Add new function g_markup_collect_attributes (bug #496847).

2007-11-26  Ryan Lortie  <desrt@desrt.ca>
 
        Add new function g_markup_collect_attributes (bug #496847).
 
        * glib/glib.symbols: add g_markup_collect_attributes
 
        * docs/reference/glib/glib-sections.txt:
        * glib/gmarkup.h:
        * glib/gmarkup.c: add g_markup_collect_attributes and new enumerated
        type GMarkupCollectType.  Add new error code
        G_MARKUP_ERROR_MISSING_ATTRIBUTE that is thrown by the attribute
        collector.


svn path=/trunk/; revision=5947

6 files changed, 394 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index f7e25bb82..7926d80e6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2007-11-26  Ryan Lortie  <desrt@desrt.ca>
+ 
+ 	Add new function g_markup_collect_attributes (bug #496847).
+ 
+ 	* glib/glib.symbols: add g_markup_collect_attributes
+ 
+ 	* docs/reference/glib/glib-sections.txt: 
+ 	* glib/gmarkup.h:
+ 	* glib/gmarkup.c: add g_markup_collect_attributes and new enumerated
+ 	type GMarkupCollectType.  Add new error code
+ 	G_MARKUP_ERROR_MISSING_ATTRIBUTE that is thrown by the attribute
+ 	collector.
+
 2007-11-27  Tor Lillqvist  <tml@novell.com>
 
 	* glib/win_iconv.c: Some improvements, being upstreamed.
diff --git a/docs/reference/glib/glib-sections.txt b/docs/reference/glib/glib-sections.txt
index cf5a52402..85de15aa9 100644
--- a/docs/reference/glib/glib-sections.txt
+++ b/docs/reference/glib/glib-sections.txt
@@ -999,6 +999,9 @@ g_markup_parse_context_get_element
 g_markup_parse_context_get_element_stack
 g_markup_parse_context_new
 g_markup_parse_context_parse
+<SUBSECTION>
+GMarkupCollectType
+g_markup_collect_attributes
 <SUBSECTION Private>
 g_markup_error_quark
 </SECTION>
diff --git a/glib/glib.symbols b/glib/glib.symbols
index bb01702d8..64b59de57 100644
--- a/glib/glib.symbols
+++ b/glib/glib.symbols
@@ -652,6 +652,7 @@ g_markup_parse_context_new
 g_markup_parse_context_parse
 g_markup_printf_escaped G_GNUC_PRINTF(1,2)
 g_markup_vprintf_escaped
+g_markup_collect_attributes
 #endif
 #endif
 
diff --git a/glib/gmarkup.c b/glib/gmarkup.c
index 2399c70ec..cde95f29c 100644
--- a/glib/gmarkup.c
+++ b/glib/gmarkup.c
@@ -2326,5 +2326,357 @@ g_markup_printf_escaped (const char *format, ...)
   return result;
 }
 
+static gboolean
+g_markup_parse_boolean (const char  *string,
+                        gboolean    *value)
+{
+  char const * const falses[] = { "false", "f", "no", "n", "0" };
+  char const * const trues[] = { "true", "t", "yes", "y", "1" };
+  int i;
+
+  for (i = 0; i < G_N_ELEMENTS (falses); i++)
+    {
+      if (g_ascii_strcasecmp (string, falses[i]) == 0)
+        {
+          if (value != NULL)
+            *value = FALSE;
+
+          return TRUE;
+        }
+    }
+
+  for (i = 0; i < G_N_ELEMENTS (trues); i++)
+    {
+      if (g_ascii_strcasecmp (string, trues[i]) == 0)
+        {
+          if (value != NULL)
+            *value = TRUE;
+
+          return TRUE;
+        }
+    }
+
+  return FALSE;
+}
+
+/**
+ * GMarkupCollectType:
+ * @G_MARKUP_COLLECT_INVALID: used to terminate the list of attributes
+ *                            to collect.
+ * @G_MARKUP_COLLECT_STRING: collect the string pointer directly from
+ *                           the attribute_values[] array.  Expects a
+ *                           parameter of type (const char **).  If
+ *                           %G_MARKUP_COLLECT_OPTIONAL is specified
+ *                           and the attribute isn't present then the
+ *                           pointer will be set to %NULL.
+ * @G_MARKUP_COLLECT_STRDUP: as with %G_MARKUP_COLLECT_STRING, but
+ *                           expects a paramter of type (char **) and
+ *                           g_strdup()s the returned pointer.  The
+ *                           pointer must be freed with g_free().
+ * @G_MARKUP_COLLECT_BOOLEAN: expects a parameter of type (gboolean *)
+ *                            and parses the attribute value as a
+ *                            boolean.  Sets %FALSE if the attribute
+ *                            isn't present.  Valid boolean values
+ *                            consist of (case insensitive) "false",
+ *                            "f", "no", "n", "0" and "true", "t",
+ *                            "yes", "y", "1".
+ * @G_MARKUP_COLLECT_TRISTATE: as with %G_MARKUP_COLLECT_BOOLEAN, but
+ *                             in the case of a missing attribute a
+ *                             value is set that compares equal to
+ *                             neither %FALSE nor %TRUE.
+ *                             G_MARKUP_COLLECT_OPTIONAL is implied.
+ * @G_MARKUP_COLLECT_OPTIONAL: can be bitwise ORed with the other
+ *                             fields.  If present, allows the
+ *                             attribute not to appear.  A default
+ *                             value is set depending on what value
+ *                             type is used.
+ *
+ * A mixed enumerated type and flags field.  You must specify one type
+ * (string, strdup, boolean, tristate).  Additionally, you may
+ * optionally bitwise OR the type with the flag
+ * %G_MARKUP_COLLECT_OPTIONAL.
+ *
+ * It is likely that this enum will be extended in the future to
+ * support other types.
+ **/
+
+/**
+ * g_markup_collect_attributes:
+ * @element_name: the current tag name
+ * @attribute_names: the attribute names
+ * @attribute_values: the attribute values
+ * @error: a pointer to a #GError or %NULL
+ * @first_type: the #GMarkupCollectType of the
+ *              first attribute
+ * @first_attr: the name of the first attribute
+ * @...: a pointer to the storage location of the
+ *       first attribute (or %NULL), followed by
+ *       more types names and pointers, ending
+ *       with %G_MARKUP_COLLECT_INVALID.
+ * 
+ * Collects the attributes of the element from the
+ * data passed to the #GMarkupParser start_element
+ * function, dealing with common error conditions
+ * and supporting boolean values.
+ *
+ * This utility function is not required to write
+ * a parser but can save a lot of typing.
+ *
+ * The @element_name, @attribute_names,
+ * @attribute_values and @error parameters passed
+ * to the start_element callback should be passed
+ * unmodified to this function.
+ *
+ * Following these arguments is a list of
+ * "supported" attributes to collect.  It is an
+ * error to specify multiple attributes with the
+ * same name.  If any attribute not in the list
+ * appears in the @attribute_names array then an
+ * unknown attribute error will result.
+ *
+ * The #GMarkupCollectType field allows specifying
+ * the type of collection to perform and if a
+ * given attribute must appear or is optional.
+ *
+ * The attribute name is simply the name of the
+ * attribute to collect.
+ *
+ * The pointer should be of the appropriate type
+ * (see the descriptions under
+ * #GMarkupCollectType) and may be %NULL in case a
+ * particular attribute is to be allowed but
+ * ignored.
+ *
+ * This function deals with issuing errors for
+ * missing attributes, unknown attributes and
+ * duplicate attributes as well as parse errors
+ * for boolean-valued attributes.  In all of these
+ * cases %FALSE will be returned and @error will
+ * be set as appropriate.
+ *
+ * Return value: %TRUE if successful
+ **/
+
+gboolean
+g_markup_collect_attributes (const gchar         *element_name,
+                             const gchar        **attribute_names,
+                             const gchar        **attribute_values,
+                             GError             **error,
+                             GMarkupCollectType   first_type,
+                             const gchar         *first_attr,
+                             ...)
+{
+  GMarkupCollectType type;
+  const gchar *attr;
+  guint64 collected;
+  int written;
+  va_list ap;
+  int i;
+
+  type = first_type;
+  attr = first_attr;
+  collected = 0;
+  written = 0;
+
+  va_start (ap, first_attr);
+  while (type != G_MARKUP_COLLECT_INVALID)
+    {
+      gboolean mandatory;
+      const gchar *value;
+
+      mandatory = !(type & G_MARKUP_COLLECT_OPTIONAL);
+      type &= (G_MARKUP_COLLECT_OPTIONAL - 1);
+
+      /* tristate records a value != TRUE and != FALSE
+       * for the case where the attribute is missing
+       */
+      if (type == G_MARKUP_COLLECT_TRISTATE)
+        mandatory = FALSE;
+
+      for (i = 0; attribute_names[i]; i++)
+        if (i >= 40 || !(collected & (1ull << i)))
+          if (!strcmp (attribute_names[i], attr))
+            break;
+
+      /* ISO C99 only promises that the user can pass up to 127 arguments.
+       * Subtracting the first 4 arguments plus the final NULL and dividing
+       * by 3 arguments per collected attribute, we are left with a maximum
+       * number of supported attributes of (127 - 5) / 3 = 40.
+       *
+       * In reality, nobody is ever going to call us with anywhere close to
+       * 40 attributes to collect, so it is safe to assume that if i > 40
+       * then the user has given some invalid or repeated arguments.  These
+       * problems will be caught and reported at the end of the function.
+       *
+       * We know at this point that we have an error, but we don't know
+       * what error it is, so just continue...
+       */
+      if (i < 40)
+        collected |= (1ull << i);
+
+      value = attribute_values[i];
+
+      if (value == NULL && mandatory)
+        {
+          g_set_error (error, G_MARKUP_ERROR,
+                       G_MARKUP_ERROR_MISSING_ATTRIBUTE,
+                       "element '%s' requires attribute '%s'",
+                       element_name, attr);
+
+          va_end (ap);
+          goto failure;
+        }
+
+      switch (type)
+        {
+        case G_MARKUP_COLLECT_STRING:
+          {
+            const char **str_ptr;
+
+            str_ptr = va_arg (ap, const char **);
+
+            if (str_ptr != NULL)
+              *str_ptr = value;
+          }
+          break;
+
+        case G_MARKUP_COLLECT_STRDUP:
+          {
+            char **str_ptr;
+
+            str_ptr = va_arg (ap, char **);
+
+            if (str_ptr != NULL)
+              *str_ptr = g_strdup (value);
+          }
+          break;
+
+        case G_MARKUP_COLLECT_BOOLEAN:
+        case G_MARKUP_COLLECT_TRISTATE:
+          if (value == NULL)
+            {
+              gboolean *bool_ptr;
+
+              bool_ptr = va_arg (ap, gboolean *);
+
+              if (bool_ptr != NULL)
+                {
+                  if (type == G_MARKUP_COLLECT_TRISTATE)
+                    /* constructivists rejoice!
+                     * neither false nor true...
+                     */
+                    *bool_ptr = -1;
+
+                  else /* G_MARKUP_COLLECT_BOOLEAN */
+                    *bool_ptr = FALSE;
+                }
+            }
+          else
+            {
+              if (!g_markup_parse_boolean (value, va_arg (ap, gboolean *)))
+                {
+                  g_set_error (error, G_MARKUP_ERROR,
+                               G_MARKUP_ERROR_INVALID_CONTENT,
+                               "element '%s', attribute '%s', value '%s' "
+                               "cannot be parsed as a boolean value",
+                               element_name, attr, value);
+
+                  va_end (ap);
+                  goto failure;
+                }
+            }
+
+          break;
+
+        default:
+          g_assert_not_reached ();
+        }
+
+      type = va_arg (ap, GMarkupCollectType);
+      attr = va_arg (ap, const char *);
+      written++;
+    }
+  va_end (ap);
+
+  /* ensure we collected all the arguments */
+  for (i = 0; attribute_names[i]; i++)
+    if ((collected & (1 << i)) == 0)
+      {
+        /* attribute not collected:  could be caused by two things.
+         *
+         * 1) it doesn't exist in our list of attributes
+         * 2) it existed but was matched by a duplicate attribute earlier
+         *
+         * find out.
+         */
+        int j;
+
+        for (j = 0; j < i; j++)
+          if (strcmp (attribute_names[i], attribute_names[j]) == 0)
+            /* duplicate! */
+            break;
+
+        /* j is now the first occurance of attribute_names[i] */
+        if (i == j)
+          g_set_error (error, G_MARKUP_ERROR,
+                       G_MARKUP_ERROR_UNKNOWN_ATTRIBUTE,
+                       "attribute '%s' invalid for element '%s'",
+                       attribute_names[i], element_name);
+        else
+          g_set_error (error, G_MARKUP_ERROR,
+                       G_MARKUP_ERROR_INVALID_CONTENT,
+                       "attribute '%s' given multiple times for element '%s'",
+                       attribute_names[i], element_name);
+
+        goto failure;
+      }
+
+  return TRUE;
+
+failure:
+  /* replay the above to free allocations */
+  type = first_type;
+  attr = first_attr;
+
+  va_start (ap, first_attr);
+  while (type != G_MARKUP_COLLECT_INVALID)
+    {
+      gpointer ptr;
+
+      ptr = va_arg (ap, gpointer);
+
+      if (ptr == NULL)
+        continue;
+
+      switch (type & (G_MARKUP_COLLECT_OPTIONAL - 1))
+        {
+        case G_MARKUP_COLLECT_STRDUP:
+          if (written)
+            g_free (*(char **) ptr);
+
+        case G_MARKUP_COLLECT_STRING:
+          *(char **) ptr = NULL;
+          break;
+
+        case G_MARKUP_COLLECT_BOOLEAN:
+          *(gboolean *) ptr = FALSE;
+          break;
+
+        case G_MARKUP_COLLECT_TRISTATE:
+          *(gboolean *) ptr = -1;
+          break;
+        }
+
+      type = va_arg (ap, GMarkupCollectType);
+      attr = va_arg (ap, const char *);
+
+      if (written)
+        written--;
+    }
+  va_end (ap);
+
+  return FALSE;
+}
+
 #define __G_MARKUP_C__
 #include "galiasdef.c"
diff --git a/glib/gmarkup.h b/glib/gmarkup.h
index 5021b1ee5..63edba748 100644
--- a/glib/gmarkup.h
+++ b/glib/gmarkup.h
@@ -38,7 +38,8 @@ typedef enum
    */
   G_MARKUP_ERROR_UNKNOWN_ELEMENT,
   G_MARKUP_ERROR_UNKNOWN_ATTRIBUTE,
-  G_MARKUP_ERROR_INVALID_CONTENT
+  G_MARKUP_ERROR_INVALID_CONTENT,
+  G_MARKUP_ERROR_MISSING_ATTRIBUTE
 } GMarkupError;
 
 #define G_MARKUP_ERROR g_markup_error_quark ()
@@ -127,6 +128,27 @@ gchar *g_markup_printf_escaped (const char *format,
 gchar *g_markup_vprintf_escaped (const char *format,
 				 va_list     args);
 
+typedef enum
+{
+  G_MARKUP_COLLECT_INVALID,
+  G_MARKUP_COLLECT_STRING,
+  G_MARKUP_COLLECT_STRDUP,
+  G_MARKUP_COLLECT_BOOLEAN,
+  G_MARKUP_COLLECT_TRISTATE,
+
+  G_MARKUP_COLLECT_OPTIONAL = (1 << 16)
+} GMarkupCollectType;
+
+
+/* useful from start_element */
+gboolean   g_markup_collect_attributes (const gchar         *element_name,
+                                        const gchar        **attribute_names,
+                                        const gchar        **attribute_values,
+                                        GError             **error,
+                                        GMarkupCollectType   first_type,
+                                        const gchar         *first_attr,
+                                        ...);
+
 G_END_DECLS
 
 #endif /* __G_MARKUP_H__ */
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 6872ad426..1d3878f1e 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -105,6 +105,7 @@ test_programs =					\
 	list-test				\
 	mainloop-test				\
 	mapping-test				\
+	markup-collect				\
 	markup-escape-test			\
 	module-test				\
 	node-test				\
@@ -216,6 +217,7 @@ utf8_validate_LDADD = $(progs_ldadd)
 utf8_pointer_LDADD = $(progs_ldadd)
 uri_test_LDADD = $(progs_ldadd)
 regex_test_LDADD = $(progs_ldadd)
+markup_collect_LDADD = $(progs_ldadd)
 
 lib_LTLIBRARIES = libmoduletestplugin_a.la libmoduletestplugin_b.la