manual/examples/twalk.c

   1 /* Implement twalk using twalk_r.
   2    Copyright (C) 2019-2023 Free Software Foundation, Inc.
   3
   4    The GNU C 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 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C 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 General Public License
  15    along with this program; if not, see <https://www.gnu.org/licenses/>.
  16 */
  17
  18 #include <search.h>
  19
  20 struct twalk_with_twalk_r_closure
  21 {
  22   void (*action) (const void *, VISIT, int);
  23   int depth;
  24 };
  25
  26 static void
  27 twalk_with_twalk_r_action (const void *nodep, VISIT which, void *closure0)
  28 {
  29   struct twalk_with_twalk_r_closure *closure = closure0;
  30
  31   switch (which)
  32     {
  33     case leaf:
  34       closure->action (nodep, which, closure->depth);
  35       break;
  36     case preorder:
  37       closure->action (nodep, which, closure->depth);
  38       ++closure->depth;
  39       break;
  40     case postorder:
  41       /* The preorder action incremented the depth.  */
  42       closure->action (nodep, which, closure->depth - 1);
  43       break;
  44     case endorder:
  45       --closure->depth;
  46       closure->action (nodep, which, closure->depth);
  47       break;
  48     }
  49 }
  50
  51 void
  52 twalk (const void *root, void (*action) (const void *, VISIT, int))
  53 {
  54   struct twalk_with_twalk_r_closure closure = { action, 0 };
  55   twalk_r (root, twalk_with_twalk_r_action, &closure);
  56 }