Make YA_NULL use a singleton, so that YA_NULL can use a pointer, which is required by YA_LIST and YA_BRANCH.

Author: takev

yyast/leaf.c

@@ -39,6 +39,8 @@
 #include <yyast/utils.h>
 #include <yyast/error.h>
 
+ya_t ya_null_singleton;
+
 ya_t ya_literal(const char * restrict name, ya_type_t type, const void * restrict buf, size_t buf_size)
 {
     size_t aligned_buf_size = ya_align64(buf_size);

yyast/leaf.h

@@ -28,6 +28,22 @@
 #include <yyast/types.h>
 #include <yyast/utils.h>
 
+/** Ya_null is a singleton, so that it can be
+ * referenced by pointer by the YA_NULL macro.
+ *
+ * The singleton is initialized in ya_main().
+ * The node functions will not free this, or any, ya_null leafs.
+ */
+extern ya_t ya_null_singleton;
+
+/** Null node, unused child entry.
+ */
+ya_t ya_null(void);
+
+/** Null node, unused child entry.
+ */
+#define YA_NULL (&ya_null_singleton)
+
 /** Create an literal node.
  *
  * @param name      name of the node.
@@ -117,12 +133,4 @@ ya_t ya_leaf(const char * restrict name);
  */
 #define YA_LEAF(name) ya_leaf(name)
 
-/** Null node, unused child entry.
- */
-ya_t ya_null(void);
-
-/** Null node, unused child entry.
- */
-#define YA_NULL ya_null()
-
 #endif

yyast/main.c

@@ -30,18 +30,19 @@
 #include <yyast/utils.h>
 #include <yyast/node.h>
 #include <yyast/count.h>
+#include <yyast/leaf.h>
 
 extern FILE *yyin;
 int yyparse();
 
 char *ya_output_filename = NULL;
 char *ya_input_filename = NULL;
 
-void ya_usage(int exit_code)
+void ya_usage(char *application, int exit_code)
 {
     fprintf(stderr, "Usage:\n");
-    fprintf(stderr, "  application -h\n");
-    fprintf(stderr, "  application [-c] [-o output file] input file\n");
+    fprintf(stderr, "  %s -h\n", application);
+    fprintf(stderr, "  %s [-c] [-o output file] input file\n", application);
     fprintf(stderr, "\n");
     fprintf(stderr, "Options:\n");
     fprintf(stderr, "  -h   Show help message\n");
@@ -69,29 +70,29 @@ void ya_parse_options(int argc, char *argv[], char *extension)
             break;
         case 'h':
             // Help, just shows usage without error.
-            ya_usage(0);
+            ya_usage(argv[0], 0);
         case 'c':
             // Compile, which is the only mode it supports.
             break;
         case 0:
             break;
         case ':':
             fprintf(stderr, "Missing option argument.");
-            ya_usage(2);
+            ya_usage(argv[0], 2);
         case '?':
             fprintf(stderr, "Unknown option.");
-            ya_usage(2);
+            ya_usage(argv[0], 2);
         default:
             fprintf(stderr, "Unknown error in getopt_long().");
-            ya_usage(2);
+            ya_usage(argv[0], 2);
         }
     }
     argc -= optind;
     argv += optind;
 
     if (argc != 1) {
         fprintf(stderr, "Expecting a single filename.\n");
-        ya_usage(2);
+        ya_usage(argv[0], 2);
     }
 
     ya_input_filename = argv[0];
@@ -107,6 +108,9 @@ int ya_main(int argc, char *argv[], char *extension)
     FILE    *out;
     char    *reposition_s;
 
+    // Initialize singletons.
+    ya_null_singleton = ya_null();
+
     ya_parse_options(argc, argv, extension);
 
     if (strcmp(ya_input_filename, "-") == 0) {

yyast/node.c

@@ -123,7 +123,10 @@ ya_t ya_generic_nodev(const char * restrict name, ya_type_t type, va_list ap)
         }
 
         // Now that the child node is copied in self, we should free() it.
-        free(item->node);
+        // The singleton YA_NULL, should not be free-ed.
+        if (item->type != YA_NODE_TYPE_NULL) {
+            free(item->node);
+        }
     }
 
     va_end(ap2);