block-parser: Add support for custom block functions

Similar to replace-table custom functions, this brings an ability
to register custom block functions that can be called from templates
with variable arguments.

The syntax is as follows:

<!-- $(if (function_name(arg1, "arg2", 'arg3'))) -->
...
<!-- $(endif (function_name(arg1, "arg2", 'arg3'))) -->

An optional exclamation mark before the function name reverts the result
(negates) the predicate.

This allows template flexibility with respect to the currently processed image.

1 files changed, 11 insertions, 0 deletions

diff --git a/src/block-parser.h b/src/block-parser.h
index 96c7fb8..edf6dd2 100644
--- a/src/block-parser.h
+++ b/src/block-parser.h
@@ -26,6 +26,11 @@ G_BEGIN_DECLS
 
 typedef struct BlockParser BlockParser;
 
+/*
+ *  conditional function callback, arguments passed as strings. Returning TRUE means not to ignore the block.
+ */
+typedef gboolean (*BlockParserConditionalFunction) (gchar **args, gpointer user_data);
+
 
 BlockParser * block_parser_new ();
 
@@ -47,6 +52,12 @@ void block_parser_set_conditionals (BlockParser *parser, GHashTable *conditional
 void block_parser_register_key (BlockParser *parser, const gchar *key, const gchar *replace_key);
 
 /*
+ *   block_parser_register_function: function called to determine whether a block should be ignored or not
+ *
+ */
+void block_parser_register_function (BlockParser *parser, const gchar *conditional_name, BlockParserConditionalFunction callback, gpointer user_data);
+
+/*
  *   block_parser_get_data: return retrieved data or NULL if none read yet
  *      returns newly allocated string, caller is responsible for freeing
  *