src/namecmp.c

   1 /* namecmp.c */
   2 /* Ordering function for station names */
   3 /* Copyright (C) 1991-2002,2004 Olly Betts
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18  */
  19
  20 #ifdef HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #include <string.h>
  25 #include <ctype.h>
  26
  27 #include "namecmp.h"
  28
  29 int
  30 name_cmp(const char *a, const char *b, int separator)
  31 {
  32    while (1) {
  33       int cha = (unsigned char)*a, chb = (unsigned char)*b;
  34
  35       /* done if end of either first string */
  36       if (!cha || !chb) return cha - chb;
  37
  38       /* check for end of non-numeric prefix */
  39       if (isdigit(cha)) {
  40          /* sort numbers numerically and before non-numbers */
  41          const char *sa, *sb, *ea, *eb;
  42          int res;
  43
  44          if (!isdigit(chb)) return chb == separator ? 1 : -1;
  45
  46          sa = a;
  47          while (*sa == '0') sa++;
  48          ea = sa;
  49          while (isdigit((unsigned char)*ea)) ea++;
  50
  51          sb = b;
  52          while (*sb == '0') sb++;
  53          eb = sb;
  54          while (isdigit((unsigned char)*eb)) eb++;
  55
  56          /* shorter sorts first */
  57          res = (ea - sa) - (eb - sb);
  58          /* same length, all digits, so memcmp() sorts numerically */
  59          if (!res) res = memcmp(sa, sb, ea - sa);
  60          /* more leading zeros sorts first */
  61          if (!res) res = (sb - b) - (sa - a);
  62          if (res) return res;
  63
  64          /* if numbers match, sort by suffix */
  65          a = ea;
  66          b = eb;
  67          continue;
  68       }
  69
  70       if (cha != chb) {
  71          if (cha == separator) return -1;
  72          if (isdigit(chb) || chb == separator) return 1;
  73          return cha - chb;
  74       }
  75
  76       a++;
  77       b++;
  78    }
  79 }