/*
 * Copyright (c) 2001-2003, Richard Eckart
 *
 *----------------------------------------------------------------------
 * This file is part of gtk-gnutella.
 *
 *  gtk-gnutella is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  gtk-gnutella is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with gtk-gnutella; if not, write to the Free Software
 *  Foundation, Inc.:
 *      59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *----------------------------------------------------------------------
 */

#ifndef _listener_h_
#define _listener_h_

#include <glib.h>

/*
 * To use the macros below with a "node_added" signal for example, 
 * you need to have a storage stucture to hold the listeners list
 * This needs to be defined in the following fashion. The name is
 * important for the macros to access the structure. For a "node_removed"
 * signal replace node_added_listeners with node_removed_listeners.
 *
 * listeners_t node_added_listeners = NULL;
 *
 * You also need a special type defined which holds the signature of the
 * callback function. For example:
 *
 * typedef void (*node_added_listener_t) (gnutella_node_t *, const gchar *);
 *
 * Again the name is important (like above).
 */

typedef GSList *listeners_t;

#define LISTENER_ADD(signal, callback)                                 \
    g_assert(callback != NULL);                                        \
    signal##_listeners = g_slist_append(signal##_listeners, callback);

#define LISTENER_REMOVE(signal, callback)                              \
    g_assert(callback != NULL);                                        \
    signal##_listeners = g_slist_remove(signal##_listeners, callback);

#define LISTENER_EMIT(signal, ...)                                     \
    {                                                                  \
        GSList *l;                                                     \
        for (l = signal##_listeners; l != NULL; l = g_slist_next(l)) { \
            signal##_listener_t fn = (signal##_listener_t) l->data;    \
            (*fn)(__VA_ARGS__);                                        \
        }                                                              \
    }

#endif /* _listener_h_ */
