stdlib/grouping.c

   1 /* Internal header for proving correct grouping in strings of numbers.
   2    Copyright (C) 1995,1996,1997,1998,2000,2003 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.
   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 <limits.h>
  22 #include <stddef.h>
  23 #include <string.h>
  24
  25 #ifndef MAX
  26 #define MAX(a,b)        ({ typeof(a) _a = (a); typeof(b) _b = (b); \
  27                            _a > _b ? _a : _b; })
  28 #endif
  29
  30 #ifdef USE_WIDE_CHAR
  31 # include <wctype.h>
  32 # define L_(Ch) L##Ch
  33 # define UCHAR_TYPE wint_t
  34 # define STRING_TYPE wchar_t
  35 #else
  36 # define L_(Ch) Ch
  37 # define UCHAR_TYPE unsigned char
  38 # define STRING_TYPE char
  39 #endif
  40
  41 #include "grouping.h"
  42
  43 /* Find the maximum prefix of the string between BEGIN and END which
  44    satisfies the grouping rules.  It is assumed that at least one digit
  45    follows BEGIN directly.  */
  46
  47 const STRING_TYPE *
  48 #ifdef USE_WIDE_CHAR
  49 __correctly_grouped_prefixwc (const STRING_TYPE *begin, const STRING_TYPE *end,
  50                               wchar_t thousands,
  51 #else
  52 __correctly_grouped_prefixmb (const STRING_TYPE *begin, const STRING_TYPE *end,
  53                               const char *thousands,
  54 #endif
  55                               const char *grouping)
  56 {
  57 #ifndef USE_WIDE_CHAR
  58   size_t thousands_len;
  59   int cnt;
  60 #endif
  61
  62   if (grouping == NULL)
  63     return end;
  64
  65 #ifndef USE_WIDE_CHAR
  66   thousands_len = strlen (thousands);
  67 #endif
  68
  69   while (end > begin)
  70     {
  71       const STRING_TYPE *cp = end - 1;
  72       const char *gp = grouping;
  73
  74       /* Check first group.  */
  75       while (cp >= begin)
  76         {
  77 #ifdef USE_WIDE_CHAR
  78           if (*cp == thousands)
  79             break;
  80 #else
  81           if (cp[thousands_len - 1] == *thousands)
  82             {
  83               for (cnt = 1; thousands[cnt] != '\0'; ++cnt)
  84                 if (thousands[cnt] != cp[thousands_len - 1 - cnt])
  85                   break;
  86               if (thousands[cnt] == '\0')
  87                 break;
  88             }
  89 #endif
  90           --cp;
  91         }
  92
  93       /* We allow the representation to contain no grouping at all even if
  94          the locale specifies we can have grouping.  */
  95       if (cp < begin)
  96         return end;
  97
  98       if (end - cp == (int) *gp + 1)
  99         {
 100           /* This group matches the specification.  */
 101
 102           const STRING_TYPE *new_end;
 103
 104           if (cp < begin)
 105             /* There is just one complete group.  We are done.  */
 106             return end;
 107
 108           /* CP points to a thousands separator character.  The preceding
 109              remainder of the string from BEGIN to NEW_END is the part we
 110              will consider if there is a grouping error in this trailing
 111              portion from CP to END.  */
 112           new_end = cp - 1;
 113
 114           /* Loop while the grouping is correct.  */
 115           while (1)
 116             {
 117               /* Get the next grouping rule.  */
 118               ++gp;
 119               if (*gp == 0)
 120                 /* If end is reached use last rule.  */
 121                 --gp;
 122
 123               /* Skip the thousands separator.  */
 124               --cp;
 125
 126               if (*gp == CHAR_MAX
 127 #if CHAR_MIN < 0
 128                   || *gp < 0
 129 #endif
 130                   )
 131                 {
 132                   /* No more thousands separators are allowed to follow.  */
 133                   while (cp >= begin)
 134                     {
 135 #ifdef USE_WIDE_CHAR
 136                       if (*cp == thousands)
 137                         break;
 138 #else
 139                       for (cnt = 0; thousands[cnt] != '\0'; ++cnt)
 140                         if (thousands[cnt] != cp[thousands_len - cnt - 1])
 141                           break;
 142                       if (thousands[cnt] == '\0')
 143                         break;
 144 #endif
 145                       --cp;
 146                     }
 147
 148                   if (cp < begin)
 149                     /* OK, only digits followed.  */
 150                     return end;
 151                 }
 152               else
 153                 {
 154                   /* Check the next group.  */
 155                   const STRING_TYPE *group_end = cp;
 156
 157                   while (cp >= begin)
 158                     {
 159 #ifdef USE_WIDE_CHAR
 160                       if (*cp == thousands)
 161                         break;
 162 #else
 163                       for (cnt = 0; thousands[cnt] != '\0'; ++cnt)
 164                         if (thousands[cnt] != cp[thousands_len - cnt - 1])
 165                           break;
 166                       if (thousands[cnt] == '\0')
 167                         break;
 168 #endif
 169                       --cp;
 170                     }
 171
 172                   if (cp < begin && group_end - cp <= (int) *gp)
 173                     /* Final group is correct.  */
 174                     return end;
 175
 176                   if (cp < begin || group_end - cp != (int) *gp)
 177                     /* Incorrect group.  Punt.  */
 178                     break;
 179                 }
 180             }
 181
 182           /* The trailing portion of the string starting at NEW_END
 183              contains a grouping error.  So we will look for a correctly
 184              grouped number in the preceding portion instead.  */
 185           end = new_end;
 186         }
 187       else
 188         {
 189           /* Even the first group was wrong; determine maximum shift.  */
 190           if (end - cp > (int) *gp + 1)
 191             end = cp + (int) *gp + 1;
 192           else if (cp < begin)
 193             /* This number does not fill the first group, but is correct.  */
 194             return end;
 195           else
 196             /* CP points to a thousands separator character.  */
 197             end = cp;
 198         }
 199     }
 200
 201   return MAX (begin, end);
 202 }