Add debugging macros

Similarly to what GTK+ and Clutter do, we can use macros that evaluate
to nothing if JSON_ENABLE_DEBUG is disabled; they evaluate to messages
when the JSON_DEBUG environment variable is set to a debug domain.

3 files changed, 85 insertions, 1 deletions

diff --git a/json-glib/Makefile.am b/json-glib/Makefile.am
index 8492be2..d83c735 100644
--- a/json-glib/Makefile.am
+++ b/json-glib/Makefile.am
@@ -37,13 +37,15 @@ source_h = \
 	$(NULL)
 
 source_h_private = \
-	$(top_srcdir)/json-glib/json-scanner.h 		\
+	$(top_srcdir)/json-glib/json-debug.h		\
 	$(top_srcdir)/json-glib/json-gobject-private.h	\
+	$(top_srcdir)/json-glib/json-scanner.h 		\
 	$(top_srcdir)/json-glib/json-types-private.h	\
 	$(NULL)
 
 source_c = \
 	$(srcdir)/json-array.c 		\
+	$(srcdir)/json-debug.c		\
 	$(srcdir)/json-gboxed.c		\
 	$(srcdir)/json-generator.c 	\
 	$(srcdir)/json-gobject.c 	\
diff --git a/json-glib/json-debug.c b/json-glib/json-debug.c
new file mode 100644
index 0000000..471d082
--- /dev/null
+++ b/json-glib/json-debug.c
@@ -0,0 +1,37 @@
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "json-debug.h"
+
+static unsigned int json_debug_flags     = 0;
+static gboolean     json_debug_flags_set = FALSE;
+
+#ifdef JSON_ENABLE_DEBUG
+static const GDebugKey json_debug_keys[] = {
+  { "parser", JSON_DEBUG_PARSER }
+};
+#endif /* JSON_ENABLE_DEBUG */
+
+JsonDebugFlags
+_json_get_debug_flags (void)
+{
+#ifdef JSON_ENABLE_DEBUG
+  const gchar *env_str;
+
+  if (json_debug_flags_set)
+    return json_debug_flags;
+
+  env_str = g_getenv ("JSON_DEBUG");
+  if (env_str != NULL && *env_str != '\0')
+    {
+      json_debug_flags |= g_parse_debug_string (env_str,
+                                                json_debug_keys,
+                                                G_N_ELEMENTS (json_debug_keys));
+    }
+
+  json_debug_flags_set = TRUE;
+#endif /* JSON_ENABLE_DEBUG */
+
+  return json_debug_flags;
+}
diff --git a/json-glib/json-debug.h b/json-glib/json-debug.h
new file mode 100644
index 0000000..dc0d861
--- /dev/null
+++ b/json-glib/json-debug.h
@@ -0,0 +1,45 @@
+#ifndef __JSON_DEBUG_H__
+#define __JSON_DEBUG_H__
+
+#include <glib.h>
+
+G_BEGIN_DECLS
+
+typedef enum {
+  JSON_DEBUG_PARSER = 1 << 0
+} JsonDebugFlags;
+
+#ifdef JSON_ENABLE_DEBUG
+
+# ifdef __GNUC__
+
+# define JSON_NOTE(type,x,a...)                 G_STMT_START {  \
+        if (_json_get_debug_flags () & JSON_DEBUG_##type) {     \
+          g_message ("[" #type "] " G_STRLOC ": " x, ##a);      \
+        }                                       } G_STMT_END
+
+# else
+/* Try the C99 version; unfortunately, this does not allow us to pass
+ * empty arguments to the macro, which means we have to
+ * do an intemediate printf.
+ */
+# define JSON_NOTE(type,...)                    G_STMT_START {  \
+        if (_json_get_debug_flags () & JSON_DEBUG_##type) {     \
+            gchar * _fmt = g_strdup_printf (__VA_ARGS__);       \
+            g_message ("[" #type "] " G_STRLOC ": %s",_fmt);    \
+            g_free (_fmt);                                      \
+        }                                       } G_STMT_END
+
+# endif /* __GNUC__ */
+
+#else
+
+#define JSON_NOTE(type,...)         G_STMT_START { } G_STMT_END
+
+#endif /* JSON_ENABLE_DEBUG */
+
+JsonDebugFlags _json_get_debug_flags (void);
+
+G_END_DECLS
+
+#endif /* __JSON_DEBUG_H__ */