lib/strutil/strverscmp.c

   1 /* Compare strings while treating digits characters numerically.
   2    Copyright (C) 1997, 2002 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Jean-Fran�ois 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 <ctype.h>
  22 #ifdef HAVE_STRVERSCMP
  23 #include <string.h>
  24 #endif /* HAVE_STRVERSCMP */
  25
  26 #include "lib/strutil.h"
  27
  28 /* states: S_N: normal, S_I: comparing integral part, S_F: comparing
  29    fractionnal 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 /* Compare S1 and S2 as strings holding indices/version numbers,
  41    returning less than, equal to or greater than zero if S1 is less than,
  42    equal to or greater than S2 (for more info, see the texinfo doc).
  43  */
  44
  45 int
  46 str_verscmp (const char *s1, const char *s2)
  47 {
  48 #ifdef HAVE_STRVERSCMP
  49     return strverscmp (s1, s2);
  50 #else /* HAVE_STRVERSCMP */
  51     unsigned char *p1 = (unsigned char *) s1;
  52     unsigned char *p2 = (unsigned char *) s2;
  53     unsigned char c1, c2;
  54     int state;
  55     int diff;
  56
  57     /* Symbol(s)    0       [1-9]   others  (padding)
  58        Transition   (10) 0  (01) d  (00) x  (11) -   */
  59     static const unsigned int next_state[] = {
  60         /* state    x    d    0    - */
  61         /* S_N */ S_N, S_I, S_Z, S_N,
  62         /* S_I */ S_N, S_I, S_I, S_I,
  63         /* S_F */ S_N, S_F, S_F, S_F,
  64         /* S_Z */ S_N, S_F, S_Z, S_Z
  65     };
  66
  67     static const int result_type[] = {
  68         /* state   x/x  x/d  x/0  x/-  d/x  d/d  d/0  d/-
  69            0/x  0/d  0/0  0/-  -/x  -/d  -/0  -/- */
  70
  71         /* S_N */ CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
  72         CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
  73         /* S_I */ CMP, -1, -1, CMP, +1, LEN, LEN, CMP,
  74         +1, LEN, LEN, CMP, CMP, CMP, CMP, CMP,
  75         /* S_F */ CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
  76         CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
  77         /* S_Z */ CMP, +1, +1, CMP, -1, CMP, CMP, CMP,
  78         -1, CMP, CMP, CMP
  79     };
  80
  81     if (p1 == p2)
  82         return 0;
  83
  84     c1 = *p1++;
  85     c2 = *p2++;
  86     /* Hint: '0' is a digit too.  */
  87     state = S_N | ((c1 == '0') + (isdigit (c1) != 0));
  88
  89     while ((diff = c1 - c2) == 0 && c1 != '\0')
  90     {
  91         state = next_state[state];
  92         c1 = *p1++;
  93         c2 = *p2++;
  94         state |= (c1 == '0') + (isdigit (c1) != 0);
  95     }
  96
  97     state = result_type[state << 2 | (((c2 == '0') + (isdigit (c2) != 0)))];
  98
  99     switch (state)
 100     {
 101     case CMP:
 102         return diff;
 103
 104     case LEN:
 105         while (isdigit (*p1++))
 106             if (!isdigit (*p2++))
 107                 return 1;
 108
 109         return isdigit (*p2) ? -1 : diff;
 110
 111     default:
 112         return state;
 113     }
 114 #endif /* HAVE_STRVERSCMP */
 115
 116 }