeSet or NULL
 * @param set2  the second NodeSet
 * @returns `set1` once extended or NULL in case of error.
 */
static xmlNodeSetPtr
xmlXPathNodeSetMergeAndClearNoDupls(xmlNodeSetPtr set1, xmlNodeSetPtr set2)
{
    {
	int i;
	xmlNodePtr n2;

	for (i = 0;i < set2->nodeNr;i++) {
	    n2 = set2->nodeTab[i];
            if (set1->nodeNr >= set1->nodeMax) {
                if (xmlXPathNodeSetGrow(set1) < 0)
                    goto error;
            }
	    set1->nodeTab[set1->nodeNr++] = n2;
            set2->nodeTab[i] = NULL;
	}
    }
    set2->nodeNr = 0;
    return(set1);

error:
    xmlXPathFreeNodeSet(set1);
    xmlXPathNodeSetClear(set2, 1);
    return(NULL);
}

/**
 * Removes an xmlNodePtr from an existing NodeSet
 *
 * @param cur  the initial node set
 * @param val  an xmlNodePtr
 */
void
xmlXPathNodeSetDel(xmlNodeSetPtr cur, xmlNodePtr val) {
    int i;

    if (cur == NULL) return;
    if (val == NULL) return;

    /*
     * find node in nodeTab
     */
    for (i = 0;i < cur->nodeNr;i++)
        if (cur->nodeTab[i] == val) break;

    if (i >= cur->nodeNr) {	/* not found */
        return;
    }
    if ((cur->nodeTab[i] != NULL) &&
	(cur->nodeTab[i]->type == XML_NAMESPACE_DECL))
	xmlXPathNodeSetFreeNs((xmlNsPtr) cur->nodeTab[i]);
    cur->nodeNr--;
    for (;i < cur->nodeNr;i++)
        cur->nodeTab[i] = cur->nodeTab[i + 1];
    cur->nodeTab[cur->nodeNr] = NULL;
}

/**
 * Removes an entry from an existing NodeSet list.
 *
 * @param cur  the initial node set
 * @param val  the index to remove
 */
void
xmlXPathNodeSetRemove(xmlNodeSetPtr cur, int val) {
    if (cur == NULL) return;
    if (val >= cur->nodeNr) return;
    if ((cur->nodeTab[val] != NULL) &&
	(cur->nodeTab[val]->type == XML_NAMESPACE_DECL))
	xmlXPathNodeSetFreeNs((xmlNsPtr) cur->nodeTab[val]);
    cur->nodeNr--;
    for (;val < cur->nodeNr;val++)
        cur->nodeTab[val] = cur->nodeTab[val + 1];
    cur->nodeTab[cur->nodeNr] = NULL;
}

/**
 * Free the NodeSet compound (not the actual nodes !).
 *
 * @param obj  the xmlNodeSetPtr to free
 */
void
xmlXPathFreeNodeSet(xmlNodeSetPtr obj) {
    if (obj == NULL) return;
    if (obj->nodeTab != NULL) {
	int i;

	/* @@ with_ns to check whether namespace nodes should be looked at @@ */
	for (i = 0;i < obj->nodeNr;i++)
	    if ((obj->nodeTab[i] != NULL) &&
		(obj->nodeTab[i]->type == XML_NAMESPACE_DECL))
		xmlXPathNodeSetFreeNs((xmlNsPtr) obj->nodeTab[i]);
	xmlFree(obj->nodeTab);
    }
    xmlFree(obj);
}

/**
 * Clears the list from temporary XPath objects (e.g. namespace nodes
 * are feed) starting with the entry at `pos`, but does *not* free the list
 * itself. Sets the length of the list to `pos`.
 *
 * @param set  the node set to be cleared
 * @param pos  the start position to clear from
 * @param hasNsNodes  the node set might contain namespace nodes
 */
static void
xmlXPathNodeSetClearFromPos(xmlNodeSetPtr set, int pos, int hasNsNodes)
{
    if ((set == NULL) || (pos >= set->nodeNr))
	return;
    else if ((hasNsNodes)) {
	int i;
	xmlNodePtr node;

	for (i = pos; i < set->nodeNr; i++) {
	    node = set->nodeTab[i];
	    if ((node != NULL) &&
		(node->type == XML_NAMESPACE_DECL))
		xmlXPathNodeSetFreeNs((xmlNsPtr) node);
	}
    }
    set->nodeNr = pos;
}

/**
 * Clears the list from all temporary XPath objects (e.g. namespace nodes
 * are feed), but does *not* free the list itself. Sets the length of the
 * list to 0.
 *
 * @param set  the node set to clear
 * @param hasNsNodes  the node set might contain namespace nodes
 */
static void
xmlXPathNodeSetClear(xmlNodeSetPtr set, int hasNsNodes)
{
    xmlXPathNodeSetClearFromPos(set, 0, hasNsNodes);
}

/**
 * Move the last node to the first position and clear temporary XPath objects
 * (e.g. namespace nodes) from all other nodes. Sets the length of the list
 * to 1.
 *
 * @param set  the node set to be cleared
 */
static void
xmlXPathNodeSetKeepLast(xmlNodeSetPtr set)
{
    int i;
    xmlNodePtr node;

    if ((set == NULL) || (set->nodeNr <= 1))
	return;
    for (i = 0; i < set->nodeNr - 1; i++) {
        node = set->nodeTab[i];
        if ((node != NULL) &&
            (node->type == XML_NAMESPACE_DECL))
            xmlXPathNodeSetFreeNs((xmlNsPtr) node);
    }
    set->nodeTab[0] = set->nodeTab[set->nodeNr-1];
    set->nodeNr = 1;
}

/**
 * Create a new xmlXPathObjectPtr of type NodeSet and initialize
 * it with the single Node `val`
 *
 * @param val  the NodePtr value
 * @returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPathNewNodeSet(xmlNodePtr val) {
    xmlXPathObjectPtr ret;

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL)
	return(NULL);
    memset(ret, 0 , sizeof(xmlXPathObject));
    ret->type = XPATH_NODESET;
    ret->boolval = 0;
    ret->nodesetval = xmlXPathNodeSetCreate(val);
    if (ret->nodesetval == NULL) {
        xmlFree(ret);
        return(NULL);
    }
    /* @@ with_ns to check whether namespace nodes should be looked at @@ */
    return(ret);
}

/**
 * Create a new xmlXPathObjectPtr of type Value Tree (XSLT) and initialize
 * it with the tree root `val`
 *
 * @param val  the NodePtr value
 * @returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPathNewValueTree(xmlNodePtr val) {
    xmlXPathObjectPtr ret;

    ret = xmlXPathNewNodeSet(val);
    if (ret == NULL)
	return(NULL);
    ret->type = XPATH_XSLT_TREE;

    return(ret);
}

/**
 * Create a new xmlXPathObjectPtr of type NodeSet and initialize
 * it with the Nodeset `val`
 *
 * @param val  an existing NodeSet
 * @returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPathNewNodeSetList(xmlNodeSetPtr val)
{
    xmlXPathObjectPtr ret;

    if (val == NULL)
        ret = NULL;
    else if (val->nodeTab == NULL)
        ret = xmlXPathNewNodeSet(NULL);
    else {
        ret = xmlXPathNewNodeSet(val->nodeTab[0]);
        if (ret) {
            ret->nodesetval = xmlXPathNodeSetMerge(NULL, val);
            if (ret->nodesetval == NULL) {
                xmlFree(ret);
                return(NULL);
            }
        }
    }

    return (ret);
}

/**
 * Wrap the Nodeset `val` in a new xmlXPathObjectPtr
 *
 * In case of error the node set is destroyed and NULL is returned.
 * @param val  the NodePtr value
 * @returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPathWrapNodeSet(xmlNodeSetPtr val) {
    xmlXPathObjectPtr ret;

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL) {
        xmlXPathFreeNodeSet(val);
	return(NULL);
    }
    memset(ret, 0 , sizeof(xmlXPathObject));
    ret->type = XPATH_NODESET;
    ret->nodesetval = val;
    return(ret);
}

/**
 * Free up the xmlXPathObjectPtr `obj` but don't deallocate the objects in
 * the list contrary to xmlXPathFreeObject().
 *
 * @param obj  an existing NodeSetList object
 */
void
xmlXPathFreeNodeSetList(xmlXPathObjectPtr obj) {
    if (obj == NULL) return;
    xmlFree(obj);
}

/**
 * Implements the EXSLT - Sets difference() function:
 *    node-set set:difference (node-set, node-set)
 *
 * @param nodes1  a node-set
 * @param nodes2  a node-set
 * @returns the difference between the two node sets, or nodes1 if
 *         nodes2 is empty
 */
xmlNodeSetPtr
xmlXPathDifference (xmlNodeSetPtr nodes1, xmlNodeSetPtr nodes2) {
    xmlNodeSetPtr ret;
    int i, l1;
    xmlNodePtr cur;

    if (xmlXPathNodeSetIsEmpty(nodes2))
	return(nodes1);

    ret = xmlXPathNodeSetCreate(NULL);
    if (ret == NULL)
        return(NULL);
    if (xmlXPathNodeSetIsEmpty(nodes1))
	return(ret);

    l1 = xmlXPathNodeSetGetLength(nodes1);

    for (i = 0; i < l1; i++) {
	cur = xmlXPathNodeSetItem(nodes1, i);
	if (!xmlXPathNodeSetContains(nodes2, cur)) {
	    if (xmlXPathNodeSetAddUnique(ret, cur) < 0) {
                xmlXPathFreeNodeSet(ret);
	        return(NULL);
            }
	}
    }
    return(ret);
}

/**
 * Implements the EXSLT - Sets intersection() function:
 *    node-set set:intersection (node-set, node-set)
 *
 * @param nodes1  a node-set
 * @param nodes2  a node-set
 * @returns a node set comprising the nodes that are within both the
 *         node sets passed as arguments
 */
xmlNodeSetPtr
xmlXPathIntersection (xmlNodeSetPtr nodes1, xmlNodeSetPtr nodes2) {
    xmlNodeSetPtr ret = xmlXPathNodeSetCreate(NULL);
    int i, l1;
    xmlNodePtr cur;

    if (ret == NULL)
        return(ret);
    if (xmlXPathNodeSetIsEmpty(nodes1))
	return(ret);
    if (xmlXPathNodeSetIsEmpty(nodes2))
	return(ret);

    l1 = xmlXPathNodeSetGetLength(nodes1);

    for (i = 0; i < l1; i++) {
	cur = xmlXPathNodeSetItem(nodes1, i);
	if (xmlXPathNodeSetContains(nodes2, cur)) {
	    if (xmlXPathNodeSetAddUnique(ret, cur) < 0) {
                xmlXPathFreeNodeSet(ret);
	        return(NULL);
            }
	}
    }
    return(ret);
}

/**
 * Implements the EXSLT - Sets distinct() function:
 *    node-set set:distinct (node-set)
 *
 * @param nodes  a node-set, sorted by document order
 * @returns a subset of the nodes contained in `nodes`, or `nodes` if
 *         it is empty
 */
xmlNodeSetPtr
xmlXPathDistinctSorted (xmlNodeSetPtr nodes) {
    xmlNodeSetPtr ret;
    xmlHashTablePtr hash;
    int i, l;
    xmlChar * strval;
    xmlNodePtr cur;

    if (xmlXPathNodeSetIsEmpty(nodes))
	return(nodes);

    ret = xmlXPathNodeSetCreate(NULL);
    if (ret == NULL)
        return(ret);
    l = xmlXPathNodeSetGetLength(nodes);
    hash = xmlHashCreate (l);
    for (i = 0; i < l; i++) {
	cur = xmlXPathNodeSetItem(nodes, i);
	strval = xmlXPathCastNodeToString(cur);
	if (xmlHashLookup(hash, strval) == NULL) {
	    if (xmlHashAddEntry(hash, strval, strval) < 0) {
                xmlFree(strval);
                goto error;
            }
	    if (xmlXPathNodeSetAddUnique(ret, cur) < 0)
	        goto error;
	} else {
	    xmlFree(strval);
	}
    }
    xmlHashFree(hash, xmlHashDefaultDeallocator);
    return(ret);

error:
    xmlHashFree(hash, xmlHashDefaultDeallocator);
    xmlXPathFreeNodeSet(ret);
    return(NULL);
}

/**
 * Implements the EXSLT - Sets distinct() function:
 *    node-set set:distinct (node-set)
 * `nodes` is sorted by document order, then exslSetsDistinctSorted
 * is called with the sorted node-set
 *
 * @param nodes  a node-set
 * @returns a subset of the nodes contained in `nodes`, or `nodes` if
 *         it is empty
 */
xmlNodeSetPtr
xmlXPathDistinct (xmlNodeSetPtr nodes) {
    if (xmlXPathNodeSetIsEmpty(nodes))
	return(nodes);

    xmlXPathNodeSetSort(nodes);
    return(xmlXPathDistinctSorted(nodes));
}

/**
 * Implements the EXSLT - Sets has-same-nodes function:
 *    boolean set:has-same-node(node-set, node-set)
 *
 * @param nodes1  a node-set
 * @param nodes2  a node-set
 * @returns true (1) if `nodes1` shares any node with `nodes2`, false (0)
 *         otherwise
 */
int
xmlXPathHasSameNodes (xmlNodeSetPtr nodes1, xmlNodeSetPtr nodes2) {
    int i, l;
    xmlNodePtr cur;

    if (xmlXPathNodeSetIsEmpty(nodes1) ||
	xmlXPathNodeSetIsEmpty(nodes2))
	return(0);

    l = xmlXPathNodeSetGetLength(nodes1);
    for (i = 0; i < l; i++) {
	cur = xmlXPathNodeSetItem(nodes1, i);
	if (xmlXPathNodeSetContains(nodes2, cur))
	    return(1);
    }
    return(0);
}

/**
 * Implements the EXSLT - Sets leading() function:
 *    node-set set:leading (node-set, node-set)
 *
 * @param nodes  a node-set, sorted by document order
 * @param node  a node
 * @returns the nodes in `nodes` that precede `node` in document order,
 *         `nodes` if `node` is NULL or an empty node-set if `nodes`
 *         doesn't contain `node`
 */
xmlNodeSetPtr
xmlXPathNodeLeadingSorted (xmlNodeSetPtr nodes, xmlNodePtr node) {
    int i, l;
    xmlNodePtr cur;
    xmlNodeSetPtr ret;

    if (node == NULL)
	return(nodes);

    ret = xmlXPathNodeSetCreate(NULL);
    if (ret == NULL)
        return(ret);
    if (xmlXPathNodeSetIsEmpty(nodes) ||
	(!xmlXPathNodeSetContains(nodes, node)))
	return(ret);

    l = xmlXPathNodeSetGetLength(nodes);
    for (i = 0; i < l; i++) {
	cur = xmlXPathNodeSetItem(nodes, i);
	if (cur == node)
	    break;
	if (xmlXPathNodeSetAddUnique(ret, cur) < 0) {
            xmlXPathFreeNodeSet(ret);
	    return(NULL);
        }
    }
    return(ret);
}

/**
 * Implements the EXSLT - Sets leading() function:
 *    node-set set:leading (node-set, node-set)
 * `nodes` is sorted by document order, then exslSetsNodeLeadingSorted
 * is called.
 *
 * @param nodes  a node-set
 * @param node  a node
 * @returns the nodes in `nodes` that precede `node` in document order,
 *         `nodes` if `node` is NULL or an empty node-set if `nodes`
 *         doesn't contain `node`
 */
xmlNodeSetPtr
xmlXPathNodeLeading (xmlNodeSetPtr nodes, xmlNodePtr node) {
    xmlXPathNodeSetSort(nodes);
    return(xmlXPathNodeLeadingSorted(nodes, node));
}

/**
 * Implements the EXSLT - Sets leading() function:
 *    node-set set:leading (node-set, node-set)
 *
 * @param nodes1  a node-set, sorted by document order
 * @param nodes2  a node-set, sorted by document order
 * @returns the nodes in `nodes1` that precede the first node in `nodes2`
 *         in document order, `nodes1` if `nodes2` is NULL or empty or
 *         an empty node-set if `nodes1` doesn't contain `nodes2`
 */
xmlNodeSetPtr
xmlXPathLeadingSorted (xmlNodeSetPtr nodes1, xmlNodeSetPtr nodes2) {
    if (xmlXPathNodeSetIsEmpty(nodes2))
	return(nodes1);
    return(xmlXPathNodeLeadingSorted(nodes1,
				     xmlXPathNodeSetItem(nodes2, 1)));
}

/**
 * Implements the EXSLT - Sets leading() function:
 *    node-set set:leading (node-set, node-set)
 * `nodes1` and `nodes2` are sorted by document order, then
 * exslSetsLeadingSorted is called.
 *
 * @param nodes1  a node-set
 * @param nodes2  a node-set
 * @returns the nodes in `nodes1` that precede the first node in `nodes2`
 *         in document order, `nodes1` if `nodes2` is NULL or empty or
 *         an empty node-set if `nodes1` doesn't contain `nodes2`
 */
xmlNodeSetPtr
xmlXPathLeading (xmlNodeSetPtr nodes1, xmlNodeSetPtr nodes2) {
    if (xmlXPathNodeSetIsEmpty(nodes2))
	return(nodes1);
    if (xmlXPathNodeSetIsEmpty(nodes1))
	return(xmlXPathNodeSetCreate(NULL));
    xmlXPathNodeSetSort(nodes1);
    xmlXPathNodeSetSort(nodes2);
    return(xmlXPathNodeLeadingSorted(nodes1,
				     xmlXPathNodeSetItem(nodes2, 1)));
}

/**
 * Implements the EXSLT - Sets trailing() function:
 *    node-set set:trailing (node-set, node-set)
 *
 * @param nodes  a node-set, sorted by document order
 * @param node  a node
 * @returns the nodes in `nodes` that follow `node` in document order,
 *         `nodes` if `node` is NULL or an empty node-set if `nodes`
 *         doesn't contain `node`
 */
xmlNodeSetPtr
xmlXPathNodeTrailingSorted (xmlNodeSetPtr nodes, xmlNodePtr node) {
    int i, l;
    xmlNodePtr cur;
    xmlNodeSetPtr ret;

    if (node == NULL)
	return(nodes);

    ret = xmlXPathNodeSetCreate(NULL);
    if (ret == NULL)
        return(ret);
    if (xmlXPathNodeSetIsEmpty(nodes) ||
	(!xmlXPathNodeSetContains(nodes, node)))
	return(ret);

    l = xmlXPathNodeSetGetLength(nodes);
    for (i = l - 1; i >= 0; i--) {
	cur = xmlXPathNodeSetItem(nodes, i);
	if (cur == node)
	    break;
	if (xmlXPathNodeSetAddUnique(ret, cur) < 0) {
            xmlXPathFreeNodeSet(ret);
	    return(NULL);
        }
    }
    xmlXPathNodeSetSort(ret);	/* bug 413451 */
    return(ret);
}

/**
 * Implements the EXSLT - Sets trailing() function:
 *    node-set set:trailing (node-set, node-set)
 * `nodes` is sorted by document order, then xmlXPathNodeTrailingSorted()
 * is called.
 *
 * @param nodes  a node-set
 * @param node  a node
 * @returns the nodes in `nodes` that follow `node` in document order,
 *         `nodes` if `node` is NULL or an empty node-set if `nodes`
 *         doesn't contain `node`
 */
xmlNodeSetPtr
xmlXPathNodeTrailing (xmlNodeSetPtr nodes, xmlNodePtr node) {
    xmlXPathNodeSetSort(nodes);
    return(xmlXPathNodeTrailingSorted(nodes, node));
}

/**
 * Implements the EXSLT - Sets trailing() function:
 *    node-set set:trailing (node-set, node-set)
 *
 * @param nodes1  a node-set, sorted by document order
 * @param nodes2  a node-set, sorted by document order
 * @returns the nodes in `nodes1` that follow the first node in `nodes2`
 *         in document order, `nodes1` if `nodes2` is NULL or empty or
 *         an empty node-set if `nodes1` doesn't contain `nodes2`
 */
xmlNodeSetPtr
xmlXPathTrailingSorted (xmlNodeSetPtr nodes1, xmlNodeSetPtr nodes2) {
    if (xmlXPathNodeSetIsEmpty(nodes2))
	return(nodes1);
    return(xmlXPathNodeTrailingSorted(nodes1,
				      xmlXPathNodeSetItem(nodes2, 0)));
}

/**
 * Implements the EXSLT - Sets trailing() function:
 *    node-set set:trailing (node-set, node-set)
 * `nodes1` and `nodes2` are sorted by document order, then
 * xmlXPathTrailingSorted() is called.
 *
 * @param nodes1  a node-set
 * @param nodes2  a node-set
 * @returns the nodes in `nodes1` that follow the first node in `nodes2`
 *         in document order, `nodes1` if `nodes2` is NULL or empty or
 *         an empty node-set if `nodes1` doesn't contain `nodes2`
 */
xmlNodeSetPtr
xmlXPathTrailing (xmlNodeSetPtr nodes1, xmlNodeSetPtr nodes2) {
    if (xmlXPathNodeSetIsEmpty(nodes2))
	return(nodes1);
    if (xmlXPathNodeSetIsEmpty(nodes1))
	return(xmlXPathNodeSetCreate(NULL));
    xmlXPathNodeSetSort(nodes1);
    xmlXPathNodeSetSort(nodes2);
    return(xmlXPathNodeTrailingSorted(nodes1,
				      xmlXPathNodeSetItem(nodes2, 0)));
}

/************************************************************************
 *									*
 *		Routines to handle extra functions			*
 *									*
 ************************************************************************/

/**
 * Register a new function. If `f` is NULL it unregisters the function
 *
 * @param ctxt  the XPath context
 * @param name  the function name
 * @param f  the function implementation or NULL
 * @returns 0 in case of success, -1 in case of error
 */
int
xmlXPathRegisterFunc(xmlXPathContextPtr ctxt, const xmlChar *name,
		     xmlXPathFunction f) {
    return(xmlXPathRegisterFuncNS(ctxt, name, NULL, f));
}

/**
 * Register a new function. If `f` is NULL it unregisters the function
 *
 * @param ctxt  the XPath context
 * @param name  the function name
 * @param ns_uri  the function namespace URI
 * @param f  the function implementation or NULL
 * @returns 0 in case of success, -1 in case of error
 */
int
xmlXPathRegisterFuncNS(xmlXPathContextPtr ctxt, const xmlChar *name,
		       const xmlChar *ns_uri, xmlXPathFunction f) {
    int ret;
    void *payload;

    if (ctxt == NULL)
	return(-1);
    if (name == NULL)
	return(-1);

    if (ctxt->funcHash == NULL)
	ctxt->funcHash = xmlHashCreate(0);
    if (ctxt->funcHash == NULL) {
        xmlXPathErrMemory(ctxt);
	return(-1);
    }
    if (f == NULL)
        return(xmlHashRemoveEntry2(ctxt->funcHash, name, ns_uri, NULL));
    memcpy(&payload, &f, sizeof(f));
    ret = xmlHashAddEntry2(ctxt->funcHash, name, ns_uri, payload);
    if (ret < 0) {
        xmlXPathErrMemory(ctxt);
        return(-1);
    }

    return(0);
}

/**
 * Registers an external mechanism to do function lookup.
 *
 * @param ctxt  the XPath context
 * @param f  the lookup function
 * @param funcCtxt  the lookup data
 */
void
xmlXPathRegisterFuncLookup (xmlXPathContextPtr ctxt,
			    xmlXPathFuncLookupFunc f,
			    void *funcCtxt) {
    if (ctxt == NULL)
	return;
    ctxt->funcLookupFunc = f;
    ctxt->funcLookupData = funcCtxt;
}

/**
 * Search in the Function array of the context for the given
 * function.
 *
 * @param ctxt  the XPath context
 * @param name  the function name
 * @returns the xmlXPathFunction or NULL if not found
 */
xmlXPathFunction
xmlXPathFunctionLookup(xmlXPathContextPtr ctxt, const xmlChar *name) {
    return(xmlXPathFunctionLookupNS(ctxt, name, NULL));
}

/**
 * Search in the Function array of the context for the given
 * function.
 *
 * @param ctxt  the XPath context
 * @param name  the function name
 * @param ns_uri  the function namespace URI
 * @returns the xmlXPathFunction or NULL if not found
 */
xmlXPathFunction
xmlXPathFunctionLookupNS(xmlXPathContextPtr ctxt, const xmlChar *name,
			 const xmlChar *ns_uri) {
    xmlXPathFunction ret;
    void *payload;

    if (ctxt == NULL)
	return(NULL);
    if (name == NULL)
	return(NULL);

    if (ns_uri == NULL) {
        int bucketIndex = xmlXPathSFComputeHash(name) % SF_HASH_SIZE;

        while (xmlXPathSFHash[bucketIndex] != UCHAR_MAX) {
            int funcIndex = xmlXPathSFHash[bucketIndex];

            if (strcmp(xmlXPathStandardFunctions[funcIndex].name,
                       (char *) name) == 0)
                return(xmlXPathStandardFunctions[funcIndex].func);

            bucketIndex += 1;
            if (bucketIndex >= SF_HASH_SIZE)
                bucketIndex = 0;
        }
    }

    if (ctxt->funcLookupFunc != NULL) {
	xmlXPathFuncLookupFunc f;

	f = ctxt->funcLookupFunc;
	ret = f(ctxt->funcLookupData, name, ns_uri);
	if (ret != NULL)
	    return(ret);
    }

    if (ctxt->funcHash == NULL)
	return(NULL);

    payload = xmlHashLookup2(ctxt->funcHash, name, ns_uri);
    memcpy(&ret, &payload, sizeof(payload));

    return(ret);
}

/**
 * Cleanup the XPath context data associated to registered functions
 *
 * @param ctxt  the XPath context
 */
void
xmlXPathRegisteredFuncsCleanup(xmlXPathContextPtr ctxt) {
    if (ctxt == NULL)
	return;

    xmlHashFree(ctxt->funcHash, NULL);
    ctxt->funcHash = NULL;
}

/************************************************************************
 *									*
 *			Routines to handle Variables			*
 *									*
 ************************************************************************/

/**
 * Register a new variable value. If `value` is NULL it unregisters
 * the variable
 *
 * @param ctxt  the XPath context
 * @param name  the variable name
 * @param value  the variable value or NULL
 * @returns 0 in case of success, -1 in case of error
 */
int
xmlXPathRegisterVariable(xmlXPathContextPtr ctxt, const xmlChar *name,
			 xmlXPathObjectPtr value) {
    return(xmlXPathRegisterVariableNS(ctxt, name, NULL, value));
}

/**
 * Register a new variable value. If `value` is NULL it unregisters
 * the variable
 *
 * @param ctxt  the XPath context
 * @param name  the variable name
 * @param ns_uri  the variable namespace URI
 * @param value  the variable value or NULL
 * @returns 0 in case of success, -1 in case of error
 */
int
xmlXPathRegisterVariableNS(xmlXPathContextPtr ctxt, const xmlChar *name,
			   const xmlChar *ns_uri,
			   xmlXPathObjectPtr value) {
    if (ctxt == NULL)
	return(-1);
    if (name == NULL)
	return(-1);

    if (ctxt->varHash == NULL)
	ctxt->varHash = xmlHashCreate(0);
    if (ctxt->varHash == NULL)
	return(-1);
    if (value == NULL)
        return(xmlHashRemoveEntry2(ctxt->varHash, name, ns_uri,
	                           xmlXPathFreeObjectEntry));
    return(xmlHashUpdateEntry2(ctxt->varHash, name, ns_uri,
			       (void *) value, xmlXPathFreeObjectEntry));
}

/**
 * register an external mechanism to do variable lookup
 *
 * @param ctxt  the XPath context
 * @param f  the lookup function
 * @param data  the lookup data
 */
void
xmlXPathRegisterVariableLookup(xmlXPathContextPtr ctxt,
	 xmlXPathVariableLookupFunc f, void *data) {
    if (ctxt == NULL)
	return;
    ctxt->varLookupFunc = f;
    ctxt->varLookupData = data;
}

/**
 * Search in the Variable array of the context for the given
 * variable value.
 *
 * @param ctxt  the XPath context
 * @param name  the variable name
 * @returns a copy of the value or NULL if not found
 */
xmlXPathObjectPtr
xmlXPathVariableLookup(xmlXPathContextPtr ctxt, const xmlChar *name) {
    if (ctxt == NULL)
	return(NULL);

    if (ctxt->varLookupFunc != NULL) {
	xmlXPathObjectPtr ret;

	ret = ((xmlXPathVariableLookupFunc)ctxt->varLookupFunc)
	        (ctxt->varLookupData, name, NULL);
	return(ret);
    }
    return(xmlXPathVariableLookupNS(ctxt, name, NULL));
}

/**
 * Search in the Variable array of the context for the given
 * variable value.
 *
 * @param ctxt  the XPath context
 * @param name  the variable name
 * @param ns_uri  the variable namespace URI
 * @returns the a copy of the value or NULL if not found
 */
xmlXPathObjectPtr
xmlXPathVariableLookupNS(xmlXPathContextPtr ctxt, const xmlChar *name,
			 const xmlChar *ns_uri) {
    if (ctxt == NULL)
	return(NULL);

    if (ctxt->varLookupFunc != NULL) {
	xmlXPathObjectPtr ret;

	ret = ((xmlXPathVariableLookupFunc)ctxt->varLookupFunc)
	        (ctxt->varLookupData, name, ns_uri);
	if (ret != NULL) return(ret);
    }

    if (ctxt->varHash == NULL)
	return(NULL);
    if (name == NULL)
	return(NULL);

    return(xmlXPathObjectCopy(xmlHashLookup2(ctxt->varHash, name, ns_uri)));
}

/**
 * Cleanup the XPath context data associated to registered variables
 *
 * @param ctxt  the XPath context
 */
void
xmlXPathRegisteredVariablesCleanup(xmlXPathContextPtr ctxt) {
    if (ctxt == NULL)
	return;

    xmlHashFree(ctxt->varHash, xmlXPathFreeObjectEntry);
    ctxt->varHash = NULL;
}

/**
 * Register a new namespace. If `ns_uri` is NULL it unregisters
 * the namespace
 *
 * @param ctxt  the XPath context
 * @param prefix  the namespace prefix cannot be NULL or empty string
 * @param ns_uri  the namespace name
 * @returns 0 in case of success, -1 in case of error
 */
int
xmlXPathRegisterNs(xmlXPathContextPtr ctxt, const xmlChar *prefix,
			   const xmlChar *ns_uri) {
    xmlChar *copy;

    if (ctxt == NULL)
	return(-1);
    if (prefix == NULL)
	return(-1);
    if (prefix[0] == 0)
	return(-1);

    if (ctxt->nsHash == NULL)
	ctxt->nsHash = xmlHashCreate(10);
    if (ctxt->nsHash == NULL) {
        xmlXPathErrMemory(ctxt);
	return(-1);
    }
    if (ns_uri == NULL)
        return(xmlHashRemoveEntry(ctxt->nsHash, prefix,
	                          xmlHashDefaultDeallocator));

    copy = xmlStrdup(ns_uri);
    if (copy == NULL) {
        xmlXPathErrMemory(ctxt);
        return(-1);
    }
    if (xmlHashUpdateEntry(ctxt->nsHash, prefix, copy,
                           xmlHashDefaultDeallocator) < 0) {
        xmlXPathErrMemory(ctxt);
        xmlFree(copy);
        return(-1);
    }

    return(0);
}

/**
 * Search in the namespace declaration array of the context for the given
 * namespace name associated to the given prefix
 *
 * @param ctxt  the XPath context
 * @param prefix  the namespace prefix value
 * @returns the value or NULL if not found
 */
const xmlChar *
xmlXPathNsLookup(xmlXPathContextPtr ctxt, const xmlChar *prefix) {
    if (ctxt == NULL)
	return(NULL);
    if (prefix == NULL)
	return(NULL);

    if (xmlStrEqual(prefix, (const xmlChar *) "xml"))
	return(XML_XML_NAMESPACE);

    if (ctxt->namespaces != NULL) {
	int i;

	for (i = 0;i < ctxt->nsNr;i++) {
	    if ((ctxt->namespaces[i] != NULL) &&
		(xmlStrEqual(ctxt->namespaces[i]->prefix, prefix)))
		return(ctxt->namespaces[i]->href);
	}
    }

    return((const xmlChar *) xmlHashLookup(ctxt->nsHash, prefix));
}

/**
 * Cleanup the XPath context data associated to registered variables
 *
 * @param ctxt  the XPath context
 */
void
xmlXPathRegisteredNsCleanup(xmlXPathContextPtr ctxt) {
    if (ctxt == NULL)
	return;

    xmlHashFree(ctxt->nsHash, xmlHashDefaultDeallocator);
    ctxt->nsHash = NULL;
}

/************************************************************************
 *									*
 *			Routines to handle Values			*
 *									*
 ************************************************************************/

/* Allocations are terrible, one needs to optimize all this !!! */

/**
 * Create a new xmlXPathObjectPtr of type double and of value `val`
 *
 * @param val  the double value
 * @returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPathNewFloat(double val) {
    xmlXPathObjectPtr ret;

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL)
	return(NULL);
    memset(ret, 0 , sizeof(xmlXPathObject));
    ret->type = XPATH_NUMBER;
    ret->floatval = val;
    return(ret);
}

/**
 * Create a new xmlXPathObjectPtr of type boolean and of value `val`
 *
 * @param val  the boolean value
 * @returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPathNewBoolean(int val) {
    xmlXPathObjectPtr ret;

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL)
	return(NULL);
    memset(ret, 0 , sizeof(xmlXPathObject));
    ret->type = XPATH_BOOLEAN;
    ret->boolval = (val != 0);
    return(ret);
}

/**
 * Create a new xmlXPathObjectPtr of type string and of value `val`
 *
 * @param val  the xmlChar * value
 * @returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPathNewString(const xmlChar *val) {
    xmlXPathObjectPtr ret;

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL)
	return(NULL);
    memset(ret, 0 , sizeof(xmlXPathObject));
    ret->type = XPATH_STRING;
    if (val == NULL)
        val = BAD_CAST "";
    ret->stringval = xmlStrdup(val);
    if (ret->stringval == NULL) {
        xmlFree(ret);
        return(NULL);
    }
    return(ret);
}

/**
 * Wraps the `val` string into an XPath object.
 *
 * Frees `val` in case of error.
 * @param val  the xmlChar * value
 * @returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPathWrapString (xmlChar *val) {
    xmlXPathObjectPtr ret;

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL) {
        xmlFree(val);
	return(NULL);
    }
    memset(ret, 0 , sizeof(xmlXPathObject));
    ret->type = XPATH_STRING;
    ret->stringval = val;
    return(ret);
}

/**
 * Create a new xmlXPathObjectPtr of type string and of value `val`
 *
 * @param val  the char * value
 * @returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPathNewCString(const char *val) {
    return(xmlXPathNewString(BAD_CAST val));
}

/**
 * Wraps a string into an XPath object.
 *
 * @param val  the char * value
 * @returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPathWrapCString (char * val) {
    return(xmlXPathWrapString((xmlChar *)(val)));
}

/**
 * Wraps the `val` data into an XPath object.
 *
 * @param val  the user data
 * @returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPathWrapExternal (void *val) {
    xmlXPathObjectPtr ret;

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL)
	return(NULL);
    memset(ret, 0 , sizeof(xmlXPathObject));
    ret->type = XPATH_USERS;
    ret->user = val;
    return(ret);
}

/**
 * allocate a new copy of a given object
 *
 * @param val  the original object
 * @returns the newly created object.
 */
xmlXPathObjectPtr
xmlXPathObjectCopy(xmlXPathObjectPtr val) {
    xmlXPathObjectPtr ret;

    if (val == NULL)
	return(NULL);

    ret = (xmlXPathObjectPtr) xmlMalloc(sizeof(xmlXPathObject));
    if (ret == NULL)
	return(NULL);
    memcpy(ret, val , sizeof(xmlXPathObject));
    switch (val->type) {
	case XPATH_BOOLEAN:
	case XPATH_NUMBER:
	    break;
	case XPATH_STRING:
	    ret->stringval = xmlStrdup(val->stringval);
            if (ret->stringval == NULL) {
                xmlFree(ret);
                return(NULL);
            }
	    break;
	case XPATH_XSLT_TREE:
	case XPATH_NODESET:
	    ret->nodesetval = xmlXPathNodeSetMerge(NULL, val->nodesetval);
            if (ret->nodesetval == NULL) {
                xmlFree(ret);
                return(NULL);
            }
	    /* Do not deallocate the copied tree value */
	    ret->boolval = 0;
	    break;
        case XPATH_USERS:
	    ret->user = val->user;
	    break;
        default:
            xmlFree(ret);
            ret = NULL;
	    break;
    }
    return(ret);
}

/**
 * Free up an xmlXPathObjectPtr object.
 *
 * @param obj  the object to free
 */
void
xmlXPathFreeObject(xmlXPathObjectPtr obj) {
    if (obj == NULL) return;
    if ((obj->type == XPATH_NODESET) || (obj->type == XPATH_XSLT_TREE)) {
        if (obj->nodesetval != NULL)
            xmlXPathFreeNodeSet(obj->nodesetval);
    } else if (obj->type == XPATH_STRING) {
	if (obj->stringval != NULL)
	    xmlFree(obj->stringval);
    }
    xmlFree(obj);
}

static void
xmlXPathFreeObjectEntry(void *obj, const xmlChar *name ATTRIBUTE_UNUSED) {
    xmlXPathFreeObject((xmlXPathObjectPtr) obj);
}

/**
 * Depending on the state of the cache this frees the given
 * XPath object or stores it in the cache.
 *
 * @param ctxt  XPath context
 * @param obj  the xmlXPathObjectPtr to free or to cache
 */
static void
xmlXPathReleaseObject(xmlXPathContextPtr ctxt, xmlXPathObjectPtr obj)
{
    if (obj == NULL)
	return;
    if ((ctxt == NULL) || (ctxt->cache == NULL)) {
	 xmlXPathFreeObject(obj);
    } else {
	xmlXPathContextCachePtr cache =
	    (xmlXPathContextCachePtr) ctxt->cache;

	switch (obj->type) {
	    case XPATH_NODESET:
	    case XPATH_XSLT_TREE:
		if (obj->nodesetval != NULL) {
		    if ((obj->nodesetval->nodeMax <= 40) &&
			(cache->numNodeset < cache->maxNodeset)) {
                        obj->stringval = (void *) cache->nodesetObjs;
                        cache->nodesetObjs = obj;
                        cache->numNodeset += 1;
			goto obj_cached;
		    } else {
			xmlXPathFreeNodeSet(obj->nodesetval);
			obj->nodesetval = NULL;
		    }
		}
		break;
	    case XPATH_STRING:
		if (obj->stringval != NULL)
		    xmlFree(obj->stringval);
                obj->stringval = NULL;
		break;
	    case XPATH_BOOLEAN:
	    case XPATH_NUMBER:
		break;
	    default:
		goto free_obj;
	}

	/*
	* Fallback to adding to the misc-objects slot.
	*/
        if (cache->numMisc >= cache->maxMisc)
	    goto free_obj;
        obj->stringval = (void *) cache->miscObjs;
        cache->miscObjs = obj;
        cache->numMisc += 1;

obj_cached:
        obj->boolval = 0;
	if (obj->nodesetval != NULL) {
	    xmlNodeSetPtr tmpset = obj->nodesetval;

	    /*
	    * Due to those nasty ns-nodes, we need to traverse
	    * the list and free the ns-nodes.
	    */
	    if (tmpset->nodeNr > 0) {
		int i;
		xmlNodePtr node;

		for (i = 0; i < tmpset->nodeNr; i++) {
		    node = tmpset->nodeTab[i];
		    if ((node != NULL) &&
			(node->type == XML_NAMESPACE_DECL))
		    {
			xmlXPathNodeSetFreeNs((xmlNsPtr) node);
		    }
		}
	    }
	    tmpset->nodeNr = 0;
        }

	return;

free_obj:
	/*
	* Cache is full; free the object.
	*/
	if (obj->nodesetval != NULL)
	    xmlXPathFreeNodeSet(obj->nodesetval);
	xmlFree(obj);
    }
}


/************************************************************************
 *									*
 *			Type Casting Routines				*
 *									*
 ************************************************************************/

/**
 * Converts a boolean to its string value.
 *
 * @param val  a boolean
 * @returns a newly allocated string.
 */
xmlChar *
xmlXPathCastBooleanToString (int val) {
    xmlChar *ret;
    if (val)
	ret = xmlStrdup((const xmlChar *) "true");
    else
	ret = xmlStrdup((const xmlChar *) "false");
    return(ret);
}

/**
 * Converts a number to its string value.
 *
 * @param val  a number
 * @returns a newly allocated string.
 */
xmlChar *
xmlXPathCastNumberToString (double val) {
    xmlChar *ret;
    switch (xmlXPathIsInf(val)) {
    case 1:
	ret = xmlStrdup((const xmlChar *) "Infinity");
	break;
    case -1:
	ret = xmlStrdup((const xmlChar *) "-Infinity");
	break;
    default:
	if (xmlXPathIsNaN(val)) {
	    ret = xmlStrdup((const xmlChar *) "NaN");
	} else if (val == 0) {
            /* Omit sign for negative zero. */
	    ret = xmlStrdup((const xmlChar *) "0");
	} else {
	    /* could be improved */
	    char buf[100];
	    xmlXPathFormatNumber(val, buf, 99);
	    buf[99] = 0;
	    ret = xmlStrdup((const xmlChar *) buf);
	}
    }
    return(ret);
}

/**
 * Converts a node to its string value.
 *
 * @param node  a node
 * @returns a newly allocated string.
 */
xmlChar *
xmlXPathCastNodeToString (xmlNodePtr node) {
    return(xmlNodeGetContent(node));
}

/**
 * Converts a node-set to its string value.
 *
 * @param ns  a node-set
 * @returns a newly allocated string.
 */
xmlChar *
xmlXPathCastNodeSetToString (xmlNodeSetPtr ns) {
    if ((ns == NULL) || (ns->nodeNr == 0) || (ns->nodeTab == NULL))
	return(xmlStrdup((const xmlChar *) ""));

    if (ns->nodeNr > 1)
	xmlXPathNodeSetSort(ns);
    return(xmlXPathCastNodeToString(ns->nodeTab[0]));
}

/**
 * Converts an existing object to its string() equivalent
 *
 * @param val  an XPath object
 * @returns the allocated string value of the object, NULL in case of error.
 *         It's up to the caller to free the string memory with xmlFree().
 */
xmlChar *
xmlXPathCastToString(xmlXPathObjectPtr val) {
    xmlChar *ret = NULL;

    if (val == NULL)
	return(xmlStrdup((const xmlChar *) ""));
    switch (val->type) {
	case XPATH_UNDEFINED:
	    ret = xmlStrdup((const xmlChar *) "");
	    break;
        case XPATH_NODESET:
        case XPATH_XSLT_TREE:
	    ret = xmlXPathCastNodeSetToString(val->nodesetval);
	    break;
	case XPATH_STRING:
	    return(xmlStrdup(val->stringval));
        case XPATH_BOOLEAN:
	    ret = xmlXPathCastBooleanToString(val->boolval);
	    break;
	case XPATH_NUMBER: {
	    ret = xmlXPathCastNumberToString(val->floatval);
	    break;
	}
	case XPATH_USERS:
	    /* TODO */
	    ret = xmlStrdup((const xmlChar *) "");
	    break;
    }
    return(ret);
}

/**
 * Converts an existing object to its string() equivalent
 *
 * @param val  an XPath object
 * @returns the new object, the old one is freed (or the operation
 *         is done directly on `val`)
 */
xmlXPathObjectPtr
xmlXPathConvertString(xmlXPathObjectPtr val) {
    xmlChar *res = NULL;

    if (val == NULL)
	return(xmlXPathNewCString(""));

    switch (val->type) {
    case XPATH_UNDEFINED:
	break;
    case XPATH_NODESET:
    case XPATH_XSLT_TREE:
	res = xmlXPathCastNodeSetToString(val->nodesetval);
	break;
    case XPATH_STRING:
	return(val);
    case XPATH_BOOLEAN:
	res = xmlXPathCastBooleanToString(val->boolval);
	break;
    case XPATH_NUMBER:
	res = xmlXPathCastNumberToString(val->floatval);
	break;
    case XPATH_USERS:
	/* TODO */
	break;
    }
    xmlXPathFreeObject(val);
    if (res == NULL)
	return(xmlXPathNewCString(""));
    return(xmlXPathWrapString(res));
}

/**
 * Converts a boolean to its number value
 *
 * @param val  a boolean
 * @returns the number value
 */
double
xmlXPathCastBooleanToNumber(int val) {
    if (val)
	return(1.0);
    return(0.0);
}

/**
 * Converts a string to its number value
 *
 * @param val  a string
 * @returns the number value
 */
double
xmlXPathCastStringToNumber(const xmlChar * val) {
    return(xmlXPathStringEvalNumber(val));
}

/**
 * Converts a node to its number value
 *
 * @param ctxt  XPath parser context
 * @param node  a node
 * @returns the number value
 */
static double
xmlXPathNodeToNumberInternal(xmlXPathParserContextPtr ctxt, xmlNodePtr node) {
    xmlChar *strval;
    double ret;

    if (node == NULL)
	return(xmlXPathNAN);
    strval = xmlXPathCastNodeToString(node);
    if (strval == NULL) {
        xmlXPathPErrMemory(ctxt);
	return(xmlXPathNAN);
    }
    ret = xmlXPathCastStringToNumber(strval);
    xmlFree(strval);

    return(ret);
}

/**
 * Converts a node to its number value
 *
 * @param node  a node
 * @returns the number value
 */
double
xmlXPathCastNodeToNumber (xmlNodePtr node) {
    return(xmlXPathNodeToNumberInternal(NULL, node));
}

/**
 * Converts a node-set to its number value
 *
 * @param ns  a node-set
 * @returns the number value
 */
double
xmlXPathCastNodeSetToNumber (xmlNodeSetPtr ns) {
    xmlChar *str;
    double ret;

    if (ns == NULL)
	return(xmlXPathNAN);
    str = xmlXPathCastNodeSetToString(ns);
    ret = xmlXPathCastStringToNumber(str);
    xmlFree(str);
    return(ret);
}

/**
 * Converts an XPath object to its number value
 *
 * @param val  an XPath object
 * @returns the number value
 */
double
xmlXPathCastToNumber(xmlXPathObjectPtr val) {
    return(xmlXPathCastToNumberInternal(NULL, val));
}

/**
 * Converts an existing object to its number() equivalent
 *
 * @param val  an XPath object
 * @returns the new object, the old one is freed (or the operation
 *         is done directly on `val`)
 */
xmlXPathObjectPtr
xmlXPathConvertNumber(xmlXPathObjectPtr val) {
    xmlXPathObjectPtr ret;

    if (val == NULL)
	return(xmlXPathNewFloat(0.0));
    if (val->type == XPATH_NUMBER)
	return(val);
    ret = xmlXPathNewFloat(xmlXPathCastToNumber(val));
    xmlXPathFreeObject(val);
    return(ret);
}

/**
 * Converts a number to its boolean value
 *
 * @param val  a number
 * @returns the boolean value
 */
int
xmlXPathCastNumberToBoolean (double val) {
     if (xmlXPathIsNaN(val) || (val == 0.0))
	 return(0);
     return(1);
}

/**
 * Converts a string to its boolean value
 *
 * @param val  a string
 * @returns the boolean value
 */
int
xmlXPathCastStringToBoolean (const xmlChar *val) {
    if ((val == NULL) || (xmlStrlen(val) == 0))
	return(0);
    return(1);
}

/**
 * Converts a node-set to its boolean value
 *
 * @param ns  a node-set
 * @returns the boolean value
 */
int
xmlXPathCastNodeSetToBoolean (xmlNodeSetPtr ns) {
    if ((ns == NULL) || (ns->nodeNr == 0))
	return(0);
    return(1);
}

/**
 * Converts an XPath object to its boolean value
 *
 * @param val  an XPath object
 * @returns the boolean value
 */
int
xmlXPathCastToBoolean (xmlXPathObjectPtr val) {
    int ret = 0;

    if (val == NULL)
	return(0);
    switch (val->type) {
    case XPATH_UNDEFINED:
	ret = 0;
	break;
    case XPATH_NODESET:
    case XPATH_XSLT_TREE:
	ret = xmlXPathCastNodeSetToBoolean(val->nodesetval);
	break;
    case XPATH_STRING:
	ret = xmlXPathCastStringToBoolean(val->stringval);
	break;
    case XPATH_NUMBER:
	ret = xmlXPathCastNumberToBoolean(val->floatval);
	break;
    case XPATH_BOOLEAN:
	ret = val->boolval;
	break;
    case XPATH_USERS:
	/* TODO */
	ret = 0;
	break;
    }
    return(ret);
}


/**
 * Converts an existing object to its boolean() equivalent
 *
 * @param val  an XPath object
 * @returns the new object, the old one is freed (or the operation
 *         is done directly on `val`)
 */
xmlXPathObjectPtr
xmlXPathConvertBoolean(xmlXPathObjectPtr val) {
    xmlXPathObjectPtr ret;

    if (val == NULL)
	return(xmlXPathNewBoolean(0));
    if (val->type == XPATH_BOOLEAN)
	return(val);
    ret = xmlXPathNewBoolean(xmlXPathCastToBoolean(val));
    xmlXPathFreeObject(val);
    return(ret);
}

/************************************************************************
 *									*
 *		Routines to handle XPath contexts			*
 *									*
 ************************************************************************/

/**
 * Create a new xmlXPathContext
 *
 * @param doc  the XML document
 * @returns the xmlXPathContext just allocated. The caller will need to free it.
 */
xmlXPathContextPtr
xmlXPathNewContext(xmlDocPtr doc) {
    xmlXPathContextPtr ret;

    ret = (xmlXPathContextPtr) xmlMalloc(sizeof(xmlXPathContext));
    if (ret == NULL)
	return(NULL);
    memset(ret, 0 , sizeof(xmlXPathContext));
    ret->doc = doc;
    ret->node = NULL;

    ret->varHash = NULL;

    ret->nb_types = 0;
    ret->max_types = 0;
    ret->types = NULL;

    ret->nb_axis = 0;
    ret->max_axis = 0;
    ret->axis = NULL;

    ret->nsHash = NULL;
    ret->user = NULL;

    ret->contextSize = -1;
    ret->proximityPosition = -1;

#ifdef XP_DEFAULT_CACHE_ON
    if (xmlXPathContextSetCache(ret, 1, -1, 0) == -1) {
	xmlXPathFreeContext(ret);
	return(NULL);
    }
#endif

    return(ret);
}

/**
 * Free up an xmlXPathContext
 *
 * @param ctxt  the context to free
 */
void
xmlXPathFreeContext(xmlXPathContextPtr ctxt) {
    if (ctxt == NULL) return;

    if (ctxt->cache != NULL)
	xmlXPathFreeCache((xmlXPathContextCachePtr) ctxt->cache);
    xmlXPathRegisteredNsCleanup(ctxt);
    xmlXPathRegisteredFuncsCleanup(ctxt);
    xmlXPathRegisteredVariablesCleanup(ctxt);
    xmlResetError(&ctxt->lastError);
    xmlFree(ctxt);
}

/**
 * Register a callback function that will be called on errors and
 * warnings. If handler is NULL, the error handler will be deactivated.
 *
 * @since 2.13.0
 * @param ctxt  the XPath context
 * @param handler  error handler
 * @param data  user data which will be passed to the handler
 */
void
xmlXPathSetErrorHandler(xmlXPathContextPtr ctxt,
                        xmlStructuredErrorFunc handler, void *data) {
    if (ctxt == NULL)
        return;

    ctxt->error = handler;
    ctxt->userData = data;
}

/************************************************************************
 *									*
 *		Routines to handle XPath parser contexts		*
 *									*
 ************************************************************************/

/**
 * Create a new xmlXPathParserContext
 *
 * @param str  the XPath expression
 * @param ctxt  the XPath context
 * @returns the xmlXPathParserContext just allocated.
 */
xmlXPathParserContextPtr
xmlXPathNewParserContext(const xmlChar *str, xmlXPathContextPtr ctxt) {
    xmlXPathParserContextPtr ret;

    ret = (xmlXPathParserContextPtr) xmlMalloc(sizeof(xmlXPathParserContext));
    if (ret == NULL) {
        xmlXPathErrMemory(ctxt);
	return(NULL);
    }
    memset(ret, 0 , sizeof(xmlXPathParserContext));
    ret->cur = ret->base = str;
    ret->context = ctxt;

    ret->comp = xmlXPathNewCompExpr();
    if (ret->comp == NULL) {
        xmlXPathErrMemory(ctxt);
	xmlFree(ret->valueTab);
	xmlFree(ret);
	return(NULL);
    }
    if ((ctxt != NULL) && (ctxt->dict != NULL)) {
        ret->comp->dict = ctxt->dict;
	xmlDictReference(ret->comp->dict);
    }

    return(ret);
}

/**
 * Create a new xmlXPathParserContext when processing a compiled expression
 *
 * @param comp  the XPath compiled expression
 * @param ctxt  the XPath context
 * @returns the xmlXPathParserContext just allocated.
 */
static xmlXPathParserContextPtr
xmlXPathCompParserContext(xmlXPathCompExprPtr comp, xmlXPathContextPtr ctxt) {
    xmlXPathParserContextPtr ret;

    ret = (xmlXPathParserContextPtr) xmlMalloc(sizeof(xmlXPathParserContext));
    if (ret == NULL) {
        xmlXPathErrMemory(ctxt);
	return(NULL);
    }
    memset(ret, 0 , sizeof(xmlXPathParserContext));

    /* Allocate the value stack */
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
    ret->valueMax = 1;
#else
    ret->valueMax = 10;
#endif
    ret->valueTab = xmlMalloc(ret->valueMax * sizeof(xmlXPathObjectPtr));
    if (ret->valueTab == NULL) {
	xmlFree(ret);
	xmlXPathErrMemory(ctxt);
	return(NULL);
    }
    ret->valueNr = 0;
    ret->value = NULL;

    ret->context = ctxt;
    ret->comp = comp;

    return(ret);
}

/**
 * Free up an xmlXPathParserContext
 *
 * @param ctxt  the context to free
 */
void
xmlXPathFreeParserContext(xmlXPathParserContextPtr ctxt) {
    int i;

    if (ctxt == NULL)
        return;

    if (ctxt->valueTab != NULL) {
        for (i = 0; i < ctxt->valueNr; i++) {
            if (ctxt->context)
                xmlXPathReleaseObject(ctxt->context, ctxt->valueTab[i]);
            else
                xmlXPathFreeObject(ctxt->valueTab[i]);
        }
        xmlFree(ctxt->valueTab);
    }
    if (ctxt->comp != NULL) {
#ifdef XPATH_STREAMING
	if (ctxt->comp->stream != NULL) {
	    xmlFreePatternList(ctxt->comp->stream);
	    ctxt->comp->stream = NULL;
	}
#endif
	xmlXPathFreeCompExpr(ctxt->comp);
    }
    xmlFree(ctxt);
}

/************************************************************************
 *									*
 *		The implicit core function library			*
 *									*
 ************************************************************************/

/**
 * Function computing the beginning of the string value of the node,
 * used to speed up comparisons
 *
 * @param node  a node pointer
 * @returns an int usable as a hash
 */
static unsigned int
xmlXPathNodeValHash(xmlNodePtr node) {
    int len = 2;
    const xmlChar * string = NULL;
    xmlNodePtr tmp = NULL;
    unsigned int ret = 0;

    if (node == NULL)
	return(0);

    if (node->type == XML_DOCUMENT_NODE) {
	tmp = xmlDocGetRootElement((xmlDocPtr) node);
	if (tmp == NULL)
	    node = node->children;
	else
	    node = tmp;

	if (node == NULL)
	    return(0);
    }

    switch (node->type) {
	case XML_COMMENT_NODE:
	case XML_PI_NODE:
	case XML_CDATA_SECTION_NODE:
	case XML_TEXT_NODE:
	    string = node->content;
	    if (string == NULL)
		return(0);
	    if (string[0] == 0)
		return(0);
	    return(string[0] + (string[1] << 8));
	case XML_NAMESPACE_DECL:
	    string = ((xmlNsPtr)node)->href;
	    if (string == NULL)
		return(0);
	    if (string[0] == 0)
		return(0);
	    return(string[0] + (string[1] << 8));
	case XML_ATTRIBUTE_NODE:
	    tmp = ((xmlAttrPtr) node)->children;
	    break;
	case XML_ELEMENT_NODE:
	    tmp = node->children;
	    break;
	default:
	    return(0);
    }
    while (tmp != NULL) {
	switch (tmp->type) {
	    case XML_CDATA_SECTION_NODE:
	    case XML_TEXT_NODE:
		string = tmp->content;
		break;
	    default:
                string = NULL;
		break;
	}
	if ((string != NULL) && (string[0] != 0)) {
	    if (len == 1) {
		return(ret + (string[0] << 8));
	    }
	    if (string[1] == 0) {
		len = 1;
		ret = string[0];
	    } else {
		return(string[0] + (string[1] << 8));
	    }
	}
	/*
	 * Skip to next node
	 */
        if ((tmp->children != NULL) &&
            (tmp->type != XML_DTD_NODE) &&
            (tmp->type != XML_ENTITY_REF_NODE) &&
            (tmp->children->type != XML_ENTITY_DECL)) {
            tmp = tmp->children;
            continue;
	}
	if (tmp == node)
	    break;

	if (tmp->next != NULL) {
	    tmp = tmp->next;
	    continue;
	}

	do {
	    tmp = tmp->parent;
	    if (tmp == NULL)
		break;
	    if (tmp == node) {
		tmp = NULL;
		break;
	    }
	    if (tmp->next != NULL) {
		tmp = tmp->next;
		break;
	    }
	} while (tmp != NULL);
    }
    return(ret);
}

/**
 * Function computing the beginning of the string value of the node,
 * used to speed up comparisons
 *
 * @param string  a string
 * @returns an int usable as a hash
 */
static unsigned int
xmlXPathStringHash(const xmlChar * string) {
    if (string == NULL)
	return(0);
    if (string[0] == 0)
	return(0);
    return(string[0] + (string[1] << 8));
}

/**
 * Implement the compare operation between a nodeset and a number
 *     `ns` < `val`    (1, 1, ...
 *     `ns` <= `val`   (1, 0, ...
 *     `ns` > `val`    (0, 1, ...
 *     `ns` >= `val`   (0, 0, ...
 *
 * If one object to be compared is a node-set and the other is a number,
 * then the comparison will be true if and only if there is a node in the
 * node-set such that the result of performing the comparison on the number
 * to be compared and on the result of converting the string-value of that
 * node to a number using the number function is true.
 *
 * @param ctxt  the XPath Parser context
 * @param inf  less than (1) or greater than (0)
 * @param strict  is the comparison strict
 * @param arg  the node set
 * @param f  the value
 * @returns 0 or 1 depending on the results of the test.
 */
static int
xmlXPathCompareNodeSetFloat(xmlXPathParserContextPtr ctxt, int inf, int strict,
	                    xmlXPathObjectPtr arg, xmlXPathObjectPtr f) {
    int i, ret = 0;
    xmlNodeSetPtr ns;
    xmlChar *str2;

    if ((f == NULL) || (arg == NULL) ||
	((arg->type != XPATH_NODESET) && (arg->type != XPATH_XSLT_TREE))) {
	xmlXPathReleaseObject(ctxt->context, arg);
	xmlXPathReleaseObject(ctxt->context, f);
        return(0);
    }
    ns = arg->nodesetval;
    if (ns != NULL) {
	for (i = 0;i < ns->nodeNr;i++) {
	     str2 = xmlXPathCastNodeToString(ns->nodeTab[i]);
	     if (str2 != NULL) {
		 xmlXPathValuePush(ctxt, xmlXPathCacheNewString(ctxt, str2));
		 xmlFree(str2);
		 xmlXPathNumberFunction(ctxt, 1);
		 xmlXPathValuePush(ctxt, xmlXPathCacheObjectCopy(ctxt, f));
		 ret = xmlXPathCompareValues(ctxt, inf, strict);
		 if (ret)
		     break;
	     } else {
                 xmlXPathPErrMemory(ctxt);
             }
	}
    }
    xmlXPathReleaseObject(ctxt->context, arg);
    xmlXPathReleaseObject(ctxt->context, f);
    return(ret);
}

/**
 * Implement the compare operation between a nodeset and a string
 *     `ns` < `val`    (1, 1, ...
 *     `ns` <= `val`   (1, 0, ...
 *     `ns` > `val`    (0, 1, ...
 *     `ns` >= `val`   (0, 0, ...
 *
 * If one object to be compared is a node-set and the other is a string,
 * then the comparison will be true if and only if there is a node in
 * the node-set such that the result of performing the comparison on the
 * string-value of the node and the other string is true.
 *
 * @param ctxt  the XPath Parser context
 * @param inf  less than (1) or greater than (0)
 * @param strict  is the comparison strict
 * @param arg  the node set
 * @param s  the value
 * @returns 0 or 1 depending on the results of the test.
 */
static int
xmlXPathCompareNodeSetString(xmlXPathParserContextPtr ctxt, int inf, int strict,
	                    xmlXPathObjectPtr arg, xmlXPathObjectPtr s) {
    int i, ret = 0;
    xmlNodeSetPtr ns;
    xmlChar *str2;

    if ((s == NULL) || (arg == NULL) ||
	((arg->type != XPATH_NODESET) && (arg->type != XPATH_XSLT_TREE))) {
	xmlXPathReleaseObject(ctxt->context, arg);
	xmlXPathReleaseObject(ctxt->context, s);
        return(0);
    }
    ns = arg->nodesetval;
    if (ns != NULL) {
	for (i = 0;i < ns->nodeNr;i++) {
	     str2 = xmlXPathCastNodeToString(ns->nodeTab[i]);
	     if (str2 != NULL) {
		 xmlXPathValuePush(ctxt,
			   xmlXPathCacheNewString(ctxt, str2));
		 xmlFree(str2);
		 xmlXPathValuePush(ctxt, xmlXPathCacheObjectCopy(ctxt, s));
		 ret = xmlXPathCompareValues(ctxt, inf, strict);
		 if (ret)
		     break;
	     } else {
                 xmlXPathPErrMemory(ctxt);
             }
	}
    }
    xmlXPathReleaseObject(ctxt->context, arg);
    xmlXPathReleaseObject(ctxt->context, s);
    return(ret);
}

/**
 * Implement the compare operation on nodesets:
 *
 * If both objects to be compared are node-sets, then the comparison
 * will be true if and only if there is a node in the first node-set
 * and a node in the second node-set such that the result of performing
 * the comparison on the string-values of the two nodes is true.
 * ....
 * When neither object to be compared is a node-set and the operator
 * is <=, <, >= or >, then the objects are compared by converting both
 * objects to numbers and comparing the numbers according to IEEE 754.
 * ....
 * The number function converts its argument to a number as follows:
 *  - a string that consists of optional whitespace followed by an
 *    optional minus sign followed by a Number followed by whitespace
 *    is converted to the IEEE 754 number that is nearest (according
 *    to the IEEE 754 round-to-nearest rule) to the mathematical value
 *    represented by the string; any other string is converted to NaN
 *
 * Conclusion all nodes need to be converted first to their string value
 * and then the comparison must be done when possible
 * @param ctxt  XPath parser context
 * @param inf  less than (1) or greater than (0)
 * @param strict  is the comparison strict
 * @param arg1  the first node set object
 * @param arg2  the second node set object
 */
static int
xmlXPathCompareNodeSets(xmlXPathParserContextPtr ctxt, int inf, int strict,
	                xmlXPathObjectPtr arg1, xmlXPathObjectPtr arg2) {
    int i, j, init = 0;
    double val1;
    double *values2;
    int ret = 0;
    xmlNodeSetPtr ns1;
    xmlNodeSetPtr ns2;

    if ((arg1 == NULL) ||
	((arg1->type != XPATH_NODESET) && (arg1->type != XPATH_XSLT_TREE))) {
	xmlXPathFreeObject(arg2);
        return(0);
    }
    if ((arg2 == NULL) ||
	((arg2->type != XPATH_NODESET) && (arg2->type != XPATH_XSLT_TREE))) {
	xmlXPathFreeObject(arg1);
	xmlXPathFreeObject(arg2);
        return(0);
    }

    ns1 = arg1->nodesetval;
    ns2 = arg2->nodesetval;

    if ((ns1 == NULL) || (ns1->nodeNr <= 0)) {
	xmlXPathFreeObject(arg1);
	xmlXPathFreeObject(arg2);
	return(0);
    }
    if ((ns2 == NULL) || (ns2->nodeNr <= 0)) {
	xmlXPathFreeObject(arg1);
	xmlXPathFreeObject(arg2);
	return(0);
    }

    values2 = (double *) xmlMalloc(ns2->nodeNr * sizeof(double));
    if (values2 == NULL) {
        xmlXPathPErrMemory(ctxt);
	xmlXPathFreeObject(arg1);
	xmlXPathFreeObject(arg2);
	return(0);
    }
    for (i = 0;i < ns1->nodeNr;i++) {
	val1 = xmlXPathNodeToNumberInternal(ctxt, ns1->nodeTab[i]);
	if (xmlXPathIsNaN(val1))
	    continue;
	for (j = 0;j < ns2->nodeNr;j++) {
	    if (init == 0) {
		values2[j] = xmlXPathNodeToNumberInternal(ctxt,
                                                          ns2->nodeTab[j]);
	    }
	    if (xmlXPathIsNaN(values2[j]))
		continue;
	    if (inf && strict)
		ret = (val1 < values2[j]);
	    else if (inf && !strict)
		ret = (val1 <= values2[j]);
	    else if (!inf && strict)
		ret = (val1 > values2[j]);
	    else if (!inf && !strict)
		ret = (val1 >= values2[j]);
	    if (ret)
		break;
	}
	if (ret)
	    break;
	init = 1;
    }
    xmlFree(values2);
    xmlXPathFreeObject(arg1);
    xmlXPathFreeObject(arg2);
    return(ret);
}

/**
 * Implement the compare operation between a nodeset and a value
 *     `ns` < `val`    (1, 1, ...
 *     `ns` <= `val`   (1, 0, ...
 *     `ns` > `val`    (0, 1, ...
 *     `ns` >= `val`   (0, 0, ...
 *
 * If one object to be compared is a node-set and the other is a boolean,
 * then the comparison will be true if and only if the result of performing
 * the comparison on the boolean and on the result of converting
 * the node-set to a boolean using the boolean function is true.
 *
 * @param ctxt  the XPath Parser context
 * @param inf  less than (1) or greater than (0)
 * @param strict  is the comparison strict
 * @param arg  the node set
 * @param val  the value
 * @returns 0 or 1 depending on the results of the test.
 */
static int
xmlXPathCompareNodeSetValue(xmlXPathParserContextPtr ctxt, int inf, int strict,
	                    xmlXPathObjectPtr arg, xmlXPathObjectPtr val) {
    if ((val == NULL) || (arg == NULL) ||
	((arg->type != XPATH_NODESET) && (arg->type != XPATH_XSLT_TREE)))
        return(0);

    switch(val->type) {
        case XPATH_NUMBER:
	    return(xmlXPathCompareNodeSetFloat(ctxt, inf, strict, arg, val));
        case XPATH_NODESET:
        case XPATH_XSLT_TREE:
	    return(xmlXPathCompareNodeSets(ctxt, inf, strict, arg, val));
        case XPATH_STRING:
	    return(xmlXPathCompareNodeSetString(ctxt, inf, strict, arg, val));
        case XPATH_BOOLEAN:
	    xmlXPathValuePush(ctxt, arg);
	    xmlXPathBooleanFunction(ctxt, 1);
	    xmlXPathValuePush(ctxt, val);
	    return(xmlXPathCompareValues(ctxt, inf, strict));
	default:
            xmlXPathReleaseObject(ctxt->context, arg);
            xmlXPathReleaseObject(ctxt->context, val);
            XP_ERROR0(XPATH_INVALID_TYPE);
    }
    return(0);
}

/**
 * Implement the equal operation on XPath objects content: `arg1` == `arg2`
 * If one object to be compared is a node-set and the other is a string,
 * then the comparison will be true if and only if there is a node in
 * the node-set such that the result of performing the comparison on the
 * string-value of the node and the other string is true.
 *
 * @param ctxt  XPath parser context
 * @param arg  the nodeset object argument
 * @param str  the string to compare to.
 * @param neq  flag to show whether for '=' (0) or '!=' (1)
 * @returns 0 or 1 depending on the results of the test.
 */
static int
xmlXPathEqualNodeSetString(xmlXPathParserContextPtr ctxt,
                           xmlXPathObjectPtr arg, const xmlChar * str, int neq)
{
    int i;
    xmlNodeSetPtr ns;
    xmlChar *str2;
    unsigned int hash;

    if ((str == NULL) || (arg == NULL) ||
        ((arg->type != XPATH_NODESET) && (arg->type != XPATH_XSLT_TREE)))
        return (0);
    ns = arg->nodesetval;
    /*
     * A NULL nodeset compared with a string is always false
     * (since there is no node equal, and no node not equal)
     */
    if ((ns == NULL) || (ns->nodeNr <= 0) )
        return (0);
    hash = xmlXPathStringHash(str);
    for (i = 0; i < ns->nodeNr; i++) {
        if (xmlXPathNodeValHash(ns->nodeTab[i]) == hash) {
            str2 = xmlNodeGetContent(ns->nodeTab[i]);
            if (str2 == NULL) {
                xmlXPathPErrMemory(ctxt);
                return(0);
            }
            if (xmlStrEqual(str, str2)) {
                xmlFree(str2);
		if (neq)
		    continue;
                return (1);
            } else if (neq) {
		xmlFree(str2);
		return (1);
	    }
            xmlFree(str2);
        } else if (neq)
	    return (1);
    }
    return (0);
}

/**
 * Implement the equal operation on XPath objects content: `arg1` == `arg2`
 * If one object to be compared is a node-set and the other is a number,
 * then the comparison will be true if and only if there is a node in
 * the node-set such that the result of performing the comparison on the
 * number to be compared and on the result of converting the string-value
 * of that node to a number using the number function is true.
 *
 * @param ctxt  XPath parser context
 * @param arg  the nodeset object argument
 * @param f  the float to compare to
 * @param neq  flag to show whether to compare '=' (0) or '!=' (1)
 * @returns 0 or 1 depending on the results of the test.
 */
static int
xmlXPathEqualNodeSetFloat(xmlXPathParserContextPtr ctxt,
    xmlXPathObjectPtr arg, double f, int neq) {
  int i, ret=0;
  xmlNodeSetPtr ns;
  xmlChar *str2;
  xmlXPathObjectPtr val;
  double v;

    if ((arg == NULL) ||
	((arg->type != XPATH_NODESET) && (arg->type != XPATH_XSLT_TREE)))
        return(0);

    ns = arg->nodesetval;
    if (ns != NULL) {
	for (i=0;i<ns->nodeNr;i++) {
	    str2 = xmlXPathCastNodeToString(ns->nodeTab[i]);
	    if (str2 != NULL) {
		xmlXPathValuePush(ctxt, xmlXPathCacheNewString(ctxt, str2));
		xmlFree(str2);
		xmlXPathNumberFunction(ctxt, 1);
                CHECK_ERROR0;
		val = xmlXPathValuePop(ctxt);
		v = val->floatval;
		xmlXPathReleaseObject(ctxt->context, val);
		if (!xmlXPathIsNaN(v)) {
		    if ((!neq) && (v==f)) {
			ret = 1;
			break;
		    } else if ((neq) && (v!=f)) {
			ret = 1;
			break;
		    }
		} else {	/* NaN is unequal to any value */
		    if (neq)
			ret = 1;
		}
	    } else {
                xmlXPathPErrMemory(ctxt);
            }
	}
    }

    return(ret);
}


/**
 * Implement the equal / not equal operation on XPath nodesets:
 * `arg1` == `arg2`  or  `arg1` != `arg2`
 * If both objects to be compared are node-sets, then the comparison
 * will be true if and only if there is a node in the first node-set and
 * a node in the second node-set such that the result of performing the
 * comparison on the string-values of the two nodes is true.
 *
 * (needless to say, this is a costly operation)
 *
 * @param ctxt  XPath parser context
 * @param arg1  first nodeset object argument
 * @param arg2  second nodeset object argument
 * @param neq  flag to show whether to test '=' (0) or '!=' (1)
 * @returns 0 or 1 depending on the results of the test.
 */
static int
xmlXPathEqualNodeSets(xmlXPathParserContextPtr ctxt, xmlXPathObjectPtr arg1,
                      xmlXPathObjectPtr arg2, int neq) {
    int i, j;
    unsigned int *hashs1;
    unsigned int *hashs2;
    xmlChar **values1;
    xmlChar **values2;
    int ret = 0;
    xmlNodeSetPtr ns1;
    xmlNodeSetPtr ns2;

    if ((arg1 == NULL) ||
	((arg1->type != XPATH_NODESET) && (arg1->type != XPATH_XSLT_TREE)))
        return(0);
    if ((arg2 == NULL) ||
	((arg2->type != XPATH_NODESET) && (arg2->type != XPATH_XSLT_TREE)))
        return(0);

    ns1 = arg1->nodesetval;
    ns2 = arg2->nodesetval;

    if ((ns1 == NULL) || (ns1->nodeNr <= 0))
	return(0);
    if ((ns2 == NULL) || (ns2->nodeNr <= 0))
	return(0);

    /*
     * for equal, check if there is a node pertaining to both sets
     */
    if (neq == 0)
	for (i = 0;i < ns1->nodeNr;i++)
	    for (j = 0;j < ns2->nodeNr;j++)
		if (ns1->nodeTab[i] == ns2->nodeTab[j])
		    return(1);

    values1 = (xmlChar **) xmlMalloc(ns1->nodeNr * sizeof(xmlChar *));
    if (values1 == NULL) {
        xmlXPathPErrMemory(ctxt);
	return(0);
    }
    hashs1 = (unsigned int *) xmlMalloc(ns1->nodeNr * sizeof(unsigned int));
    if (hashs1 == NULL) {
        xmlXPathPErrMemory(ctxt);
	xmlFree(values1);
	return(0);
    }
    memset(values1, 0, ns1->nodeNr * sizeof(xmlChar *));
    values2 = (xmlChar **) xmlMalloc(ns2->nodeNr * sizeof(xmlChar *));
    if (values2 == NULL) {
        xmlXPathPErrMemory(ctxt);
	xmlFree(hashs1);
	xmlFree(values1);
	return(0);
    }
    hashs2 = (unsigned int *) xmlMalloc(ns2->nodeNr * sizeof(unsigned int));
    if (hashs2 == NULL) {
        xmlXPathPErrMemory(ctxt);
	xmlFree(hashs1);
	xmlFree(values1);
	xmlFree(values2);
	return(0);
    }
    memset(values2, 0, ns2->nodeNr * sizeof(xmlChar *));
    for (i = 0;i < ns1->nodeNr;i++) {
	hashs1[i] = xmlXPathNodeValHash(ns1->nodeTab[i]);
	for (j = 0;j < ns2->nodeNr;j++) {
	    if (i == 0)
		hashs2[j] = xmlXPathNodeValHash(ns2->nodeTab[j]);
	    if (hashs1[i] != hashs2[j]) {
		if (neq) {
		    ret = 1;
		    break;
		}
	    }
	    else {
		if (values1[i] == NULL) {
		    values1[i] = xmlNodeGetContent(ns1->nodeTab[i]);
                    if (values1[i] == NULL)
                        xmlXPathPErrMemory(ctxt);
                }
		if (values2[j] == NULL) {
		    values2[j] = xmlNodeGetContent(ns2->nodeTab[j]);
                    if (values2[j] == NULL)
                        xmlXPathPErrMemory(ctxt);
                }
		ret = xmlStrEqual(values1[i], values2[j]) ^ neq;
		if (ret)
		    break;
	    }
	}
	if (ret)
	    break;
    }
    for (i = 0;i < ns1->nodeNr;i++)
	if (values1[i] != NULL)
	    xmlFree(values1[i]);
    for (j = 0;j < ns2->nodeNr;j++)
	if (values2[j] != NULL)
	    xmlFree(values2[j]);
    xmlFree(values1);
    xmlFree(values2);
    xmlFree(hashs1);
    xmlFree(hashs2);
    return(ret);
}

static int
xmlXPathEqualValuesCommon(xmlXPathParserContextPtr ctxt,
  xmlXPathObjectPtr arg1, xmlXPathObjectPtr arg2) {
    int ret = 0;
    /*
     *At this point we are assured neither arg1 nor arg2
     *is a nodeset, so we can just pick the appropriate routine.
     */
    switch (arg1->type) {
        case XPATH_UNDEFINED:
	    break;
        case XPATH_BOOLEAN:
	    switch (arg2->type) {
	        case XPATH_UNDEFINED:
		    break;
		case XPATH_BOOLEAN:
		    ret = (arg1->boolval == arg2->boolval);
		    break;
		case XPATH_NUMBER:
		    ret = (arg1->boolval ==
			   xmlXPathCastNumberToBoolean(arg2->floatval));
		    break;
		case XPATH_STRING:
		    if ((arg2->stringval == NULL) ||
			(arg2->stringval[0] == 0)) ret = 0;
		    else
			ret = 1;
		    ret = (arg1->boolval == ret);
		    break;
		case XPATH_USERS:
		    /* TODO */
		    break;
		case XPATH_NODESET:
		case XPATH_XSLT_TREE:
		    break;
	    }
	    break;
        case XPATH_NUMBER:
	    switch (arg2->type) {
	        case XPATH_UNDEFINED:
		    break;
		case XPATH_BOOLEAN:
		    ret = (arg2->boolval==
			   xmlXPathCastNumberToBoolean(arg1->floatval));
		    break;
		case XPATH_STRING:
		    xmlXPathValuePush(ctxt, arg2);
		    xmlXPathNumberFunction(ctxt, 1);
		    arg2 = xmlXPathValuePop(ctxt);
                    if (ctxt->error)
                        break;
                    /* Falls through. */
		case XPATH_NUMBER:
		    /* Hand check NaN and Infinity equalities */
		    if (xmlXPathIsNaN(arg1->floatval) ||
			    xmlXPathIsNaN(arg2->floatval)) {
		        ret = 0;
		    } else if (xmlXPathIsInf(arg1->floatval) == 1) {
		        if (xmlXPathIsInf(arg2->floatval) == 1)
			    ret = 1;
			else
			    ret = 0;
		    } else if (xmlXPathIsInf(arg1->floatval) == -1) {
			if (xmlXPathIsInf(arg2->floatval) == -1)
			    ret = 1;
			else
			    ret = 0;
		    } else if (xmlXPathIsInf(arg2->floatval) == 1) {
			if (xmlXPathIsInf(arg1->floatval) == 1)
			    ret = 1;
			else
			    ret = 0;
		    } else if (xmlXPathIsInf(arg2->floatval) == -1) {
			if (xmlXPathIsInf(arg1->floatval) == -1)
			    ret = 1;
			else
			    ret = 0;
		    } else {
		        ret = (arg1->floatval == arg2->floatval);
		    }
		    break;
		case XPATH_USERS:
		    /* TODO */
		    break;
		case XPATH_NODESET:
		case XPATH_XSLT_TREE:
		    break;
	    }
	    break;
        case XPATH_STRING:
	    switch (arg2->type) {
	        case XPATH_UNDEFINED:
		    break;
		case XPATH_BOOLEAN:
		    if ((arg1->stringval == NULL) ||
			(arg1->stringval[0] == 0)) ret = 0;
		    else
			ret = 1;
		    ret = (arg2->boolval == ret);
		    break;
		case XPATH_STRING:
		    ret = xmlStrEqual(arg1->stringval, arg2->stringval);
		    break;
		case XPATH_NUMBER:
		    xmlXPathValuePush(ctxt, arg1);
		    xmlXPathNumberFunction(ctxt, 1);
		    arg1 = xmlXPathValuePop(ctxt);
                    if (ctxt->error)
                        break;
		    /* Hand check NaN and Infinity equalities */
		    if (xmlXPathIsNaN(arg1->floatval) ||
			    xmlXPathIsNaN(arg2->floatval)) {
		        ret = 0;
		    } else if (xmlXPathIsInf(arg1->floatval) == 1) {
			if (xmlXPathIsInf(arg2->floatval) == 1)
			    ret = 1;
			else
			    ret = 0;
		    } else if (xmlXPathIsInf(arg1->floatval) == -1) {
			if (xmlXPathIsInf(arg2->floatval) == -1)
			    ret = 1;
			else
			    ret = 0;
		    } else if (xmlXPathIsInf(arg2->floatval) == 1) {
			if (xmlXPathIsInf(arg1->floatval) == 1)
			    ret = 1;
			else
			    ret = 0;
		    } else if (xmlXPathIsInf(arg2->floatval) == -1) {
			if (xmlXPathIsInf(arg1->floatval) == -1)
			    ret = 1;
			else
			    ret = 0;
		    } else {
		        ret = (arg1->floatval == arg2->floatval);
		    }
		    break;
		case XPATH_USERS:
		    /* TODO */
		    break;
		case XPATH_NODESET:
		case XPATH_XSLT_TREE:
		    break;
	    }
	    break;
        case XPATH_USERS:
	    /* TODO */
	    break;
	case XPATH_NODESET:
	case XPATH_XSLT_TREE:
	    break;
    }
    xmlXPathReleaseObject(ctxt->context, arg1);
    xmlXPathReleaseObject(ctxt->context, arg2);
    return(ret);
}

/**
 * Implement the equal operation on XPath objects content: `arg1` == `arg2`
 *
 * @param ctxt  the XPath Parser context
 * @returns 0 or 1 depending on the results of the test.
 */
int
xmlXPathEqualValues(xmlXPathParserContextPtr ctxt) {
    xmlXPathObjectPtr arg1, arg2, argtmp;
    int ret = 0;

    if ((ctxt == NULL) || (ctxt->context == NULL)) return(0);
    arg2 = xmlXPathValuePop(ctxt);
    arg1 = xmlXPathValuePop(ctxt);
    if ((arg1 == NULL) || (arg2 == NULL)) {
	if (arg1 != NULL)
	    xmlXPathReleaseObject(ctxt->context, arg1);
	else
	    xmlXPathReleaseObject(ctxt->context, arg2);
	XP_ERROR0(XPATH_INVALID_OPERAND);
    }

    if (arg1 == arg2) {
	xmlXPathFreeObject(arg1);
        return(1);
    }

    /*
     *If either argument is a nodeset, it's a 'special case'
     */
    if ((arg2->type == XPATH_NODESET) || (arg2->type == XPATH_XSLT_TREE) ||
      (arg1->type == XPATH_NODESET) || (arg1->type == XPATH_XSLT_TREE)) {
	/*
	 *Hack it to assure arg1 is the nodeset
	 */
	if ((arg1->type != XPATH_NODESET) && (arg1->type != XPATH_XSLT_TREE)) {
		argtmp = arg2;
		arg2 = arg1;
		arg1 = argtmp;
	}
	switch (arg2->type) {
	    case XPATH_UNDEFINED:
		break;
	    case XPATH_NODESET:
	    case XPATH_XSLT_TREE:
		ret = xmlXPathEqualNodeSets(ctxt, arg1, arg2, 0);
		break;
	    case XPATH_BOOLEAN:
		if ((arg1->nodesetval == NULL) ||
		  (arg1->nodesetval->nodeNr == 0)) ret = 0;
		else
		    ret = 1;
		ret = (ret == arg2->boolval);
		break;
	    case XPATH_NUMBER:
		ret = xmlXPathEqualNodeSetFloat(ctxt, arg1, arg2->floatval, 0);
		break;
	    case XPATH_STRING:
		ret = xmlXPathEqualNodeSetString(ctxt, arg1,
                                                 arg2->stringval, 0);
		break;
	    case XPATH_USERS:
		/* TODO */
		break;
	}
	xmlXPathReleaseObject(ctxt->context, arg1);
	xmlXPathReleaseObject(ctxt->context, arg2);
	return(ret);
    }

    return (xmlXPathEqualValuesCommon(ctxt, arg1, arg2));
}

/**
 * Implement the equal operation on XPath objects content: `arg1` == `arg2`
 *
 * @param ctxt  the XPath Parser context
 * @returns 0 or 1 depending on the results of the test.
 */
int
xmlXPathNotEqualValues(xmlXPathParserContextPtr ctxt) {
    xmlXPathObjectPtr arg1, arg2, argtmp;
    int ret = 0;

    if ((ctxt == NULL) || (ctxt->context == NULL)) return(0);
    arg2 = xmlXPathValuePop(ctxt);
    arg1 = xmlXPathValuePop(ctxt);
    if ((arg1 == NULL) || (arg2 == NULL)) {
	if (arg1 != NULL)
	    xmlXPathReleaseObject(ctxt->context, arg1);
	else
	    xmlXPathReleaseObject(ctxt->context, arg2);
	XP_ERROR0(XPATH_INVALID_OPERAND);
    }

    if (arg1 == arg2) {
	xmlXPathReleaseObject(ctxt->context, arg1);
        return(0);
    }

    /*
     *If either argument is a nodeset, it's a 'special case'
     */
    if ((arg2->type == XPATH_NODESET) || (arg2->type == XPATH_XSLT_TREE) ||
      (arg1->type == XPATH_NODESET) || (arg1->type == XPATH_XSLT_TREE)) {
	/*
	 *Hack it to assure arg1 is the nodeset
	 */
	if ((arg1->type != XPATH_NODESET) && (arg1->type != XPATH_XSLT_TREE)) {
		argtmp = arg2;
		arg2 = arg1;
		arg1 = argtmp;
	}
	switch (arg2->type) {
	    case XPATH_UNDEFINED:
		break;
	    case XPATH_NODESET:
	    case XPATH_XSLT_TREE:
		ret = xmlXPathEqualNodeSets(ctxt, arg1, arg2, 1);
		break;
	    case XPATH_BOOLEAN:
		if ((arg1->nodesetval == NULL) ||
		  (arg1->nodesetval->nodeNr == 0)) ret = 0;
		else
		    ret = 1;
		ret = (ret != arg2->boolval);
		break;
	    case XPATH_NUMBER:
		ret = xmlXPathEqualNodeSetFloat(ctxt, arg1, arg2->floatval, 1);
		break;
	    case XPATH_STRING:
		ret = xmlXPathEqualNodeSetString(ctxt, arg1,
                                                 arg2->stringval, 1);
		break;
	    case XPATH_USERS:
		/* TODO */
		break;
	}
	xmlXPathReleaseObject(ctxt->context, arg1);
	xmlXPathReleaseObject(ctxt->context, arg2);
	return(ret);
    }

    return (!xmlXPathEqualValuesCommon(ctxt, arg1, arg2));
}

/**
 * Implement the compare operation on XPath objects:
 *     `arg1` < `arg2`    (1, 1, ...
 *     `arg1` <= `arg2`   (1, 0, ...
 *     `arg1` > `arg2`    (0, 1, ...
 *     `arg1` >= `arg2`   (0, 0, ...
 *
 * When neither object to be compared is a node-set and the operator is
 * <=, <, >=, >, then the objects are compared by converted both objects
 * to numbers and comparing the numbers according to IEEE 754. The <
 * comparison will be true if and only if the first number is less than the
 * second number. The <= comparison will be true if and only if the first
 * number is less than or equal to the second number. The > comparison
 * will be true if and only if the first number is greater than the second
 * number. The >= comparison will be true if and only if the first number
 * is greater than or equal to the second number.
 *
 * @param ctxt  the XPath Parser context
 * @param inf  less than (1) or greater than (0)
 * @param strict  is the comparison strict
 * @returns 1 if the comparison succeeded, 0 if it failed
 */
int
xmlXPathCompareValues(xmlXPathParserContextPtr ctxt, int inf, int strict) {
    int ret = 0, arg1i = 0, arg2i = 0;
    xmlXPathObjectPtr arg1, arg2;

    if ((ctxt == NULL) || (ctxt->context == NULL)) return(0);
    arg2 = xmlXPathValuePop(ctxt);
    arg1 = xmlXPathValuePop(ctxt);
    if ((arg1 == NULL) || (arg2 == NULL)) {
	if (arg1 != NULL)
	    xmlXPathReleaseObject(ctxt->context, arg1);
	else
	    xmlXPathReleaseObject(ctxt->context, arg2);
	XP_ERROR0(XPATH_INVALID_OPERAND);
    }

    if ((arg2->type == XPATH_NODESET) || (arg2->type == XPATH_XSLT_TREE) ||
      (arg1->type == XPATH_NODESET) || (arg1->type == XPATH_XSLT_TREE)) {
	/*
	 * If either argument is a XPATH_NODESET or XPATH_XSLT_TREE the two arguments
	 * are not freed from within this routine; they will be freed from the
	 * called routine, e.g. xmlXPathCompareNodeSets or xmlXPathCompareNodeSetValue
	 */
	if (((arg2->type == XPATH_NODESET) || (arg2->type == XPATH_XSLT_TREE)) &&
	  ((arg1->type == XPATH_NODESET) || (arg1->type == XPATH_XSLT_TREE))){
	    ret = xmlXPathCompareNodeSets(ctxt, inf, strict, arg1, arg2);
	} else {
	    if ((arg1->type == XPATH_NODESET) || (arg1->type == XPATH_XSLT_TREE)) {
		ret = xmlXPathCompareNodeSetValue(ctxt, inf, strict,
			                          arg1, arg2);
	    } else {
		ret = xmlXPathCompareNodeSetValue(ctxt, !inf, strict,
			                          arg2, arg1);
	    }
	}
	return(ret);
    }

    if (arg1->type != XPATH_NUMBER) {
	xmlXPathValuePush(ctxt, arg1);
	xmlXPathNumberFunction(ctxt, 1);
	arg1 = xmlXPathValuePop(ctxt);
    }
    if (arg2->type != XPATH_NUMBER) {
	xmlXPathValuePush(ctxt, arg2);
	xmlXPathNumberFunction(ctxt, 1);
	arg2 = xmlXPathValuePop(ctxt);
    }
    if (ctxt->error)
        goto error;
    /*
     * Add tests for infinity and nan
     * => feedback on 3.4 for Inf and NaN
     */
    /* Hand check NaN and Infinity comparisons */
    if (xmlXPathIsNaN(arg1->floatval) || xmlXPathIsNaN(arg2->floatval)) {
	ret=0;
    } else {
	arg1i=xmlXPathIsInf(arg1->floatval);
	arg2i=xmlXPathIsInf(arg2->floatval);
	if (inf && strict) {
	    if ((arg1i == -1 && arg2i != -1) ||
		(arg2i == 1 && arg1i != 1)) {
		ret = 1;
	    } else if (arg1i == 0 && arg2i == 0) {
		ret = (arg1->floatval < arg2->floatval);
	    } else {
		ret = 0;
	    }
	}
	else if (inf && !strict) {
	    if (arg1i == -1 || arg2i == 1) {
		ret = 1;
	    } else if (arg1i == 0 && arg2i == 0) {
		ret = (arg1->floatval <= arg2->floatval);
	    } else {
		ret = 0;
	    }
	}
	else if (!inf && strict) {
	    if ((arg1i == 1 && arg2i != 1) ||
		(arg2i == -1 && arg1i != -1)) {
		ret = 1;
	    } else if (arg1i == 0 && arg2i == 0) {
		ret = (arg1->floatval > arg2->floatval);
	    } else {
		ret = 0;
	    }
	}
	else if (!inf && !strict) {
	    if (arg1i == 1 || arg2i == -1) {
		ret = 1;
	    } else if (arg1i == 0 && arg2i == 0) {
		ret = (arg1->floatval >= arg2->floatval);
	    } else {
		ret = 0;
	    }
	}
    }
error:
    xmlXPathReleaseObject(ctxt->context, arg1);
    xmlXPathReleaseObject(ctxt->context, arg2);
    return(ret);
}

/**
 * Implement the unary - operation on an XPath object
 * The numeric operators convert their operands to numbers as if
 * by calling the number function.
 *
 * @param ctxt  the XPath Parser context
 */
void
xmlXPathValueFlipSign(xmlXPathParserContextPtr ctxt) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return;
    CAST_TO_NUMBER;
    CHECK_TYPE(XPATH_NUMBER);
    ctxt->value->floatval = -ctxt->value->floatval;
}

/**
 * Implement the add operation on XPath objects:
 * The numeric operators convert their operands to numbers as if
 * by calling the number function.
 *
 * @param ctxt  the XPath Parser context
 */
void
xmlXPathAddValues(xmlXPathParserContextPtr ctxt) {
    xmlXPathObjectPtr arg;
    double val;

    arg = xmlXPathValuePop(ctxt);
    if (arg == NULL)
	XP_ERROR(XPATH_INVALID_OPERAND);
    val = xmlXPathCastToNumberInternal(ctxt, arg);
    xmlXPathReleaseObject(ctxt->context, arg);
    CAST_TO_NUMBER;
    CHECK_TYPE(XPATH_NUMBER);
    ctxt->value->floatval += val;
}

/**
 * Implement the subtraction operation on XPath objects:
 * The numeric operators convert their operands to numbers as if
 * by calling the number function.
 *
 * @param ctxt  the XPath Parser context
 */
void
xmlXPathSubValues(xmlXPathParserContextPtr ctxt) {
    xmlXPathObjectPtr arg;
    double val;

    arg = xmlXPathValuePop(ctxt);
    if (arg == NULL)
	XP_ERROR(XPATH_INVALID_OPERAND);
    val = xmlXPathCastToNumberInternal(ctxt, arg);
    xmlXPathReleaseObject(ctxt->context, arg);
    CAST_TO_NUMBER;
    CHECK_TYPE(XPATH_NUMBER);
    ctxt->value->floatval -= val;
}

/**
 * Implement the multiply operation on XPath objects:
 * The numeric operators convert their operands to numbers as if
 * by calling the number function.
 *
 * @param ctxt  the XPath Parser context
 */
void
xmlXPathMultValues(xmlXPathParserContextPtr ctxt) {
    xmlXPathObjectPtr arg;
    double val;

    arg = xmlXPathValuePop(ctxt);
    if (arg == NULL)
	XP_ERROR(XPATH_INVALID_OPERAND);
    val = xmlXPathCastToNumberInternal(ctxt, arg);
    xmlXPathReleaseObject(ctxt->context, arg);
    CAST_TO_NUMBER;
    CHECK_TYPE(XPATH_NUMBER);
    ctxt->value->floatval *= val;
}

/**
 * Implement the div operation on XPath objects `arg1` / `arg2`.
 * The numeric operators convert their operands to numbers as if
 * by calling the number function.
 *
 * @param ctxt  the XPath Parser context
 */
ATTRIBUTE_NO_SANITIZE("float-divide-by-zero")
void
xmlXPathDivValues(xmlXPathParserContextPtr ctxt) {
    xmlXPathObjectPtr arg;
    double val;

    arg = xmlXPathValuePop(ctxt);
    if (arg == NULL)
	XP_ERROR(XPATH_INVALID_OPERAND);
    val = xmlXPathCastToNumberInternal(ctxt, arg);
    xmlXPathReleaseObject(ctxt->context, arg);
    CAST_TO_NUMBER;
    CHECK_TYPE(XPATH_NUMBER);
    ctxt->value->floatval /= val;
}

/**
 * Implement the mod operation on XPath objects: `arg1` / `arg2`
 * The numeric operators convert their operands to numbers as if
 * by calling the number function.
 *
 * @param ctxt  the XPath Parser context
 */
void
xmlXPathModValues(xmlXPathParserContextPtr ctxt) {
    xmlXPathObjectPtr arg;
    double arg1, arg2;

    arg = xmlXPathValuePop(ctxt);
    if (arg == NULL)
	XP_ERROR(XPATH_INVALID_OPERAND);
    arg2 = xmlXPathCastToNumberInternal(ctxt, arg);
    xmlXPathReleaseObject(ctxt->context, arg);
    CAST_TO_NUMBER;
    CHECK_TYPE(XPATH_NUMBER);
    arg1 = ctxt->value->floatval;
    if (arg2 == 0)
	ctxt->value->floatval = xmlXPathNAN;
    else {
	ctxt->value->floatval = fmod(arg1, arg2);
    }
}

/************************************************************************
 *									*
 *		The traversal functions					*
 *									*
 ************************************************************************/

/*
 * A traversal function enumerates nodes along an axis.
 * Initially it must be called with NULL, and it indicates
 * termination on the axis by returning NULL.
 */
typedef xmlNodePtr (*xmlXPathTraversalFunction)
                    (xmlXPathParserContextPtr ctxt, xmlNodePtr cur);

/*
 * A traversal function enumerates nodes along an axis.
 * Initially it must be called with NULL, and it indicates
 * termination on the axis by returning NULL.
 * The context node of the traversal is specified via `contextNode`.
 */
typedef xmlNodePtr (*xmlXPathTraversalFunctionExt)
                    (xmlNodePtr cur, xmlNodePtr contextNode);

/*
 * Used for merging node sets in xmlXPathCollectAndTest().
 */
typedef xmlNodeSetPtr (*xmlXPathNodeSetMergeFunction)
		    (xmlNodeSetPtr, xmlNodeSetPtr);


/**
 * Traversal function for the "self" direction
 * The self axis contains just the context node itself
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current node in the traversal
 * @returns the next element following that axis
 */
xmlNodePtr
xmlXPathNextSelf(xmlXPathParserContextPtr ctxt, xmlNodePtr cur) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    if (cur == NULL)
        return(ctxt->context->node);
    return(NULL);
}

/**
 * Traversal function for the "child" direction
 * The child axis contains the children of the context node in document order.
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current node in the traversal
 * @returns the next element following that axis
 */
xmlNodePtr
xmlXPathNextChild(xmlXPathParserContextPtr ctxt, xmlNodePtr cur) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    if (cur == NULL) {
	if (ctxt->context->node == NULL) return(NULL);
	switch (ctxt->context->node->type) {
            case XML_ELEMENT_NODE:
            case XML_TEXT_NODE:
            case XML_CDATA_SECTION_NODE:
            case XML_ENTITY_REF_NODE:
            case XML_ENTITY_NODE:
            case XML_PI_NODE:
            case XML_COMMENT_NODE:
            case XML_NOTATION_NODE:
            case XML_DTD_NODE:
		return(ctxt->context->node->children);
            case XML_DOCUMENT_NODE:
            case XML_DOCUMENT_TYPE_NODE:
            case XML_DOCUMENT_FRAG_NODE:
            case XML_HTML_DOCUMENT_NODE:
		return(((xmlDocPtr) ctxt->context->node)->children);
	    case XML_ELEMENT_DECL:
	    case XML_ATTRIBUTE_DECL:
	    case XML_ENTITY_DECL:
            case XML_ATTRIBUTE_NODE:
	    case XML_NAMESPACE_DECL:
	    case XML_XINCLUDE_START:
	    case XML_XINCLUDE_END:
		return(NULL);
	}
	return(NULL);
    }
    if ((cur->type == XML_DOCUMENT_NODE) ||
        (cur->type == XML_HTML_DOCUMENT_NODE))
	return(NULL);
    return(cur->next);
}

/**
 * Traversal function for the "child" direction and nodes of type element.
 * The child axis contains the children of the context node in document order.
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current node in the traversal
 * @returns the next element following that axis
 */
static xmlNodePtr
xmlXPathNextChildElement(xmlXPathParserContextPtr ctxt, xmlNodePtr cur) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    if (cur == NULL) {
	cur = ctxt->context->node;
	if (cur == NULL) return(NULL);
	/*
	* Get the first element child.
	*/
	switch (cur->type) {
            case XML_ELEMENT_NODE:
	    case XML_DOCUMENT_FRAG_NODE:
	    case XML_ENTITY_REF_NODE: /* URGENT TODO: entify-refs as well? */
            case XML_ENTITY_NODE:
		cur = cur->children;
		if (cur != NULL) {
		    if (cur->type == XML_ELEMENT_NODE)
			return(cur);
		    do {
			cur = cur->next;
		    } while ((cur != NULL) &&
			(cur->type != XML_ELEMENT_NODE));
		    return(cur);
		}
		return(NULL);
            case XML_DOCUMENT_NODE:
            case XML_HTML_DOCUMENT_NODE:
		return(xmlDocGetRootElement((xmlDocPtr) cur));
	    default:
		return(NULL);
	}
	return(NULL);
    }
    /*
    * Get the next sibling element node.
    */
    switch (cur->type) {
	case XML_ELEMENT_NODE:
	case XML_TEXT_NODE:
	case XML_ENTITY_REF_NODE:
	case XML_ENTITY_NODE:
	case XML_CDATA_SECTION_NODE:
	case XML_PI_NODE:
	case XML_COMMENT_NODE:
	case XML_XINCLUDE_END:
	    break;
	/* case XML_DTD_NODE: */ /* URGENT TODO: DTD-node as well? */
	default:
	    return(NULL);
    }
    if (cur->next != NULL) {
	if (cur->next->type == XML_ELEMENT_NODE)
	    return(cur->next);
	cur = cur->next;
	do {
	    cur = cur->next;
	} while ((cur != NULL) && (cur->type != XML_ELEMENT_NODE));
	return(cur);
    }
    return(NULL);
}

/**
 * Traversal function for the "descendant" direction
 * the descendant axis contains the descendants of the context node in document
 * order; a descendant is a child or a child of a child and so on.
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current node in the traversal
 * @returns the next element following that axis
 */
xmlNodePtr
xmlXPathNextDescendant(xmlXPathParserContextPtr ctxt, xmlNodePtr cur) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    if (cur == NULL) {
	if (ctxt->context->node == NULL)
	    return(NULL);
	if ((ctxt->context->node->type == XML_ATTRIBUTE_NODE) ||
	    (ctxt->context->node->type == XML_NAMESPACE_DECL))
	    return(NULL);

        if (ctxt->context->node == (xmlNodePtr) ctxt->context->doc)
	    return(ctxt->context->doc->children);
        return(ctxt->context->node->children);
    }

    if (cur->type == XML_NAMESPACE_DECL)
        return(NULL);
    if (cur->children != NULL) {
	/*
	 * Do not descend on entities declarations
	 */
	if (cur->children->type != XML_ENTITY_DECL) {
	    cur = cur->children;
	    /*
	     * Skip DTDs
	     */
	    if (cur->type != XML_DTD_NODE)
		return(cur);
	}
    }

    if (cur == ctxt->context->node) return(NULL);

    while (cur->next != NULL) {
	cur = cur->next;
	if ((cur->type != XML_ENTITY_DECL) &&
	    (cur->type != XML_DTD_NODE))
	    return(cur);
    }

    do {
        cur = cur->parent;
	if (cur == NULL) break;
	if (cur == ctxt->context->node) return(NULL);
	if (cur->next != NULL) {
	    cur = cur->next;
	    return(cur);
	}
    } while (cur != NULL);
    return(cur);
}

/**
 * Traversal function for the "descendant-or-self" direction
 * the descendant-or-self axis contains the context node and the descendants
 * of the context node in document order; thus the context node is the first
 * node on the axis, and the first child of the context node is the second node
 * on the axis
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current node in the traversal
 * @returns the next element following that axis
 */
xmlNodePtr
xmlXPathNextDescendantOrSelf(xmlXPathParserContextPtr ctxt, xmlNodePtr cur) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    if (cur == NULL)
        return(ctxt->context->node);

    if (ctxt->context->node == NULL)
        return(NULL);
    if ((ctxt->context->node->type == XML_ATTRIBUTE_NODE) ||
        (ctxt->context->node->type == XML_NAMESPACE_DECL))
        return(NULL);

    return(xmlXPathNextDescendant(ctxt, cur));
}

/**
 * Traversal function for the "parent" direction
 * The parent axis contains the parent of the context node, if there is one.
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current node in the traversal
 * @returns the next element following that axis
 */
xmlNodePtr
xmlXPathNextParent(xmlXPathParserContextPtr ctxt, xmlNodePtr cur) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    /*
     * the parent of an attribute or namespace node is the element
     * to which the attribute or namespace node is attached
     * Namespace handling !!!
     */
    if (cur == NULL) {
	if (ctxt->context->node == NULL) return(NULL);
	switch (ctxt->context->node->type) {
            case XML_ELEMENT_NODE:
            case XML_TEXT_NODE:
            case XML_CDATA_SECTION_NODE:
            case XML_ENTITY_REF_NODE:
            case XML_ENTITY_NODE:
            case XML_PI_NODE:
            case XML_COMMENT_NODE:
            case XML_NOTATION_NODE:
            case XML_DTD_NODE:
	    case XML_ELEMENT_DECL:
	    case XML_ATTRIBUTE_DECL:
	    case XML_XINCLUDE_START:
	    case XML_XINCLUDE_END:
	    case XML_ENTITY_DECL:
		if (ctxt->context->node->parent == NULL)
		    return((xmlNodePtr) ctxt->context->doc);
		if ((ctxt->context->node->parent->type == XML_ELEMENT_NODE) &&
		    ((ctxt->context->node->parent->name[0] == ' ') ||
		     (xmlStrEqual(ctxt->context->node->parent->name,
				 BAD_CAST "fake node libxslt"))))
		    return(NULL);
		return(ctxt->context->node->parent);
            case XML_ATTRIBUTE_NODE: {
		xmlAttrPtr att = (xmlAttrPtr) ctxt->context->node;

		return(att->parent);
	    }
            case XML_DOCUMENT_NODE:
            case XML_DOCUMENT_TYPE_NODE:
            case XML_DOCUMENT_FRAG_NODE:
            case XML_HTML_DOCUMENT_NODE:
                return(NULL);
	    case XML_NAMESPACE_DECL: {
		xmlNsPtr ns = (xmlNsPtr) ctxt->context->node;

		if ((ns->next != NULL) &&
		    (ns->next->type != XML_NAMESPACE_DECL))
		    return((xmlNodePtr) ns->next);
                return(NULL);
	    }
	}
    }
    return(NULL);
}

/**
 * Traversal function for the "ancestor" direction
 * the ancestor axis contains the ancestors of the context node; the ancestors
 * of the context node consist of the parent of context node and the parent's
 * parent and so on; the nodes are ordered in reverse document order; thus the
 * parent is the first node on the axis, and the parent's parent is the second
 * node on the axis
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current node in the traversal
 * @returns the next element following that axis
 */
xmlNodePtr
xmlXPathNextAncestor(xmlXPathParserContextPtr ctxt, xmlNodePtr cur) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    /*
     * the parent of an attribute or namespace node is the element
     * to which the attribute or namespace node is attached
     * !!!!!!!!!!!!!
     */
    if (cur == NULL) {
	if (ctxt->context->node == NULL) return(NULL);
	switch (ctxt->context->node->type) {
            case XML_ELEMENT_NODE:
            case XML_TEXT_NODE:
            case XML_CDATA_SECTION_NODE:
            case XML_ENTITY_REF_NODE:
            case XML_ENTITY_NODE:
            case XML_PI_NODE:
            case XML_COMMENT_NODE:
	    case XML_DTD_NODE:
	    case XML_ELEMENT_DECL:
	    case XML_ATTRIBUTE_DECL:
	    case XML_ENTITY_DECL:
            case XML_NOTATION_NODE:
	    case XML_XINCLUDE_START:
	    case XML_XINCLUDE_END:
		if (ctxt->context->node->parent == NULL)
		    return((xmlNodePtr) ctxt->context->doc);
		if ((ctxt->context->node->parent->type == XML_ELEMENT_NODE) &&
		    ((ctxt->context->node->parent->name[0] == ' ') ||
		     (xmlStrEqual(ctxt->context->node->parent->name,
				 BAD_CAST "fake node libxslt"))))
		    return(NULL);
		return(ctxt->context->node->parent);
            case XML_ATTRIBUTE_NODE: {
		xmlAttrPtr tmp = (xmlAttrPtr) ctxt->context->node;

		return(tmp->parent);
	    }
            case XML_DOCUMENT_NODE:
            case XML_DOCUMENT_TYPE_NODE:
            case XML_DOCUMENT_FRAG_NODE:
            case XML_HTML_DOCUMENT_NODE:
                return(NULL);
	    case XML_NAMESPACE_DECL: {
		xmlNsPtr ns = (xmlNsPtr) ctxt->context->node;

		if ((ns->next != NULL) &&
		    (ns->next->type != XML_NAMESPACE_DECL))
		    return((xmlNodePtr) ns->next);
		/* Bad, how did that namespace end up here ? */
                return(NULL);
	    }
	}
	return(NULL);
    }
    if (cur == ctxt->context->doc->children)
	return((xmlNodePtr) ctxt->context->doc);
    if (cur == (xmlNodePtr) ctxt->context->doc)
	return(NULL);
    switch (cur->type) {
	case XML_ELEMENT_NODE:
	case XML_TEXT_NODE:
	case XML_CDATA_SECTION_NODE:
	case XML_ENTITY_REF_NODE:
	case XML_ENTITY_NODE:
	case XML_PI_NODE:
	case XML_COMMENT_NODE:
	case XML_NOTATION_NODE:
	case XML_DTD_NODE:
        case XML_ELEMENT_DECL:
        case XML_ATTRIBUTE_DECL:
        case XML_ENTITY_DECL:
	case XML_XINCLUDE_START:
	case XML_XINCLUDE_END:
	    if (cur->parent == NULL)
		return(NULL);
	    if ((cur->parent->type == XML_ELEMENT_NODE) &&
		((cur->parent->name[0] == ' ') ||
		 (xmlStrEqual(cur->parent->name,
			      BAD_CAST "fake node libxslt"))))
		return(NULL);
	    return(cur->parent);
	case XML_ATTRIBUTE_NODE: {
	    xmlAttrPtr att = (xmlAttrPtr) cur;

	    return(att->parent);
	}
	case XML_NAMESPACE_DECL: {
	    xmlNsPtr ns = (xmlNsPtr) cur;

	    if ((ns->next != NULL) &&
	        (ns->next->type != XML_NAMESPACE_DECL))
	        return((xmlNodePtr) ns->next);
	    /* Bad, how did that namespace end up here ? */
            return(NULL);
	}
	case XML_DOCUMENT_NODE:
	case XML_DOCUMENT_TYPE_NODE:
	case XML_DOCUMENT_FRAG_NODE:
	case XML_HTML_DOCUMENT_NODE:
	    return(NULL);
    }
    return(NULL);
}

/**
 * Traversal function for the "ancestor-or-self" direction
 * he ancestor-or-self axis contains the context node and ancestors of
 * the context node in reverse document order; thus the context node is
 * the first node on the axis, and the context node's parent the second;
 * parent here is defined the same as with the parent axis.
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current node in the traversal
 * @returns the next element following that axis
 */
xmlNodePtr
xmlXPathNextAncestorOrSelf(xmlXPathParserContextPtr ctxt, xmlNodePtr cur) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    if (cur == NULL)
        return(ctxt->context->node);
    return(xmlXPathNextAncestor(ctxt, cur));
}

/**
 * Traversal function for the "following-sibling" direction
 * The following-sibling axis contains the following siblings of the context
 * node in document order.
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current node in the traversal
 * @returns the next element following that axis
 */
xmlNodePtr
xmlXPathNextFollowingSibling(xmlXPathParserContextPtr ctxt, xmlNodePtr cur) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    if ((ctxt->context->node->type == XML_ATTRIBUTE_NODE) ||
	(ctxt->context->node->type == XML_NAMESPACE_DECL))
	return(NULL);
    if (cur == (xmlNodePtr) ctxt->context->doc)
        return(NULL);
    if (cur == NULL)
        return(ctxt->context->node->next);
    return(cur->next);
}

/**
 * Traversal function for the "preceding-sibling" direction
 * The preceding-sibling axis contains the preceding siblings of the context
 * node in reverse document order; the first preceding sibling is first on the
 * axis; the sibling preceding that node is the second on the axis and so on.
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current node in the traversal
 * @returns the next element following that axis
 */
xmlNodePtr
xmlXPathNextPrecedingSibling(xmlXPathParserContextPtr ctxt, xmlNodePtr cur) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    if ((ctxt->context->node->type == XML_ATTRIBUTE_NODE) ||
	(ctxt->context->node->type == XML_NAMESPACE_DECL))
	return(NULL);
    if (cur == (xmlNodePtr) ctxt->context->doc)
        return(NULL);
    if (cur == NULL)
        return(ctxt->context->node->prev);
    if ((cur->prev != NULL) && (cur->prev->type == XML_DTD_NODE)) {
	cur = cur->prev;
	if (cur == NULL)
	    return(ctxt->context->node->prev);
    }
    return(cur->prev);
}

/**
 * Traversal function for the "following" direction
 * The following axis contains all nodes in the same document as the context
 * node that are after the context node in document order, excluding any
 * descendants and excluding attribute nodes and namespace nodes; the nodes
 * are ordered in document order
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current node in the traversal
 * @returns the next element following that axis
 */
xmlNodePtr
xmlXPathNextFollowing(xmlXPathParserContextPtr ctxt, xmlNodePtr cur) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    if ((cur != NULL) && (cur->type  != XML_ATTRIBUTE_NODE) &&
        (cur->type != XML_NAMESPACE_DECL) && (cur->children != NULL))
        return(cur->children);

    if (cur == NULL) {
        cur = ctxt->context->node;
        if (cur->type == XML_ATTRIBUTE_NODE) {
            cur = cur->parent;
        } else if (cur->type == XML_NAMESPACE_DECL) {
            xmlNsPtr ns = (xmlNsPtr) cur;

            if ((ns->next == NULL) ||
                (ns->next->type == XML_NAMESPACE_DECL))
                return (NULL);
            cur = (xmlNodePtr) ns->next;
        }
    }
    if (cur == NULL) return(NULL) ; /* ERROR */
    if (cur->next != NULL) return(cur->next) ;
    do {
        cur = cur->parent;
        if (cur == NULL) break;
        if (cur == (xmlNodePtr) ctxt->context->doc) return(NULL);
        if (cur->next != NULL) return(cur->next);
    } while (cur != NULL);
    return(cur);
}

/*
 * @param ancestor  the ancestor node
 * @param node  the current node
 *
 * Check that `ancestor` is a `node`'s ancestor
 *
 * @returns 1 if `ancestor` is a `node`'s ancestor, 0 otherwise.
 */
static int
xmlXPathIsAncestor(xmlNodePtr ancestor, xmlNodePtr node) {
    if ((ancestor == NULL) || (node == NULL)) return(0);
    if (node->type == XML_NAMESPACE_DECL)
        return(0);
    if (ancestor->type == XML_NAMESPACE_DECL)
        return(0);
    /* nodes need to be in the same document */
    if (ancestor->doc != node->doc) return(0);
    /* avoid searching if ancestor or node is the root node */
    if (ancestor == (xmlNodePtr) node->doc) return(1);
    if (node == (xmlNodePtr) ancestor->doc) return(0);
    while (node->parent != NULL) {
        if (node->parent == ancestor)
            return(1);
	node = node->parent;
    }
    return(0);
}

/**
 * Traversal function for the "preceding" direction
 * the preceding axis contains all nodes in the same document as the context
 * node that are before the context node in document order, excluding any
 * ancestors and excluding attribute nodes and namespace nodes; the nodes are
 * ordered in reverse document order
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current node in the traversal
 * @returns the next element following that axis
 */
xmlNodePtr
xmlXPathNextPreceding(xmlXPathParserContextPtr ctxt, xmlNodePtr cur)
{
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    if (cur == NULL) {
        cur = ctxt->context->node;
        if (cur->type == XML_ATTRIBUTE_NODE) {
            cur = cur->parent;
        } else if (cur->type == XML_NAMESPACE_DECL) {
            xmlNsPtr ns = (xmlNsPtr) cur;

            if ((ns->next == NULL) ||
                (ns->next->type == XML_NAMESPACE_DECL))
                return (NULL);
            cur = (xmlNodePtr) ns->next;
        }
    }
    if ((cur == NULL) || (cur->type == XML_NAMESPACE_DECL))
	return (NULL);
    if ((cur->prev != NULL) && (cur->prev->type == XML_DTD_NODE))
	cur = cur->prev;
    do {
        if (cur->prev != NULL) {
            for (cur = cur->prev; cur->last != NULL; cur = cur->last) ;
            return (cur);
        }

        cur = cur->parent;
        if (cur == NULL)
            return (NULL);
        if (cur == ctxt->context->doc->children)
            return (NULL);
    } while (xmlXPathIsAncestor(cur, ctxt->context->node));
    return (cur);
}

/**
 * Traversal function for the "preceding" direction
 * the preceding axis contains all nodes in the same document as the context
 * node that are before the context node in document order, excluding any
 * ancestors and excluding attribute nodes and namespace nodes; the nodes are
 * ordered in reverse document order
 * This is a faster implementation but internal only since it requires a
 * state kept in the parser context: ctxt->ancestor.
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current node in the traversal
 * @returns the next element following that axis
 */
static xmlNodePtr
xmlXPathNextPrecedingInternal(xmlXPathParserContextPtr ctxt,
                              xmlNodePtr cur)
{
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    if (cur == NULL) {
        cur = ctxt->context->node;
        if (cur == NULL)
            return (NULL);
        if (cur->type == XML_ATTRIBUTE_NODE) {
            cur = cur->parent;
        } else if (cur->type == XML_NAMESPACE_DECL) {
            xmlNsPtr ns = (xmlNsPtr) cur;

            if ((ns->next == NULL) ||
                (ns->next->type == XML_NAMESPACE_DECL))
                return (NULL);
            cur = (xmlNodePtr) ns->next;
        }
        ctxt->ancestor = cur->parent;
    }
    if (cur->type == XML_NAMESPACE_DECL)
        return(NULL);
    if ((cur->prev != NULL) && (cur->prev->type == XML_DTD_NODE))
	cur = cur->prev;
    while (cur->prev == NULL) {
        cur = cur->parent;
        if (cur == NULL)
            return (NULL);
        if (cur == ctxt->context->doc->children)
            return (NULL);
        if (cur != ctxt->ancestor)
            return (cur);
        ctxt->ancestor = cur->parent;
    }
    cur = cur->prev;
    while (cur->last != NULL)
        cur = cur->last;
    return (cur);
}

/**
 * Traversal function for the "namespace" direction
 * the namespace axis contains the namespace nodes of the context node;
 * the order of nodes on this axis is implementation-defined; the axis will
 * be empty unless the context node is an element
 *
 * We keep the XML namespace node at the end of the list.
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current attribute in the traversal
 * @returns the next element following that axis
 */
xmlNodePtr
xmlXPathNextNamespace(xmlXPathParserContextPtr ctxt, xmlNodePtr cur) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    if (ctxt->context->node->type != XML_ELEMENT_NODE) return(NULL);
    if (cur == NULL) {
        if (ctxt->context->tmpNsList != NULL)
	    xmlFree(ctxt->context->tmpNsList);
	ctxt->context->tmpNsNr = 0;
        if (xmlGetNsListSafe(ctxt->context->doc, ctxt->context->node,
                             &ctxt->context->tmpNsList) < 0) {
            xmlXPathPErrMemory(ctxt);
            return(NULL);
        }
        if (ctxt->context->tmpNsList != NULL) {
            while (ctxt->context->tmpNsList[ctxt->context->tmpNsNr] != NULL) {
                ctxt->context->tmpNsNr++;
            }
        }
	return((xmlNodePtr) xmlXPathXMLNamespace);
    }
    if (ctxt->context->tmpNsNr > 0) {
	return (xmlNodePtr)ctxt->context->tmpNsList[--ctxt->context->tmpNsNr];
    } else {
	if (ctxt->context->tmpNsList != NULL)
	    xmlFree(ctxt->context->tmpNsList);
	ctxt->context->tmpNsList = NULL;
	return(NULL);
    }
}

/**
 * Traversal function for the "attribute" direction
 * TODO: support DTD inherited default attributes
 *
 * @param ctxt  the XPath Parser context
 * @param cur  the current attribute in the traversal
 * @returns the next element following that axis
 */
xmlNodePtr
xmlXPathNextAttribute(xmlXPathParserContextPtr ctxt, xmlNodePtr cur) {
    if ((ctxt == NULL) || (ctxt->context == NULL)) return(NULL);
    if (ctxt->context->node == NULL)
	return(NULL);
    if (ctxt->context->node->type != XML_ELEMENT_NODE)
	return(NULL);
    if (cur == NULL) {
        if (ctxt->context->node == (xmlNodePtr) ctxt->context->doc)
	    return(NULL);
        return((xmlNodePtr)ctxt->context->node->properties);
    }
    return((xmlNodePtr)cur->next);
}

/************************************************************************
 *									*
 *		NodeTest Functions					*
 *									*
 ************************************************************************/

#define IS_FUNCTION			200


/************************************************************************
 *									*
 *		Implicit tree core function library			*
 *									*
 ************************************************************************/

/**
 * Initialize the context to the root of the document
 *
 * @param ctxt  the XPath Parser context
 */
void
xmlXPathRoot(xmlXPathParserContextPtr ctxt) {
    if ((ctxt == NULL) || (ctxt->context == NULL))
	return;
    xmlXPathValuePush(ctxt, xmlXPathCacheNewNodeSet(ctxt,
                                            (xmlNodePtr) ctxt->context->doc));
}

/************************************************************************
 *									*
 *		The explicit core function library			*
 *http://www.w3.org/Style/XSL/Group/1999/07/xpath-19990705.html#corelib	*
 *									*
 ************************************************************************/


/**
 * Implement the last() XPath function
 *    number last()
 * The last function returns the number of nodes in the context node list.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathLastFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    CHECK_ARITY(0);
    if (ctxt->context->contextSize >= 0) {
	xmlXPathValuePush(ctxt,
	    xmlXPathCacheNewFloat(ctxt, (double) ctxt->context->contextSize));
    } else {
	XP_ERROR(XPATH_INVALID_CTXT_SIZE);
    }
}

/**
 * Implement the position() XPath function
 *    number position()
 * The position function returns the position of the context node in the
 * context node list. The first position is 1, and so the last position
 * will be equal to last().
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathPositionFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    CHECK_ARITY(0);
    if (ctxt->context->proximityPosition >= 0) {
	xmlXPathValuePush(ctxt, xmlXPathCacheNewFloat(ctxt,
            (double) ctxt->context->proximityPosition));
    } else {
	XP_ERROR(XPATH_INVALID_CTXT_POSITION);
    }
}

/**
 * Implement the count() XPath function
 *    number count(node-set)
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathCountFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr cur;

    CHECK_ARITY(1);
    if ((ctxt->value == NULL) ||
	((ctxt->value->type != XPATH_NODESET) &&
	 (ctxt->value->type != XPATH_XSLT_TREE)))
	XP_ERROR(XPATH_INVALID_TYPE);
    cur = xmlXPathValuePop(ctxt);

    if ((cur == NULL) || (cur->nodesetval == NULL))
	xmlXPathValuePush(ctxt, xmlXPathCacheNewFloat(ctxt, 0.0));
    else
	xmlXPathValuePush(ctxt, xmlXPathCacheNewFloat(ctxt,
	    (double) cur->nodesetval->nodeNr));
    xmlXPathReleaseObject(ctxt->context, cur);
}

/**
 * Selects elements by their unique ID.
 *
 * @param doc  the document
 * @param ids  a whitespace separated list of IDs
 * @returns a node-set of selected elements.
 */
static xmlNodeSetPtr
xmlXPathGetElementsByIds (xmlDocPtr doc, const xmlChar *ids) {
    xmlNodeSetPtr ret;
    const xmlChar *cur = ids;
    xmlChar *ID;
    xmlAttrPtr attr;
    xmlNodePtr elem = NULL;

    if (ids == NULL) return(NULL);

    ret = xmlXPathNodeSetCreate(NULL);
    if (ret == NULL)
        return(ret);

    while (IS_BLANK_CH(*cur)) cur++;
    while (*cur != 0) {
	while ((!IS_BLANK_CH(*cur)) && (*cur != 0))
	    cur++;

        ID = xmlStrndup(ids, cur - ids);
	if (ID == NULL) {
            xmlXPathFreeNodeSet(ret);
            return(NULL);
        }
        /*
         * We used to check the fact that the value passed
         * was an NCName, but this generated much troubles for
         * me and Aleksey Sanin, people blatantly violated that
         * constraint, like Visa3D spec.
         * if (xmlValidateNCName(ID, 1) == 0)
         */
        attr = xmlGetID(doc, ID);
        xmlFree(ID);
        if (attr != NULL) {
            if (attr->type == XML_ATTRIBUTE_NODE)
                elem = attr->parent;
            else if (attr->type == XML_ELEMENT_NODE)
                elem = (xmlNodePtr) attr;
            else
                elem = NULL;
            if (elem != NULL) {
                if (xmlXPathNodeSetAdd(ret, elem) < 0) {
                    xmlXPathFreeNodeSet(ret);
                    return(NULL);
                }
            }
        }

	while (IS_BLANK_CH(*cur)) cur++;
	ids = cur;
    }
    return(ret);
}

/**
 * Implement the id() XPath function
 *    node-set id(object)
 * The id function selects elements by their unique ID
 * (see [5.2.1 Unique IDs]). When the argument to id is of type node-set,
 * then the result is the union of the result of applying id to the
 * string value of each of the nodes in the argument node-set. When the
 * argument to id is of any other type, the argument is converted to a
 * string as if by a call to the string function; the string is split
 * into a whitespace-separated list of tokens (whitespace is any sequence
 * of characters matching the production S); the result is a node-set
 * containing the elements in the same document as the context node that
 * have a unique ID equal to any of the tokens in the list.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathIdFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlChar *tokens;
    xmlNodeSetPtr ret;
    xmlXPathObjectPtr obj;

    CHECK_ARITY(1);
    obj = xmlXPathValuePop(ctxt);
    if (obj == NULL) XP_ERROR(XPATH_INVALID_OPERAND);
    if ((obj->type == XPATH_NODESET) || (obj->type == XPATH_XSLT_TREE)) {
	xmlNodeSetPtr ns;
	int i;

	ret = xmlXPathNodeSetCreate(NULL);
        if (ret == NULL)
            xmlXPathPErrMemory(ctxt);

	if (obj->nodesetval != NULL) {
	    for (i = 0; i < obj->nodesetval->nodeNr; i++) {
		tokens =
		    xmlXPathCastNodeToString(obj->nodesetval->nodeTab[i]);
                if (tokens == NULL)
                    xmlXPathPErrMemory(ctxt);
		ns = xmlXPathGetElementsByIds(ctxt->context->doc, tokens);
                if (ns == NULL)
                    xmlXPathPErrMemory(ctxt);
		ret = xmlXPathNodeSetMerge(ret, ns);
                if (ret == NULL)
                    xmlXPathPErrMemory(ctxt);
		xmlXPathFreeNodeSet(ns);
		if (tokens != NULL)
		    xmlFree(tokens);
	    }
	}
	xmlXPathReleaseObject(ctxt->context, obj);
	xmlXPathValuePush(ctxt, xmlXPathCacheWrapNodeSet(ctxt, ret));
	return;
    }
    tokens = xmlXPathCastToString(obj);
    if (tokens == NULL)
        xmlXPathPErrMemory(ctxt);
    xmlXPathReleaseObject(ctxt->context, obj);
    ret = xmlXPathGetElementsByIds(ctxt->context->doc, tokens);
    if (ret == NULL)
        xmlXPathPErrMemory(ctxt);
    xmlFree(tokens);
    xmlXPathValuePush(ctxt, xmlXPathCacheWrapNodeSet(ctxt, ret));
}

/**
 * Implement the local-name() XPath function
 *    string local-name(node-set?)
 * The local-name function returns a string containing the local part
 * of the name of the node in the argument node-set that is first in
 * document order. If the node-set is empty or the first node has no
 * name, an empty string is returned. If the argument is omitted it
 * defaults to the context node.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathLocalNameFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr cur;

    if (ctxt == NULL) return;

    if (nargs == 0) {
	xmlXPathValuePush(ctxt, xmlXPathCacheNewNodeSet(ctxt, ctxt->context->node));
	nargs = 1;
    }

    CHECK_ARITY(1);
    if ((ctxt->value == NULL) ||
	((ctxt->value->type != XPATH_NODESET) &&
	 (ctxt->value->type != XPATH_XSLT_TREE)))
	XP_ERROR(XPATH_INVALID_TYPE);
    cur = xmlXPathValuePop(ctxt);

    if ((cur->nodesetval == NULL) || (cur->nodesetval->nodeNr == 0)) {
	xmlXPathValuePush(ctxt, xmlXPathCacheNewCString(ctxt, ""));
    } else {
	int i = 0; /* Should be first in document order !!!!! */
	switch (cur->nodesetval->nodeTab[i]->type) {
	case XML_ELEMENT_NODE:
	case XML_ATTRIBUTE_NODE:
	case XML_PI_NODE:
	    if (cur->nodesetval->nodeTab[i]->name[0] == ' ')
		xmlXPathValuePush(ctxt, xmlXPathCacheNewCString(ctxt, ""));
	    else
		xmlXPathValuePush(ctxt, xmlXPathCacheNewString(ctxt,
			cur->nodesetval->nodeTab[i]->name));
	    break;
	case XML_NAMESPACE_DECL:
	    xmlXPathValuePush(ctxt, xmlXPathCacheNewString(ctxt,
			((xmlNsPtr)cur->nodesetval->nodeTab[i])->prefix));
	    break;
	default:
	    xmlXPathValuePush(ctxt, xmlXPathCacheNewCString(ctxt, ""));
	}
    }
    xmlXPathReleaseObject(ctxt->context, cur);
}

/**
 * Implement the namespace-uri() XPath function
 *    string namespace-uri(node-set?)
 * The namespace-uri function returns a string containing the
 * namespace URI of the expanded name of the node in the argument
 * node-set that is first in document order. If the node-set is empty,
 * the first node has no name, or the expanded name has no namespace
 * URI, an empty string is returned. If the argument is omitted it
 * defaults to the context node.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathNamespaceURIFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr cur;

    if (ctxt == NULL) return;

    if (nargs == 0) {
	xmlXPathValuePush(ctxt, xmlXPathCacheNewNodeSet(ctxt, ctxt->context->node));
	nargs = 1;
    }
    CHECK_ARITY(1);
    if ((ctxt->value == NULL) ||
	((ctxt->value->type != XPATH_NODESET) &&
	 (ctxt->value->type != XPATH_XSLT_TREE)))
	XP_ERROR(XPATH_INVALID_TYPE);
    cur = xmlXPathValuePop(ctxt);

    if ((cur->nodesetval == NULL) || (cur->nodesetval->nodeNr == 0)) {
	xmlXPathValuePush(ctxt, xmlXPathCacheNewCString(ctxt, ""));
    } else {
	int i = 0; /* Should be first in document order !!!!! */
	switch (cur->nodesetval->nodeTab[i]->type) {
	case XML_ELEMENT_NODE:
	case XML_ATTRIBUTE_NODE:
	    if (cur->nodesetval->nodeTab[i]->ns == NULL)
		xmlXPathValuePush(ctxt, xmlXPathCacheNewCString(ctxt, ""));
	    else
		xmlXPathValuePush(ctxt, xmlXPathCacheNewString(ctxt,
			  cur->nodesetval->nodeTab[i]->ns->href));
	    break;
	default:
	    xmlXPathValuePush(ctxt, xmlXPathCacheNewCString(ctxt, ""));
	}
    }
    xmlXPathReleaseObject(ctxt->context, cur);
}

/**
 * Implement the name() XPath function
 *    string name(node-set?)
 * The name function returns a string containing a QName representing
 * the name of the node in the argument node-set that is first in document
 * order. The QName must represent the name with respect to the namespace
 * declarations in effect on the node whose name is being represented.
 * Typically, this will be the form in which the name occurred in the XML
 * source. This need not be the case if there are namespace declarations
 * in effect on the node that associate multiple prefixes with the same
 * namespace. However, an implementation may include information about
 * the original prefix in its representation of nodes; in this case, an
 * implementation can ensure that the returned string is always the same
 * as the QName used in the XML source. If the argument it omitted it
 * defaults to the context node.
 * Libxml keep the original prefix so the "real qualified name" used is
 * returned.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
static void
xmlXPathNameFunction(xmlXPathParserContextPtr ctxt, int nargs)
{
    xmlXPathObjectPtr cur;

    if (nargs == 0) {
	xmlXPathValuePush(ctxt, xmlXPathCacheNewNodeSet(ctxt, ctxt->context->node));
        nargs = 1;
    }

    CHECK_ARITY(1);
    if ((ctxt->value == NULL) ||
        ((ctxt->value->type != XPATH_NODESET) &&
         (ctxt->value->type != XPATH_XSLT_TREE)))
        XP_ERROR(XPATH_INVALID_TYPE);
    cur = xmlXPathValuePop(ctxt);

    if ((cur->nodesetval == NULL) || (cur->nodesetval->nodeNr == 0)) {
        xmlXPathValuePush(ctxt, xmlXPathCacheNewCString(ctxt, ""));
    } else {
        int i = 0;              /* Should be first in document order !!!!! */

        switch (cur->nodesetval->nodeTab[i]->type) {
            case XML_ELEMENT_NODE:
            case XML_ATTRIBUTE_NODE:
		if (cur->nodesetval->nodeTab[i]->name[0] == ' ')
		    xmlXPathValuePush(ctxt,
			xmlXPathCacheNewCString(ctxt, ""));
		else if ((cur->nodesetval->nodeTab[i]->ns == NULL) ||
                         (cur->nodesetval->nodeTab[i]->ns->prefix == NULL)) {
		    xmlXPathValuePush(ctxt, xmlXPathCacheNewString(ctxt,
			    cur->nodesetval->nodeTab[i]->name));
		} else {
		    xmlChar *fullname;

		    fullname = xmlBuildQName(cur->nodesetval->nodeTab[i]->name,
				     cur->nodesetval->nodeTab[i]->ns->prefix,
				     NULL, 0);
		    if (fullname == cur->nodesetval->nodeTab[i]->name)
			fullname = xmlStrdup(cur->nodesetval->nodeTab[i]->name);
		    if (fullname == NULL)
                        xmlXPathPErrMemory(ctxt);
		    xmlXPathValuePush(ctxt, xmlXPathCacheWrapString(ctxt, fullname));
                }
                break;
            default:
		xmlXPathValuePush(ctxt, xmlXPathCacheNewNodeSet(ctxt,
		    cur->nodesetval->nodeTab[i]));
                xmlXPathLocalNameFunction(ctxt, 1);
        }
    }
    xmlXPathReleaseObject(ctxt->context, cur);
}


/**
 * Implement the string() XPath function
 *    string string(object?)
 * The string function converts an object to a string as follows:
 *    - A node-set is converted to a string by returning the value of
 *      the node in the node-set that is first in document order.
 *      If the node-set is empty, an empty string is returned.
 *    - A number is converted to a string as follows
 *      + NaN is converted to the string NaN
 *      + positive zero is converted to the string 0
 *      + negative zero is converted to the string 0
 *      + positive infinity is converted to the string Infinity
 *      + negative infinity is converted to the string -Infinity
 *      + if the number is an integer, the number is represented in
 *        decimal form as a Number with no decimal point and no leading
 *        zeros, preceded by a minus sign (-) if the number is negative
 *      + otherwise, the number is represented in decimal form as a
 *        Number including a decimal point with at least one digit
 *        before the decimal point and at least one digit after the
 *        decimal point, preceded by a minus sign (-) if the number
 *        is negative; there must be no leading zeros before the decimal
 *        point apart possibly from the one required digit immediately
 *        before the decimal point; beyond the one required digit
 *        after the decimal point there must be as many, but only as
 *        many, more digits as are needed to uniquely distinguish the
 *        number from all other IEEE 754 numeric values.
 *    - The boolean false value is converted to the string false.
 *      The boolean true value is converted to the string true.
 *
 * If the argument is omitted, it defaults to a node-set with the
 * context node as its only member.
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathStringFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr cur;
    xmlChar *stringval;

    if (ctxt == NULL) return;
    if (nargs == 0) {
        stringval = xmlXPathCastNodeToString(ctxt->context->node);
        if (stringval == NULL)
            xmlXPathPErrMemory(ctxt);
        xmlXPathValuePush(ctxt, xmlXPathCacheWrapString(ctxt, stringval));
	return;
    }

    CHECK_ARITY(1);
    cur = xmlXPathValuePop(ctxt);
    if (cur == NULL) XP_ERROR(XPATH_INVALID_OPERAND);
    if (cur->type != XPATH_STRING) {
        stringval = xmlXPathCastToString(cur);
        if (stringval == NULL)
            xmlXPathPErrMemory(ctxt);
        xmlXPathReleaseObject(ctxt->context, cur);
        cur = xmlXPathCacheWrapString(ctxt, stringval);
    }
    xmlXPathValuePush(ctxt, cur);
}

/**
 * Implement the string-length() XPath function
 *    number string-length(string?)
 * The string-length returns the number of characters in the string
 * (see [3.6 Strings]). If the argument is omitted, it defaults to
 * the context node converted to a string, in other words the value
 * of the context node.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathStringLengthFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr cur;

    if (nargs == 0) {
        if ((ctxt == NULL) || (ctxt->context == NULL))
	    return;
	if (ctxt->context->node == NULL) {
	    xmlXPathValuePush(ctxt, xmlXPathCacheNewFloat(ctxt, 0));
	} else {
	    xmlChar *content;

	    content = xmlXPathCastNodeToString(ctxt->context->node);
            if (content == NULL)
                xmlXPathPErrMemory(ctxt);
	    xmlXPathValuePush(ctxt, xmlXPathCacheNewFloat(ctxt,
		xmlUTF8Strlen(content)));
	    xmlFree(content);
	}
	return;
    }
    CHECK_ARITY(1);
    CAST_TO_STRING;
    CHECK_TYPE(XPATH_STRING);
    cur = xmlXPathValuePop(ctxt);
    xmlXPathValuePush(ctxt, xmlXPathCacheNewFloat(ctxt,
	xmlUTF8Strlen(cur->stringval)));
    xmlXPathReleaseObject(ctxt->context, cur);
}

/**
 * Implement the concat() XPath function
 *    string concat(string, string, string*)
 * The concat function returns the concatenation of its arguments.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathConcatFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr cur, newobj;
    xmlChar *tmp;

    if (ctxt == NULL) return;
    if (nargs < 2) {
	CHECK_ARITY(2);
    }

    CAST_TO_STRING;
    cur = xmlXPathValuePop(ctxt);
    if ((cur == NULL) || (cur->type != XPATH_STRING)) {
	xmlXPathReleaseObject(ctxt->context, cur);
	return;
    }
    nargs--;

    while (nargs > 0) {
	CAST_TO_STRING;
	newobj = xmlXPathValuePop(ctxt);
	if ((newobj == NULL) || (newobj->type != XPATH_STRING)) {
	    xmlXPathReleaseObject(ctxt->context, newobj);
	    xmlXPathReleaseObject(ctxt->context, cur);
	    XP_ERROR(XPATH_INVALID_TYPE);
	}
	tmp = xmlStrcat(newobj->stringval, cur->stringval);
        if (tmp == NULL)
            xmlXPathPErrMemory(ctxt);
	newobj->stringval = cur->stringval;
	cur->stringval = tmp;
	xmlXPathReleaseObject(ctxt->context, newobj);
	nargs--;
    }
    xmlXPathValuePush(ctxt, cur);
}

/**
 * Implement the contains() XPath function
 *    boolean contains(string, string)
 * The contains function returns true if the first argument string
 * contains the second argument string, and otherwise returns false.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathContainsFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr hay, needle;

    CHECK_ARITY(2);
    CAST_TO_STRING;
    CHECK_TYPE(XPATH_STRING);
    needle = xmlXPathValuePop(ctxt);
    CAST_TO_STRING;
    hay = xmlXPathValuePop(ctxt);

    if ((hay == NULL) || (hay->type != XPATH_STRING)) {
	xmlXPathReleaseObject(ctxt->context, hay);
	xmlXPathReleaseObject(ctxt->context, needle);
	XP_ERROR(XPATH_INVALID_TYPE);
    }
    if (xmlStrstr(hay->stringval, needle->stringval))
	xmlXPathValuePush(ctxt, xmlXPathCacheNewBoolean(ctxt, 1));
    else
	xmlXPathValuePush(ctxt, xmlXPathCacheNewBoolean(ctxt, 0));
    xmlXPathReleaseObject(ctxt->context, hay);
    xmlXPathReleaseObject(ctxt->context, needle);
}

/**
 * Implement the starts-with() XPath function
 *    boolean starts-with(string, string)
 * The starts-with function returns true if the first argument string
 * starts with the second argument string, and otherwise returns false.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathStartsWithFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr hay, needle;
    int n;

    CHECK_ARITY(2);
    CAST_TO_STRING;
    CHECK_TYPE(XPATH_STRING);
    needle = xmlXPathValuePop(ctxt);
    CAST_TO_STRING;
    hay = xmlXPathValuePop(ctxt);

    if ((hay == NULL) || (hay->type != XPATH_STRING)) {
	xmlXPathReleaseObject(ctxt->context, hay);
	xmlXPathReleaseObject(ctxt->context, needle);
	XP_ERROR(XPATH_INVALID_TYPE);
    }
    n = xmlStrlen(needle->stringval);
    if (xmlStrncmp(hay->stringval, needle->stringval, n))
        xmlXPathValuePush(ctxt, xmlXPathCacheNewBoolean(ctxt, 0));
    else
        xmlXPathValuePush(ctxt, xmlXPathCacheNewBoolean(ctxt, 1));
    xmlXPathReleaseObject(ctxt->context, hay);
    xmlXPathReleaseObject(ctxt->context, needle);
}

/**
 * Implement the substring() XPath function
 *    string substring(string, number, number?)
 * The substring function returns the substring of the first argument
 * starting at the position specified in the second argument with
 * length specified in the third argument. For example,
 * substring("12345",2,3) returns "234". If the third argument is not
 * specified, it returns the substring starting at the position specified
 * in the second argument and continuing to the end of the string. For
 * example, substring("12345",2) returns "2345".  More precisely, each
 * character in the string (see [3.6 Strings]) is considered to have a
 * numeric position: the position of the first character is 1, the position
 * of the second character is 2 and so on. The returned substring contains
 * those characters for which the position of the character is greater than
 * or equal to the second argument and, if the third argument is specified,
 * less than the sum of the second and third arguments; the comparisons
 * and addition used for the above follow the standard IEEE 754 rules. Thus:
 *  - substring("12345", 1.5, 2.6) returns "234"
 *  - substring("12345", 0, 3) returns "12"
 *  - substring("12345", 0 div 0, 3) returns ""
 *  - substring("12345", 1, 0 div 0) returns ""
 *  - substring("12345", -42, 1 div 0) returns "12345"
 *  - substring("12345", -1 div 0, 1 div 0) returns ""
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathSubstringFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr str, start, len;
    double le=0, in;
    int i = 1, j = INT_MAX;

    if (nargs < 2) {
	CHECK_ARITY(2);
    }
    if (nargs > 3) {
	CHECK_ARITY(3);
    }
    /*
     * take care of possible last (position) argument
    */
    if (nargs == 3) {
	CAST_TO_NUMBER;
	CHECK_TYPE(XPATH_NUMBER);
	len = xmlXPathValuePop(ctxt);
	le = len->floatval;
	xmlXPathReleaseObject(ctxt->context, len);
    }

    CAST_TO_NUMBER;
    CHECK_TYPE(XPATH_NUMBER);
    start = xmlXPathValuePop(ctxt);
    in = start->floatval;
    xmlXPathReleaseObject(ctxt->context, start);
    CAST_TO_STRING;
    CHECK_TYPE(XPATH_STRING);
    str = xmlXPathValuePop(ctxt);

    if (!(in < INT_MAX)) { /* Logical NOT to handle NaNs */
        i = INT_MAX;
    } else if (in >= 1.0) {
        i = (int)in;
        if (in - floor(in) >= 0.5)
            i += 1;
    }

    if (nargs == 3) {
        double rin, rle, end;

        rin = floor(in);
        if (in - rin >= 0.5)
            rin += 1.0;

        rle = floor(le);
        if (le - rle >= 0.5)
            rle += 1.0;

        end = rin + rle;
        if (!(end >= 1.0)) { /* Logical NOT to handle NaNs */
            j = 1;
        } else if (end < INT_MAX) {
            j = (int)end;
        }
    }

    i -= 1;
    j -= 1;

    if ((i < j) && (i < xmlUTF8Strlen(str->stringval))) {
        xmlChar *ret = xmlUTF8Strsub(str->stringval, i, j - i);
        if (ret == NULL)
            xmlXPathPErrMemory(ctxt);
	xmlXPathValuePush(ctxt, xmlXPathCacheNewString(ctxt, ret));
	xmlFree(ret);
    } else {
	xmlXPathValuePush(ctxt, xmlXPathCacheNewCString(ctxt, ""));
    }

    xmlXPathReleaseObject(ctxt->context, str);
}

/**
 * Implement the substring-before() XPath function
 *    string substring-before(string, string)
 * The substring-before function returns the substring of the first
 * argument string that precedes the first occurrence of the second
 * argument string in the first argument string, or the empty string
 * if the first argument string does not contain the second argument
 * string. For example, substring-before("1999/04/01","/") returns 1999.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathSubstringBeforeFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr str = NULL;
    xmlXPathObjectPtr find = NULL;
    const xmlChar *point;
    xmlChar *result;

    CHECK_ARITY(2);
    CAST_TO_STRING;
    find = xmlXPathValuePop(ctxt);
    CAST_TO_STRING;
    str = xmlXPathValuePop(ctxt);
    if (ctxt->error != 0)
        goto error;

    point = xmlStrstr(str->stringval, find->stringval);
    if (point == NULL) {
        result = xmlStrdup(BAD_CAST "");
    } else {
        result = xmlStrndup(str->stringval, point - str->stringval);
    }
    if (result == NULL) {
        xmlXPathPErrMemory(ctxt);
        goto error;
    }
    xmlXPathValuePush(ctxt, xmlXPathCacheWrapString(ctxt, result));

error:
    xmlXPathReleaseObject(ctxt->context, str);
    xmlXPathReleaseObject(ctxt->context, find);
}

/**
 * Implement the substring-after() XPath function
 *    string substring-after(string, string)
 * The substring-after function returns the substring of the first
 * argument string that follows the first occurrence of the second
 * argument string in the first argument string, or the empty string
 * if the first argument string does not contain the second argument
 * string. For example, substring-after("1999/04/01","/") returns 04/01,
 * and substring-after("1999/04/01","19") returns 99/04/01.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathSubstringAfterFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr str = NULL;
    xmlXPathObjectPtr find = NULL;
    const xmlChar *point;
    xmlChar *result;

    CHECK_ARITY(2);
    CAST_TO_STRING;
    find = xmlXPathValuePop(ctxt);
    CAST_TO_STRING;
    str = xmlXPathValuePop(ctxt);
    if (ctxt->error != 0)
        goto error;

    point = xmlStrstr(str->stringval, find->stringval);
    if (point == NULL) {
        result = xmlStrdup(BAD_CAST "");
    } else {
        result = xmlStrdup(point + xmlStrlen(find->stringval));
    }
    if (result == NULL) {
        xmlXPathPErrMemory(ctxt);
        goto error;
    }
    xmlXPathValuePush(ctxt, xmlXPathCacheWrapString(ctxt, result));

error:
    xmlXPathReleaseObject(ctxt->context, str);
    xmlXPathReleaseObject(ctxt->context, find);
}

/**
 * Implement the normalize-space() XPath function
 *    string normalize-space(string?)
 * The normalize-space function returns the argument string with white
 * space normalized by stripping leading and trailing whitespace
 * and replacing sequences of whitespace characters by a single
 * space. Whitespace characters are the same allowed by the S production
 * in XML. If the argument is omitted, it defaults to the context
 * node converted to a string, in other words the value of the context node.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathNormalizeFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlChar *source, *target;
    int blank;

    if (ctxt == NULL) return;
    if (nargs == 0) {
        /* Use current context node */
        source = xmlXPathCastNodeToString(ctxt->context->node);
        if (source == NULL)
            xmlXPathPErrMemory(ctxt);
        xmlXPathValuePush(ctxt, xmlXPathCacheWrapString(ctxt, source));
        nargs = 1;
    }

    CHECK_ARITY(1);
    CAST_TO_STRING;
    CHECK_TYPE(XPATH_STRING);
    source = ctxt->value->stringval;
    if (source == NULL)
        return;
    target = source;

    /* Skip leading whitespaces */
    while (IS_BLANK_CH(*source))
        source++;

    /* Collapse intermediate whitespaces, and skip trailing whitespaces */
    blank = 0;
    while (*source) {
        if (IS_BLANK_CH(*source)) {
	    blank = 1;
        } else {
            if (blank) {
                *target++ = 0x20;
                blank = 0;
            }
            *target++ = *source;
        }
        source++;
    }
    *target = 0;
}

/**
 * Implement the translate() XPath function
 *    string translate(string, string, string)
 * The translate function returns the first argument string with
 * occurrences of characters in the second argument string replaced
 * by the character at the corresponding position in the third argument
 * string. For example, translate("bar","abc","ABC") returns the string
 * BAr. If there is a character in the second argument string with no
 * character at a corresponding position in the third argument string
 * (because the second argument string is longer than the third argument
 * string), then occurrences of that character in the first argument
 * string are removed. For example,
 * translate("--aaa--","abc-","ABC") returns "AAA".
 * If a character occurs more than once in second
 * argument string, then the first occurrence determines the replacement
 * character. If the third argument string is longer than the second
 * argument string, then excess characters are ignored.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathTranslateFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr str = NULL;
    xmlXPathObjectPtr from = NULL;
    xmlXPathObjectPtr to = NULL;
    xmlBufPtr target;
    int offset, max;
    int ch;
    const xmlChar *point;
    xmlChar *cptr, *content;

    CHECK_ARITY(3);

    CAST_TO_STRING;
    to = xmlXPathValuePop(ctxt);
    CAST_TO_STRING;
    from = xmlXPathValuePop(ctxt);
    CAST_TO_STRING;
    str = xmlXPathValuePop(ctxt);
    if (ctxt->error != 0)
        goto error;

    /*
     * Account for quadratic runtime
     */
    if (ctxt->context->opLimit != 0) {
        unsigned long f1 = xmlStrlen(from->stringval);
        unsigned long f2 = xmlStrlen(str->stringval);

        if ((f1 > 0) && (f2 > 0)) {
            unsigned long p;

            f1 = f1 / 10 + 1;
            f2 = f2 / 10 + 1;
            p = f1 > ULONG_MAX / f2 ? ULONG_MAX : f1 * f2;
            if (xmlXPathCheckOpLimit(ctxt, p) < 0)
                goto error;
        }
    }

    target = xmlBufCreate(50);
    if (target == NULL) {
        xmlXPathPErrMemory(ctxt);
        goto error;
    }

    max = xmlUTF8Strlen(to->stringval);
    for (cptr = str->stringval; (ch=*cptr); ) {
        offset = xmlUTF8Strloc(from->stringval, cptr);
        if (offset >= 0) {
            if (offset < max) {
                point = xmlUTF8Strpos(to->stringval, offset);
                if (point)
                    xmlBufAdd(target, point, xmlUTF8Strsize(point, 1));
            }
        } else
            xmlBufAdd(target, cptr, xmlUTF8Strsize(cptr, 1));

        /* Step to next character in input */
        cptr++;
        if ( ch & 0x80 ) {
            /* if not simple ascii, verify proper format */
            if ( (ch & 0xc0) != 0xc0 ) {
                xmlXPathErr(ctxt, XPATH_INVALID_CHAR_ERROR);
                break;
            }
            /* then skip over remaining bytes for this char */
            while ( (ch <<= 1) & 0x80 )
                if ( (*cptr++ & 0xc0) != 0x80 ) {
                    xmlXPathErr(ctxt, XPATH_INVALID_CHAR_ERROR);
                    break;
                }
            if (ch & 0x80) /* must have had error encountered */
                break;
        }
    }

    content = xmlBufDetach(target);
    if (content == NULL)
        xmlXPathPErrMemory(ctxt);
    else
        xmlXPathValuePush(ctxt, xmlXPathCacheWrapString(ctxt, content));
    xmlBufFree(target);
error:
    xmlXPathReleaseObject(ctxt->context, str);
    xmlXPathReleaseObject(ctxt->context, from);
    xmlXPathReleaseObject(ctxt->context, to);
}

/**
 * Implement the boolean() XPath function
 *    boolean boolean(object)
 * The boolean function converts its argument to a boolean as follows:
 *    - a number is true if and only if it is neither positive or
 *      negative zero nor NaN
 *    - a node-set is true if and only if it is non-empty
 *    - a string is true if and only if its length is non-zero
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathBooleanFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr cur;

    CHECK_ARITY(1);
    cur = xmlXPathValuePop(ctxt);
    if (cur == NULL) XP_ERROR(XPATH_INVALID_OPERAND);
    if (cur->type != XPATH_BOOLEAN) {
        int boolval = xmlXPathCastToBoolean(cur);

        xmlXPathReleaseObject(ctxt->context, cur);
        cur = xmlXPathCacheNewBoolean(ctxt, boolval);
    }
    xmlXPathValuePush(ctxt, cur);
}

/**
 * Implement the not() XPath function
 *    boolean not(boolean)
 * The not function returns true if its argument is false,
 * and false otherwise.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathNotFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    CHECK_ARITY(1);
    CAST_TO_BOOLEAN;
    CHECK_TYPE(XPATH_BOOLEAN);
    ctxt->value->boolval = ! ctxt->value->boolval;
}

/**
 * Implement the true() XPath function
 *    boolean true()
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathTrueFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    CHECK_ARITY(0);
    xmlXPathValuePush(ctxt, xmlXPathCacheNewBoolean(ctxt, 1));
}

/**
 * Implement the false() XPath function
 *    boolean false()
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathFalseFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    CHECK_ARITY(0);
    xmlXPathValuePush(ctxt, xmlXPathCacheNewBoolean(ctxt, 0));
}

/**
 * Implement the lang() XPath function
 *    boolean lang(string)
 * The lang function returns true or false depending on whether the
 * language of the context node as specified by xml:lang attributes
 * is the same as or is a sublanguage of the language specified by
 * the argument string. The language of the context node is determined
 * by the value of the xml:lang attribute on the context node, or, if
 * the context node has no xml:lang attribute, by the value of the
 * xml:lang attribute on the nearest ancestor of the context node that
 * has an xml:lang attribute. If there is no such attribute, then
 * lang returns false. If there is such an attribute, then lang returns
 * true if the attribute value is equal to the argument ignoring case,
 * or if there is some suffix starting with - such that the attribute
 * value is equal to the argument ignoring that suffix of the attribute
 * value and ignoring case.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathLangFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr val;
    xmlNodePtr cur;
    xmlChar *theLang;
    const xmlChar *lang;
    int ret = 0;
    int i;

    CHECK_ARITY(1);
    CAST_TO_STRING;
    CHECK_TYPE(XPATH_STRING);
    val = xmlXPathValuePop(ctxt);
    lang = val->stringval;
    cur = ctxt->context->node;
    while (cur != NULL) {
        if (xmlNodeGetAttrValue(cur, BAD_CAST "lang", XML_XML_NAMESPACE,
                                &theLang) < 0)
            xmlXPathPErrMemory(ctxt);
        if (theLang != NULL)
            break;
        cur = cur->parent;
    }
    if ((theLang != NULL) && (lang != NULL)) {
        for (i = 0;lang[i] != 0;i++)
            if (toupper(lang[i]) != toupper(theLang[i]))
                goto not_equal;
        if ((theLang[i] == 0) || (theLang[i] == '-'))
            ret = 1;
    }
not_equal:
    if (theLang != NULL)
	xmlFree((void *)theLang);

    xmlXPathReleaseObject(ctxt->context, val);
    xmlXPathValuePush(ctxt, xmlXPathCacheNewBoolean(ctxt, ret));
}

/**
 * Implement the number() XPath function
 *    number number(object?)
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathNumberFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr cur;
    double res;

    if (ctxt == NULL) return;
    if (nargs == 0) {
	if (ctxt->context->node == NULL) {
	    xmlXPathValuePush(ctxt, xmlXPathCacheNewFloat(ctxt, 0.0));
	} else {
	    xmlChar* content = xmlNodeGetContent(ctxt->context->node);
            if (content == NULL)
                xmlXPathPErrMemory(ctxt);

	    res = xmlXPathStringEvalNumber(content);
	    xmlXPathValuePush(ctxt, xmlXPathCacheNewFloat(ctxt, res));
	    xmlFree(content);
	}
	return;
    }

    CHECK_ARITY(1);
    cur = xmlXPathValuePop(ctxt);
    if (cur->type != XPATH_NUMBER) {
        double floatval;

        floatval = xmlXPathCastToNumberInternal(ctxt, cur);
        xmlXPathReleaseObject(ctxt->context, cur);
        cur = xmlXPathCacheNewFloat(ctxt, floatval);
    }
    xmlXPathValuePush(ctxt, cur);
}

/**
 * Implement the sum() XPath function
 *    number sum(node-set)
 * The sum function returns the sum of the values of the nodes in
 * the argument node-set.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathSumFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr cur;
    int i;
    double res = 0.0;

    CHECK_ARITY(1);
    if ((ctxt->value == NULL) ||
	((ctxt->value->type != XPATH_NODESET) &&
	 (ctxt->value->type != XPATH_XSLT_TREE)))
	XP_ERROR(XPATH_INVALID_TYPE);
    cur = xmlXPathValuePop(ctxt);

    if ((cur->nodesetval != NULL) && (cur->nodesetval->nodeNr != 0)) {
	for (i = 0; i < cur->nodesetval->nodeNr; i++) {
	    res += xmlXPathNodeToNumberInternal(ctxt,
                                                cur->nodesetval->nodeTab[i]);
	}
    }
    xmlXPathValuePush(ctxt, xmlXPathCacheNewFloat(ctxt, res));
    xmlXPathReleaseObject(ctxt->context, cur);
}

/**
 * Implement the floor() XPath function
 *    number floor(number)
 * The floor function returns the largest (closest to positive infinity)
 * number that is not greater than the argument and that is an integer.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathFloorFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    CHECK_ARITY(1);
    CAST_TO_NUMBER;
    CHECK_TYPE(XPATH_NUMBER);

    ctxt->value->floatval = floor(ctxt->value->floatval);
}

/**
 * Implement the ceiling() XPath function
 *    number ceiling(number)
 * The ceiling function returns the smallest (closest to negative infinity)
 * number that is not less than the argument and that is an integer.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathCeilingFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    CHECK_ARITY(1);
    CAST_TO_NUMBER;
    CHECK_TYPE(XPATH_NUMBER);

#ifdef _AIX
    /* Work around buggy ceil() function on AIX */
    ctxt->value->floatval = copysign(ceil(ctxt->value->floatval), ctxt->value->floatval);
#else
    ctxt->value->floatval = ceil(ctxt->value->floatval);
#endif
}

/**
 * Implement the round() XPath function
 *    number round(number)
 * The round function returns the number that is closest to the
 * argument and that is an integer. If there are two such numbers,
 * then the one that is closest to positive infinity is returned.
 *
 * @param ctxt  the XPath Parser context
 * @param nargs  the number of arguments
 */
void
xmlXPathRoundFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    double f;

    CHECK_ARITY(1);
    CAST_TO_NUMBER;
    CHECK_TYPE(XPATH_NUMBER);

    f = ctxt->value->floatval;

    if ((f >= -0.5) && (f < 0.5)) {
        /* Handles negative zero. */
        ctxt->value->floatval *= 0.0;
    }
    else {
        double rounded = floor(f);
        if (f - rounded >= 0.5)
            rounded += 1.0;
        ctxt->value->floatval = rounded;
    }
}

/************************************************************************
 *									*
 *			The Parser					*
 *									*
 ************************************************************************/

/*
 * a few forward declarations since we use a recursive call based
 * implementation.
 */
static void xmlXPathCompileExpr(xmlXPathParserContextPtr ctxt, int sort);
static void xmlXPathCompPredicate(xmlXPathParserContextPtr ctxt, int filter);
static void xmlXPathCompLocationPath(xmlXPathParserContextPtr ctxt);
static void xmlXPathCompRelativeLocationPath(xmlXPathParserContextPtr ctxt);
static xmlChar * xmlXPathParseNameComplex(xmlXPathParserContextPtr ctxt,
	                                  int qualified);

/**
 * The current char value, if using UTF-8 this may actually span multiple
 * bytes in the input buffer.
 *
 * @param ctxt  the XPath parser context
 * @param len  pointer to the length of the char read
 * @returns the current char value and its length
 */

static int
xmlXPathCurrentChar(xmlXPathParserContextPtr ctxt, int *len) {
    unsigned char c;
    unsigned int val;
    const xmlChar *cur;

    if (ctxt == NULL)
	return(0);
    cur = ctxt->cur;

    /*
     * We are supposed to handle UTF8, check it's valid
     * From rfc2044: encoding of the Unicode values on UTF-8:
     *
     * UCS-4 range (hex.)           UTF-8 octet sequence (binary)
     * 0000 0000-0000 007F   0xxxxxxx
     * 0000 0080-0000 07FF   110xxxxx 10xxxxxx
     * 0000 0800-0000 FFFF   1110xxxx 10xxxxxx 10xxxxxx
     *
     * Check for the 0x110000 limit too
     */
    c = *cur;
    if (c & 0x80) {
	if ((cur[1] & 0xc0) != 0x80)
	    goto encoding_error;
	if ((c & 0xe0) == 0xe0) {

	    if ((cur[2] & 0xc0) != 0x80)
		goto encoding_error;
	    if ((c & 0xf0) == 0xf0) {
		if (((c & 0xf8) != 0xf0) ||
		    ((cur[3] & 0xc0) != 0x80))
		    goto encoding_error;
		/* 4-byte code */
		*len = 4;
		val = (cur[0] & 0x7) << 18;
		val |= (cur[1] & 0x3f) << 12;
		val |= (cur[2] & 0x3f) << 6;
		val |= cur[3] & 0x3f;
	    } else {
	      /* 3-byte code */
		*len = 3;
		val = (cur[0] & 0xf) << 12;
		val |= (cur[1] & 0x3f) << 6;
		val |= cur[2] & 0x3f;
	    }
	} else {
	  /* 2-byte code */
	    *len = 2;
	    val = (cur[0] & 0x1f) << 6;
	    val |= cur[1] & 0x3f;
	}
	if (!IS_CHAR(val)) {
	    XP_ERROR0(XPATH_INVALID_CHAR_ERROR);
	}
	return(val);
    } else {
	/* 1-byte code */
	*len = 1;
	return(*cur);
    }
encoding_error:
    /*
     * If we detect an UTF8 error that probably means that the
     * input encoding didn't get properly advertised in the
     * declaration header. Report the error and switch the encoding
     * to ISO-Latin-1 (if you don't like this policy, just declare the
     * encoding !)
     */
    *len = 0;
    XP_ERROR0(XPATH_ENCODING_ERROR);
}

/**
 * parse an XML namespace non qualified name.
 *
 * [NS 3] NCName ::= (Letter | '_') (NCNameChar)*
 *
 * [NS 4] NCNameChar ::= Letter | Digit | '.' | '-' | '_' |
 *                       CombiningChar | Extender
 *
 * @param ctxt  the XPath Parser context
 * @returns the namespace name or NULL
 */

xmlChar *
xmlXPathParseNCName(xmlXPathParserContextPtr ctxt) {
    const xmlChar *in;
    xmlChar *ret;
    int count = 0;

    if ((ctxt == NULL) || (ctxt->cur == NULL)) return(NULL);
    /*
     * Accelerator for simple ASCII names
     */
    in = ctxt->cur;
    if (((*in >= 0x61) && (*in <= 0x7A)) ||
	((*in >= 0x41) && (*in <= 0x5A)) ||
	(*in == '_')) {
	in++;
	while (((*in >= 0x61) && (*in <= 0x7A)) ||
	       ((*in >= 0x41) && (*in <= 0x5A)) ||
	       ((*in >= 0x30) && (*in <= 0x39)) ||
	       (*in == '_') || (*in == '.') ||
	       (*in == '-'))
	    in++;
	if ((*in == ' ') || (*in == '>') || (*in == '/') ||
            (*in == '[') || (*in == ']') || (*in == ':') ||
            (*in == '@') || (*in == '*')) {
	    count = in - ctxt->cur;
	    if (count == 0)
		return(NULL);
	    ret = xmlStrndup(ctxt->cur, count);
            if (ret == NULL)
                xmlXPathPErrMemory(ctxt);
	    ctxt->cur = in;
	    return(ret);
	}
    }
    return(xmlXPathParseNameComplex(ctxt, 0));
}


/**
 * parse an XML qualified name
 *
 * [NS 5] QName ::= (Prefix ':')? LocalPart
 *
 * [NS 6] Prefix ::= NCName
 *
 * [NS 7] LocalPart ::= NCName
 *
 * @param ctxt  the XPath Parser context
 * @param prefix  a xmlChar **
 * @returns the function returns the local part, and prefix is updated
 *   to get the Prefix if any.
 */

static xmlChar *
xmlXPathParseQName(xmlXPathParserContextPtr ctxt, xmlChar **prefix) {
    xmlChar *ret = NULL;

    *prefix = NULL;
    ret = xmlXPathParseNCName(ctxt);
    if (ret && CUR == ':') {
        *prefix = ret;
	NEXT;
	ret = xmlXPathParseNCName(ctxt);
    }
    return(ret);
}

/**
 * parse an XML name
 *
 * [4] NameChar ::= Letter | Digit | '.' | '-' | '_' | ':' |
 *                  CombiningChar | Extender
 *
 * [5] Name ::= (Letter | '_' | ':') (NameChar)*
 *
 * @param ctxt  the XPath Parser context
 * @returns the namespace name or NULL
 */

xmlChar *
xmlXPathParseName(xmlXPathParserContextPtr ctxt) {
    const xmlChar *in;
    xmlChar *ret;
    size_t count = 0;

    if ((ctxt == NULL) || (ctxt->cur == NULL)) return(NULL);
    /*
     * Accelerator for simple ASCII names
     */
    in = ctxt->cur;
    if (((*in >= 0x61) && (*in <= 0x7A)) ||
	((*in >= 0x41) && (*in <= 0x5A)) ||
	(*in == '_') || (*in == ':')) {
	in++;
	while (((*in >= 0x61) && (*in <= 0x7A)) ||
	       ((*in >= 0x41) && (*in <= 0x5A)) ||
	       ((*in >= 0x30) && (*in <= 0x39)) ||
	       (*in == '_') || (*in == '-') ||
	       (*in == ':') || (*in == '.'))
	    in++;
	if ((*in > 0) && (*in < 0x80)) {
	    count = in - ctxt->cur;
            if (count > XML_MAX_NAME_LENGTH) {
                ctxt->cur = in;
                XP_ERRORNULL(XPATH_EXPR_ERROR);
            }
	    ret = xmlStrndup(ctxt->cur, count);
            if (ret == NULL)
                xmlXPathPErrMemory(ctxt);
	    ctxt->cur = in;
	    return(ret);
	}
    }
    return(xmlXPathParseNameComplex(ctxt, 1));
}

static xmlChar *
xmlXPathParseNameComplex(xmlXPathParserContextPtr ctxt, int qualified) {
    xmlChar *ret;
    xmlChar buf[XML_MAX_NAMELEN + 5];
    int len = 0, l;
    int c;

    /*
     * Handler for more complex cases
     */
    c = CUR_CHAR(l);
    if ((c == ' ') || (c == '>') || (c == '/') || /* accelerators */
        (c == '[') || (c == ']') || (c == '@') || /* accelerators */
        (c == '*') || /* accelerators */
	(!IS_LETTER(c) && (c != '_') &&
         ((!qualified) || (c != ':')))) {
	return(NULL);
    }

    while ((c != ' ') && (c != '>') && (c != '/') && /* test bigname.xml */
	   ((IS_LETTER(c)) || (IS_DIGIT(c)) ||
            (c == '.') || (c == '-') ||
	    (c == '_') || ((qualified) && (c == ':')) ||
	    (IS_COMBINING(c)) ||
	    (IS_EXTENDER(c)))) {
	COPY_BUF(buf,len,c);
	NEXTL(l);
	c = CUR_CHAR(l);
	if (len >= XML_MAX_NAMELEN) {
	    /*
	     * Okay someone managed to make a huge name, so he's ready to pay
	     * for the processing speed.
	     */
	    xmlChar *buffer;
	    int max = len * 2;

            if (len > XML_MAX_NAME_LENGTH) {
                XP_ERRORNULL(XPATH_EXPR_ERROR);
            }
	    buffer = xmlMalloc(max);
	    if (buffer == NULL) {
                xmlXPathPErrMemory(ctxt);
                return(NULL);
	    }
	    memcpy(buffer, buf, len);
	    while ((IS_LETTER(c)) || (IS_DIGIT(c)) || /* test bigname.xml */
		   (c == '.') || (c == '-') ||
		   (c == '_') || ((qualified) && (c == ':')) ||
		   (IS_COMBINING(c)) ||
		   (IS_EXTENDER(c))) {
		if (len + 10 > max) {
                    xmlChar *tmp;
                    int newSize;

                    newSize = xmlGrowCapacity(max, 1, 1, XML_MAX_NAME_LENGTH);
                    if (newSize < 0) {
                        xmlFree(buffer);
                        xmlXPathErr(ctxt, XPATH_EXPR_ERROR);
                        return(NULL);
                    }
		    tmp = xmlRealloc(buffer, newSize);
		    if (tmp == NULL) {
                        xmlFree(buffer);
                        xmlXPathPErrMemory(ctxt);
                        return(NULL);
		    }
                    buffer = tmp;
		    max = newSize;
		}
		COPY_BUF(buffer,len,c);
		NEXTL(l);
		c = CUR_CHAR(l);
	    }
	    buffer[len] = 0;
	    return(buffer);
	}
    }
    if (len == 0)
	return(NULL);
    ret = xmlStrndup(buf, len);
    if (ret == NULL)
        xmlXPathPErrMemory(ctxt);
    return(ret);
}

#define MAX_FRAC 20

/**
 *  [30a]  Float  ::= Number ('e' Digits?)?
 *
 *  [30]   Number ::=   Digits ('.' Digits?)?
 *                    | '.' Digits
 *  [31]   Digits ::=   [0-9]+
 *
 * Compile a Number in the string
 * In complement of the Number expression, this function also handles
 * negative values : '-' Number.
 *
 * @param str  A string to scan
 * @returns the double value.
 */
double
xmlXPathStringEvalNumber(const xmlChar *str) {
    const xmlChar *cur = str;
    double ret;
    int ok = 0;
    int isneg = 0;
    int exponent = 0;
    int is_exponent_negative = 0;
#ifdef __GNUC__
    unsigned long tmp = 0;
    double temp;
#endif
    if (cur == NULL) return(0);
    while (IS_BLANK_CH(*cur)) cur++;
    if (*cur == '-') {
	isneg = 1;
	cur++;
    }
    if ((*cur != '.') && ((*cur < '0') || (*cur > '9'))) {
        return(xmlXPathNAN);
    }

#ifdef __GNUC__
    /*
     * tmp/temp is a workaround against a gcc compiler bug
     * http://veillard.com/gcc.bug
     */
    ret = 0;
    while ((*cur >= '0') && (*cur <= '9')) {
	ret = ret * 10;
	tmp = (*cur - '0');
	ok = 1;
	cur++;
	temp = (double) tmp;
	ret = ret + temp;
    }
#else
    ret = 0;
    while ((*cur >= '0') && (*cur <= '9')) {
	ret = ret * 10 + (*cur - '0');
	ok = 1;
	cur++;
    }
#endif

    if (*cur == '.') {
	int v, frac = 0, max;
	double fraction = 0;

        cur++;
	if (((*cur < '0') || (*cur > '9')) && (!ok)) {
	    return(xmlXPathNAN);
	}
        while (*cur == '0') {
	    frac = frac + 1;
	    cur++;
        }
        max = frac + MAX_FRAC;
	while (((*cur >= '0') && (*cur <= '9')) && (frac < max)) {
	    v = (*cur - '0');
	    fraction = fraction * 10 + v;
	    frac = frac + 1;
	    cur++;
	}
	fraction /= pow(10.0, frac);
	ret = ret + fraction;
	while ((*cur >= '0') && (*cur <= '9'))
	    cur++;
    }
    if ((*cur == 'e') || (*cur == 'E')) {
      cur++;
      if (*cur == '-') {
	is_exponent_negative = 1;
	cur++;
      } else if (*cur == '+') {
        cur++;
      }
      while ((*cur >= '0') && (*cur <= '9')) {
        if (exponent < 1000000)
	  exponent = exponent * 10 + (*cur - '0');
	cur++;
      }
    }
    while (IS_BLANK_CH(*cur)) cur++;
    if (*cur != 0) return(xmlXPathNAN);
    if (isneg) ret = -ret;
    if (is_exponent_negative) exponent = -exponent;
    ret *= pow(10.0, (double)exponent);
    return(ret);
}

/**
 *  [30]   Number ::=   Digits ('.' Digits?)?
 *                    | '.' Digits
 *  [31]   Digits ::=   [0-9]+
 *
 * Compile a Number, then push it on the stack
 *
 * @param ctxt  the XPath Parser context
 */
static void
xmlXPathCompNumber(xmlXPathParserContextPtr ctxt)
{
    double ret = 0.0;
    int ok = 0;
    int exponent = 0;
    int is_exponent_negative = 0;
    xmlXPathObjectPtr num;
#ifdef __GNUC__
    unsigned long tmp = 0;
    double temp;
#endif

    CHECK_ERROR;
    if ((CUR != '.') && ((CUR < '0') || (CUR > '9'))) {
        XP_ERROR(XPATH_NUMBER_ERROR);
    }
#ifdef __GNUC__
    /*
     * tmp/temp is a workaround against a gcc compiler bug
     * http://veillard.com/gcc.bug
     */
    ret = 0;
    while ((CUR >= '0') && (CUR <= '9')) {
	ret = ret * 10;
	tmp = (CUR - '0');
        ok = 1;
        NEXT;
	temp = (double) tmp;
	ret = ret + temp;
    }
#else
    ret = 0;
    while ((CUR >= '0') && (CUR <= '9')) {
	ret = ret * 10 + (CUR - '0');
	ok = 1;
	NEXT;
    }
#endif
    if (CUR == '.') {
	int v, frac = 0, max;
	double fraction = 0;

        NEXT;
        if (((CUR < '0') || (CUR > '9')) && (!ok)) {
            XP_ERROR(XPATH_NUMBER_ERROR);
        }
        while (CUR == '0') {
            frac = frac + 1;
            NEXT;
        }
        max = frac + MAX_FRAC;
        while ((CUR >= '0') && (CUR <= '9') && (frac < max)) {
	    v = (CUR - '0');
	    fraction = fraction * 10 + v;
	    frac = frac + 1;
            NEXT;
        }
        fraction /= pow(10.0, frac);
        ret = ret + fraction;
        while ((CUR >= '0') && (CUR <= '9'))
            NEXT;
    }
    if ((CUR == 'e') || (CUR == 'E')) {
        NEXT;
        if (CUR == '-') {
            is_exponent_negative = 1;
            NEXT;
        } else if (CUR == '+') {
	    NEXT;
	}
        while ((CUR >= '0') && (CUR <= '9')) {
            if (exponent < 1000000)
                exponent = exponent * 10 + (CUR - '0');
            NEXT;
        }
        if (is_exponent_negative)
            exponent = -exponent;
        ret *= pow(10.0, (double) exponent);
    }
    num = xmlXPathCacheNewFloat(ctxt, ret);
    if (num == NULL) {
	ctxt->error = XPATH_MEMORY_ERROR;
    } else if (PUSH_LONG_EXPR(XPATH_OP_VALUE, XPATH_NUMBER, 0, 0, num,
                              NULL) == -1) {
        xmlXPathReleaseObject(ctxt->context, num);
    }
}

/**
 * Parse a Literal
 *
 *  [29]   Literal ::=   '"' [^"]* '"'
 *                    | "'" [^']* "'"
 *
 * @param ctxt  the XPath Parser context
 * @returns the value found or NULL in case of error
 */
static xmlChar *
xmlXPathParseLiteral(xmlXPathParserContextPtr ctxt) {
    const xmlChar *q;
    xmlChar *ret = NULL;
    int quote;

    if (CUR == '"') {
        quote = '"';
    } else if (CUR == '\'') {
        quote = '\'';
    } else {
	XP_ERRORNULL(XPATH_START_LITERAL_ERROR);
    }

    NEXT;
    q = CUR_PTR;
    while (CUR != quote) {
        int ch;
        int len = 4;

        if (CUR == 0)
            XP_ERRORNULL(XPATH_UNFINISHED_LITERAL_ERROR);
        ch = xmlGetUTF8Char(CUR_PTR, &len);
        if ((ch < 0) || (IS_CHAR(ch) == 0))
            XP_ERRORNULL(XPATH_INVALID_CHAR_ERROR);
        CUR_PTR += len;
    }
    ret = xmlStrndup(q, CUR_PTR - q);
    if (ret == NULL)
        xmlXPathPErrMemory(ctxt);
    NEXT;
    return(ret);
}

/**
 * Parse a Literal and push it on the stack.
 *
 *  [29]   Literal ::=   '"' [^"]* '"'
 *                    | "'" [^']* "'"
 *
 * TODO: xmlXPathCompLiteral() memory allocation could be improved.
 * @param ctxt  the XPath Parser context
 */
static void
xmlXPathCompLiteral(xmlXPathParserContextPtr ctxt) {
    xmlChar *ret = NULL;
    xmlXPathObjectPtr lit;

    ret = xmlXPathParseLiteral(ctxt);
    if (ret == NULL)
        return;
    lit = xmlXPathCacheNewString(ctxt, ret);
    if (lit == NULL) {
        ctxt->error = XPATH_MEMORY_ERROR;
    } else if (PUSH_LONG_EXPR(XPATH_OP_VALUE, XPATH_STRING, 0, 0, lit,
                              NULL) == -1) {
        xmlXPathReleaseObject(ctxt->context, lit);
    }
    xmlFree(ret);
}

/**
 * Parse a VariableReference, evaluate it and push it on the stack.
 *
 * The variable bindings consist of a mapping from variable names
 * to variable values. The value of a variable is an object, which can be
 * of any of the types that are possible for the value of an expression,
 * and may also be of additional types not specified here.
 *
 * Early evaluation is possible since:
 * The variable bindings [...] used to evaluate a subexpression are
 * always the same as those used to evaluate the containing expression.
 *
 *  [36]   VariableReference ::=   '$' QName
 * @param ctxt  the XPath Parser context
 */
static void
xmlXPathCompVariableReference(xmlXPathParserContextPtr ctxt) {
    xmlChar *name;
    xmlChar *prefix;

    SKIP_BLANKS;
    if (CUR != '$') {
	XP_ERROR(XPATH_VARIABLE_REF_ERROR);
    }
    NEXT;
    name = xmlXPathParseQName(ctxt, &prefix);
    if (name == NULL) {
        xmlFree(prefix);
	XP_ERROR(XPATH_VARIABLE_REF_ERROR);
    }
    ctxt->comp->last = -1;
    if (PUSH_LONG_EXPR(XPATH_OP_VARIABLE, 0, 0, 0, name, prefix) == -1) {
        xmlFree(prefix);
        xmlFree(name);
    }
    SKIP_BLANKS;
    if ((ctxt->context != NULL) && (ctxt->context->flags & XML_XPATH_NOVAR)) {
	XP_ERROR(XPATH_FORBID_VARIABLE_ERROR);
    }
}

/**
 * Is the name given a NodeType one.
 *
 *  [38]   NodeType ::=   'comment'
 *                    | 'text'
 *                    | 'processing-instruction'
 *                    | 'node'
 *
 * @param name  a name string
 * @returns 1 if true 0 otherwise
 */
int
xmlXPathIsNodeType(const xmlChar *name) {
    if (name == NULL)
	return(0);

    if (xmlStrEqual(name, BAD_CAST "node"))
	return(1);
    if (xmlStrEqual(name, BAD_CAST "text"))
	return(1);
    if (xmlStrEqual(name, BAD_CAST "comment"))
	return(1);
    if (xmlStrEqual(name, BAD_CAST "processing-instruction"))
	return(1);
    return(0);
}

/**
 *  [16]   FunctionCall ::=   FunctionName '(' ( Argument ( ',' Argument)*)? ')'
 *  [17]   Argument ::=   Expr
 *
 * Compile a function call, the evaluation of all arguments are
 * pushed on the stack
 * @param ctxt  the XPath Parser context
 */
static void
xmlXPathCompFunctionCall(xmlXPathParserContextPtr ctxt) {
    xmlChar *name;
    xmlChar *prefix;
    int nbargs = 0;
    int sort = 1;

    name = xmlXPathParseQName(ctxt, &prefix);
    if (name == NULL) {
	xmlFree(prefix);
	XP_ERROR(XPATH_EXPR_ERROR);
    }
    SKIP_BLANKS;

    if (CUR != '(') {
	xmlFree(name);
	xmlFree(prefix);
	XP_ERROR(XPATH_EXPR_ERROR);
    }
    NEXT;
    SKIP_BLANKS;

    /*
    * Optimization for count(): we don't need the node-set to be sorted.
    */
    if ((prefix == NULL) && (name[0] == 'c') &&
	xmlStrEqual(name, BAD_CAST "count"))
    {
	sort = 0;
    }
    ctxt->comp->last = -1;
    if (CUR != ')') {
	while (CUR != 0) {
	    int op1 = ctxt->comp->last;
	    ctxt->comp->last = -1;
	    xmlXPathCompileExpr(ctxt, sort);
	    if (ctxt->error != XPATH_EXPRESSION_OK) {
		xmlFree(name);
		xmlFree(prefix);
		return;
	    }
	    PUSH_BINARY_EXPR(XPATH_OP_ARG, op1, ctxt->comp->last, 0, 0);
	    nbargs++;
	    if (CUR == ')') break;
	    if (CUR != ',') {
		xmlFree(name);
		xmlFree(prefix);
		XP_ERROR(XPATH_EXPR_ERROR);
	    }
	    NEXT;
	    SKIP_BLANKS;
	}
    }
    if (PUSH_LONG_EXPR(XPATH_OP_FUNCTION, nbargs, 0, 0, name, prefix) == -1) {
        xmlFree(prefix);
        xmlFree(name);
    }
    NEXT;
    SKIP_BLANKS;
}

/**
 *  [15]   PrimaryExpr ::=   VariableReference
 *                | '(' Expr ')'
 *                | Literal
 *                | Number
 *                | FunctionCall
 *
 * Compile a primary expression.
 * @param ctxt  the XPath Parser context
 */
static void
xmlXPathCompPrimaryExpr(xmlXPathParserContextPtr ctxt) {
    SKIP_BLANKS;
    if (CUR == '$') xmlXPathCompVariableReference(ctxt);
    else if (CUR == '(') {
	NEXT;
	SKIP_BLANKS;
	xmlXPathCompileExpr(ctxt, 1);
	CHECK_ERROR;
	if (CUR != ')') {
	    XP_ERROR(XPATH_EXPR_ERROR);
	}
	NEXT;
	SKIP_BLANKS;
    } else if (IS_ASCII_DIGIT(CUR) || (CUR == '.' && IS_ASCII_DIGIT(NXT(1)))) {
	xmlXPathCompNumber(ctxt);
    } else if ((CUR == '\'') || (CUR == '"')) {
	xmlXPathCompLiteral(ctxt);
    } else {
	xmlXPathCompFunctionCall(ctxt);
    }
    SKIP_BLANKS;
}

/**
 *  [20]   FilterExpr ::=   PrimaryExpr
 *               | FilterExpr Predicate
 *
 * Compile a filter expression.
 * Square brackets are used to filter expressions in the same way that
 * they are used in location paths. It is an error if the expression to
 * be filtered does not evaluate to a node-set. The context node list
 * used for evaluating the expression in square brackets is the node-set
 * to be filtered listed in document order.
 * @param ctxt  the XPath Parser context
 */

static void
xmlXPathCompFilterExpr(xmlXPathParserContextPtr ctxt) {
    xmlXPathCompPrimaryExpr(ctxt);
    CHECK_ERROR;
    SKIP_BLANKS;

    while (CUR == '[') {
	xmlXPathCompPredicate(ctxt, 1);
	SKIP_BLANKS;
    }


}

/**
 * Trickery: parse an XML name but without consuming the input flow
 * Needed to avoid insanity in the parser state.
 *
 * [4] NameChar ::= Letter | Digit | '.' | '-' | '_' | ':' |
 *                  CombiningChar | Extender
 *
 * [5] Name ::= (Letter | '_' | ':') (NameChar)*
 *
 * [6] Names ::= Name (S Name)*
 *
 * @param ctxt  the XPath Parser context
 * @returns the Name parsed or NULL
 */

static xmlChar *
xmlXPathScanName(xmlXPathParserContextPtr ctxt) {
    int l;
    int c;
    const xmlChar *cur;
    xmlChar *ret;

    cur = ctxt->cur;

    c = CUR_CHAR(l);
    if ((c == ' ') || (c == '>') || (c == '/') || /* accelerators */
	(!IS_LETTER(c) && (c != '_') &&
         (c != ':'))) {
	return(NULL);
    }

    while ((c != ' ') && (c != '>') && (c != '/') && /* test bigname.xml */
	   ((IS_LETTER(c)) || (IS_DIGIT(c)) ||
            (c == '.') || (c == '-') ||
	    (c == '_') || (c == ':') ||
	    (IS_COMBINING(c)) ||
	    (IS_EXTENDER(c)))) {
	NEXTL(l);
	c = CUR_CHAR(l);
    }
    ret = xmlStrndup(cur, ctxt->cur - cur);
    if (ret == NULL)
        xmlXPathPErrMemory(ctxt);
    ctxt->cur = cur;
    return(ret);
}

/**
 *  [19]   PathExpr ::=   LocationPath
 *               | FilterExpr
 *               | FilterExpr '/' RelativeLocationPath
 *               | FilterExpr '//' RelativeLocationPath
 *
 * Compile a path expression.
 * @param ctxt  the XPath Parser context
 */

static void
xmlXPathCompPathExpr(xmlXPathParserContextPtr ctxt) {
    int lc = 1;           /* Should we branch to LocationPath ?         */
    xmlChar *name = NULL; /* we may have to preparse a name to find out */

    SKIP_BLANKS;
    if ((CUR == '$') || (CUR == '(') ||
	(IS_ASCII_DIGIT(CUR)) ||
        (CUR == '\'') || (CUR == '"') ||
	(CUR == '.' && IS_ASCII_DIGIT(NXT(1)))) {
	lc = 0;
    } else if (CUR == '*') {
	/* relative or absolute location path */
	lc = 1;
    } else if (CUR == '/') {
	/* relative or absolute location path */
	lc = 1;
    } else if (CUR == '@') {
	/* relative abbreviated attribute location path */
	lc = 1;
    } else if (CUR == '.') {
	/* relative abbreviated attribute location path */
	lc = 1;
    } else {
	/*
	 * Problem is finding if we have a name here whether it's:
	 *   - a nodetype
	 *   - a function call in which case it's followed by '('
	 *   - an axis in which case it's followed by ':'
	 *   - a element name
	 * We do an a priori analysis here rather than having to
	 * maintain parsed token content through the recursive function
	 * calls. This looks uglier but makes the code easier to
	 * read/write/debug.
	 */
	SKIP_BLANKS;
	name = xmlXPathScanName(ctxt);
	if ((name != NULL) && (xmlStrstr(name, (xmlChar *) "::") != NULL)) {
	    lc = 1;
	    xmlFree(name);
	} else if (name != NULL) {
	    int len =xmlStrlen(name);


	    while (NXT(len) != 0) {
		if (NXT(len) == '/') {
		    /* element name */
		    lc = 1;
		    break;
		} else if (IS_BLANK_CH(NXT(len))) {
		    /* ignore blanks */
		    ;
		} else if (NXT(len) == ':') {
		    lc = 1;
		    break;
		} else if ((NXT(len) == '(')) {
		    /* Node Type or Function */
		    if (xmlXPathIsNodeType(name)) {
			lc = 1;
		    } else {
			lc = 0;
		    }
                    break;
		} else if ((NXT(len) == '[')) {
		    /* element name */
		    lc = 1;
		    break;
		} else if ((NXT(len) == '<') || (NXT(len) == '>') ||
			   (NXT(len) == '=')) {
		    lc = 1;
		    break;
		} else {
		    lc = 1;
		    break;
		}
		len++;
	    }
	    if (NXT(len) == 0) {
		/* element name */
		lc = 1;
	    }
	    xmlFree(name);
	} else {
	    /* make sure all cases are covered explicitly */
	    XP_ERROR(XPATH_EXPR_ERROR);
	}
    }

    if (lc) {
	if (CUR == '/') {
	    PUSH_LEAVE_EXPR(XPATH_OP_ROOT, 0, 0);
	} else {
	    PUSH_LEAVE_EXPR(XPATH_OP_NODE, 0, 0);
	}
	xmlXPathCompLocationPath(ctxt);
    } else {
	xmlXPathCompFilterExpr(ctxt);
	CHECK_ERROR;
	if ((CUR == '/') && (NXT(1) == '/')) {
	    SKIP(2);
	    SKIP_BLANKS;

	    PUSH_LONG_EXPR(XPATH_OP_COLLECT, AXIS_DESCENDANT_OR_SELF,
		    NODE_TEST_TYPE, NODE_TYPE_NODE, NULL, NULL);

	    xmlXPathCompRelativeLocationPath(ctxt);
	} else if (CUR == '/') {
	    xmlXPathCompRelativeLocationPath(ctxt);
	}
    }
    SKIP_BLANKS;
}

/**
 *  [18]   UnionExpr ::=   PathExpr
 *               | UnionExpr '|' PathExpr
 *
 * Compile an union expression.
 * @param ctxt  the XPath Parser context
 */

static void
xmlXPathCompUnionExpr(xmlXPathParserContextPtr ctxt) {
    xmlXPathCompPathExpr(ctxt);
    CHECK_ERROR;
    SKIP_BLANKS;
    while (CUR == '|') {
	int op1 = ctxt->comp->last;
	PUSH_LEAVE_EXPR(XPATH_OP_NODE, 0, 0);

	NEXT;
	SKIP_BLANKS;
	xmlXPathCompPathExpr(ctxt);

	PUSH_BINARY_EXPR(XPATH_OP_UNION, op1, ctxt->comp->last, 0, 0);

	SKIP_BLANKS;
    }
}

/**
 *  [27]   UnaryExpr ::=   UnionExpr
 *                   | '-' UnaryExpr
 *
 * Compile an unary expression.
 * @param ctxt  the XPath Parser context
 */

static void
xmlXPathCompUnaryExpr(xmlXPathParserContextPtr ctxt) {
    int minus = 0;
    int found = 0;

    SKIP_BLANKS;
    while (CUR == '-') {
        minus = 1 - minus;
	found = 1;
	NEXT;
	SKIP_BLANKS;
    }

    xmlXPathCompUnionExpr(ctxt);
    CHECK_ERROR;
    if (found) {
	if (minus)
	    PUSH_UNARY_EXPR(XPATH_OP_PLUS, ctxt->comp->last, 2, 0);
	else
	    PUSH_UNARY_EXPR(XPATH_OP_PLUS, ctxt->comp->last, 3, 0);
    }
}

/**
 *  [26]   MultiplicativeExpr ::=   UnaryExpr
 *                   | MultiplicativeExpr MultiplyOperator UnaryExpr
 *                   | MultiplicativeExpr 'div' UnaryExpr
 *                   | MultiplicativeExpr 'mod' UnaryExpr
 *  [34]   MultiplyOperator ::=   '*'
 *
 * Compile an Additive expression.
 * @param ctxt  the XPath Parser context
 */

static void
xmlXPathCompMultiplicativeExpr(xmlXPathParserContextPtr ctxt) {
    xmlXPathCompUnaryExpr(ctxt);
    CHECK_ERROR;
    SKIP_BLANKS;
    while ((CUR == '*') ||
           ((CUR == 'd') && (NXT(1) == 'i') && (NXT(2) == 'v')) ||
           ((CUR == 'm') && (NXT(1) == 'o') && (NXT(2) == 'd'))) {
	int op = -1;
	int op1 = ctxt->comp->last;

        if (CUR == '*') {
	    op = 0;
	    NEXT;
	} else if (CUR == 'd') {
	    op = 1;
	    SKIP(3);
	} else if (CUR == 'm') {
	    op = 2;
	    SKIP(3);
	}
	SKIP_BLANKS;
        xmlXPathCompUnaryExpr(ctxt);
	CHECK_ERROR;
	PUSH_BINARY_EXPR(XPATH_OP_MULT, op1, ctxt->comp->last, op, 0);
	SKIP_BLANKS;
    }
}

/**
 *  [25]   AdditiveExpr ::=   MultiplicativeExpr
 *                   | AdditiveExpr '+' MultiplicativeExpr
 *                   | AdditiveExpr '-' MultiplicativeExpr
 *
 * Compile an Additive expression.
 * @param ctxt  the XPath Parser context
 */

static void
xmlXPathCompAdditiveExpr(xmlXPathParserContextPtr ctxt) {

    xmlXPathCompMultiplicativeExpr(ctxt);
    CHECK_ERROR;
    SKIP_BLANKS;
    while ((CUR == '+') || (CUR == '-')) {
	int plus;
	int op1 = ctxt->comp->last;

        if (CUR == '+') plus = 1;
	else plus = 0;
	NEXT;
	SKIP_BLANKS;
        xmlXPathCompMultiplicativeExpr(ctxt);
	CHECK_ERROR;
	PUSH_BINARY_EXPR(XPATH_OP_PLUS, op1, ctxt->comp->last, plus, 0);
	SKIP_BLANKS;
    }
}

/**
 *  [24]   RelationalExpr ::=   AdditiveExpr
 *                 | RelationalExpr '<' AdditiveExpr
 *                 | RelationalExpr '>' AdditiveExpr
 *                 | RelationalExpr '<=' AdditiveExpr
 *                 | RelationalExpr '>=' AdditiveExpr
 *
 *  A <= B > C is allowed ? Answer from James, yes with
 *  (AdditiveExpr <= AdditiveExpr) > AdditiveExpr
 *  which is basically what got implemented.
 *
 * Compile a Relational expression, then push the result
 * on the stack
 * @param ctxt  the XPath Parser context
 */

static void
xmlXPathCompRelationalExpr(xmlXPathParserContextPtr ctxt) {
    xmlXPathCompAdditiveExpr(ctxt);
    CHECK_ERROR;
    SKIP_BLANKS;
    while ((CUR == '<') || (CUR == '>')) {
	int inf, strict;
	int op1 = ctxt->comp->last;

        if (CUR == '<') inf = 1;
	else inf = 0;
	if (NXT(1) == '=') strict = 0;
	else strict = 1;
	NEXT;
	if (!strict) NEXT;
	SKIP_BLANKS;
        xmlXPathCompAdditiveExpr(ctxt);
	CHECK_ERROR;
	PUSH_BINARY_EXPR(XPATH_OP_CMP, op1, ctxt->comp->last, inf, strict);
	SKIP_BLANKS;
    }
}

/**
 *  [23]   EqualityExpr ::=   RelationalExpr
 *                 | EqualityExpr '=' RelationalExpr
 *                 | EqualityExpr '!=' RelationalExpr
 *
 *  A != B != C is allowed ? Answer from James, yes with
 *  (RelationalExpr = RelationalExpr) = RelationalExpr
 *  (RelationalExpr != RelationalExpr) != RelationalExpr
 *  which is basically what got implemented.
 *
 * Compile an Equality expression.
 *
 * @param ctxt  the XPath Parser context
 */
static void
xmlXPathCompEqualityExpr(xmlXPathParserContextPtr ctxt) {
    xmlXPathCompRelationalExpr(ctxt);
    CHECK_ERROR;
    SKIP_BLANKS;
    while ((CUR == '=') || ((CUR == '!') && (NXT(1) == '='))) {
	int eq;
	int op1 = ctxt->comp->last;

        if (CUR == '=') eq = 1;
	else eq = 0;
	NEXT;
	if (!eq) NEXT;
	SKIP_BLANKS;
        xmlXPathCompRelationalExpr(ctxt);
	CHECK_ERROR;
	PUSH_BINARY_EXPR(XPATH_OP_EQUAL, op1, ctxt->comp->last, eq, 0);
	SKIP_BLANKS;
    }
}

/**
 *  [22]   AndExpr ::=   EqualityExpr
 *                 | AndExpr 'and' EqualityExpr
 *
 * Compile an AND expression.
 *
 * @param ctxt  the XPath Parser context
 */
static void
xmlXPathCompAndExpr(xmlXPathParserContextPtr ctxt) {
    xmlXPathCompEqualityExpr(ctxt);
    CHECK_ERROR;
    SKIP_BLANKS;
    while ((CUR == 'a') && (NXT(1) == 'n') && (NXT(2) == 'd')) {
	int op1 = ctxt->comp->last;
        SKIP(3);
	SKIP_BLANKS;
        xmlXPathCompEqualityExpr(ctxt);
	CHECK_ERROR;
	PUSH_BINARY_EXPR(XPATH_OP_AND, op1, ctxt->comp->last, 0, 0);
	SKIP_BLANKS;
    }
}

/**
 *  [14]   Expr ::=   OrExpr
 *  [21]   OrExpr ::=   AndExpr
 *                 | OrExpr 'or' AndExpr
 *
 * Parse and compile an expression
 * @param ctxt  the XPath Parser context
 * @param sort  whether to sort the resulting node set
 */
static void
xmlXPathCompileExpr(xmlXPathParserContextPtr ctxt, int sort) {
    xmlXPathContextPtr xpctxt = ctxt->context;

    if (xpctxt != NULL) {
        if (xpctxt->depth >= XPATH_MAX_RECURSION_DEPTH)
            XP_ERROR(XPATH_RECURSION_LIMIT_EXCEEDED);
        /*
         * Parsing a single '(' pushes about 10 functions on the call stack
         * before recursing!
         */
        xpctxt->depth += 10;
    }

    xmlXPathCompAndExpr(ctxt);
    CHECK_ERROR;
    SKIP_BLANKS;
    while ((CUR == 'o') && (NXT(1) == 'r')) {
	int op1 = ctxt->comp->last;
        SKIP(2);
	SKIP_BLANKS;
        xmlXPathCompAndExpr(ctxt);
	CHECK_ERROR;
	PUSH_BINARY_EXPR(XPATH_OP_OR, op1, ctxt->comp->last, 0, 0);
	SKIP_BLANKS;
    }
    if ((sort) && (ctxt->comp->steps[ctxt->comp->last].op != XPATH_OP_VALUE)) {
	/* more ops could be optimized too */
	/*
	* This is the main place to eliminate sorting for
	* operations which don't require a sorted node-set.
	* E.g. count().
	*/
	PUSH_UNARY_EXPR(XPATH_OP_SORT, ctxt->comp->last , 0, 0);
    }

    if (xpctxt != NULL)
        xpctxt->depth -= 10;
}

/**
 *  [8]   Predicate ::=   '[' PredicateExpr ']'
 *  [9]   PredicateExpr ::=   Expr
 *
 * Compile a predicate expression
 * @param ctxt  the XPath Parser context
 * @param filter  act as a filter
 */
static void
xmlXPathCompPredicate(xmlXPathParserContextPtr ctxt, int filter) {
    int op1 = ctxt->comp->last;

    SKIP_BLANKS;
    if (CUR != '[') {
	XP_ERROR(XPATH_INVALID_PREDICATE_ERROR);
    }
    NEXT;
    SKIP_BLANKS;

    ctxt->comp->last = -1;
    /*
    * This call to xmlXPathCompileExpr() will deactivate sorting
    * of the predicate result.
    * TODO: Sorting is still activated for filters, since I'm not
    *  sure if needed. Normally sorting should not be needed, since
    *  a filter can only diminish the number of items in a sequence,
    *  but won't change its order; so if the initial sequence is sorted,
    *  subsequent sorting is not needed.
    */
    if (! filter)
	xmlXPathCompileExpr(ctxt, 0);
    else
	xmlXPathCompileExpr(ctxt, 1);
    CHECK_ERROR;

    if (CUR != ']') {
	XP_ERROR(XPATH_INVALID_PREDICATE_ERROR);
    }

    if (filter)
	PUSH_BINARY_EXPR(XPATH_OP_FILTER, op1, ctxt->comp->last, 0, 0);
    else
	PUSH_BINARY_EXPR(XPATH_OP_PREDICATE, op1, ctxt->comp->last, 0, 0);

    NEXT;
    SKIP_BLANKS;
}

/**
 * ```
 * [7] NodeTest ::=   NameTest
 *		    | NodeType '(' ')'
 *		    | 'processing-instruction' '(' Literal ')'
 *
 * [37] NameTest ::=  '*'
 *		    | NCName ':' '*'
 *		    | QName
 * [38] NodeType ::= 'comment'
 *		   | 'text'
 *		   | 'processing-instruction'
 *		   | 'node'
 * ```
 *
 * @param ctxt  the XPath Parser context
 * @param test  pointer to a xmlXPathTestVal
 * @param type  pointer to a xmlXPathTypeVal
 * @param prefix  placeholder for a possible name prefix
 * @param name  current name token (optional)
 * @returns the name found and updates `test`, `type` and `prefix` appropriately
 */
static xmlChar *
xmlXPathCompNodeTest(xmlXPathParserContextPtr ctxt, xmlXPathTestVal *test,
	             xmlXPathTypeVal *type, xmlChar **prefix,
		     xmlChar *name) {
    int blanks;

    if ((test == NULL) || (type == NULL) || (prefix == NULL)) {
	return(NULL);
    }
    *type = (xmlXPathTypeVal) 0;
    *test = (xmlXPathTestVal) 0;
    *prefix = NULL;
    SKIP_BLANKS;

    if ((name == NULL) && (CUR == '*')) {
	/*
	 * All elements
	 */
	NEXT;
	*test = NODE_TEST_ALL;
	return(NULL);
    }

    if (name == NULL)
	name = xmlXPathParseNCName(ctxt);
    if (name == NULL) {
	XP_ERRORNULL(XPATH_EXPR_ERROR);
    }

    blanks = IS_BLANK_CH(CUR);
    SKIP_BLANKS;
    if (CUR == '(') {
	NEXT;
	/*
	 * NodeType or PI search
	 */
	if (xmlStrEqual(name, BAD_CAST "comment"))
	    *type = NODE_TYPE_COMMENT;
	else if (xmlStrEqual(name, BAD_CAST "node"))
	    *type = NODE_TYPE_NODE;
	else if (xmlStrEqual(name, BAD_CAST "processing-instruction"))
	    *type = NODE_TYPE_PI;
	else if (xmlStrEqual(name, BAD_CAST "text"))
	    *type = NODE_TYPE_TEXT;
	else {
	    if (name != NULL)
		xmlFree(name);
	    XP_ERRORNULL(XPATH_EXPR_ERROR);
	}

	*test = NODE_TEST_TYPE;

	SKIP_BLANKS;
	if (*type == NODE_TYPE_PI) {
	    /*
	     * Specific case: search a PI by name.
	     */
	    if (name != NULL)
		xmlFree(name);
	    name = NULL;
	    if (CUR != ')') {
		name = xmlXPathParseLiteral(ctxt);
		*test = NODE_TEST_PI;
		SKIP_BLANKS;
	    }
	}
	if (CUR != ')') {
	    if (name != NULL)
		xmlFree(name);
	    XP_ERRORNULL(XPATH_UNCLOSED_ERROR);
	}
	NEXT;
	return(name);
    }
    *test = NODE_TEST_NAME;
    if ((!blanks) && (CUR == ':')) {
	NEXT;

	/*
	 * Since currently the parser context don't have a
	 * namespace list associated:
	 * The namespace name for this prefix can be computed
	 * only at evaluation time. The compilation is done
	 * outside of any context.
	 */
	*prefix = name;

	if (CUR == '*') {
	    /*
	     * All elements
	     */
	    NEXT;
	    *test = NODE_TEST_ALL;
	    return(NULL);
	}

	name = xmlXPathParseNCName(ctxt);
	if (name == NULL) {
	    XP_ERRORNULL(XPATH_EXPR_ERROR);
	}
    }
    return(name);
}

/**
 * [6] AxisName ::=   'ancestor'
 *                  | 'ancestor-or-self'
 *                  | 'attribute'
 *                  | 'child'
 *                  | 'descendant'
 *                  | 'descendant-or-self'
 *                  | 'following'
 *                  | 'following-sibling'
 *                  | 'namespace'
 *                  | 'parent'
 *                  | 'preceding'
 *                  | 'preceding-sibling'
 *                  | 'self'
 *
 * @param name  a preparsed name token
 * @returns the axis or 0
 */
static xmlXPathAxisVal
xmlXPathIsAxisName(const xmlChar *name) {
    xmlXPathAxisVal ret = (xmlXPathAxisVal) 0;
    switch (name[0]) {
	case 'a':
	    if (xmlStrEqual(name, BAD_CAST "ancestor"))
		ret = AXIS_ANCESTOR;
	    if (xmlStrEqual(name, BAD_CAST "ancestor-or-self"))
		ret = AXIS_ANCESTOR_OR_SELF;
	    if (xmlStrEqual(name, BAD_CAST "attribute"))
		ret = AXIS_ATTRIBUTE;
	    break;
	case 'c':
	    if (xmlStrEqual(name, BAD_CAST "child"))
		ret = AXIS_CHILD;
	    break;
	case 'd':
	    if (xmlStrEqual(name, BAD_CAST "descendant"))
		ret = AXIS_DESCENDANT;
	    if (xmlStrEqual(name, BAD_CAST "descendant-or-self"))
		ret = AXIS_DESCENDANT_OR_SELF;
	    break;
	case 'f':
	    if (xmlStrEqual(name, BAD_CAST "following"))
		ret = AXIS_FOLLOWING;
	    if (xmlStrEqual(name, BAD_CAST "following-sibling"))
		ret = AXIS_FOLLOWING_SIBLING;
	    break;
	case 'n':
	    if (xmlStrEqual(name, BAD_CAST "namespace"))
		ret = AXIS_NAMESPACE;
	    break;
	case 'p':
	    if (xmlStrEqual(name, BAD_CAST "parent"))
		ret = AXIS_PARENT;
	    if (xmlStrEqual(name, BAD_CAST "preceding"))
		ret = AXIS_PRECEDING;
	    if (xmlStrEqual(name, BAD_CAST "preceding-sibling"))
		ret = AXIS_PRECEDING_SIBLING;
	    break;
	case 's':
	    if (xmlStrEqual(name, BAD_CAST "self"))
		ret = AXIS_SELF;
	    break;
    }
    return(ret);
}

/**
 * [4] Step ::=   AxisSpecifier NodeTest Predicate*
 *                  | AbbreviatedStep
 *
 * [12] AbbreviatedStep ::=   '.' | '..'
 *
 * [5] AxisSpecifier ::= AxisName '::'
 *                  | AbbreviatedAxisSpecifier
 *
 * [13] AbbreviatedAxisSpecifier ::= '@'?
 *
 * Modified for XPtr range support as:
 *
 *  [4xptr] Step ::= AxisSpecifier NodeTest Predicate*
 *                     | AbbreviatedStep
 *                     | 'range-to' '(' Expr ')' Predicate*
 *
 * Compile one step in a Location Path
 * @param ctxt  the XPath Parser context
 */
static void
xmlXPathCompStep(xmlXPathParserContextPtr ctxt) {
    SKIP_BLANKS;
    if ((CUR == '.') && (NXT(1) == '.')) {
	SKIP(2);
	SKIP_BLANKS;
	PUSH_LONG_EXPR(XPATH_OP_COLLECT, AXIS_PARENT,
		    NODE_TEST_TYPE, NODE_TYPE_NODE, NULL, NULL);
    } else if (CUR == '.') {
	NEXT;
	SKIP_BLANKS;
    } else {
	xmlChar *name = NULL;
	xmlChar *prefix = NULL;
	xmlXPathTestVal test = (xmlXPathTestVal) 0;
	xmlXPathAxisVal axis = (xmlXPathAxisVal) 0;
	xmlXPathTypeVal type = (xmlXPathTypeVal) 0;
	int op1;

	if (CUR == '*') {
	    axis = AXIS_CHILD;
	} else {
	    if (name == NULL)
		name = xmlXPathParseNCName(ctxt);
	    if (name != NULL) {
		axis = xmlXPathIsAxisName(name);
		if (axis != 0) {
		    SKIP_BLANKS;
		    if ((CUR == ':') && (NXT(1) == ':')) {
			SKIP(2);
			xmlFree(name);
			name = NULL;
		    } else {
			/* an element name can conflict with an axis one :-\ */
			axis = AXIS_CHILD;
		    }
		} else {
		    axis = AXIS_CHILD;
		}
	    } else if (CUR == '@') {
		NEXT;
		axis = AXIS_ATTRIBUTE;
	    } else {
		axis = AXIS_CHILD;
	    }
	}

        if (ctxt->error != XPATH_EXPRESSION_OK) {
            xmlFree(name);
            return;
        }

	name = xmlXPathCompNodeTest(ctxt, &test, &type, &prefix, name);
	if (test == 0)
	    return;

        if ((prefix != NULL) && (ctxt->context != NULL) &&
	    (ctxt->context->flags & XML_XPATH_CHECKNS)) {
	    if (xmlXPathNsLookup(ctxt->context, prefix) == NULL) {
		xmlXPathErr(ctxt, XPATH_UNDEF_PREFIX_ERROR);
	    }
	}

	op1 = ctxt->comp->last;
	ctxt->comp->last = -1;

	SKIP_BLANKS;
	while (CUR == '[') {
	    xmlXPathCompPredicate(ctxt, 0);
	}

        if (PUSH_FULL_EXPR(XPATH_OP_COLLECT, op1, ctxt->comp->last, axis,
                           test, type, (void *)prefix, (void *)name) == -1) {
            xmlFree(prefix);
            xmlFree(name);
        }
    }
}

/**
 *  [3]   RelativeLocationPath ::=   Step
 *                     | RelativeLocationPath '/' Step
 *                     | AbbreviatedRelativeLocationPath
 *  [11]  AbbreviatedRelativeLocationPath ::=   RelativeLocationPath '//' Step
 *
 * Compile a relative location path.
 * @param ctxt  the XPath Parser context
 */
static void
xmlXPathCompRelativeLocationPath
(xmlXPathParserContextPtr ctxt) {
    SKIP_BLANKS;
    if ((CUR == '/') && (NXT(1) == '/')) {
	SKIP(2);
	SKIP_BLANKS;
	PUSH_LONG_EXPR(XPATH_OP_COLLECT, AXIS_DESCENDANT_OR_SELF,
		         NODE_TEST_TYPE, NODE_TYPE_NODE, NULL, NULL);
    } else if (CUR == '/') {
	    NEXT;
	SKIP_BLANKS;
    }
    xmlXPathCompStep(ctxt);
    CHECK_ERROR;
    SKIP_BLANKS;
    while (CUR == '/') {
	if ((CUR == '/') && (NXT(1) == '/')) {
	    SKIP(2);
	    SKIP_BLANKS;
	    PUSH_LONG_EXPR(XPATH_OP_COLLECT, AXIS_DESCENDANT_OR_SELF,
			     NODE_TEST_TYPE, NODE_TYPE_NODE, NULL, NULL);
	    xmlXPathCompStep(ctxt);
	} else if (CUR == '/') {
	    NEXT;
	    SKIP_BLANKS;
	    xmlXPathCompStep(ctxt);
	}
	SKIP_BLANKS;
    }
}

/**
 *  [1]   LocationPath ::=   RelativeLocationPath
 *                     | AbsoluteLocationPath
 *  [2]   AbsoluteLocationPath ::=   '/' RelativeLocationPath?
 *                     | AbbreviatedAbsoluteLocationPath
 *  [10]   AbbreviatedAbsoluteLocationPath ::=
 *                           '//' RelativeLocationPath
 *
 * Compile a location path
 * @param ctxt  the XPath Parser context
 */
static void
xmlXPathCompLocationPath(xmlXPathParserContextPtr ctxt) {
    SKIP_BLANKS;
    if (CUR != '/') {
        xmlXPathCompRelativeLocationPath(ctxt);
    } else {
	while (CUR == '/') {
	    if ((CUR == '/') && (NXT(1) == '/')) {
		SKIP(2);
		SKIP_BLANKS;
		PUSH_LONG_EXPR(XPATH_OP_COLLECT, AXIS_DESCENDANT_OR_SELF,
			     NODE_TEST_TYPE, NODE_TYPE_NODE, NULL, NULL);
		xmlXPathCompRelativeLocationPath(ctxt);
	    } else if (CUR == '/') {
		NEXT;
		SKIP_BLANKS;
		if ((CUR != 0) &&
		    ((IS_ASCII_LETTER(CUR)) || (CUR >= 0x80) ||
                     (CUR == '_') || (CUR == '.') ||
		     (CUR == '@') || (CUR == '*')))
		    xmlXPathCompRelativeLocationPath(ctxt);
	    }
	    CHECK_ERROR;
	}
    }
}

/************************************************************************
 *									*
 *		XPath precompiled expression evaluation			*
 *									*
 ************************************************************************/

static int
xmlXPathCompOpEval(xmlXPathParserContextPtr ctxt, xmlXPathStepOpPtr op);

/**
 * Filter a node set, keeping only nodes for which the predicate expression
 * matches. Afterwards, keep only nodes between minPos and maxPos in the
 * filtered result.
 *
 * @param ctxt  the XPath Parser context
 * @param set  the node set to filter
 * @param filterOpIndex  the index of the predicate/filter op
 * @param minPos  minimum position in the filtered set (1-based)
 * @param maxPos  maximum position in the filtered set (1-based)
 * @param hasNsNodes  true if the node set may contain namespace nodes
 */
static void
xmlXPathNodeSetFilter(xmlXPathParserContextPtr ctxt,
		      xmlNodeSetPtr set,
		      int filterOpIndex,
                      int minPos, int maxPos,
		      int hasNsNodes)
{
    xmlXPathContextPtr xpctxt;
    xmlNodePtr oldnode;
    xmlDocPtr olddoc;
    xmlXPathStepOpPtr filterOp;
    int oldcs, oldpp;
    int i, j, pos;

    if ((set == NULL) || (set->nodeNr == 0))
        return;

    /*
    * Check if the node set contains a sufficient number of nodes for
    * the requested range.
    */
    if (set->nodeNr < minPos) {
        xmlXPathNodeSetClear(set, hasNsNodes);
        return;
    }

    xpctxt = ctxt->context;
    oldnode = xpctxt->node;
    olddoc = xpctxt->doc;
    oldcs = xpctxt->contextSize;
    oldpp = xpctxt->proximityPosition;
    filterOp = &ctxt->comp->steps[filterOpIndex];

    xpctxt->contextSize = set->nodeNr;

    for (i = 0, j = 0, pos = 1; i < set->nodeNr; i++) {
        xmlNodePtr node = set->nodeTab[i];
        int res;

        xpctxt->node = node;
        xpctxt->proximityPosition = i + 1;

        /*
        * Also set the xpath document in case things like
        * key() are evaluated in the predicate.
        *
        * TODO: Get real doc for namespace nodes.
        */
        if ((node->type != XML_NAMESPACE_DECL) &&
            (node->doc != NULL))
            xpctxt->doc = node->doc;

        res = xmlXPathCompOpEvalToBoolean(ctxt, filterOp, 1);

        if (ctxt->error != XPATH_EXPRESSION_OK)
            break;
        if (res < 0) {
            /* Shouldn't happen */
            xmlXPathErr(ctxt, XPATH_EXPR_ERROR);
            break;
        }

        if ((res != 0) && ((pos >= minPos) && (pos <= maxPos))) {
            if (i != j) {
                set->nodeTab[j] = node;
                set->nodeTab[i] = NULL;
            }

            j += 1;
        } else {
            /* Remove the entry from the initial node set. */
            set->nodeTab[i] = NULL;
            if (node->type == XML_NAMESPACE_DECL)
                xmlXPathNodeSetFreeNs((xmlNsPtr) node);
        }

        if (res != 0) {
            if (pos == maxPos) {
                i += 1;
                break;
            }

            pos += 1;
        }
    }

    /* Free remaining nodes. */
    if (hasNsNodes) {
        for (; i < set->nodeNr; i++) {
            xmlNodePtr node = set->nodeTab[i];
            if ((node != NULL) && (node->type == XML_NAMESPACE_DECL))
                xmlXPathNodeSetFreeNs((xmlNsPtr) node);
        }
    }

    set->nodeNr = j;

    /* If too many elements were removed, shrink table to preserve memory. */
    if ((set->nodeMax > XML_NODESET_DEFAULT) &&
        (set->nodeNr < set->nodeMax / 2)) {
        xmlNodePtr *tmp;
        int nodeMax = set->nodeNr;

        if (nodeMax < XML_NODESET_DEFAULT)
            nodeMax = XML_NODESET_DEFAULT;
        tmp = (xmlNodePtr *) xmlRealloc(set->nodeTab,
                nodeMax * sizeof(xmlNodePtr));
        if (tmp == NULL) {
            xmlXPathPErrMemory(ctxt);
        } else {
            set->nodeTab = tmp;
            set->nodeMax = nodeMax;
        }
    }

    xpctxt->node = oldnode;
    xpctxt->doc = olddoc;
    xpctxt->contextSize = oldcs;
    xpctxt->proximityPosition = oldpp;
}

/**
 * Filter a node set, keeping only nodes for which the sequence of predicate
 * expressions matches. Afterwards, keep only nodes between minPos and maxPos
 * in the filtered result.
 *
 * @param ctxt  the XPath Parser context
 * @param op  the predicate op
 * @param set  the node set to filter
 * @param minPos  minimum position in the filtered set (1-based)
 * @param maxPos  maximum position in the filtered set (1-based)
 * @param hasNsNodes  true if the node set may contain namespace nodes
 */
static void
xmlXPathCompOpEvalPredicate(xmlXPathParserContextPtr ctxt,
			    xmlXPathStepOpPtr op,
			    xmlNodeSetPtr set,
                            int minPos, int maxPos,
			    int hasNsNodes)
{
    if (op->ch1 != -1) {
	xmlXPathCompExprPtr comp = ctxt->comp;
	/*
	* Process inner predicates first.
	*/
	if (comp->steps[op->ch1].op != XPATH_OP_PREDICATE) {
            XP_ERROR(XPATH_INVALID_OPERAND);
	}
        if (ctxt->context->depth >= XPATH_MAX_RECURSION_DEPTH)
            XP_ERROR(XPATH_RECURSION_LIMIT_EXCEEDED);
        ctxt->context->depth += 1;
	xmlXPathCompOpEvalPredicate(ctxt, &comp->steps[op->ch1], set,
                                    1, set->nodeNr, hasNsNodes);
        ctxt->context->depth -= 1;
	CHECK_ERROR;
    }

    if (op->ch2 != -1)
        xmlXPathNodeSetFilter(ctxt, set, op->ch2, minPos, maxPos, hasNsNodes);
}

static int
xmlXPathIsPositionalPredicate(xmlXPathParserContextPtr ctxt,
			    xmlXPathStepOpPtr op,
			    int *maxPos)
{

    xmlXPathStepOpPtr exprOp;

    /*
    * BIG NOTE: This is not intended for XPATH_OP_FILTER yet!
    */

    /*
    * If not -1, then ch1 will point to:
    * 1) For predicates (XPATH_OP_PREDICATE):
    *    - an inner predicate operator
    * 2) For filters (XPATH_OP_FILTER):
    *    - an inner filter operator OR
    *    - an expression selecting the node set.
    *      E.g. "key('a', 'b')" or "(//foo | //bar)".
    */
    if ((op->op != XPATH_OP_PREDICATE) && (op->op != XPATH_OP_FILTER))
	return(0);

    if (op->ch2 != -1) {
	exprOp = &ctxt->comp->steps[op->ch2];
    } else
	return(0);

    if ((exprOp != NULL) &&
	(exprOp->op == XPATH_OP_VALUE) &&
	(exprOp->value4 != NULL) &&
	(((xmlXPathObjectPtr) exprOp->value4)->type == XPATH_NUMBER))
    {
        double floatval = ((xmlXPathObjectPtr) exprOp->value4)->floatval;

	/*
	* We have a "[n]" predicate here.
	* TODO: Unfortunately this simplistic test here is not
	* able to detect a position() predicate in compound
	* expressions like "[@attr = 'a" and position() = 1],
	* and even not the usage of position() in
	* "[position() = 1]"; thus - obviously - a position-range,
	* like it "[position() < 5]", is also not detected.
	* Maybe we could rewrite the AST to ease the optimization.
	*/

        if ((floatval > INT_MIN) && (floatval < INT_MAX)) {
	    *maxPos = (int) floatval;
            if (floatval == (double) *maxPos)
                return(1);
        }
    }
    return(0);
}

static int
xmlXPathNodeCollectAndTest(xmlXPathParserContextPtr ctxt,
                           xmlXPathStepOpPtr op,
			   xmlNodePtr * first, xmlNodePtr * last,
			   int toBool)
{

#define XP_TEST_HIT \
    if (hasAxisRange != 0) { \
	if (++pos == maxPos) { \
	    if (addNode(seq, cur) < 0) \
	        xmlXPathPErrMemory(ctxt); \
	    goto axis_range_end; } \
    } else { \
	if (addNode(seq, cur) < 0) \
	    xmlXPathPErrMemory(ctxt); \
	if (breakOnFirstHit) goto first_hit; }

#define XP_TEST_HIT_NS \
    if (hasAxisRange != 0) { \
	if (++pos == maxPos) { \
	    hasNsNodes = 1; \
	    if (xmlXPathNodeSetAddNs(seq, xpctxt->node, (xmlNsPtr) cur) < 0) \
	        xmlXPathPErrMemory(ctxt); \
	goto axis_range_end; } \
    } else { \
	hasNsNodes = 1; \
	if (xmlXPathNodeSetAddNs(seq, xpctxt->node, (xmlNsPtr) cur) < 0) \
	    xmlXPathPErrMemory(ctxt); \
	if (breakOnFirstHit) goto first_hit; }

    xmlXPathAxisVal axis = (xmlXPathAxisVal) op->value;
    xmlXPathTestVal test = (xmlXPathTestVal) op->value2;
    xmlXPathTypeVal type = (xmlXPathTypeVal) op->value3;
    const xmlChar *prefix = op->value4;
    const xmlChar *name = op->value5;
    const xmlChar *URI = NULL;

    int total = 0, hasNsNodes = 0;
    /* The popped object holding the context nodes */
    xmlXPathObjectPtr obj;
    /* The set of context nodes for the node tests */
    xmlNodeSetPtr contextSeq;
    int contextIdx;
    xmlNodePtr contextNode;
    /* The final resulting node set wrt to all context nodes */
    xmlNodeSetPtr outSeq;
    /*
    * The temporary resulting node set wrt 1 context node.
    * Used to feed predicate evaluation.
    */
    xmlNodeSetPtr seq;
    xmlNodePtr cur;
    /* First predicate operator */
    xmlXPathStepOpPtr predOp;
    int maxPos; /* The requested position() (when a "[n]" predicate) */
    int hasPredicateRange, hasAxisRange, pos;
    int breakOnFirstHit;

    xmlXPathTraversalFunction next = NULL;
    int (*addNode) (xmlNodeSetPtr, xmlNodePtr);
    xmlXPathNodeSetMergeFunction mergeAndClear;
    xmlNodePtr oldContextNode;
    xmlXPathContextPtr xpctxt = ctxt->context;


    CHECK_TYPE0(XPATH_NODESET);
    obj = xmlXPathValuePop(ctxt);
    /*
    * Setup namespaces.
    */
    if (prefix != NULL) {
        URI = xmlXPathNsLookup(xpctxt, prefix);
        if (URI == NULL) {
	    xmlXPathReleaseObject(xpctxt, obj);
            XP_ERROR0(XPATH_UNDEF_PREFIX_ERROR);
	}
    }
    /*
    * Setup axis.
    *
    * MAYBE FUTURE TODO: merging optimizations:
    * - If the nodes to be traversed wrt to the initial nodes and
    *   the current axis cannot overlap, then we could avoid searching
    *   for duplicates during the merge.
    *   But the question is how/when to evaluate if they cannot overlap.
    *   Example: if we know that for two initial nodes, the one is
    *   not in the ancestor-or-self axis of the other, then we could safely
    *   avoid a duplicate-aware merge, if the axis to be traversed is e.g.
    *   the descendant-or-self axis.
    */
    mergeAndClear = xmlXPathNodeSetMergeAndClear;
    switch (axis) {
        case AXIS_ANCESTOR:
            first = NULL;
            next = xmlXPathNextAncestor;
            break;
        case AXIS_ANCESTOR_OR_SELF:
            first = NULL;
            next = xmlXPathNextAncestorOrSelf;
            break;
        case AXIS_ATTRIBUTE:
            first = NULL;
	    last = NULL;
            next = xmlXPathNextAttribute;
	    mergeAndClear = xmlXPathNodeSetMergeAndClearNoDupls;
            break;
        case AXIS_CHILD:
	    last = NULL;
	    if (((test == NODE_TEST_NAME) || (test == NODE_TEST_ALL)) &&
		(type == NODE_TYPE_NODE))
	    {
		/*
		* Optimization if an element node type is 'element'.
		*/
		next = xmlXPathNextChildElement;
	    } else
		next = xmlXPathNextChild;
	    mergeAndClear = xmlXPathNodeSetMergeAndClearNoDupls;
            break;
        case AXIS_DESCENDANT:
	    last = NULL;
            next = xmlXPathNextDescendant;
            break;
        case AXIS_DESCENDANT_OR_SELF:
	    last = NULL;
            next = xmlXPathNextDescendantOrSelf;
            break;
        case AXIS_FOLLOWING:
	    last = NULL;
            next = xmlXPathNextFollowing;
            break;
        case AXIS_FOLLOWING_SIBLING:
	    last = NULL;
            next = xmlXPathNextFollowingSibling;
            break;
        case AXIS_NAMESPACE:
            first = NULL;
	    last = NULL;
            next = (xmlXPathTraversalFunction) xmlXPathNextNamespace;
	    mergeAndClear = xmlXPathNodeSetMergeAndClearNoDupls;
            break;
        case AXIS_PARENT:
            first = NULL;
            next = xmlXPathNextParent;
            break;
        case AXIS_PRECEDING:
            first = NULL;
            next = xmlXPathNextPrecedingInternal;
            break;
        case AXIS_PRECEDING_SIBLING:
            first = NULL;
            next = xmlXPathNextPrecedingSibling;
            break;
        case AXIS_SELF:
            first = NULL;
	    last = NULL;
            next = xmlXPathNextSelf;
	    mergeAndClear = xmlXPathNodeSetMergeAndClearNoDupls;
            break;
    }

    if (next == NULL) {
	xmlXPathReleaseObject(xpctxt, obj);
        return(0);
    }
    contextSeq = obj->nodesetval;
    if ((contextSeq == NULL) || (contextSeq->nodeNr <= 0)) {
        xmlXPathValuePush(ctxt, obj);
        return(0);
    }
    /*
    * Predicate optimization ---------------------------------------------
    * If this step has a last predicate, which contains a position(),
    * then we'll optimize (although not exactly "position()", but only
    * the  short-hand form, i.e., "[n]".
    *
    * Example - expression "/foo[parent::bar][1]":
    *
    * COLLECT 'child' 'name' 'node' foo    -- op (we are here)
    *   ROOT                               -- op->ch1
    *   PREDICATE                          -- op->ch2 (predOp)
    *     PREDICATE                          -- predOp->ch1 = [parent::bar]
    *       SORT
    *         COLLECT  'parent' 'name' 'node' bar
    *           NODE
    *     ELEM Object is a number : 1        -- predOp->ch2 = [1]
    *
    */
    maxPos = 0;
    predOp = NULL;
    hasPredicateRange = 0;
    hasAxisRange = 0;
    if (op->ch2 != -1) {
	/*
	* There's at least one predicate. 16 == XPATH_OP_PREDICATE
	*/
	predOp = &ctxt->comp->steps[op->ch2];
	if (xmlXPathIsPositionalPredicate(ctxt, predOp, &maxPos)) {
	    if (predOp->ch1 != -1) {
		/*
		* Use the next inner predicate operator.
		*/
		predOp = &ctxt->comp->steps[predOp->ch1];
		hasPredicateRange = 1;
	    } else {
		/*
		* There's no other predicate than the [n] predicate.
		*/
		predOp = NULL;
		hasAxisRange = 1;
	    }
	}
    }
    breakOnFirstHit = ((toBool) && (predOp == NULL)) ? 1 : 0;
    /*
    * Axis traversal -----------------------------------------------------
    */
    /*
     * 2.3 Node Tests
     *  - For the attribute axis, the principal node type is attribute.
     *  - For the namespace axis, the principal node type is namespace.
     *  - For other axes, the principal node type is element.
     *
     * A node test * is true for any node of the
     * principal node type. For example, child::* will
     * select all element children of the context node
     */
    oldContextNode = xpctxt->node;
    addNode = xmlXPathNodeSetAddUnique;
    outSeq = NULL;
    seq = NULL;
    contextNode = NULL;
    contextIdx = 0;


    while (((contextIdx < contextSeq->nodeNr) || (contextNode != NULL)) &&
           (ctxt->error == XPATH_EXPRESSION_OK)) {
	xpctxt->node = contextSeq->nodeTab[contextIdx++];

	if (seq == NULL) {
	    seq = xmlXPathNodeSetCreate(NULL);
	    if (seq == NULL) {
                xmlXPathPErrMemory(ctxt);
		total = 0;
		goto error;
	    }
	}
	/*
	* Traverse the axis and test the nodes.
	*/
	pos = 0;
	cur = NULL;
	hasNsNodes = 0;
        do {
            if (OP_LIMIT_EXCEEDED(ctxt, 1))
                goto error;

            cur = next(ctxt, cur);
            if (cur == NULL)
                break;

	    /*
	    * QUESTION TODO: What does the "first" and "last" stuff do?
	    */
            if ((first != NULL) && (*first != NULL)) {
		if (*first == cur)
		    break;
		if (((total % 256) == 0) &&
#ifdef XP_OPTIMIZED_NON_ELEM_COMPARISON
		    (xmlXPathCmpNodesExt(*first, cur) >= 0))
#else
		    (xmlXPathCmpNodes(*first, cur) >= 0))
#endif
		{
		    break;
		}
	    }
	    if ((last != NULL) && (*last != NULL)) {
		if (*last == cur)
		    break;
		if (((total % 256) == 0) &&
#ifdef XP_OPTIMIZED_NON_ELEM_COMPARISON
		    (xmlXPathCmpNodesExt(cur, *last) >= 0))
#else
		    (xmlXPathCmpNodes(cur, *last) >= 0))
#endif
		{
		    break;
		}
	    }

            total++;

	    switch (test) {
                case NODE_TEST_NONE:
		    total = 0;
		    goto error;
                case NODE_TEST_TYPE:
		    if (type == NODE_TYPE_NODE) {
			switch (cur->type) {
			    case XML_DOCUMENT_NODE:
			    case XML_HTML_DOCUMENT_NODE:
			    case XML_ELEMENT_NODE:
			    case XML_ATTRIBUTE_NODE:
			    case XML_PI_NODE:
			    case XML_COMMENT_NODE:
			    case XML_CDATA_SECTION_NODE:
			    case XML_TEXT_NODE:
				XP_TEST_HIT
				break;
			    case XML_NAMESPACE_DECL: {
				if (axis == AXIS_NAMESPACE) {
				    XP_TEST_HIT_NS
				} else {
	                            hasNsNodes = 1;
				    XP_TEST_HIT
				}
				break;
                            }
			    default:
				break;
			}
		    } else if (cur->type == (xmlElementType) type) {
			if (cur->type == XML_NAMESPACE_DECL)
			    XP_TEST_HIT_NS
			else
			    XP_TEST_HIT
		    } else if ((type == NODE_TYPE_TEXT) &&
			 (cur->type == XML_CDATA_SECTION_NODE))
		    {
			XP_TEST_HIT
		    }
		    break;
                case NODE_TEST_PI:
                    if ((cur->type == XML_PI_NODE) &&
                        ((name == NULL) || xmlStrEqual(name, cur->name)))
		    {
			XP_TEST_HIT
                    }
                    break;
                case NODE_TEST_ALL:
                    if (axis == AXIS_ATTRIBUTE) {
                        if (cur->type == XML_ATTRIBUTE_NODE)
			{
                            if (prefix == NULL)
			    {
				XP_TEST_HIT
                            } else if ((cur->ns != NULL) &&
				(xmlStrEqual(URI, cur->ns->href)))
			    {
				XP_TEST_HIT
                            }
                        }
                    } else if (axis == AXIS_NAMESPACE) {
                        if (cur->type == XML_NAMESPACE_DECL)
			{
			    XP_TEST_HIT_NS
                        }
                    } else {
                        if (cur->type == XML_ELEMENT_NODE) {
                            if (prefix == NULL)
			    {
				XP_TEST_HIT

                            } else if ((cur->ns != NULL) &&
				(xmlStrEqual(URI, cur->ns->href)))
			    {
				XP_TEST_HIT
                            }
                        }
                    }
                    break;
                case NODE_TEST_NS:{
                        /* TODO */
                        break;
                    }
                case NODE_TEST_NAME:
                    if (axis == AXIS_ATTRIBUTE) {
                        if (cur->type != XML_ATTRIBUTE_NODE)
			    break;
		    } else if (axis == AXIS_NAMESPACE) {
                        if (cur->type != XML_NAMESPACE_DECL)
			    break;
		    } else {
		        if (cur->type != XML_ELEMENT_NODE)
			    break;
		    }
                    switch (cur->type) {
                        case XML_ELEMENT_NODE:
                            if (xmlStrEqual(name, cur->name)) {
                                if (prefix == NULL) {
                                    if (cur->ns == NULL)
				    {
					XP_TEST_HIT
                                    }
                                } else {
                                    if ((cur->ns != NULL) &&
                                        (xmlStrEqual(URI, cur->ns->href)))
				    {
					XP_TEST_HIT
                                    }
                                }
                            }
                            break;
                        case XML_ATTRIBUTE_NODE:{
                                xmlAttrPtr attr = (xmlAttrPtr) cur;

                                if (xmlStrEqual(name, attr->name)) {
                                    if (prefix == NULL) {
                                        if ((attr->ns == NULL) ||
                                            (attr->ns->prefix == NULL))
					{
					    XP_TEST_HIT
                                        }
                                    } else {
                                        if ((attr->ns != NULL) &&
                                            (xmlStrEqual(URI,
					      attr->ns->href)))
					{
					    XP_TEST_HIT
                                        }
                                    }
                                }
                                break;
                            }
                        case XML_NAMESPACE_DECL:
                            if (cur->type == XML_NAMESPACE_DECL) {
                                xmlNsPtr ns = (xmlNsPtr) cur;

                                if ((ns->prefix != NULL) && (name != NULL)
                                    && (xmlStrEqual(ns->prefix, name)))
				{
				    XP_TEST_HIT_NS
                                }
                            }
                            break;
                        default:
                            break;
                    }
                    break;
	    } /* switch(test) */
        } while ((cur != NULL) && (ctxt->error == XPATH_EXPRESSION_OK));

	goto apply_predicates;

axis_range_end: /* ----------------------------------------------------- */
	/*
	* We have a "/foo[n]", and position() = n was reached.
	* Note that we can have as well "/foo/::parent::foo[1]", so
	* a duplicate-aware merge is still needed.
	* Merge with the result.
	*/
	if (outSeq == NULL) {
	    outSeq = seq;
	    seq = NULL;
	} else {
	    outSeq = mergeAndClear(outSeq, seq);
            if (outSeq == NULL)
                xmlXPathPErrMemory(ctxt);
        }
	/*
	* Break if only a true/false result was requested.
	*/
	if (toBool)
	    break;
	continue;

first_hit: /* ---------------------------------------------------------- */
	/*
	* Break if only a true/false result was requested and
	* no predicates existed and a node test succeeded.
	*/
	if (outSeq == NULL) {
	    outSeq = seq;
	    seq = NULL;
	} else {
	    outSeq = mergeAndClear(outSeq, seq);
            if (outSeq == NULL)
                xmlXPathPErrMemory(ctxt);
        }
	break;

apply_predicates: /* --------------------------------------------------- */
        if (ctxt->error != XPATH_EXPRESSION_OK)
	    goto error;

        /*
	* Apply predicates.
	*/
        if ((predOp != NULL) && (seq->nodeNr > 0)) {
	    /*
	    * E.g. when we have a "/foo[some expression][n]".
	    */
	    /*
	    * QUESTION TODO: The old predicate evaluation took into
	    *  account location-sets.
	    *  (E.g. ctxt->value->type == XPATH_LOCATIONSET)
	    *  Do we expect such a set here?
	    *  All what I learned now from the evaluation semantics
	    *  does not indicate that a location-set will be processed
	    *  here, so this looks OK.
	    */
	    /*
	    * Iterate over all predicates, starting with the outermost
	    * predicate.
	    * TODO: Problem: we cannot execute the inner predicates first
	    *  since we cannot go back *up* the operator tree!
	    *  Options we have:
	    *  1) Use of recursive functions (like is it currently done
	    *     via xmlXPathCompOpEval())
	    *  2) Add a predicate evaluation information stack to the
	    *     context struct
	    *  3) Change the way the operators are linked; we need a
	    *     "parent" field on xmlXPathStepOp
	    *
	    * For the moment, I'll try to solve this with a recursive
	    * function: xmlXPathCompOpEvalPredicate().
	    */
	    if (hasPredicateRange != 0)
		xmlXPathCompOpEvalPredicate(ctxt, predOp, seq, maxPos, maxPos,
					    hasNsNodes);
	    else
		xmlXPathCompOpEvalPredicate(ctxt, predOp, seq, 1, seq->nodeNr,
					    hasNsNodes);

	    if (ctxt->error != XPATH_EXPRESSION_OK) {
		total = 0;
		goto error;
	    }
        }

        if (seq->nodeNr > 0) {
	    /*
	    * Add to result set.
	    */
	    if (outSeq == NULL) {
		outSeq = seq;
		seq = NULL;
	    } else {
		outSeq = mergeAndClear(outSeq, seq);
                if (outSeq == NULL)
                    xmlXPathPErrMemory(ctxt);
	    }

            if (toBool)
                break;
	}
    }

error:
    if ((obj->boolval) && (obj->user != NULL)) {
	/*
	* QUESTION TODO: What does this do and why?
	* TODO: Do we have to do this also for the "error"
	* cleanup further down?
	*/
	ctxt->value->boolval = 1;
	ctxt->value->user = obj->user;
	obj->user = NULL;
	obj->boolval = 0;
    }
    xmlXPathReleaseObject(xpctxt, obj);

    /*
    * Ensure we return at least an empty set.
    */
    if (outSeq == NULL) {
	if ((seq != NULL) && (seq->nodeNr == 0)) {
	    outSeq = seq;
        } else {
	    outSeq = xmlXPathNodeSetCreate(NULL);
            if (outSeq == NULL)
                xmlXPathPErrMemory(ctxt);
        }
    }
    if ((seq != NULL) && (seq != outSeq)) {
	 xmlXPathFreeNodeSet(seq);
    }
    /*
    * Hand over the result. Better to push the set also in
    * case of errors.
    */
    xmlXPathValuePush(ctxt, xmlXPathCacheWrapNodeSet(ctxt, outSeq));
    /*
    * Reset the context node.
    */
    xpctxt->node = oldContextNode;
    /*
    * When traversing the namespace axis in "toBool" mode, it's
    * possible that tmpNsList wasn't freed.
    */
    if (xpctxt->tmpNsList != NULL) {
        xmlFree(xpctxt->tmpNsList);
        xpctxt->tmpNsList = NULL;
    }

    return(total);
}

static int
xmlXPathCompOpEvalFilterFirst(xmlXPathParserContextPtr ctxt,
			      xmlXPathStepOpPtr op, xmlNodePtr * first);

/**
 * Evaluate the Precompiled XPath operation searching only the first
 * element in document order
 *
 * @param ctxt  the XPath parser context with the compiled expression
 * @param op  an XPath compiled operation
 * @param first  the first elem found so far
 * @returns the number of examined objects.
 */
static int
xmlXPathCompOpEvalFirst(xmlXPathParserContextPtr ctxt,
                        xmlXPathStepOpPtr op, xmlNodePtr * first)
{
    int total = 0, cur;
    xmlXPathCompExprPtr comp;
    xmlXPathObjectPtr arg1, arg2;

    CHECK_ERROR0;
    if (OP_LIMIT_EXCEEDED(ctxt, 1))
        return(0);
    if (ctxt->context->depth >= XPATH_MAX_RECURSION_DEPTH)
        XP_ERROR0(XPATH_RECURSION_LIMIT_EXCEEDED);
    ctxt->context->depth += 1;
    comp = ctxt->comp;
    switch (op->op) {
        case XPATH_OP_END:
            break;
        case XPATH_OP_UNION:
            total =
                xmlXPathCompOpEvalFirst(ctxt, &comp->steps[op->ch1],
                                        first);
	    CHECK_ERROR0;
            if ((ctxt->value != NULL)
                && (ctxt->value->type == XPATH_NODESET)
                && (ctxt->value->nodesetval != NULL)
                && (ctxt->value->nodesetval->nodeNr >= 1)) {
                /*
                 * limit tree traversing to first node in the result
                 */
		/*
		* OPTIMIZE TODO: This implicitly sorts
		*  the result, even if not needed. E.g. if the argument
		*  of the count() function, no sorting is needed.
		* OPTIMIZE TODO: How do we know if the node-list wasn't
		*  already sorted?
		*/
		if (ctxt->value->nodesetval->nodeNr > 1)
		    xmlXPathNodeSetSort(ctxt->value->nodesetval);
                *first = ctxt->value->nodesetval->nodeTab[0];
            }
            cur =
                xmlXPathCompOpEvalFirst(ctxt, &comp->steps[op->ch2],
                                        first);
	    CHECK_ERROR0;

            arg2 = xmlXPathValuePop(ctxt);
            arg1 = xmlXPathValuePop(ctxt);
            if ((arg1 == NULL) || (arg1->type != XPATH_NODESET) ||
                (arg2 == NULL) || (arg2->type != XPATH_NODESET)) {
	        xmlXPathReleaseObject(ctxt->context, arg1);
	        xmlXPathReleaseObject(ctxt->context, arg2);
                XP_ERROR0(XPATH_INVALID_TYPE);
            }
            if ((ctxt->context->opLimit != 0) &&
                (((arg1->nodesetval != NULL) &&
                  (xmlXPathCheckOpLimit(ctxt,
                                        arg1->nodesetval->nodeNr) < 0)) ||
                 ((arg2->nodesetval != NULL) &&
                  (xmlXPathCheckOpLimit(ctxt,
                                        arg2->nodesetval->nodeNr) < 0)))) {
	        xmlXPathReleaseObject(ctxt->context, arg1);
	        xmlXPathReleaseObject(ctxt->context, arg2);
                break;
            }

            if ((arg2->nodesetval != NULL) &&
                (arg2->nodesetval->nodeNr != 0)) {
                arg1->nodesetval = xmlXPathNodeSetMerge(arg1->nodesetval,
                                                        arg2->nodesetval);
                if (arg1->nodesetval == NULL)
                    xmlXPathPErrMemory(ctxt);
            }
            xmlXPathValuePush(ctxt, arg1);
	    xmlXPathReleaseObject(ctxt->context, arg2);
            total += cur;
            break;
        case XPATH_OP_ROOT:
            xmlXPathRoot(ctxt);
            break;
        case XPATH_OP_NODE:
            if (op->ch1 != -1)
                total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
	    CHECK_ERROR0;
            if (op->ch2 != -1)
                total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch2]);
	    CHECK_ERROR0;
	    xmlXPathValuePush(ctxt, xmlXPathCacheNewNodeSet(ctxt,
		ctxt->context->node));
            break;
        case XPATH_OP_COLLECT:{
                if (op->ch1 == -1)
                    break;

                total = xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
		CHECK_ERROR0;

                total += xmlXPathNodeCollectAndTest(ctxt, op, first, NULL, 0);
                break;
            }
        case XPATH_OP_VALUE:
            xmlXPathValuePush(ctxt, xmlXPathCacheObjectCopy(ctxt, op->value4));
            break;
        case XPATH_OP_SORT:
            if (op->ch1 != -1)
                total +=
                    xmlXPathCompOpEvalFirst(ctxt, &comp->steps[op->ch1],
                                            first);
	    CHECK_ERROR0;
            if ((ctxt->value != NULL)
                && (ctxt->value->type == XPATH_NODESET)
                && (ctxt->value->nodesetval != NULL)
		&& (ctxt->value->nodesetval->nodeNr > 1))
                xmlXPathNodeSetSort(ctxt->value->nodesetval);
            break;
#ifdef XP_OPTIMIZED_FILTER_FIRST
	case XPATH_OP_FILTER:
                total += xmlXPathCompOpEvalFilterFirst(ctxt, op, first);
            break;
#endif
        default:
            total += xmlXPathCompOpEval(ctxt, op);
            break;
    }

    ctxt->context->depth -= 1;
    return(total);
}

/**
 * Evaluate the Precompiled XPath operation searching only the last
 * element in document order
 *
 * @param ctxt  the XPath parser context with the compiled expression
 * @param op  an XPath compiled operation
 * @param last  the last elem found so far
 * @returns the number of nodes traversed
 */
static int
xmlXPathCompOpEvalLast(xmlXPathParserContextPtr ctxt, xmlXPathStepOpPtr op,
                       xmlNodePtr * last)
{
    int total = 0, cur;
    xmlXPathCompExprPtr comp;
    xmlXPathObjectPtr arg1, arg2;

    CHECK_ERROR0;
    if (OP_LIMIT_EXCEEDED(ctxt, 1))
        return(0);
    if (ctxt->context->depth >= XPATH_MAX_RECURSION_DEPTH)
        XP_ERROR0(XPATH_RECURSION_LIMIT_EXCEEDED);
    ctxt->context->depth += 1;
    comp = ctxt->comp;
    switch (op->op) {
        case XPATH_OP_END:
            break;
        case XPATH_OP_UNION:
            total =
                xmlXPathCompOpEvalLast(ctxt, &comp->steps[op->ch1], last);
	    CHECK_ERROR0;
            if ((ctxt->value != NULL)
                && (ctxt->value->type == XPATH_NODESET)
                && (ctxt->value->nodesetval != NULL)
                && (ctxt->value->nodesetval->nodeNr >= 1)) {
                /*
                 * limit tree traversing to first node in the result
                 */
		if (ctxt->value->nodesetval->nodeNr > 1)
		    xmlXPathNodeSetSort(ctxt->value->nodesetval);
                *last =
                    ctxt->value->nodesetval->nodeTab[ctxt->value->
                                                     nodesetval->nodeNr -
                                                     1];
            }
            cur =
                xmlXPathCompOpEvalLast(ctxt, &comp->steps[op->ch2], last);
	    CHECK_ERROR0;
            if ((ctxt->value != NULL)
                && (ctxt->value->type == XPATH_NODESET)
                && (ctxt->value->nodesetval != NULL)
                && (ctxt->value->nodesetval->nodeNr >= 1)) { /* TODO: NOP ? */
            }

            arg2 = xmlXPathValuePop(ctxt);
            arg1 = xmlXPathValuePop(ctxt);
            if ((arg1 == NULL) || (arg1->type != XPATH_NODESET) ||
                (arg2 == NULL) || (arg2->type != XPATH_NODESET)) {
	        xmlXPathReleaseObject(ctxt->context, arg1);
	        xmlXPathReleaseObject(ctxt->context, arg2);
                XP_ERROR0(XPATH_INVALID_TYPE);
            }
            if ((ctxt->context->opLimit != 0) &&
                (((arg1->nodesetval != NULL) &&
                  (xmlXPathCheckOpLimit(ctxt,
                                        arg1->nodesetval->nodeNr) < 0)) ||
                 ((arg2->nodesetval != NULL) &&
                  (xmlXPathCheckOpLimit(ctxt,
                                        arg2->nodesetval->nodeNr) < 0)))) {
	        xmlXPathReleaseObject(ctxt->context, arg1);
	        xmlXPathReleaseObject(ctxt->context, arg2);
                break;
            }

            if ((arg2->nodesetval != NULL) &&
                (arg2->nodesetval->nodeNr != 0)) {
                arg1->nodesetval = xmlXPathNodeSetMerge(arg1->nodesetval,
                                                        arg2->nodesetval);
                if (arg1->nodesetval == NULL)
                    xmlXPathPErrMemory(ctxt);
            }
            xmlXPathValuePush(ctxt, arg1);
	    xmlXPathReleaseObject(ctxt->context, arg2);
            total += cur;
            break;
        case XPATH_OP_ROOT:
            xmlXPathRoot(ctxt);
            break;
        case XPATH_OP_NODE:
            if (op->ch1 != -1)
                total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
	    CHECK_ERROR0;
            if (op->ch2 != -1)
                total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch2]);
	    CHECK_ERROR0;
	    xmlXPathValuePush(ctxt, xmlXPathCacheNewNodeSet(ctxt,
		ctxt->context->node));
            break;
        case XPATH_OP_COLLECT:{
                if (op->ch1 == -1)
                    break;

                total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
		CHECK_ERROR0;

                total += xmlXPathNodeCollectAndTest(ctxt, op, NULL, last, 0);
                break;
            }
        case XPATH_OP_VALUE:
            xmlXPathValuePush(ctxt, xmlXPathCacheObjectCopy(ctxt, op->value4));
            break;
        case XPATH_OP_SORT:
            if (op->ch1 != -1)
                total +=
                    xmlXPathCompOpEvalLast(ctxt, &comp->steps[op->ch1],
                                           last);
	    CHECK_ERROR0;
            if ((ctxt->value != NULL)
                && (ctxt->value->type == XPATH_NODESET)
                && (ctxt->value->nodesetval != NULL)
		&& (ctxt->value->nodesetval->nodeNr > 1))
                xmlXPathNodeSetSort(ctxt->value->nodesetval);
            break;
        default:
            total += xmlXPathCompOpEval(ctxt, op);
            break;
    }

    ctxt->context->depth -= 1;
    return (total);
}

#ifdef XP_OPTIMIZED_FILTER_FIRST
static int
xmlXPathCompOpEvalFilterFirst(xmlXPathParserContextPtr ctxt,
			      xmlXPathStepOpPtr op, xmlNodePtr * first)
{
    int total = 0;
    xmlXPathCompExprPtr comp;
    xmlXPathObjectPtr obj;
    xmlNodeSetPtr set;

    CHECK_ERROR0;
    comp = ctxt->comp;
    /*
    * Optimization for ()[last()] selection i.e. the last elem
    */
    if ((op->ch1 != -1) && (op->ch2 != -1) &&
	(comp->steps[op->ch1].op == XPATH_OP_SORT) &&
	(comp->steps[op->ch2].op == XPATH_OP_SORT)) {
	int f = comp->steps[op->ch2].ch1;

	if ((f != -1) &&
	    (comp->steps[f].op == XPATH_OP_FUNCTION) &&
	    (comp->steps[f].value5 == NULL) &&
	    (comp->steps[f].value == 0) &&
	    (comp->steps[f].value4 != NULL) &&
	    (xmlStrEqual
	    (comp->steps[f].value4, BAD_CAST "last"))) {
	    xmlNodePtr last = NULL;

	    total +=
		xmlXPathCompOpEvalLast(ctxt,
		    &comp->steps[op->ch1],
		    &last);
	    CHECK_ERROR0;
	    /*
	    * The nodeset should be in document order,
	    * Keep only the last value
	    */
	    if ((ctxt->value != NULL) &&
		(ctxt->value->type == XPATH_NODESET) &&
		(ctxt->value->nodesetval != NULL) &&
		(ctxt->value->nodesetval->nodeTab != NULL) &&
		(ctxt->value->nodesetval->nodeNr > 1)) {
                xmlXPathNodeSetKeepLast(ctxt->value->nodesetval);
		*first = *(ctxt->value->nodesetval->nodeTab);
	    }
	    return (total);
	}
    }

    if (op->ch1 != -1)
	total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
    CHECK_ERROR0;
    if (op->ch2 == -1)
	return (total);
    if (ctxt->value == NULL)
	return (total);

    /*
     * In case of errors, xmlXPathNodeSetFilter can pop additional nodes from
     * the stack. We have to temporarily remove the nodeset object from the
     * stack to avoid freeing it prematurely.
     */
    CHECK_TYPE0(XPATH_NODESET);
    obj = xmlXPathValuePop(ctxt);
    set = obj->nodesetval;
    if (set != NULL) {
        xmlXPathNodeSetFilter(ctxt, set, op->ch2, 1, 1, 1);
        if (set->nodeNr > 0)
            *first = set->nodeTab[0];
    }
    xmlXPathValuePush(ctxt, obj);

    return (total);
}
#endif /* XP_OPTIMIZED_FILTER_FIRST */

/**
 * Evaluate the Precompiled XPath operation
 *
 * @param ctxt  the XPath parser context with the compiled expression
 * @param op  an XPath compiled operation
 * @returns the number of nodes traversed
 */
static int
xmlXPathCompOpEval(xmlXPathParserContextPtr ctxt, xmlXPathStepOpPtr op)
{
    int total = 0;
    int equal, ret;
    xmlXPathCompExprPtr comp;
    xmlXPathObjectPtr arg1, arg2;

    CHECK_ERROR0;
    if (OP_LIMIT_EXCEEDED(ctxt, 1))
        return(0);
    if (ctxt->context->depth >= XPATH_MAX_RECURSION_DEPTH)
        XP_ERROR0(XPATH_RECURSION_LIMIT_EXCEEDED);
    ctxt->context->depth += 1;
    comp = ctxt->comp;
    switch (op->op) {
        case XPATH_OP_END:
            break;
        case XPATH_OP_AND:
            total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
	    CHECK_ERROR0;
            xmlXPathBooleanFunction(ctxt, 1);
            if ((ctxt->value == NULL) || (ctxt->value->boolval == 0))
                break;
            arg2 = xmlXPathValuePop(ctxt);
            total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch2]);
	    if (ctxt->error) {
		xmlXPathFreeObject(arg2);
		break;
	    }
            xmlXPathBooleanFunction(ctxt, 1);
            if (ctxt->value != NULL)
                ctxt->value->boolval &= arg2->boolval;
	    xmlXPathReleaseObject(ctxt->context, arg2);
            break;
        case XPATH_OP_OR:
            total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
	    CHECK_ERROR0;
            xmlXPathBooleanFunction(ctxt, 1);
            if ((ctxt->value == NULL) || (ctxt->value->boolval == 1))
                break;
            arg2 = xmlXPathValuePop(ctxt);
            total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch2]);
	    if (ctxt->error) {
		xmlXPathFreeObject(arg2);
		break;
	    }
            xmlXPathBooleanFunction(ctxt, 1);
            if (ctxt->value != NULL)
                ctxt->value->boolval |= arg2->boolval;
	    xmlXPathReleaseObject(ctxt->context, arg2);
            break;
        case XPATH_OP_EQUAL:
            total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
	    CHECK_ERROR0;
            total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch2]);
	    CHECK_ERROR0;
	    if (op->value)
		equal = xmlXPathEqualValues(ctxt);
	    else
		equal = xmlXPathNotEqualValues(ctxt);
	    xmlXPathValuePush(ctxt, xmlXPathCacheNewBoolean(ctxt, equal));
            break;
        case XPATH_OP_CMP:
            total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
	    CHECK_ERROR0;
            total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch2]);
	    CHECK_ERROR0;
            ret = xmlXPathCompareValues(ctxt, op->value, op->value2);
	    xmlXPathValuePush(ctxt, xmlXPathCacheNewBoolean(ctxt, ret));
            break;
        case XPATH_OP_PLUS:
            total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
	    CHECK_ERROR0;
            if (op->ch2 != -1) {
                total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch2]);
	    }
	    CHECK_ERROR0;
            if (op->value == 0)
                xmlXPathSubValues(ctxt);
            else if (op->value == 1)
                xmlXPathAddValues(ctxt);
            else if (op->value == 2)
                xmlXPathValueFlipSign(ctxt);
            else if (op->value == 3) {
                CAST_TO_NUMBER;
                CHECK_TYPE0(XPATH_NUMBER);
            }
            break;
        case XPATH_OP_MULT:
            total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
	    CHECK_ERROR0;
            total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch2]);
	    CHECK_ERROR0;
            if (op->value == 0)
                xmlXPathMultValues(ctxt);
            else if (op->value == 1)
                xmlXPathDivValues(ctxt);
            else if (op->value == 2)
                xmlXPathModValues(ctxt);
            break;
        case XPATH_OP_UNION:
            total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
	    CHECK_ERROR0;
            total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch2]);
	    CHECK_ERROR0;

            arg2 = xmlXPathValuePop(ctxt);
            arg1 = xmlXPathValuePop(ctxt);
            if ((arg1 == NULL) || (arg1->type != XPATH_NODESET) ||
                (arg2 == NULL) || (arg2->type != XPATH_NODESET)) {
	        xmlXPathReleaseObject(ctxt->context, arg1);
	        xmlXPathReleaseObject(ctxt->context, arg2);
                XP_ERROR0(XPATH_INVALID_TYPE);
            }
            if ((ctxt->context->opLimit != 0) &&
                (((arg1->nodesetval != NULL) &&
                  (xmlXPathCheckOpLimit(ctxt,
                                        arg1->nodesetval->nodeNr) < 0)) ||
                 ((arg2->nodesetval != NULL) &&
                  (xmlXPathCheckOpLimit(ctxt,
                                        arg2->nodesetval->nodeNr) < 0)))) {
	        xmlXPathReleaseObject(ctxt->context, arg1);
	        xmlXPathReleaseObject(ctxt->context, arg2);
                break;
            }

	    if (((arg2->nodesetval != NULL) &&
		 (arg2->nodesetval->nodeNr != 0)))
	    {
		arg1->nodesetval = xmlXPathNodeSetMerge(arg1->nodesetval,
							arg2->nodesetval);
                if (arg1->nodesetval == NULL)
                    xmlXPathPErrMemory(ctxt);
	    }

            xmlXPathValuePush(ctxt, arg1);
	    xmlXPathReleaseObject(ctxt->context, arg2);
            break;
        case XPATH_OP_ROOT:
            xmlXPathRoot(ctxt);
            break;
        case XPATH_OP_NODE:
            if (op->ch1 != -1)
                total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
	    CHECK_ERROR0;
            if (op->ch2 != -1)
                total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch2]);
	    CHECK_ERROR0;
	    xmlXPathValuePush(ctxt, xmlXPathCacheNewNodeSet(ctxt,
                                                    ctxt->context->node));
            break;
        case XPATH_OP_COLLECT:{
                if (op->ch1 == -1)
                    break;

                total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
		CHECK_ERROR0;

                total += xmlXPathNodeCollectAndTest(ctxt, op, NULL, NULL, 0);
                break;
            }
        case XPATH_OP_VALUE:
            xmlXPathValuePush(ctxt, xmlXPathCacheObjectCopy(ctxt, op->value4));
            break;
        case XPATH_OP_VARIABLE:{
		xmlXPathObjectPtr val;

                if (op->ch1 != -1)
                    total +=
                        xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
                if (op->value5 == NULL) {
		    val = xmlXPathVariableLookup(ctxt->context, op->value4);
		    if (val == NULL)
			XP_ERROR0(XPATH_UNDEF_VARIABLE_ERROR);
                    xmlXPathValuePush(ctxt, val);
		} else {
                    const xmlChar *URI;

                    URI = xmlXPathNsLookup(ctxt->context, op->value5);
                    if (URI == NULL) {
                        XP_ERROR0(XPATH_UNDEF_PREFIX_ERROR);
                        break;
                    }
		    val = xmlXPathVariableLookupNS(ctxt->context,
                                                       op->value4, URI);
		    if (val == NULL)
			XP_ERROR0(XPATH_UNDEF_VARIABLE_ERROR);
                    xmlXPathValuePush(ctxt, val);
                }
                break;
            }
        case XPATH_OP_FUNCTION:{
                xmlXPathFunction func;
                const xmlChar *oldFunc, *oldFuncURI;
		int i;
                int frame;

                frame = ctxt->valueNr;
                if (op->ch1 != -1) {
                    total +=
                        xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
                    if (ctxt->error != XPATH_EXPRESSION_OK)
                        break;
                }
		if (ctxt->valueNr < frame + op->value)
		    XP_ERROR0(XPATH_INVALID_OPERAND);
		for (i = 0; i < op->value; i++) {
		    if (ctxt->valueTab[(ctxt->valueNr - 1) - i] == NULL)
			XP_ERROR0(XPATH_INVALID_OPERAND);
                }
                if (op->cache != NULL)
                    func = op->cache;
                else {
                    const xmlChar *URI = NULL;

                    if (op->value5 == NULL)
                        func =
                            xmlXPathFunctionLookup(ctxt->context,
                                                   op->value4);
                    else {
                        URI = xmlXPathNsLookup(ctxt->context, op->value5);
                        if (URI == NULL)
                            XP_ERROR0(XPATH_UNDEF_PREFIX_ERROR);
                        func = xmlXPathFunctionLookupNS(ctxt->context,
                                                        op->value4, URI);
                    }
                    if (func == NULL)
                        XP_ERROR0(XPATH_UNKNOWN_FUNC_ERROR);
                    op->cache = func;
                    op->cacheURI = (void *) URI;
                }
                oldFunc = ctxt->context->function;
                oldFuncURI = ctxt->context->functionURI;
                ctxt->context->function = op->value4;
                ctxt->context->functionURI = op->cacheURI;
                func(ctxt, op->value);
                ctxt->context->function = oldFunc;
                ctxt->context->functionURI = oldFuncURI;
                if ((ctxt->error == XPATH_EXPRESSION_OK) &&
                    (ctxt->valueNr != frame + 1))
                    XP_ERROR0(XPATH_STACK_ERROR);
                break;
            }
        case XPATH_OP_ARG:
            if (op->ch1 != -1) {
                total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
	        CHECK_ERROR0;
            }
            if (op->ch2 != -1) {
                total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch2]);
	        CHECK_ERROR0;
	    }
            break;
        case XPATH_OP_PREDICATE:
        case XPATH_OP_FILTER:{
                xmlXPathObjectPtr obj;
                xmlNodeSetPtr set;

                /*
                 * Optimization for ()[1] selection i.e. the first elem
                 */
                if ((op->ch1 != -1) && (op->ch2 != -1) &&
#ifdef XP_OPTIMIZED_FILTER_FIRST
		    /*
		    * FILTER TODO: Can we assume that the inner processing
		    *  will result in an ordered list if we have an
		    *  XPATH_OP_FILTER?
		    *  What about an additional field or flag on
		    *  xmlXPathObject like @sorted ? This way we wouldn't need
		    *  to assume anything, so it would be more robust and
		    *  easier to optimize.
		    */
                    ((comp->steps[op->ch1].op == XPATH_OP_SORT) || /* 18 */
		     (comp->steps[op->ch1].op == XPATH_OP_FILTER)) && /* 17 */
#else
		    (comp->steps[op->ch1].op == XPATH_OP_SORT) &&
#endif
                    (comp->steps[op->ch2].op == XPATH_OP_VALUE)) { /* 12 */
                    xmlXPathObjectPtr val;

                    val = comp->steps[op->ch2].value4;
                    if ((val != NULL) && (val->type == XPATH_NUMBER) &&
                        (val->floatval == 1.0)) {
                        xmlNodePtr first = NULL;

                        total +=
                            xmlXPathCompOpEvalFirst(ctxt,
                                                    &comp->steps[op->ch1],
                                                    &first);
			CHECK_ERROR0;
                        /*
                         * The nodeset should be in document order,
                         * Keep only the first value
                         */
                        if ((ctxt->value != NULL) &&
                            (ctxt->value->type == XPATH_NODESET) &&
                            (ctxt->value->nodesetval != NULL) &&
                            (ctxt->value->nodesetval->nodeNr > 1))
                            xmlXPathNodeSetClearFromPos(ctxt->value->nodesetval,
                                                        1, 1);
                        break;
                    }
                }
                /*
                 * Optimization for ()[last()] selection i.e. the last elem
                 */
                if ((op->ch1 != -1) && (op->ch2 != -1) &&
                    (comp->steps[op->ch1].op == XPATH_OP_SORT) &&
                    (comp->steps[op->ch2].op == XPATH_OP_SORT)) {
                    int f = comp->steps[op->ch2].ch1;

                    if ((f != -1) &&
                        (comp->steps[f].op == XPATH_OP_FUNCTION) &&
                        (comp->steps[f].value5 == NULL) &&
                        (comp->steps[f].value == 0) &&
                        (comp->steps[f].value4 != NULL) &&
                        (xmlStrEqual
                         (comp->steps[f].value4, BAD_CAST "last"))) {
                        xmlNodePtr last = NULL;

                        total +=
                            xmlXPathCompOpEvalLast(ctxt,
                                                   &comp->steps[op->ch1],
                                                   &last);
			CHECK_ERROR0;
                        /*
                         * The nodeset should be in document order,
                         * Keep only the last value
                         */
                        if ((ctxt->value != NULL) &&
                            (ctxt->value->type == XPATH_NODESET) &&
                            (ctxt->value->nodesetval != NULL) &&
                            (ctxt->value->nodesetval->nodeTab != NULL) &&
                            (ctxt->value->nodesetval->nodeNr > 1))
                            xmlXPathNodeSetKeepLast(ctxt->value->nodesetval);
                        break;
                    }
                }
		/*
		* Process inner predicates first.
		* Example "index[parent::book][1]":
		* ...
		*   PREDICATE   <-- we are here "[1]"
		*     PREDICATE <-- process "[parent::book]" first
		*       SORT
		*         COLLECT  'parent' 'name' 'node' book
		*           NODE
		*     ELEM Object is a number : 1
		*/
                if (op->ch1 != -1)
                    total +=
                        xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
		CHECK_ERROR0;
                if (op->ch2 == -1)
                    break;
                if (ctxt->value == NULL)
                    break;

                /*
                 * In case of errors, xmlXPathNodeSetFilter can pop additional
                 * nodes from the stack. We have to temporarily remove the
                 * nodeset object from the stack to avoid freeing it
                 * prematurely.
                 */
                CHECK_TYPE0(XPATH_NODESET);
                obj = xmlXPathValuePop(ctxt);
                set = obj->nodesetval;
                if (set != NULL)
                    xmlXPathNodeSetFilter(ctxt, set, op->ch2,
                                          1, set->nodeNr, 1);
                xmlXPathValuePush(ctxt, obj);
                break;
            }
        case XPATH_OP_SORT:
            if (op->ch1 != -1)
                total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
	    CHECK_ERROR0;
            if ((ctxt->value != NULL) &&
                (ctxt->value->type == XPATH_NODESET) &&
                (ctxt->value->nodesetval != NULL) &&
		(ctxt->value->nodesetval->nodeNr > 1))
	    {
                xmlXPathNodeSetSort(ctxt->value->nodesetval);
	    }
            break;
        default:
            XP_ERROR0(XPATH_INVALID_OPERAND);
            break;
    }

    ctxt->context->depth -= 1;
    return (total);
}

/**
 * Evaluates if the expression evaluates to true.
 *
 * @param ctxt  the XPath parser context
 * @param op  the step operation
 * @param isPredicate  whether a predicate is evaluated
 * @returns 1 if true, 0 if false and -1 on API or internal errors.
 */
static int
xmlXPathCompOpEvalToBoolean(xmlXPathParserContextPtr ctxt,
			    xmlXPathStepOpPtr op,
			    int isPredicate)
{
    xmlXPathObjectPtr resObj = NULL;

start:
    if (OP_LIMIT_EXCEEDED(ctxt, 1))
        return(0);
    /* comp = ctxt->comp; */
    switch (op->op) {
        case XPATH_OP_END:
            return (0);
	case XPATH_OP_VALUE:
	    resObj = (xmlXPathObjectPtr) op->value4;
	    if (isPredicate)
		return(xmlXPathEvaluatePredicateResult(ctxt, resObj));
	    return(xmlXPathCastToBoolean(resObj));
	case XPATH_OP_SORT:
	    /*
	    * We don't need sorting for boolean results. Skip this one.
	    */
            if (op->ch1 != -1) {
		op = &ctxt->comp->steps[op->ch1];
		goto start;
	    }
	    return(0);
	case XPATH_OP_COLLECT:
	    if (op->ch1 == -1)
		return(0);

            xmlXPathCompOpEval(ctxt, &ctxt->comp->steps[op->ch1]);
	    if (ctxt->error != XPATH_EXPRESSION_OK)
		return(-1);

            xmlXPathNodeCollectAndTest(ctxt, op, NULL, NULL, 1);
	    if (ctxt->error != XPATH_EXPRESSION_OK)
		return(-1);

	    resObj = xmlXPathValuePop(ctxt);
	    if (resObj == NULL)
		return(-1);
	    break;
	default:
	    /*
	    * Fallback to call xmlXPathCompOpEval().
	    */
	    xmlXPathCompOpEval(ctxt, op);
	    if (ctxt->error != XPATH_EXPRESSION_OK)
		return(-1);

	    resObj = xmlXPathValuePop(ctxt);
	    if (resObj == NULL)
		return(-1);
	    break;
    }

    if (resObj) {
	int res;

	if (resObj->type == XPATH_BOOLEAN) {
	    res = resObj->boolval;
	} else if (isPredicate) {
	    /*
	    * For predicates a result of type "number" is handled
	    * differently:
	    * SPEC XPath 1.0:
	    * "If the result is a number, the result will be converted
	    *  to true if the number is equal to the context position
	    *  and will be converted to false otherwise;"
	    */
	    res = xmlXPathEvaluatePredicateResult(ctxt, resObj);
	} else {
	    res = xmlXPathCastToBoolean(resObj);
	}
	xmlXPathReleaseObject(ctxt->context, resObj);
	return(res);
    }

    return(0);
}

#ifdef XPATH_STREAMING
/**
 * Evaluate the Precompiled Streamable XPath expression in the given context.
 *
 * @param pctxt  the XPath parser context with the compiled expression
 */
static int
xmlXPathRunStreamEval(xmlXPathParserContextPtr pctxt, xmlPatternPtr comp,
		      xmlXPathObjectPtr *resultSeq, int toBool)
{
    int max_depth, min_depth;
    int from_root;
    int ret, depth;
    int eval_all_nodes;
    xmlNodePtr cur = NULL, limit = NULL;
    xmlStreamCtxtPtr patstream = NULL;
    xmlXPathContextPtr ctxt = pctxt->context;

    if ((ctxt == NULL) || (comp == NULL))
        return(-1);
    max_depth = xmlPatternMaxDepth(comp);
    if (max_depth == -1)
        return(-1);
    if (max_depth == -2)
        max_depth = 10000;
    min_depth = xmlPatternMinDepth(comp);
    if (min_depth == -1)
        return(-1);
    from_root = xmlPatternFromRoot(comp);
    if (from_root < 0)
        return(-1);

    if (! toBool) {
	if (resultSeq == NULL)
	    return(-1);
	*resultSeq = xmlXPathCacheNewNodeSet(pctxt, NULL);
	if (*resultSeq == NULL)
	    return(-1);
    }

    /*
     * handle the special cases of "/" amd "." being matched
     */
    if (min_depth == 0) {
        int res;

	if (from_root) {
	    /* Select "/" */
	    if (toBool)
		return(1);
            res = xmlXPathNodeSetAddUnique((*resultSeq)->nodesetval,
                                           (xmlNodePtr) ctxt->doc);
	} else {
	    /* Select "self::node()" */
	    if (toBool)
		return(1);
            res = xmlXPathNodeSetAddUnique((*resultSeq)->nodesetval,
                                           ctxt->node);
	}

        if (res < 0)
            xmlXPathPErrMemory(pctxt);
    }
    if (max_depth == 0) {
	return(0);
    }

    if (from_root) {
        cur = (xmlNodePtr)ctxt->doc;
    } else if (ctxt->node != NULL) {
        switch (ctxt->node->type) {
            case XML_ELEMENT_NODE:
            case XML_DOCUMENT_NODE:
            case XML_DOCUMENT_FRAG_NODE:
            case XML_HTML_DOCUMENT_NODE:
	        cur = ctxt->node;
		break;
            case XML_ATTRIBUTE_NODE:
            case XML_TEXT_NODE:
            case XML_CDATA_SECTION_NODE:
            case XML_ENTITY_REF_NODE:
            case XML_ENTITY_NODE:
            case XML_PI_NODE:
            case XML_COMMENT_NODE:
            case XML_NOTATION_NODE:
            case XML_DTD_NODE:
            case XML_DOCUMENT_TYPE_NODE:
            case XML_ELEMENT_DECL:
            case XML_ATTRIBUTE_DECL:
            case XML_ENTITY_DECL:
            case XML_NAMESPACE_DECL:
            case XML_XINCLUDE_START:
            case XML_XINCLUDE_END:
		break;
	}
	limit = cur;
    }
    if (cur == NULL) {
        return(0);
    }

    patstream = xmlPatternGetStreamCtxt(comp);
    if (patstream == NULL) {
        xmlXPathPErrMemory(pctxt);
	return(-1);
    }

    eval_all_nodes = xmlStreamWantsAnyNode(patstream);

    if (from_root) {
	ret = xmlStreamPush(patstream, NULL, NULL);
	if (ret < 0) {
	} else if (ret == 1) {
	    if (toBool)
		goto return_1;
	    if (xmlXPathNodeSetAddUnique((*resultSeq)->nodesetval, cur) < 0)
                xmlXPathPErrMemory(pctxt);
	}
    }
    depth = 0;
    goto scan_children;
next_node:
    do {
        if (ctxt->opLimit != 0) {
            if (ctxt->opCount >= ctxt->opLimit) {
                xmlXPathErr(ctxt, XPATH_RECURSION_LIMIT_EXCEEDED);
                xmlFreeStreamCtxt(patstream);
                return(-1);
            }
            ctxt->opCount++;
        }

	switch (cur->type) {
	    case XML_ELEMENT_NODE:
	    case XML_TEXT_NODE:
	    case XML_CDATA_SECTION_NODE:
	    case XML_COMMENT_NODE:
	    case XML_PI_NODE:
		if (cur->type == XML_ELEMENT_NODE) {
		    ret = xmlStreamPush(patstream, cur->name,
				(cur->ns ? cur->ns->href : NULL));
		} else if (eval_all_nodes)
		    ret = xmlStreamPushNode(patstream, NULL, NULL, cur->type);
		else
		    break;

		if (ret < 0) {
		    xmlXPathPErrMemory(pctxt);
		} else if (ret == 1) {
		    if (toBool)
			goto return_1;
		    if (xmlXPathNodeSetAddUnique((*resultSeq)->nodesetval,
                                                 cur) < 0)
                        xmlXPathPErrMemory(pctxt);
		}
		if ((cur->children == NULL) || (depth >= max_depth)) {
		    ret = xmlStreamPop(patstream);
		    while (cur->next != NULL) {
			cur = cur->next;
			if ((cur->type != XML_ENTITY_DECL) &&
			    (cur->type != XML_DTD_NODE))
			    goto next_node;
		    }
		}
	    default:
		break;
	}

scan_children:
	if (cur->type == XML_NAMESPACE_DECL) break;
	if ((cur->children != NULL) && (depth < max_depth)) {
	    /*
	     * Do not descend on entities declarations
	     */
	    if (cur->children->type != XML_ENTITY_DECL) {
		cur = cur->children;
		depth++;
		/*
		 * Skip DTDs
		 */
		if (cur->type != XML_DTD_NODE)
		    continue;
	    }
	}

	if (cur == limit)
	    break;

	while (cur->next != NULL) {
	    cur = cur->next;
	    if ((cur->type != XML_ENTITY_DECL) &&
		(cur->type != XML_DTD_NODE))
		goto next_node;
	}

	do {
	    cur = cur->parent;
	    depth--;
	    if ((cur == NULL) || (cur == limit) ||
                (cur->type == XML_DOCUMENT_NODE))
	        goto done;
	    if (cur->type == XML_ELEMENT_NODE) {
		ret = xmlStreamPop(patstream);
	    } else if ((eval_all_nodes) &&
		((cur->type == XML_TEXT_NODE) ||
		 (cur->type == XML_CDATA_SECTION_NODE) ||
		 (cur->type == XML_COMMENT_NODE) ||
		 (cur->type == XML_PI_NODE)))
	    {
		ret = xmlStreamPop(patstream);
	    }
	    if (cur->next != NULL) {
		cur = cur->next;
		break;
	    }
	} while (cur != NULL);

    } while ((cur != NULL) && (depth >= 0));

done:

    if (patstream)
	xmlFreeStreamCtxt(patstream);
    return(0);

return_1:
    if (patstream)
	xmlFreeStreamCtxt(patstream);
    return(1);
}
#endif /* XPATH_STREAMING */

/**
 * Evaluate the Precompiled XPath expression in the given context.
 *
 * @param ctxt  the XPath parser context with the compiled expression
 * @param toBool  evaluate to a boolean result
 */
static int
xmlXPathRunEval(xmlXPathParserContextPtr ctxt, int toBool)
{
    xmlXPathCompExprPtr comp;
    int oldDepth;

    if ((ctxt == NULL) || (ctxt->comp == NULL))
	return(-1);

    if (ctxt->valueTab == NULL) {
#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
        int valueMax = 1;
#else
        int valueMax = 10;
#endif

	/* Allocate the value stack */
	ctxt->valueTab = xmlMalloc(valueMax * sizeof(xmlXPathObjectPtr));
	if (ctxt->valueTab == NULL) {
	    xmlXPathPErrMemory(ctxt);
	    return(-1);
	}
	ctxt->valueNr = 0;
	ctxt->valueMax = valueMax;
	ctxt->value = NULL;
    }
#ifdef XPATH_STREAMING
    if (ctxt->comp->stream) {
	int res;

	if (toBool) {
	    /*
	    * Evaluation to boolean result.
	    */
	    res = xmlXPathRunStreamEval(ctxt, ctxt->comp->stream, NULL, 1);
	    if (res != -1)
		return(res);
	} else {
	    xmlXPathObjectPtr resObj = NULL;

	    /*
	    * Evaluation to a sequence.
	    */
	    res = xmlXPathRunStreamEval(ctxt, ctxt->comp->stream, &resObj, 0);

	    if ((res != -1) && (resObj != NULL)) {
		xmlXPathValuePush(ctxt, resObj);
		return(0);
	    }
	    if (resObj != NULL)
		xmlXPathReleaseObject(ctxt->context, resObj);
	}
	/*
	* QUESTION TODO: This falls back to normal XPath evaluation
	* if res == -1. Is this intended?
	*/
    }
#endif
    comp = ctxt->comp;
    if (comp->last < 0) {
        xmlXPathErr(ctxt, XPATH_STACK_ERROR);
	return(-1);
    }
    oldDepth = ctxt->context->depth;
    if (toBool)
	return(xmlXPathCompOpEvalToBoolean(ctxt,
	    &comp->steps[comp->last], 0));
    else
	xmlXPathCompOpEval(ctxt, &comp->steps[comp->last]);
    ctxt->context->depth = oldDepth;

    return(0);
}

/************************************************************************
 *									*
 *			Public interfaces				*
 *									*
 ************************************************************************/

/**
 * Evaluate a predicate result for the current node.
 * A PredicateExpr is evaluated by evaluating the Expr and converting
 * the result to a boolean. If the result is a number, the result will
 * be converted to true if the number is equal to the position of the
 * context node in the context node list (as returned by the position
 * function) and will be converted to false otherwise; if the result
 * is not a number, then the result will be converted as if by a call
 * to the boolean function.
 *
 * @param ctxt  the XPath context
 * @param res  the Predicate Expression evaluation result
 * @returns 1 if predicate is true, 0 otherwise
 */
int
xmlXPathEvalPredicate(xmlXPathContextPtr ctxt, xmlXPathObjectPtr res) {
    if ((ctxt == NULL) || (res == NULL)) return(0);
    switch (res->type) {
        case XPATH_BOOLEAN:
	    return(res->boolval);
        case XPATH_NUMBER:
	    return(res->floatval == ctxt->proximityPosition);
        case XPATH_NODESET:
        case XPATH_XSLT_TREE:
	    if (res->nodesetval == NULL)
		return(0);
	    return(res->nodesetval->nodeNr != 0);
        case XPATH_STRING:
	    return((res->stringval != NULL) &&
	           (xmlStrlen(res->stringval) != 0));
        default:
	    break;
    }
    return(0);
}

/**
 * Evaluate a predicate result for the current node.
 * A PredicateExpr is evaluated by evaluating the Expr and converting
 * the result to a boolean. If the result is a number, the result will
 * be converted to true if the number is equal to the position of the
 * context node in the context node list (as returned by the position
 * function) and will be converted to false otherwise; if the result
 * is not a number, then the result will be converted as if by a call
 * to the boolean function.
 *
 * @param ctxt  the XPath Parser context
 * @param res  the Predicate Expression evaluation result
 * @returns 1 if predicate is true, 0 otherwise
 */
int
xmlXPathEvaluatePredicateResult(xmlXPathParserContextPtr ctxt,
                                xmlXPathObjectPtr res) {
    if ((ctxt == NULL) || (res == NULL)) return(0);
    switch (res->type) {
        case XPATH_BOOLEAN:
	    return(res->boolval);
        case XPATH_NUMBER:
#if defined(__BORLANDC__) || (defined(_MSC_VER) && (_MSC_VER == 1200))
	    return((res->floatval == ctxt->context->proximityPosition) &&
	           (!xmlXPathIsNaN(res->floatval))); /* MSC pbm Mark Vakoc !*/
#else
	    return(res->floatval == ctxt->context->proximityPosition);
#endif
        case XPATH_NODESET:
        case XPATH_XSLT_TREE:
	    if (res->nodesetval == NULL)
		return(0);
	    return(res->nodesetval->nodeNr != 0);
        case XPATH_STRING:
	    return((res->stringval != NULL) && (res->stringval[0] != 0));
        default:
	    break;
    }
    return(0);
}

#ifdef XPATH_STREAMING
/**
 * Try to compile the XPath expression as a streamable subset.
 *
 * @param ctxt  an XPath context
 * @param str  the XPath expression
 * @returns the compiled expression or NULL if failed to compile.
 */
static xmlXPathCompExprPtr
xmlXPathTryStreamCompile(xmlXPathContextPtr ctxt, const xmlChar *str) {
    /*
     * Optimization: use streaming patterns when the XPath expression can
     * be compiled to a stream lookup
     */
    xmlPatternPtr stream;
    xmlXPathCompExprPtr comp;
    xmlDictPtr dict = NULL;
    const xmlChar **namespaces = NULL;
    xmlNsPtr ns;
    int i, j;

    if ((!xmlStrchr(str, '[')) && (!xmlStrchr(str, '(')) &&
        (!xmlStrchr(str, '@'))) {
	const xmlChar *tmp;
        int res;

	/*
	 * We don't try to handle expressions using the verbose axis
	 * specifiers ("::"), just the simplified form at this point.
	 * Additionally, if there is no list of namespaces available and
	 *  there's a ":" in the expression, indicating a prefixed QName,
	 *  then we won't try to compile either. xmlPatterncompile() needs
	 *  to have a list of namespaces at compilation time in order to
	 *  compile prefixed name tests.
	 */
	tmp = xmlStrchr(str, ':');
	if ((tmp != NULL) &&
	    ((ctxt == NULL) || (ctxt->nsNr == 0) || (tmp[1] == ':')))
	    return(NULL);

	if (ctxt != NULL) {
	    dict = ctxt->dict;
	    if (ctxt->nsNr > 0) {
		namespaces = xmlMalloc(2 * (ctxt->nsNr + 1) * sizeof(xmlChar*));
		if (namespaces == NULL) {
		    xmlXPathErrMemory(ctxt);
		    return(NULL);
		}
		for (i = 0, j = 0; (j < ctxt->nsNr); j++) {
		    ns = ctxt->namespaces[j];
		    namespaces[i++] = ns->href;
		    namespaces[i++] = ns->prefix;
		}
		namespaces[i++] = NULL;
		namespaces[i] = NULL;
	    }
	}

	res = xmlPatternCompileSafe(str, dict, XML_PATTERN_XPATH, namespaces,
                                    &stream);
	if (namespaces != NULL) {
	    xmlFree((xmlChar **)namespaces);
	}
        if (res < 0) {
            xmlXPathErrMemory(ctxt);
            return(NULL);
        }
	if ((stream != NULL) && (xmlPatternStreamable(stream) == 1)) {
	    comp = xmlXPathNewCompExpr();
	    if (comp == NULL) {
		xmlXPathErrMemory(ctxt);
	        xmlFreePattern(stream);
		return(NULL);
	    }
	    comp->stream = stream;
	    comp->dict = dict;
	    if (comp->dict)
		xmlDictReference(comp->dict);
	    return(comp);
	}
	xmlFreePattern(stream);
    }
    return(NULL);
}
#endif /* XPATH_STREAMING */

static void
xmlXPathOptimizeExpression(xmlXPathParserContextPtr pctxt,
                           xmlXPathStepOpPtr op)
{
    xmlXPathCompExprPtr comp = pctxt->comp;
    xmlXPathContextPtr ctxt;

    /*
    * Try to rewrite "descendant-or-self::node()/foo" to an optimized
    * internal representation.
    */

    if ((op->op == XPATH_OP_COLLECT /* 11 */) &&
        (op->ch1 != -1) &&
        (op->ch2 == -1 /* no predicate */))
    {
        xmlXPathStepOpPtr prevop = &comp->steps[op->ch1];

        if ((prevop->op == XPATH_OP_COLLECT /* 11 */) &&
            ((xmlXPathAxisVal) prevop->value ==
                AXIS_DESCENDANT_OR_SELF) &&
            (prevop->ch2 == -1) &&
            ((xmlXPathTestVal) prevop->value2 == NODE_TEST_TYPE) &&
            ((xmlXPathTypeVal) prevop->value3 == NODE_TYPE_NODE))
        {
            /*
            * This is a "descendant-or-self::node()" without predicates.
            * Try to eliminate it.
            */

            switch ((xmlXPathAxisVal) op->value) {
                case AXIS_CHILD:
                case AXIS_DESCENDANT:
                    /*
                    * Convert "descendant-or-self::node()/child::" or
                    * "descendant-or-self::node()/descendant::" to
                    * "descendant::"
                    */
                    op->ch1   = prevop->ch1;
                    op->value = AXIS_DESCENDANT;
                    break;
                case AXIS_SELF:
                case AXIS_DESCENDANT_OR_SELF:
                    /*
                    * Convert "descendant-or-self::node()/self::" or
                    * "descendant-or-self::node()/descendant-or-self::" to
                    * to "descendant-or-self::"
                    */
                    op->ch1   = prevop->ch1;
                    op->value = AXIS_DESCENDANT_OR_SELF;
                    break;
                default:
                    break;
            }
	}
    }

    /* OP_VALUE has invalid ch1. */
    if (op->op == XPATH_OP_VALUE)
        return;

    /* Recurse */
    ctxt = pctxt->context;
    if (ctxt != NULL) {
        if (ctxt->depth >= XPATH_MAX_RECURSION_DEPTH)
            return;
        ctxt->depth += 1;
    }
    if (op->ch1 != -1)
        xmlXPathOptimizeExpression(pctxt, &comp->steps[op->ch1]);
    if (op->ch2 != -1)
	xmlXPathOptimizeExpression(pctxt, &comp->steps[op->ch2]);
    if (ctxt != NULL)
        ctxt->depth -= 1;
}

/**
 * Compile an XPath expression
 *
 * @param ctxt  an XPath context
 * @param str  the XPath expression
 * @returns the xmlXPathCompExprPtr resulting from the compilation or NULL.
 *         the caller has to free the object.
 */
xmlXPathCompExprPtr
xmlXPathCtxtCompile(xmlXPathContextPtr ctxt, const xmlChar *str) {
    xmlXPathParserContextPtr pctxt;
    xmlXPathContextPtr tmpctxt = NULL;
    xmlXPathCompExprPtr comp;
    int oldDepth = 0;

    if (str == NULL)
        return(NULL);

#ifdef XPATH_STREAMING
    comp = xmlXPathTryStreamCompile(ctxt, str);
    if (comp != NULL)
        return(comp);
#endif

    xmlInitParser();

    /*
     * We need an xmlXPathContext for the depth check.
     */
    if (ctxt == NULL) {
        tmpctxt = xmlXPathNewContext(NULL);
        if (tmpctxt == NULL)
            return(NULL);
        ctxt = tmpctxt;
    }

    pctxt = xmlXPathNewParserContext(str, ctxt);
    if (pctxt == NULL) {
        if (tmpctxt != NULL)
            xmlXPathFreeContext(tmpctxt);
        return NULL;
    }

    oldDepth = ctxt->depth;
    xmlXPathCompileExpr(pctxt, 1);
    ctxt->depth = oldDepth;

    if( pctxt->error != XPATH_EXPRESSION_OK )
    {
        xmlXPathFreeParserContext(pctxt);
        if (tmpctxt != NULL)
            xmlXPathFreeContext(tmpctxt);
        return(NULL);
    }

    if (*pctxt->cur != 0) {
	/*
	 * aleksey: in some cases this line prints *second* error message
	 * (see bug #78858) and probably this should be fixed.
	 * However, we are not sure that all error messages are printed
	 * out in other places. It's not critical so we leave it as-is for now
	 */
	xmlXPatherror(pctxt, __FILE__, __LINE__, XPATH_EXPR_ERROR);
	comp = NULL;
    } else {
	comp = pctxt->comp;
	if ((comp->nbStep > 1) && (comp->last >= 0)) {
            if (ctxt != NULL)
                oldDepth = ctxt->depth;
	    xmlXPathOptimizeExpression(pctxt, &comp->steps[comp->last]);
            if (ctxt != NULL)
                ctxt->depth = oldDepth;
	}
	pctxt->comp = NULL;
    }
    xmlXPathFreeParserContext(pctxt);
    if (tmpctxt != NULL)
        xmlXPathFreeContext(tmpctxt);

    if (comp != NULL) {
	comp->expr = xmlStrdup(str);
    }
    return(comp);
}

/**
 * Compile an XPath expression
 *
 * @param str  the XPath expression
 * @returns the xmlXPathCompExprPtr resulting from the compilation or NULL.
 *         the caller has to free the object.
 */
xmlXPathCompExprPtr
xmlXPathCompile(const xmlChar *str) {
    return(xmlXPathCtxtCompile(NULL, str));
}

/**
 * Evaluate the Precompiled XPath expression in the given context.
 * The caller has to free `resObj`.
 *
 * @param comp  the compiled XPath expression
 * @param ctxt  the XPath context
 * @param resObjPtr  the resulting XPath object or NULL
 * @param toBool  1 if only a boolean result is requested
 * @returns the xmlXPathObjectPtr resulting from the evaluation or NULL.
 *         the caller has to free the object.
 */
static int
xmlXPathCompiledEvalInternal(xmlXPathCompExprPtr comp,
			     xmlXPathContextPtr ctxt,
			     xmlXPathObjectPtr *resObjPtr,
			     int toBool)
{
    xmlXPathParserContextPtr pctxt;
    xmlXPathObjectPtr resObj = NULL;
    int res;

    if (comp == NULL)
	return(-1);
    xmlInitParser();

    xmlResetError(&ctxt->lastError);

    pctxt = xmlXPathCompParserContext(comp, ctxt);
    if (pctxt == NULL)
        return(-1);
    res = xmlXPathRunEval(pctxt, toBool);

    if (pctxt->error == XPATH_EXPRESSION_OK) {
        if (pctxt->valueNr != ((toBool) ? 0 : 1))
            xmlXPathErr(pctxt, XPATH_STACK_ERROR);
        else if (!toBool)
            resObj = xmlXPathValuePop(pctxt);
    }

    if (resObjPtr)
        *resObjPtr = resObj;
    else
        xmlXPathReleaseObject(ctxt, resObj);

    pctxt->comp = NULL;
    xmlXPathFreeParserContext(pctxt);

    return(res);
}

/**
 * Evaluate the Precompiled XPath expression in the given context.
 *
 * @param comp  the compiled XPath expression
 * @param ctx  the XPath context
 * @returns the xmlXPathObjectPtr resulting from the evaluation or NULL.
 *         the caller has to free the object.
 */
xmlXPathObjectPtr
xmlXPathCompiledEval(xmlXPathCompExprPtr comp, xmlXPathContextPtr ctx)
{
    xmlXPathObjectPtr res = NULL;

    xmlXPathCompiledEvalInternal(comp, ctx, &res, 0);
    return(res);
}

/**
 * Applies the XPath boolean() function on the result of the given
 * compiled expression.
 *
 * @param comp  the compiled XPath expression
 * @param ctxt  the XPath context
 * @returns 1 if the expression evaluated to true, 0 if to false and
 *         -1 in API and internal errors.
 */
int
xmlXPathCompiledEvalToBoolean(xmlXPathCompExprPtr comp,
			      xmlXPathContextPtr ctxt)
{
    return(xmlXPathCompiledEvalInternal(comp, ctxt, NULL, 1));
}

/**
 * Parse and evaluate an XPath expression in the given context,
 * then push the result on the context stack
 *
 * @deprecated Internal function, don't use.
 *
 * @param ctxt  the XPath Parser context
 */
void
xmlXPathEvalExpr(xmlXPathParserContextPtr ctxt) {
#ifdef XPATH_STREAMING
    xmlXPathCompExprPtr comp;
#endif
    int oldDepth = 0;

    if ((ctxt == NULL) || (ctxt->context == NULL))
        return;
    if (ctxt->context->lastError.code != 0)
        return;

#ifdef XPATH_STREAMING
    comp = xmlXPathTryStreamCompile(ctxt->context, ctxt->base);
    if ((comp == NULL) &&
        (ctxt->context->lastError.code == XML_ERR_NO_MEMORY)) {
        xmlXPathPErrMemory(ctxt);
        return;
    }
    if (comp != NULL) {
        if (ctxt->comp != NULL)
	    xmlXPathFreeCompExpr(ctxt->comp);
        ctxt->comp = comp;
    } else
#endif
    {
        if (ctxt->context != NULL)
            oldDepth = ctxt->context->depth;
	xmlXPathCompileExpr(ctxt, 1);
        if (ctxt->context != NULL)
            ctxt->context->depth = oldDepth;
        CHECK_ERROR;

        /* Check for trailing characters. */
        if (*ctxt->cur != 0)
            XP_ERROR(XPATH_EXPR_ERROR);

	if ((ctxt->comp->nbStep > 1) && (ctxt->comp->last >= 0)) {
            if (ctxt->context != NULL)
                oldDepth = ctxt->context->depth;
	    xmlXPathOptimizeExpression(ctxt,
		&ctxt->comp->steps[ctxt->comp->last]);
            if (ctxt->context != NULL)
                ctxt->context->depth = oldDepth;
        }
    }

    xmlXPathRunEval(ctxt, 0);
}

/**
 * Evaluate the XPath Location Path in the given context.
 *
 * @param str  the XPath expression
 * @param ctx  the XPath context
 * @returns the xmlXPathObjectPtr resulting from the evaluation or NULL.
 *         the caller has to free the object.
 */
xmlXPathObjectPtr
xmlXPathEval(const xmlChar *str, xmlXPathContextPtr ctx) {
    xmlXPathParserContextPtr ctxt;
    xmlXPathObjectPtr res;

    if (ctx == NULL)
        return(NULL);

    xmlInitParser();

    xmlResetError(&ctx->lastError);

    ctxt = xmlXPathNewParserContext(str, ctx);
    if (ctxt == NULL)
        return NULL;
    xmlXPathEvalExpr(ctxt);

    if (ctxt->error != XPATH_EXPRESSION_OK) {
	res = NULL;
    } else if (ctxt->valueNr != 1) {
        xmlXPathErr(ctxt, XPATH_STACK_ERROR);
	res = NULL;
    } else {
	res = xmlXPathValuePop(ctxt);
    }

    xmlXPathFreeParserContext(ctxt);
    return(res);
}

/**
 * Sets 'node' as the context node. The node must be in the same
 * document as that associated with the context.
 *
 * @param node  the node to to use as the context node
 * @param ctx  the XPath context
 * @returns -1 in case of error or 0 if successful
 */
int
xmlXPathSetContextNode(xmlNodePtr node, xmlXPathContextPtr ctx) {
    if ((node == NULL) || (ctx == NULL))
        return(-1);

    if (node->doc == ctx->doc) {
        ctx->node = node;
	return(0);
    }
    return(-1);
}

/**
 * Evaluate the XPath Location Path in the given context. The node 'node'
 * is set as the context node. The context node is not restored.
 *
 * @param node  the node to to use as the context node
 * @param str  the XPath expression
 * @param ctx  the XPath context
 * @returns the xmlXPathObjectPtr resulting from the evaluation or NULL.
 *         the caller has to free the object.
 */
xmlXPathObjectPtr
xmlXPathNodeEval(xmlNodePtr node, const xmlChar *str, xmlXPathContextPtr ctx) {
    if (str == NULL)
        return(NULL);
    if (xmlXPathSetContextNode(node, ctx) < 0)
        return(NULL);
    return(xmlXPathEval(str, ctx));
}

/**
 * Alias for xmlXPathEval().
 *
 * @param str  the XPath expression
 * @param ctxt  the XPath context
 * @returns the xmlXPathObjectPtr resulting from the evaluation or NULL.
 *         the caller has to free the object.
 */
xmlXPathObjectPtr
xmlXPathEvalExpression(const xmlChar *str, xmlXPathContextPtr ctxt) {
    return(xmlXPathEval(str, ctxt));
}

/**
 * Registers all default XPath functions in this context
 *
 * @deprecated No-op since 2.14.0.
 *
 * @param ctxt  the XPath context
 */
void
xmlXPathRegisterAllFunctions(xmlXPathContextPtr ctxt ATTRIBUTE_UNUSED)
{
}

#endif /* LIBXML_XPATH_ENABLED */