utility/iterator.c

   1 /***********************************************************************
   2  Freeciv - Copyright (C) 1996 - A Kjeldberg, L Gregersen, P Unold
   3    This program is free software; you can redistribute it and/or modify
   4    it under the terms of the GNU General Public License as published by
   5    the Free Software Foundation; either version 2, or (at your option)
   6    any later version.
   7
   8    This program is distributed in the hope that it will be useful,
   9    but WITHOUT ANY WARRANTY; without even the implied warranty of
  10    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11    GNU General Public License for more details.
  12 ***********************************************************************/
  13
  14 #ifdef HAVE_CONFIG_H
  15 #include <fc_config.h>
  16 #endif
  17
  18 /* utility */
  19 #include "shared.h"
  20
  21 #include "iterator.h"
  22
  23
  24 /***********************************************************************
  25   'next' function implementation for an "invalid" iterator.
  26 ***********************************************************************/
  27 static void invalid_iter_next(struct iterator *it)
  28 {
  29   /* Do nothing. */
  30 }
  31
  32 /***********************************************************************
  33   'get' function implementation for an "invalid" iterator.
  34 ***********************************************************************/
  35 static void *invalid_iter_get(const struct iterator *it)
  36 {
  37   return NULL;
  38 }
  39
  40 /***********************************************************************
  41   'valid' function implementation for an "invalid" iterator.
  42 ***********************************************************************/
  43 static bool invalid_iter_valid(const struct iterator *it)
  44 {
  45   return FALSE;
  46 }
  47
  48 /***********************************************************************
  49   Initializes the iterator vtable so that generic_iterate assumes that
  50   the iterator is invalid.
  51 ***********************************************************************/
  52 struct iterator *invalid_iter_init(struct iterator *it)
  53 {
  54   it->next = invalid_iter_next;
  55   it->get = invalid_iter_get;
  56   it->valid = invalid_iter_valid;
  57   return it;
  58 }