glib/gtrashstack.c

   1 /* GLIB - Library of useful routines for C programming
   2  * Copyright (C) 1995-1998  Peter Mattis, Spencer Kimball and Josh MacDonald
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser 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  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 /*
  19  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  20  * file for a list of people on the GLib Team.  See the ChangeLog
  21  * files for a list of changes.  These files are distributed with
  22  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  23  */
  24
  25 #include "config.h"
  26
  27 #include "gtrashstack.h"
  28
  29 /**
  30  * SECTION:trash_stack
  31  * @title: Trash Stacks
  32  * @short_description: maintain a stack of unused allocated memory chunks
  33  *
  34  * A #GTrashStack is an efficient way to keep a stack of unused allocated
  35  * memory chunks. Each memory chunk is required to be large enough to hold
  36  * a #gpointer. This allows the stack to be maintained without any space
  37  * overhead, since the stack pointers can be stored inside the memory chunks.
  38  *
  39  * There is no function to create a #GTrashStack. A %NULL #GTrashStack*
  40  * is a perfectly valid empty stack.
  41  *
  42  * There is no longer any good reason to use #GTrashStack.  If you have
  43  * extra pieces of memory, free() them and allocate them again later.
  44  *
  45  * Deprecated: 2.48: #GTrashStack is deprecated without replacement
  46  */
  47
  48 /**
  49  * GTrashStack:
  50  * @next: pointer to the previous element of the stack,
  51  *     gets stored in the first `sizeof (gpointer)`
  52  *     bytes of the element
  53  *
  54  * Each piece of memory that is pushed onto the stack
  55  * is cast to a GTrashStack*.
  56  *
  57  * Deprecated: 2.48: #GTrashStack is deprecated without replacement
  58  */
  59
  60 /**
  61  * g_trash_stack_push:
  62  * @stack_p: a #GTrashStack
  63  * @data_p: (not nullable): the piece of memory to push on the stack
  64  *
  65  * Pushes a piece of memory onto a #GTrashStack.
  66  * Deprecated: 2.48: #GTrashStack is deprecated without replacement
  67  */
  68 void
  69 g_trash_stack_push (GTrashStack **stack_p,
  70                     gpointer      data_p)
  71 {
  72   GTrashStack *data = (GTrashStack *) data_p;
  73
  74   data->next = *stack_p;
  75   *stack_p = data;
  76 }
  77
  78 /**
  79  * g_trash_stack_pop:
  80  * @stack_p: a #GTrashStack
  81  *
  82  * Pops a piece of memory off a #GTrashStack.
  83  *
  84  * Returns: the element at the top of the stack
  85  * Deprecated: 2.48: #GTrashStack is deprecated without replacement
  86  */
  87 gpointer
  88 g_trash_stack_pop (GTrashStack **stack_p)
  89 {
  90   GTrashStack *data;
  91
  92   data = *stack_p;
  93   if (data)
  94     {
  95       *stack_p = data->next;
  96       /* NULLify private pointer here, most platforms store NULL as
  97        * subsequent 0 bytes
  98        */
  99       data->next = NULL;
 100     }
 101
 102   return data;
 103 }
 104
 105 /**
 106  * g_trash_stack_peek:
 107  * @stack_p: a #GTrashStack
 108  *
 109  * Returns the element at the top of a #GTrashStack
 110  * which may be %NULL.
 111  *
 112  * Returns: the element at the top of the stack
 113  * Deprecated: 2.48: #GTrashStack is deprecated without replacement
 114  */
 115 gpointer
 116 g_trash_stack_peek (GTrashStack **stack_p)
 117 {
 118   GTrashStack *data;
 119
 120   data = *stack_p;
 121
 122   return data;
 123 }
 124
 125 /**
 126  * g_trash_stack_height:
 127  * @stack_p: a #GTrashStack
 128  *
 129  * Returns the height of a #GTrashStack.
 130  *
 131  * Note that execution of this function is of O(N) complexity
 132  * where N denotes the number of items on the stack.
 133  *
 134  * Returns: the height of the stack
 135  * Deprecated: 2.48: #GTrashStack is deprecated without replacement
 136  */
 137 guint
 138 g_trash_stack_height (GTrashStack **stack_p)
 139 {
 140   GTrashStack *data;
 141   guint i = 0;
 142
 143   for (data = *stack_p; data; data = data->next)
 144     i++;
 145
 146   return i;
 147 }