lib/strverscmp.c

   1 /* Compare strings while treating digits characters numerically.
   2    Copyright (C) 1997-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Jean-François 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 Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the 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    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #if !_LIBC
  21 # include <config.h>
  22 #endif
  23
  24 #include <string.h>
  25 #include <ctype.h>
  26
  27 /* states: S_N: normal, S_I: comparing integral part, S_F: comparing
  28            fractional parts, S_Z: idem but with leading Zeroes only */
  29 #define  S_N    0x0
  30 #define  S_I    0x3
  31 #define  S_F    0x6
  32 #define  S_Z    0x9
  33
  34 /* result_type: CMP: return diff; LEN: compare using len_diff/diff */
  35 #define  CMP    2
  36 #define  LEN    3
  37
  38 #ifndef weak_alias
  39 # define __strverscmp strverscmp
  40 #endif
  41
  42 /* Compare S1 and S2 as strings holding indices/version numbers,
  43    returning less than, equal to or greater than zero if S1 is less than,
  44    equal to or greater than S2 (for more info, see the texinfo doc).
  45 */
  46
  47 int
  48 __strverscmp (const char *s1, const char *s2)
  49 {
  50   const unsigned char *p1 = (const unsigned char *) s1;
  51   const unsigned char *p2 = (const unsigned char *) s2;
  52   unsigned char c1, c2;
  53   int state;
  54   int diff;
  55
  56   /* Symbol(s)    0       [1-9]   others
  57      Transition   (10) 0  (01) d  (00) x   */
  58   static const unsigned char next_state[] =
  59   {
  60       /* state    x    d    0  */
  61       /* S_N */  S_N, S_I, S_Z,
  62       /* S_I */  S_N, S_I, S_I,
  63       /* S_F */  S_N, S_F, S_F,
  64       /* S_Z */  S_N, S_F, S_Z
  65   };
  66
  67   static const signed char result_type[] =
  68   {
  69       /* state   x/x  x/d  x/0  d/x  d/d  d/0  0/x  0/d  0/0  */
  70
  71       /* S_N */  CMP, CMP, CMP, CMP, LEN, CMP, CMP, CMP, CMP,
  72       /* S_I */  CMP, -1,  -1,  +1,  LEN, LEN, +1,  LEN, LEN,
  73       /* S_F */  CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
  74       /* S_Z */  CMP, +1,  +1,  -1,  CMP, CMP, -1,  CMP, CMP
  75   };
  76
  77   if (p1 == p2)
  78     return 0;
  79
  80   c1 = *p1++;
  81   c2 = *p2++;
  82   /* Hint: '0' is a digit too.  */
  83   state = S_N + ((c1 == '0') + (isdigit (c1) != 0));
  84
  85   while ((diff = c1 - c2) == 0)
  86     {
  87       if (c1 == '\0')
  88         return diff;
  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 * 3 + (((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 }
 114 #ifdef weak_alias
 115 libc_hidden_def (__strverscmp)
 116 weak_alias (__strverscmp, strverscmp)
 117 #endif