lib/strverscmp.c

   1 /* Compare strings while treating digits characters numerically.
   2    Copyright (C) 1997, 2000, 2002 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    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    This program 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
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License along
  17    with this program; if not, write to the Free Software Foundation,
  18    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 #if HAVE_CONFIG_H
  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    0x4
  31 #define S_F    0x8
  32 #define S_Z    0xC
  33
  34 /* result_type: CMP: return diff; LEN: compare using len_diff/diff */
  35 #define CMP    2
  36 #define LEN    3
  37
  38
  39 /* ISDIGIT differs from isdigit, as follows:
  40    - Its arg may be any int or unsigned int; it need not be an unsigned char.
  41    - It's guaranteed to evaluate its argument exactly once.
  42    - It's typically faster.
  43    POSIX says that only '0' through '9' are digits.  Prefer ISDIGIT to
  44    ISDIGIT_LOCALE unless it's important to use the locale's definition
  45    of `digit' even when the host does not conform to POSIX.  */
  46 #define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
  47
  48 #undef __strverscmp
  49 #undef strverscmp
  50
  51 #ifndef weak_alias
  52 # define __strverscmp strverscmp
  53 #endif
  54
  55 /* Compare S1 and S2 as strings holding indices/version numbers,
  56    returning less than, equal to or greater than zero if S1 is less than,
  57    equal to or greater than S2 (for more info, see the texinfo doc).
  58 */
  59
  60 int
  61 __strverscmp (const char *s1, const char *s2)
  62 {
  63   const unsigned char *p1 = (const unsigned char *) s1;
  64   const unsigned char *p2 = (const unsigned char *) s2;
  65   unsigned char c1, c2;
  66   int state;
  67   int diff;
  68
  69   /* Symbol(s)    0       [1-9]   others  (padding)
  70      Transition   (10) 0  (01) d  (00) x  (11) -   */
  71   static const unsigned int next_state[] =
  72   {
  73       /* state    x    d    0    - */
  74       /* S_N */  S_N, S_I, S_Z, S_N,
  75       /* S_I */  S_N, S_I, S_I, S_I,
  76       /* S_F */  S_N, S_F, S_F, S_F,
  77       /* S_Z */  S_N, S_F, S_Z, S_Z
  78   };
  79
  80   static const int result_type[] =
  81   {
  82       /* state   x/x  x/d  x/0  x/-  d/x  d/d  d/0  d/-
  83                  0/x  0/d  0/0  0/-  -/x  -/d  -/0  -/- */
  84
  85       /* S_N */  CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
  86                  CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
  87       /* S_I */  CMP, -1,  -1,  CMP,  1,  LEN, LEN, CMP,
  88                   1,  LEN, LEN, CMP, CMP, CMP, CMP, CMP,
  89       /* S_F */  CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
  90                  CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
  91       /* S_Z */  CMP,  1,   1,  CMP, -1,  CMP, CMP, CMP,
  92                  -1,  CMP, CMP, CMP
  93   };
  94
  95   if (p1 == p2)
  96     return 0;
  97
  98   c1 = *p1++;
  99   c2 = *p2++;
 100   /* Hint: '0' is a digit too.  */
 101   state = S_N | ((c1 == '0') + (ISDIGIT (c1) != 0));
 102
 103   while ((diff = c1 - c2) == 0 && c1 != '\0')
 104     {
 105       state = next_state[state];
 106       c1 = *p1++;
 107       c2 = *p2++;
 108       state |= (c1 == '0') + (ISDIGIT (c1) != 0);
 109     }
 110
 111   state = result_type[state << 2 | ((c2 == '0') + (ISDIGIT (c2) != 0))];
 112
 113   switch (state)
 114     {
 115     case CMP:
 116       return diff;
 117
 118     case LEN:
 119       while (ISDIGIT (*p1++))
 120         if (!ISDIGIT (*p2++))
 121           return 1;
 122
 123       return ISDIGIT (*p2) ? -1 : diff;
 124
 125     default:
 126       return state;
 127     }
 128 }
 129 #ifdef weak_alias
 130 weak_alias (__strverscmp, strverscmp)
 131 #endif