/* Copyright (C) 2001-2020 Artifex Software, Inc.

   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or

   implied.

   This software is distributed under license and may not be copied,

   modified or distributed except as expressly authorized under the terms

   of the license contained in the file LICENSE in this distribution.

   Refer to licensing information at http://www.artifex.com or contact

   Artifex Software, Inc.,  1305 Grant Avenue - Suite 200, Novato,

   CA 94945, U.S.A., +1(415)492-9861, for further information.

*/

/* Notification machinery implementation */

#include "gx.h"

#include "gserrors.h"

#include "gsstruct.h"

#include "gsnotify.h"

/* GC descriptors */

private_st_gs_notify_registration();

public_st_gs_notify_list();

/* Initialize a notification list. */

void

gs_notify_init(gs_notify_list_t *nlist, gs_memory_t *mem)

{

    nlist->first = 0;

    nlist->memory = mem;

}

/* Register a client. */

int

gs_notify_register(gs_notify_list_t *nlist, gs_notify_proc_t proc,

                   void *proc_data)

{

    gs_notify_registration_t *nreg =

        gs_alloc_struct(nlist->memory, gs_notify_registration_t,

                        &st_gs_notify_registration, "gs_notify_register");

    if (nreg == 0)

        return_error(gs_error_VMerror);

    nreg->proc = proc;

    nreg->proc_data = proc_data;

    nreg->next = nlist->first;

    nlist->first = nreg;

    return 0;

}

/*

 * Unregister a client.  Return 1 if the client was registered, 0 if not.

 * If proc_data is 0, unregister all registrations of that proc; otherwise,

 * unregister only the registration of that procedure with that proc_data.

 */

static void

no_unreg_proc(void *pdata)

{

}

int

gs_notify_unregister_calling(gs_notify_list_t *nlist, gs_notify_proc_t proc,

                             void *proc_data,

                             void (*unreg_proc)(void *pdata))

{

    gs_notify_registration_t **prev = &nlist->first;

    gs_notify_registration_t *cur;

    bool found = 0;

    while ((cur = *prev) != 0)

        if (cur->proc == proc &&

            (proc_data == 0 || cur->proc_data == proc_data)

            ) {

            *prev = cur->next;

            unreg_proc(cur->proc_data);

            gs_free_object(nlist->memory, cur, "gs_notify_unregister");

            found = 1;

        } else

            prev = &cur->next;

    return found;

}

int

gs_notify_unregister(gs_notify_list_t *nlist, gs_notify_proc_t proc,

                     void *proc_data)

{

    return gs_notify_unregister_calling(nlist, proc, proc_data, no_unreg_proc);

}

/*

 * Notify the clients on a list.  If an error occurs, return the first

 * error code, but notify all clients regardless.

 */

int

gs_notify_all(gs_notify_list_t *nlist, void *event_data)

{

    gs_notify_registration_t *cur;

    gs_notify_registration_t *next;

    int ecode = 0;

    for (next = nlist->first; (cur = next) != 0;) {

        int code;

        next = cur->next;

        code = cur->proc(cur->proc_data, event_data);

        if (code < 0 && ecode == 0)

            ecode = code;

    }

    return ecode;

}

/* Release a notification list. */

void

gs_notify_release(gs_notify_list_t *nlist)

{

    gs_memory_t *mem = nlist->memory;

    while (nlist->first) {

        gs_notify_registration_t *next = nlist->first->next;

        gs_free_object(mem, nlist->first, "gs_notify_release");

        nlist->first = next;

    }

}