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 #include <config.h>
  21
  22 #include <string.h>
  23 #include <ctype.h>
  24
  25 #include "namecmp.h"
  26
  27 int
  28 name_cmp(const char *a, const char *b, int separator)
  29 {
  30    while (1) {
  31       int cha = (unsigned char)*a, chb = (unsigned char)*b;
  32
  33       /* done if end of either first string */
  34       if (!cha || !chb) return cha - chb;
  35
  36       /* check for end of non-numeric prefix */
  37       if (isdigit(cha)) {
  38          /* sort numbers numerically and before non-numbers */
  39          const char *sa, *sb, *ea, *eb;
  40          int res;
  41
  42          if (!isdigit(chb)) return chb == separator ? 1 : -1;
  43
  44          sa = a;
  45          while (*sa == '0') sa++;
  46          ea = sa;
  47          while (isdigit((unsigned char)*ea)) ea++;
  48
  49          sb = b;
  50          while (*sb == '0') sb++;
  51          eb = sb;
  52          while (isdigit((unsigned char)*eb)) eb++;
  53
  54          /* shorter sorts first */
  55          res = (ea - sa) - (eb - sb);
  56          /* same length, all digits, so memcmp() sorts numerically */
  57          if (!res) res = memcmp(sa, sb, ea - sa);
  58          /* more leading zeros sorts first */
  59          if (!res) res = (sb - b) - (sa - a);
  60          if (res) return res;
  61
  62          /* if numbers match, sort by suffix */
  63          a = ea;
  64          b = eb;
  65          continue;
  66       }
  67
  68       if (cha != chb) {
  69          if (cha == separator) return -1;
  70          if (isdigit(chb) || chb == separator) return 1;
  71          return cha - chb;
  72       }
  73
  74       a++;
  75       b++;
  76    }
  77 }