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      1 /* Compare strings while treating digits characters numerically.
      2    Copyright (C) 1997, 2000, 2002, 2004 Free Software Foundation, Inc.
      3    This file is part of the GNU C Library.
      4    Contributed by Jean-Franois Bignolles <bignolle (at) 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
     19 
     20 #ifdef 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 int) (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
    132