nkeynes@678: /**
nkeynes@678:  * $Id: hook.h 662 2008-03-02 11:38:08Z nkeynes $
nkeynes@678:  *
nkeynes@678:  * This file defines some useful generic macros for hooks
nkeynes@678:  *
nkeynes@678:  * Copyright (c) 2008 Nathan Keynes.
nkeynes@678:  *
nkeynes@678:  * This program is free software; you can redistribute it and/or modify
nkeynes@678:  * it under the terms of the GNU General Public License as published by
nkeynes@678:  * the Free Software Foundation; either version 2 of the License, or
nkeynes@678:  * (at your option) any later version.
nkeynes@678:  *
nkeynes@678:  * This program is distributed in the hope that it will be useful,
nkeynes@678:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
nkeynes@678:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
nkeynes@678:  * GNU General Public License for more details.
nkeynes@678:  */
nkeynes@678: 
nkeynes@678: #ifndef lxdream_hook_H
nkeynes@678: #define lxdream_hook_H 1
nkeynes@678: 
nkeynes@678: #include <assert.h>
nkeynes@678: 
nkeynes@678: /**
nkeynes@678:  * Hook functions are generally useful, so we'd let to limit the overhead (and 
nkeynes@678:  * opportunity for stupid bugs) by minimizing the amount of code involved. Glib
nkeynes@678:  * has GHook (and of course signals), but they don't actually simplify anything
nkeynes@678:  * at this level.
nkeynes@678:  * 
nkeynes@678:  * Hence, the gratuitous macro abuse here.
nkeynes@678:  * 
nkeynes@678:  * Usage:
nkeynes@678:  * 
nkeynes@678:  * In header file:
nkeynes@678:  * 
nkeynes@678:  * DECLARE_HOOK( hook_name, hook_fn_type );
nkeynes@678:  * 
nkeynes@678:  * In implementation file:
nkeynes@678:  * 
nkeynes@678:  * DEFINE_HOOK( hook_name, hook_fn_type );
nkeynes@678:  *
nkeynes@678:  */
nkeynes@678: #define DECLARE_HOOK( name, fn_type ) \
nkeynes@678:     void register_##name( fn_type fn, void *user_data ); \
nkeynes@968:     void unregister_##name( fn_type fn, void *user_data )
nkeynes@678: 
nkeynes@678: #define FOREACH_HOOK( h, name ) struct name##_hook_struct *h; for( h = name##_hook_list; h != NULL; h = h->next )
nkeynes@678: 
nkeynes@678: #define CALL_HOOKS( name, args... ) FOREACH_HOOK(h, name) { h->fn(args, h->user_data); } 
nkeynes@678:     
nkeynes@678: #define DEFINE_HOOK( name, fn_type ) \
nkeynes@678:     struct name##_hook_struct { \
nkeynes@678:         fn_type fn; \
nkeynes@678:         void *user_data; \
nkeynes@678:         struct name##_hook_struct *next; \
nkeynes@678:     } *name##_hook_list = NULL; \
nkeynes@678:     void register_##name( fn_type fn, void *user_data ) { \
nkeynes@678:         struct name##_hook_struct *h = malloc(sizeof(struct name##_hook_struct)); \
nkeynes@678:         assert(h != NULL); \
nkeynes@678:         h->fn = fn; \
nkeynes@678:         h->user_data = user_data; \
nkeynes@678:         h->next = name##_hook_list; \
nkeynes@678:         name##_hook_list = h; \
nkeynes@678:     } \
nkeynes@678:     void unregister_##name( fn_type fn, void *user_data ) { \
nkeynes@678:         struct name##_hook_struct *last = NULL, *h = name##_hook_list; \
nkeynes@678:         while( h != NULL )  { \
nkeynes@678:             if( h->fn == fn && h->user_data == user_data ) { \
nkeynes@678:                 if( last == NULL ) { \
nkeynes@678:                     name##_hook_list = h->next; \
nkeynes@678:                 } else { \
nkeynes@678:                     last->next = h->next; \
nkeynes@678:                 } \
nkeynes@678:                 free( h ); \
nkeynes@678:             } \
nkeynes@678:             last = h; \
nkeynes@678:             h = h->next; \
nkeynes@678:         }\
nkeynes@678:     }
nkeynes@678:     
nkeynes@678: 
nkeynes@681: #endif /* !lxdream_hook_H */