compat/strverscmp.c

   1 /* Compare strings while treating digits characters numerically.
   2    Copyright (C) 1997, 2002, 2009 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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <stdint.h>
  22 #include <string.h>
  23 #include <ctype.h>
  24
  25 /* states: S_N: normal, S_I: comparing integral part, S_F: comparing
  26            fractionnal parts, S_Z: idem but with leading Zeroes only */
  27 #define  S_N    0x0
  28 #define  S_I    0x3
  29 #define  S_F    0x6
  30 #define  S_Z    0x9
  31
  32 /* result_type: CMP: return diff; LEN: compare using len_diff/diff */
  33 #define  CMP    2
  34 #define  LEN    3
  35
  36
  37 /* Compare S1 and S2 as strings holding indices/version numbers,
  38    returning less than, equal to or greater than zero if S1 is less than,
  39    equal to or greater than S2 (for more info, see the texinfo doc).
  40 */
  41
  42 int strverscmp (const char *s1, const char *s2)
  43 {
  44   const unsigned char *p1 = (const unsigned char *) s1;
  45   const unsigned char *p2 = (const unsigned char *) s2;
  46
  47   /* Symbol(s)    0       [1-9]   others
  48      Transition   (10) 0  (01) d  (00) x   */
  49   static const uint8_t next_state[] =
  50   {
  51       /* state    x    d    0  */
  52       /* S_N */  S_N, S_I, S_Z,
  53       /* S_I */  S_N, S_I, S_I,
  54       /* S_F */  S_N, S_F, S_F,
  55       /* S_Z */  S_N, S_F, S_Z
  56   };
  57
  58   static const int8_t result_type[] =
  59   {
  60       /* state   x/x  x/d  x/0  d/x  d/d  d/0  0/x  0/d  0/0  */
  61
  62       /* S_N */  CMP, CMP, CMP, CMP, LEN, CMP, CMP, CMP, CMP,
  63       /* S_I */  CMP, -1,  -1,  +1,  LEN, LEN, +1,  LEN, LEN,
  64       /* S_F */  CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
  65       /* S_Z */  CMP, +1,  +1,  -1,  CMP, CMP, -1,  CMP, CMP
  66   };
  67
  68   if (p1 == p2)
  69     return 0;
  70
  71   unsigned char c1 = *p1++;
  72   unsigned char c2 = *p2++;
  73   /* Hint: '0' is a digit too.  */
  74   int state = S_N + ((c1 == '0') + (isdigit (c1) != 0));
  75
  76   int diff;
  77   while ((diff = c1 - c2) == 0)
  78     {
  79       if (c1 == '\0')
  80         return diff;
  81
  82       state = next_state[state];
  83       c1 = *p1++;
  84       c2 = *p2++;
  85       state += (c1 == '0') + (isdigit (c1) != 0);
  86     }
  87
  88   state = result_type[state * 3 + (((c2 == '0') + (isdigit (c2) != 0)))];
  89
  90   switch (state)
  91   {
  92     case CMP:
  93       return diff;
  94
  95     case LEN:
  96       while (isdigit (*p1++))
  97         if (!isdigit (*p2++))
  98           return 1;
  99
 100       return isdigit (*p2) ? -1 : diff;
 101
 102     default:
 103       return state;
 104   }
 105 }