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    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 /* ISDIGIT differs from isdigit, as follows:
  41    - Its arg may be any int or unsigned int; it need not be an unsigned char.
  42    - It's guaranteed to evaluate its argument exactly once.
  43    - It's typically faster.
  44    POSIX says that only '0' through '9' are digits.  Prefer ISDIGIT to
  45    ISDIGIT_LOCALE unless it's important to use the locale's definition
  46    of `digit' even when the host does not conform to POSIX.  */
  47 #define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
  48
  49 #undef __strverscmp
  50 #undef strverscmp
  51
  52 #ifndef weak_alias
  53 # define __strverscmp strverscmp
  54 #endif
  55
  56 /* Compare S1 and S2 as strings holding indices/version numbers,
  57    returning less than, equal to or greater than zero if S1 is less than,
  58    equal to or greater than S2 (for more info, see the texinfo doc).
  59 */
  60
  61 int
  62 __strverscmp (const char *s1, const char *s2)
  63 {
  64   const unsigned char *p1 = (const unsigned char *) s1;
  65   const unsigned char *p2 = (const unsigned char *) s2;
  66   unsigned char c1, c2;
  67   int state;
  68   int diff;
  69
  70   /* Symbol(s)    0       [1-9]   others  (padding)
  71      Transition   (10) 0  (01) d  (00) x  (11) -   */
  72   static const unsigned int next_state[] =
  73   {
  74       /* state    x    d    0    - */
  75       /* S_N */  S_N, S_I, S_Z, S_N,
  76       /* S_I */  S_N, S_I, S_I, S_I,
  77       /* S_F */  S_N, S_F, S_F, S_F,
  78       /* S_Z */  S_N, S_F, S_Z, S_Z
  79   };
  80
  81   static const int result_type[] =
  82   {
  83       /* state   x/x  x/d  x/0  x/-  d/x  d/d  d/0  d/-
  84                  0/x  0/d  0/0  0/-  -/x  -/d  -/0  -/- */
  85
  86       /* S_N */  CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
  87                  CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
  88       /* S_I */  CMP, -1,  -1,  CMP,  1,  LEN, LEN, CMP,
  89                   1,  LEN, LEN, CMP, CMP, CMP, CMP, CMP,
  90       /* S_F */  CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
  91                  CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
  92       /* S_Z */  CMP,  1,   1,  CMP, -1,  CMP, CMP, CMP,
  93                  -1,  CMP, CMP, CMP
  94   };
  95
  96   if (p1 == p2)
  97     return 0;
  98
  99   c1 = *p1++;
 100   c2 = *p2++;
 101   /* Hint: '0' is a digit too.  */
 102   state = S_N | ((c1 == '0') + (ISDIGIT (c1) != 0));
 103
 104   while ((diff = c1 - c2) == 0 && c1 != '\0')
 105     {
 106       state = next_state[state];
 107       c1 = *p1++;
 108       c2 = *p2++;
 109       state |= (c1 == '0') + (ISDIGIT (c1) != 0);
 110     }
 111
 112   state = result_type[state << 2 | ((c2 == '0') + (ISDIGIT (c2) != 0))];
 113
 114   switch (state)
 115     {
 116     case CMP:
 117       return diff;
 118
 119     case LEN:
 120       while (ISDIGIT (*p1++))
 121         if (!ISDIGIT (*p2++))
 122           return 1;
 123
 124       return ISDIGIT (*p2) ? -1 : diff;
 125
 126     default:
 127       return state;
 128     }
 129 }
 130 #ifdef weak_alias
 131 weak_alias (__strverscmp, strverscmp)
 132 #endif