1 /* GStreamer

     2  * Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>

     3  *

     4  * This library is free software; you can redistribute it and/or

     5  * modify it under the terms of the GNU Library General Public

     6  * License as published by the Free Software Foundation; either

     7  * version 2 of the License, or (at your option) any later version.

     8  *

     9  * This library is distributed in the hope that it will be useful,

    10  * but WITHOUT ANY WARRANTY; without even the implied warranty of

    11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    12  * Library General Public License for more details.

    13  *

    14  * You should have received a copy of the GNU Library General Public

    15  * License along with this library; if not, write to the

    16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

    17  * Boston, MA 02111-1307, USA.

    18  */

    19 

    20 /**

    21  * SECTION:gstfilter

    22  * @short_description: A utility function to filter GLists.

    23  *

    24  * <example>

    25  * <title>Filtering a list</title>

    26  *   <programlisting>

    27  *     GList *node;

    28  *     GstObject *result = NULL;

    29  *     

    30  *     node = gst_filter_run (list, (GstFilterFunc) my_filter, TRUE, NULL);

    31  *     if (node) {

    32  *       result = GST_OBJECT (node->data);

    33  *       gst_object_ref (result);

    34  *       gst_list_free (node);

    35  *     }

    36  *   </programlisting>

    37  * </example>

    38  */

    39 #include "gst_private.h"

    40 #include <gst/gstfilter.h>

    41 

    42 /**

    43  * gst_filter_run:

    44  * @list: a linked list

    45  * @func: the function to execute for each item

    46  * @first: flag to stop execution after a successful item

    47  * @user_data: user data

    48  *

    49  * Iterates over the elements in @list, calling @func with the

    50  * list item data for each item.  If @func returns TRUE, @data is

    51  * prepended to the list of results returned.  If @first is true,

    52  * the search is halted after the first result is found.

    53  *

    54  * Since gst_filter_run() knows nothing about the type of @data, no

    55  * reference will be taken (if @data refers to an object) and no copy of

    56  * @data wil be made in any other way when prepending @data to the list of

    57  * results.

    58  *

    59  * Returns: the list of results. Free with g_list_free() when no longer needed

    60  * (the data contained in the list is a flat copy and does need to be

    61  * unreferenced or freed).

    62  */

    63 #ifdef __SYMBIAN32__

    64 EXPORT_C

    65 #endif

    66 

    67 GList *

    68 gst_filter_run (const GList * list, GstFilterFunc func, gboolean first,

    69     gpointer user_data)

    70 {

    71   const GList *walk = list;

    72   GList *result = NULL;

    73 

    74   while (walk) {

    75     gboolean res = TRUE;

    76     gpointer data = walk->data;

    77 

    78     walk = g_list_next (walk);

    79 

    80     if (func)

    81       res = func (data, user_data);

    82 

    83     if (res) {

    84       result = g_list_prepend (result, data);

    85 

    86       if (first)

    87         break;

    88     }

    89   }

    90 

    91   return result;

    92 }