/*

 * Gegl id-pool

 *

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

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

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

 *

 * This library 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

 * Lesser General Public License for more details.

 *

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

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

 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 *

 * GeglIDPool: pool of reusable integer ids associated with pointers.

 *

 * Copyright (C) 2008 OpenedHand

 * Author: Øyvind Kolås <pippin@o-hand-com>

 *

 */

#define DEBUG_POOL

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include "gegl-id-pool.h"

struct _GeglIDPool

{

  GArray *array;     /* Array of pointers    */

  GSList *free_ids;  /* A stack of freed ids */

};

GeglIDPool *

gegl_id_pool_new  (guint initial_size)

{

  GeglIDPool *self;

  self = g_slice_new (GeglIDPool);

  self->array = g_array_sized_new (FALSE, FALSE,

                                   sizeof (gpointer), initial_size);

  self->free_ids = NULL;

  return self;

}

void

gegl_id_pool_free (GeglIDPool *id_pool)

{

  g_return_if_fail (id_pool != NULL);

  g_array_free (id_pool->array, TRUE);

  g_slist_free (id_pool->free_ids);

  g_slice_free (GeglIDPool, id_pool);

}

guint32

gegl_id_pool_add (GeglIDPool *id_pool,

                  gpointer    ptr)

{

  gpointer *array;

  guint32   id;

  g_return_val_if_fail (id_pool != NULL, 0);

  if (id_pool->free_ids) /* There are items on our freelist, reuse one */

    {

      array = (void*) id_pool->array->data;

      id = GPOINTER_TO_UINT (id_pool->free_ids->data);

      id_pool->free_ids = g_slist_remove (id_pool->free_ids,

                                          id_pool->free_ids->data);

      array[id] = ptr;

      return id;

    }

  /* Allocate new id */

  id = id_pool->array->len;

  g_array_append_val (id_pool->array, ptr);

  return id;

}

void

gegl_id_pool_remove (GeglIDPool *id_pool,

                     guint32     id)

{

  gpointer *array;

#ifdef DEBUG_POOL

  return;

#endif

  g_return_if_fail (id_pool != NULL);

  array = (void*) id_pool->array->data;

  array[id] = (void*)0xdecafbad;   /* set pointer to a recognizably voided

                                      value */

  id_pool->free_ids = g_slist_prepend (id_pool->free_ids,

                                       GUINT_TO_POINTER (id));

}

gpointer

gegl_id_pool_lookup (GeglIDPool *id_pool,

                     guint32     id)

{

  gpointer *array;

  g_return_val_if_fail (id_pool != NULL, NULL);

  g_return_val_if_fail (id_pool->array != NULL, NULL);

  g_return_val_if_fail (id < id_pool->array->len, NULL);

  array = (void*) id_pool->array->data;

  return array[id];

}