root/lib/strutil/strverscmp.c

/*   */

DEFINITIONS

1. str_verscmp

   1 /*
   2    Compare strings while treating digits characters numerically.
   3 
   4    Copyright (C) 1997-2025
   5    Free Software Foundation, Inc.
   6 
   7    This file is part of the GNU C Library.
   8    Contributed by Jean-François Bignolles <bignolle@ecoledoc.ibp.fr>, 1997.
   9 
  10    The GNU C Library is free software; you can redistribute it and/or
  11    modify it under the terms of the GNU Lesser General Public
  12    License as published by the Free Software Foundation; either
  13    version 2.1 of the License, or (at your option) any later version.
  14 
  15    The GNU C Library is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18    Lesser General Public License for more details.
  19 
  20    You should have received a copy of the GNU Lesser General Public
  21    License along with the GNU C Library; if not, see
  22    <https://www.gnu.org/licenses/>.
  23 
  24    This file is part of the Midnight Commander.
  25 
  26    The Midnight Commander is free software: you can redistribute it
  27    and/or modify it under the terms of the GNU General Public License as
  28    published by the Free Software Foundation, either version 3 of the License,
  29    or (at your option) any later version.
  30 
  31    The Midnight Commander is distributed in the hope that it will be useful,
  32    but WITHOUT ANY WARRANTY; without even the implied warranty of
  33    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  34    GNU General Public License for more details.
  35 
  36    You should have received a copy of the GNU General Public License
  37    along with this program.  If not, see <https://www.gnu.org/licenses/>.
  38  */
  39 
  40 #include <config.h>
  41 
  42 #ifdef HAVE_STRVERSCMP
  43 #include <string.h>
  44 #endif
  45 
  46 #include "lib/strutil.h"
  47 
  48 /*** global variables ****************************************************************************/
  49 
  50 /*** file scope macro definitions ****************************************************************/
  51 
  52 #ifndef HAVE_STRVERSCMP
  53 
  54 /* states: S_N: normal, S_I: comparing integral part, S_F: comparing
  55    fractional parts, S_Z: idem but with leading Zeroes only */
  56 #define S_N 0x0
  57 #define S_I 0x3
  58 #define S_F 0x6
  59 #define S_Z 0x9
  60 
  61 /* result_type: CMP: return diff; LEN: compare using len_diff/diff */
  62 #define CMP 2
  63 #define LEN 3
  64 
  65 #endif
  66 
  67 /*** file scope type declarations ****************************************************************/
  68 
  69 /*** file scope variables ************************************************************************/
  70 
  71 /* --------------------------------------------------------------------------------------------- */
  72 /*** file scope functions ************************************************************************/
  73 /* --------------------------------------------------------------------------------------------- */
  74 
  75 /* --------------------------------------------------------------------------------------------- */
  76 /*** public functions ****************************************************************************/
  77 /* --------------------------------------------------------------------------------------------- */
  78 /* Compare S1 and S2 as strings holding indices/version numbers,
  79    returning less than, equal to or greater than zero if S1 is less than,
  80    equal to or greater than S2 (for more info, see the texinfo doc).
  81  */
  82 int
  83 str_verscmp (const char *s1, const char *s2)
     /*   */
  84 {
  85 #ifdef HAVE_STRVERSCMP
  86     return strverscmp (s1, s2);
  87 
  88 #else  // HAVE_STRVERSCMP
  89     const unsigned char *p1 = (const unsigned char *) s1;
  90     const unsigned char *p2 = (const unsigned char *) s2;
  91     unsigned char c1, c2;
  92     int state;
  93     int diff;
  94 
  95     /* Symbol(s)    0       [1-9]   others
  96        Transition   (10) 0  (01) d  (00) x   */
  97     static const unsigned char next_state[] = {
  98         // state    x    d    0
  99         /* S_N */ S_N, S_I, S_Z,
 100         /* S_I */ S_N, S_I, S_I,
 101         /* S_F */ S_N, S_F, S_F,
 102         /* S_Z */ S_N, S_F, S_Z,
 103     };
 104 
 105     static const signed char result_type[] = {
 106         /* state  x/x  x/d  x/0  d/x  d/d  d/0  0/x  0/d  0/0  */
 107 
 108         /* S_N */ CMP, CMP, CMP, CMP, LEN, CMP, CMP, CMP, CMP,
 109         /* S_I */ CMP, -1,  -1,  +1,  LEN, LEN, +1,  LEN, LEN,
 110         /* S_F */ CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
 111         /* S_Z */ CMP, +1,  +1,  -1,  CMP, CMP, -1,  CMP, CMP
 112     };
 113 
 114     if (p1 == p2)
 115         return 0;
 116 
 117     c1 = *p1++;
 118     c2 = *p2++;
 119     // Hint: '0' is a digit too.
 120     state = S_N + ((c1 == '0') + (g_ascii_isdigit (c1) ? 1 : 0));
 121 
 122     while ((diff = c1 - c2) == 0)
 123     {
 124         if (c1 == '\0')
 125             return diff;
 126 
 127         state = next_state[state];
 128         c1 = *p1++;
 129         c2 = *p2++;
 130         state += (c1 == '0') + (g_ascii_isdigit (c1) ? 1 : 0);
 131     }
 132 
 133     state = result_type[state * 3 + (((c2 == '0') + (g_ascii_isdigit (c2) ? 1 : 0)))];
 134 
 135     switch (state)
 136     {
 137     case CMP:
 138         return diff;
 139 
 140     case LEN:
 141         while (g_ascii_isdigit (*p1++))
 142             if (!g_ascii_isdigit (*p2++))
 143                 return 1;
 144 
 145         return g_ascii_isdigit (*p2) ? -1 : diff;
 146 
 147     default:
 148         return state;
 149     }
 150 #endif
 151 }
 152 
 153 /* --------------------------------------------------------------------------------------------- */

/*   */