Feature/count expression

exist-core/src/main/antlr/org/exist/xquery/parser/XQuery.g

@@ -804,14 +804,21 @@ initialClause throws XPathException
 
 intermediateClause throws XPathException
 :
-    ( initialClause | whereClause | groupByClause | orderByClause )
+    ( initialClause | whereClause | groupByClause | orderByClause | countClause )
     ;
 
 whereClause throws XPathException
 :
 	"where"^ exprSingle
 	;
 
+countClause throws XPathException
+{ String varName; }
+:
+	"count"^ DOLLAR! varName=varName!
+	{ #countClause = #(#countClause, #[VARIABLE_BINDING, varName]); }
+	;
+
 forClause throws XPathException
 :
 	"for"^ inVarBinding ( COMMA! inVarBinding )*
@@ -2224,6 +2231,8 @@ reservedKeywords returns [String name]
 	"map" { name = "map"; }
 	|
 	"array" { name = "array"; }
+	|
+	"count" { name = "count"; }
 	;
 
 /**

exist-core/src/main/antlr/org/exist/xquery/parser/XQueryTree.g

@@ -1709,6 +1709,19 @@ throws PermissionDeniedException, EXistException, XPathException
 					clauses.add(clause);
 				}
 			)
+			|
+            #(
+            	co:"count"
+            	countVarName:VARIABLE_BINDING
+                {
+                	ForLetClause clause = new ForLetClause();
+                    clause.ast = co;
+                    clause.varName = countVarName.getText();
+                    clause.type = FLWORClause.ClauseType.COUNT;
+                    clause.inputSequence = null;
+                    clauses.add(clause);
+                }
+            )
 		)+
 		step=expr [(PathExpr) action]
 		{
@@ -1728,6 +1741,9 @@ throws PermissionDeniedException, EXistException, XPathException
 						case WHERE:
 								expr = new WhereClause(context, new DebuggableExpression(clause.inputSequence));
 								break;
+						case COUNT:
+						        expr = new CountClause(context, clause.varName);
+						        break;
             default:
                 expr= new ForExpr(context, clause.allowEmpty);
                 break;

exist-core/src/main/java/org/exist/xquery/CountClause.java

@@ -0,0 +1,52 @@
+
+package org.exist.xquery;
+
+import org.exist.dom.persistent.*;
+import org.exist.xquery.util.ExpressionDumper;
+import org.exist.xquery.value.Item;
+import org.exist.xquery.value.Sequence;
+import org.exist.xquery.value.Type;
+
+/**
+ * Implements a count clause inside a FLWOR expressions.
+ *
+ * @author
+ */
+public class CountClause extends AbstractFLWORClause {
+
+    protected String varName;
+
+    public CountClause(XQueryContext context, String countName) {
+        super(context);
+        this.varName = countName;
+    }
+
+    @Override
+    public ClauseType getType() {
+        return ClauseType.COUNT;
+    }
+
+    public String getVarName() {
+        return varName;
+    }
+
+    @Override
+    public void analyze(AnalyzeContextInfo contextInfo) throws XPathException
+    {
+
+    }
+
+    @Override
+    public Sequence eval(Sequence contextSequence, Item contextItem) throws XPathException
+    {
+        return null;
+    }
+
+    @Override
+    public void dump(ExpressionDumper dumper) {
+        dumper.display("count", this.getLine());
+        dumper.startIndent();
+        dumper.display(this.varName);
+        dumper.endIndent().nl();
+    }
+}

exist-core/src/main/java/org/exist/xquery/FLWORClause.java

@@ -31,7 +31,7 @@
 public interface FLWORClause extends Expression {
 
     enum ClauseType {
-        FOR, LET, GROUPBY, ORDERBY, WHERE, SOME, EVERY
+        FOR, LET, GROUPBY, ORDERBY, WHERE, SOME, EVERY, COUNT
     }
 
     /**

exist-core/src/test/java/org/exist/xquery/CountExpressionTest.java

@@ -0,0 +1,71 @@
+package org.exist.xquery;
+
+import antlr.RecognitionException;
+import antlr.TokenStreamException;
+import antlr.collections.AST;
+import org.exist.EXistException;
+import org.exist.storage.BrokerPool;
+import org.exist.storage.DBBroker;
+import org.exist.test.ExistEmbeddedServer;
+import org.exist.xquery.parser.XQueryAST;
+import org.exist.xquery.parser.XQueryLexer;
+import org.exist.xquery.parser.XQueryParser;
+import org.exist.xquery.parser.XQueryTreeParser;
+import org.junit.ClassRule;
+import org.junit.Test;
+
+import java.io.StringReader;
+
+import static org.junit.Assert.*;
+
+public class CountExpressionTest
+{
+
+    @ClassRule
+    public static final ExistEmbeddedServer existEmbeddedServer = new ExistEmbeddedServer(true, true);
+
+    @Test
+    public void countTest() throws EXistException, RecognitionException, XPathException, TokenStreamException
+    {
+        String query =  "xquery version \"3.1\";\n" +
+                "for $p in $products\n" +
+                "order by $p/sales descending\n" +
+                "count $rank\n" +
+                "where $rank <= 3\n" +
+                "return\n" +
+                "   <product rank=\"{$rank}\">\n" +
+                "      {$p/name, $p/sales}\n" +
+                "   </product>";
+
+        BrokerPool pool = BrokerPool.getInstance();
+        try(final DBBroker broker = pool.getBroker()) {
+            // parse the query into the internal syntax tree
+            XQueryContext context = new XQueryContext(broker.getBrokerPool());
+            XQueryLexer lexer = new XQueryLexer(context, new StringReader(query));
+            XQueryParser xparser = new XQueryParser(lexer);
+            xparser.xpath();
+            if (xparser.foundErrors()) {
+                fail(xparser.getErrorMessage());
+                return;
+            }
+
+            XQueryAST ast = (XQueryAST) xparser.getAST();
+
+            XQueryTreeParser treeParser = new XQueryTreeParser(context);
+            PathExpr expr = new PathExpr(context);
+            treeParser.xpath(ast, expr);
+            if (treeParser.foundErrors()) {
+                fail(treeParser.getErrorMessage());
+                return;
+            }
+
+            // count keyword
+            assertEquals(XQueryParser.LITERAL_count, ast.getNextSibling().getFirstChild().getNextSibling().getNextSibling().getType());
+            // rank variable binding
+            assertEquals(XQueryParser.VARIABLE_BINDING, ast.getNextSibling().getFirstChild().getNextSibling().getNextSibling().getFirstChild().getType());
+            assertTrue(((ForExpr)expr.getFirst()).returnExpr instanceof OrderByClause);
+            assertTrue(((OrderByClause)(((ForExpr)expr.getFirst()).returnExpr)).returnExpr instanceof CountClause);
+            assertEquals("rank", ((CountClause)((OrderByClause)(((ForExpr)expr.getFirst()).returnExpr)).returnExpr).varName);
+        }
+    }
+}