src/namecompare.cc

   1 /* namecompare.cc */
   2 /* Ordering function for station names */
   3 /* Copyright (C) 1991-2002,2004,2012,2016 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 "namecompare.h"
  25
  26 inline bool u_digit(unsigned ch) {
  27     return (ch - unsigned('0')) <= unsigned('9' - '0');
  28 }
  29
  30 int name_cmp(const wxString &a, const wxString &b, int separator) {
  31    size_t i = 0;
  32    size_t shorter = std::min(a.size(), b.size());
  33    while (i != shorter) {
  34       int cha = a[i];
  35       int chb = b[i];
  36       /* check for end of non-numeric prefix */
  37       if (u_digit(cha)) {
  38          /* sort numbers numerically and before non-numbers */
  39          size_t sa, sb, ea, eb;
  40          int res;
  41
  42          if (!u_digit(chb)) return chb == separator ? 1 : -1;
  43
  44          sa = i;
  45          while (sa != a.size() && a[sa] == '0') sa++;
  46          ea = sa;
  47          while (ea != a.size() && u_digit(a[ea])) ea++;
  48
  49          sb = i;
  50          while (sb != b.size() && b[sb] == '0') sb++;
  51          eb = sb;
  52          while (eb != b.size() && u_digit(b[eb])) eb++;
  53
  54          /* shorter sorts first */
  55          res = (ea - sa) - (eb - sb);
  56          /* same length, all digits, so character value compare sorts
  57           * numerically */
  58          for (size_t j = sa; !res && j != ea; ++j) {
  59             res = a[j] - b[j - sa + sb];
  60          }
  61          /* more leading zeros sorts first */
  62          if (!res) res = sb - sa;
  63          if (res) return res;
  64
  65          /* if numbers match, sort by suffix */
  66          i = ea;
  67          continue;
  68       }
  69
  70       if (cha != chb) {
  71          if (cha == separator) return -1;
  72          if (u_digit(chb) || chb == separator) return 1;
  73          return cha - chb;
  74       }
  75
  76       i++;
  77    }
  78    return int(a.size()) - int(b.size());
  79 }