oldXMenu/insque.c

   1 /*
   2 Copyright (C) 1993-1998, 2001-2011  Free Software Foundation, Inc.
   3
   4 This program is free software: you can redistribute it and/or modify
   5 it under the terms of the GNU General Public License as published by
   6 the Free Software Foundation, either version 3 of the License, or
   7 (at your option) any later version.
   8
   9 This program 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
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* This file implements the emacs_insque and emacs_remque functions,
  18    clones of the insque and remque functions of BSD.  They and all
  19    their callers have been renamed to emacs_mumble to allow us to
  20    include this file in the menu library on all systems.  */
  21
  22
  23 struct qelem {
  24   struct    qelem *q_forw;
  25   struct    qelem *q_back;
  26   char q_data[1];
  27 };
  28
  29 /* Insert ELEM into a doubly-linked list, after PREV.  */
  30
  31 void
  32 emacs_insque (struct qelem *elem, struct qelem *prev)
  33 {
  34   struct qelem *next = prev->q_forw;
  35   prev->q_forw = elem;
  36   if (next)
  37     next->q_back = elem;
  38   elem->q_forw = next;
  39   elem->q_back = prev;
  40 }
  41
  42 /* Unlink ELEM from the doubly-linked list that it is in.  */
  43
  44 emacs_remque (struct qelem *elem)
  45 {
  46   struct qelem *next = elem->q_forw;
  47   struct qelem *prev = elem->q_back;
  48   if (next)
  49     next->q_back = prev;
  50   if (prev)
  51     prev->q_forw = next;
  52 }
  53