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/* -*-c-*- ---------------- mvc.h :
* This header defines basic types supporting the MVC pattern
* ------------------------------------------------------------------
* Last change: Time-stamp: <01/02/13 02:16:08 jose>
* ------------------------------------------------------------------
* Copyright (C) 2001 Free Software Foundation, Inc.
*
* This program 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.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*/
#ifndef MVC_H
#define MVC_H
#include <glib.h>
/* the subject which is observed (the model) */
typedef struct subject_t subject_t;
/* subject's observer (the view) */
typedef struct observer_t observer_t;
/* list of observers (maintained by the subject) */
typedef GSList observer_list_t;
/* data used in callbacks */
typedef void data_t;
/* (virtual) function used by subject on each observer to notify an update */
typedef void (*update_callback_t)(observer_t *obs, data_t *data);
/* (virtual) function used by observers to notify subject of a change */
typedef void (*notify_callback_t)(subject_t *subj, data_t *data);
/* base subject type, containing a notify callback to be invoked
by observers */
struct subject_t
{
notify_callback_t notify; /* notify callback used by observers */
observer_list_t *observers; /* the list of current observers */
};
/* base observer type, containing an update callback (to be invoked by
the subject) and a pointer to the observed subject
*/
struct observer_t
{
update_callback_t update; /* update callback used by subject */
subject_t *subject; /* observed subject */
};
/* subject interface */
/* init a subject */
#define subject_init(sub) \
do { \
(sub)->notify = NULL; \
(sub)->observers = NULL; \
} while (FALSE)
/* clean up a subject */
extern void
subject_clean (subject_t *sub);
/* add a new observer */
extern void
subject_add_observer (subject_t *sub, observer_t *obs);
/* remove an observer */
extern void
subject_remove_observer (subject_t *sub, observer_t *obs);
/* notify all observers of a change */
extern void
subject_update_observers (subject_t *sub, data_t *data);
/* observer interface */
/* init an observer */
#define observer_init(obs) \
do { \
(obs)->update = NULL; \
(obs)->subject = NULL; \
} while (FALSE)
/* macro used by observers to notify their subject of a change */
#define observer_notify_subject(obs, data) \
(*((observer_t *)obs->subject->notify)((observer_t *)obs->subject, \
(data_t *)data))
#endif /* MVC_H */
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