lib/strverscmp.c

   1 /* Compare strings while treating digits characters numerically.
   2    Copyright (C) 1997 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Jean-Francois Bignolles <bignolle@ecoledoc.ibp.fr>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #if HAVE_CONFIG_H
  22 # include <config.h>
  23 #endif
  24
  25 #include <string.h>
  26 #include <ctype.h>
  27
  28 /* states: S_N: normal, S_I: comparing integral part, S_F: comparing
  29            Fractional parts, S_Z: idem but with leading Zeroes only */
  30 #define S_N    0x0
  31 #define S_I    0x4
  32 #define S_F    0x8
  33 #define S_Z    0xC
  34
  35 /* result_type: CMP: return diff; LEN: compare using len_diff/diff */
  36 #define CMP    2
  37 #define LEN    3
  38
  39
  40 /* Compare S1 and S2 as strings holding indices/version numbers,
  41    returning less than, equal to or greater than zero if S1 is less than,
  42    equal to or greater than S2 (for more info, see the texinfo doc).
  43 */
  44
  45 int
  46 strverscmp (const char *s1, const char *s2)
  47 {
  48   const unsigned char *p1 = (const unsigned char *) s1;
  49   const unsigned char *p2 = (const unsigned char *) s2;
  50   unsigned char c1, c2;
  51   int state;
  52   int diff;
  53
  54   /* Symbol(s)    0       [1-9]   others  (padding)
  55      Transition   (10) 0  (01) d  (00) x  (11) -   */
  56   static const unsigned int next_state[] =
  57   {
  58       /* state    x    d    0    - */
  59       /* S_N */  S_N, S_I, S_Z, S_N,
  60       /* S_I */  S_N, S_I, S_I, S_I,
  61       /* S_F */  S_N, S_F, S_F, S_F,
  62       /* S_Z */  S_N, S_F, S_Z, S_Z
  63   };
  64
  65   static const int result_type[] =
  66   {
  67       /* state   x/x  x/d  x/0  x/-  d/x  d/d  d/0  d/-
  68                  0/x  0/d  0/0  0/-  -/x  -/d  -/0  -/- */
  69
  70       /* S_N */  CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
  71                  CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
  72       /* S_I */  CMP, -1,  -1,  CMP,  1,  LEN, LEN, CMP,
  73                   1,  LEN, LEN, CMP, CMP, CMP, CMP, CMP,
  74       /* S_F */  CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
  75                  CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
  76       /* S_Z */  CMP,  1,   1,  CMP, -1,  CMP, CMP, CMP,
  77                  -1,  CMP, CMP, CMP
  78   };
  79
  80   if (p1 == p2)
  81     return 0;
  82
  83   c1 = *p1++;
  84   c2 = *p2++;
  85   /* Hint: '0' is a digit too.  */
  86   state = S_N | ((c1 == '0') + (isdigit (c1) != 0));
  87
  88   while ((diff = c1 - c2) == 0 && c1 != '\0')
  89     {
  90       state = next_state[state];
  91       c1 = *p1++;
  92       c2 = *p2++;
  93       state |= (c1 == '0') + (isdigit (c1) != 0);
  94     }
  95
  96   state = result_type[state << 2 | ((c2 == '0') + (isdigit (c2) != 0))];
  97
  98   switch (state)
  99     {
 100     case CMP:
 101       return diff;
 102
 103     case LEN:
 104       while (isdigit (*p1++))
 105         if (!isdigit (*p2++))
 106           return 1;
 107
 108       return isdigit (*p2) ? -1 : diff;
 109
 110     default:
 111       return state;
 112     }
 113 }