mdw@git.distorted.org.uk Git - anag/blob - mono.c

   1 /* -*-c-*-
   2  *
   3  * Monoalphabetic matcher
   4  *
   5  * (c) 2003 Mark Wooding
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Anag: a simple wordgame helper.
  11  *
  12  * Anag is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * Anag is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with Anag; if not, write to the Free Software Foundation,
  24  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 /*----- Header files ------------------------------------------------------*/
  28
  29 #include "anag.h"
  30
  31 /*----- Data structures ---------------------------------------------------*/
  32
  33 typedef struct node_mono {
  34   node n;
  35   unsigned len;
  36   unsigned char *p;
  37 } node_mono;
  38
  39 /*----- Main code ---------------------------------------------------------*/
  40
  41 /* --- Matching --- */
  42
  43 static int n_mono(node *nn, const char *p, size_t sz)
  44 {
  45   node_mono *n = (node_mono *)nn;
  46   unsigned map[UCHAR_MAX], imap[UCHAR_MAX];
  47   const unsigned char *q = n->p;
  48   int ch, i;
  49
  50   if (sz != n->len)
  51     return (0);
  52   memset(map, 0, sizeof(map));
  53   memset(imap, 0, sizeof(imap));
  54   while (*p) {
  55     ch = *p++;
  56     i = *q++;
  57     if (!map[i]) {
  58       if (imap[ch])
  59         return (0);
  60       map[i] = ch;
  61       imap[ch] = 1;
  62     } else if (map[i] != ch)
  63       return (0);
  64   }
  65   return (1);
  66 }
  67
  68 /* --- Node creation --- */
  69
  70 node *mono(const char *const *av)
  71 {
  72   unsigned char map[UCHAR_MAX];
  73   unsigned max;
  74   int ch;
  75   const char *p;
  76   unsigned char *q;
  77
  78   node_mono *n = xmalloc(sizeof(*n));
  79   n->n.func = n_mono;
  80   memset(map, UCHAR_MAX, sizeof(map));
  81   max = 0;
  82   p = av[0];
  83   n->len = strlen(p);
  84   q = xmalloc(n->len);
  85   n->p = q;
  86   while (*p) {
  87     ch = *p++;
  88     if (map[ch] >= max)
  89       map[ch] = max++;
  90     *q++ = map[ch];
  91   }
  92   return (&n->n);
  93 }
  94
  95 /*----- That's all, folks -------------------------------------------------*/