[svn-commits] rizzo: branch rizzo/video_v2 r87625 - /team/rizzo/video_v2/include/asterisk/

[SVN commits to the Digium repositories]

Author: rizzo
Date: Tue Oct 30 13:23:16 2007
New Revision: 87625

URL: http://svn.digium.com/view/asterisk?view=rev&rev=87625
Log:
stringfield cleanup - put back the const in AST_STRING_FIELD,
and document the internal management of fields as entries of
an array.


Modified:
    team/rizzo/video_v2/include/asterisk/stringfields.h

Modified: team/rizzo/video_v2/include/asterisk/stringfields.h
URL: http://svn.digium.com/view/asterisk/team/rizzo/video_v2/include/asterisk/stringfields.h?view=diff&rev=87625&r1=87624&r2=87625
==============================================================================
--- team/rizzo/video_v2/include/asterisk/stringfields.h (original)
+++ team/rizzo/video_v2/include/asterisk/stringfields.h Tue Oct 30 13:23:16 2007
@@ -184,7 +184,7 @@
   \brief Declare a string field
   \param name The field name
 */
-#define AST_STRING_FIELD(name) ast_string_field name	// was const ast_string ...
+#define AST_STRING_FIELD(name) const ast_string_field name
 
 /*!
   \brief Declare the fields needed in a structure
@@ -193,11 +193,14 @@
   followed by individual string fields, and then a struct ast_string_field_mgr
   which describes the space allocated.
   We split the two variables so they can be used as markers around the
-  field_list, and this allows us to play various tricks with them.
-
-  \note: we rely on __field_mgr_pool to be a non-const pointer,
-  so we know its size is the same as sizeof(ast_string_field) and we
-  can cast it to char * when writing to the fields.
+  field_list, and this allows us to determine how many entries are in
+  the field, and play with them.
+  In particular, for writing to the field, we rely on __field_mgr_pool to be
+  a non-const pointer, so 1) we know it has the same size as ast_string_field,
+  and 2) we can cast it to const char * and use it as the base of an array to
+  write to the fields.
+  Because of this, the low-level functions to manipulate stringfields
+  use the index instead of the name of the field.
 */
 #define AST_DECLARE_STRING_FIELDS(field_list) \
 	struct ast_string_field_pool *__field_mgr_pool;	\
@@ -312,7 +315,8 @@
   pointer is just changed to point to an empty string.
 */
 #define ast_string_field_index_free(x, index) do { \
-	(x)->__begin_field[index] = __ast_string_field_empty; \
+	const char **__p__ = (const char **)&(x)->__field_mgr_pool + 1 + index;		\
+	*__p__ = __ast_string_field_empty; \
 	} while(0)
 
 /*!
@@ -326,7 +330,7 @@
   pointer is just changed to point to an empty string.
 */
 #define ast_string_field_free(x, field) do {	\
-	(x)->field = __ast_string_field_empty ;	\
+	ast_string_field_index_free(x, ast_string_field_index(x, field)) ;	\
 	} while (0)
 
 /*!