stdlib/grouping.c

   1 /* Internal header for proving correct grouping in strings of numbers.
   2    Copyright (C) 1995-2017 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, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <limits.h>
  21 #include <stddef.h>
  22 #include <string.h>
  23
  24 #ifndef MAX
  25 #define MAX(a,b)        ({ typeof(a) _a = (a); typeof(b) _b = (b); \
  26                            _a > _b ? _a : _b; })
  27 #endif
  28
  29 #ifdef USE_WIDE_CHAR
  30 # include <wctype.h>
  31 # define L_(Ch) L##Ch
  32 # define UCHAR_TYPE wint_t
  33 # define STRING_TYPE wchar_t
  34 #else
  35 # define L_(Ch) Ch
  36 # define UCHAR_TYPE unsigned char
  37 # define STRING_TYPE char
  38 #endif
  39
  40 #include "grouping.h"
  41
  42 /* Find the maximum prefix of the string between BEGIN and END which
  43    satisfies the grouping rules.  It is assumed that at least one digit
  44    follows BEGIN directly.  */
  45
  46 const STRING_TYPE *
  47 #ifdef USE_WIDE_CHAR
  48 __correctly_grouped_prefixwc (const STRING_TYPE *begin, const STRING_TYPE *end,
  49                               wchar_t thousands,
  50 #else
  51 __correctly_grouped_prefixmb (const STRING_TYPE *begin, const STRING_TYPE *end,
  52                               const char *thousands,
  53 #endif
  54                               const char *grouping)
  55 {
  56 #ifndef USE_WIDE_CHAR
  57   size_t thousands_len;
  58   int cnt;
  59 #endif
  60
  61   if (grouping == NULL)
  62     return end;
  63
  64 #ifndef USE_WIDE_CHAR
  65   thousands_len = strlen (thousands);
  66 #endif
  67
  68   while (end > begin)
  69     {
  70       const STRING_TYPE *cp = end - 1;
  71       const char *gp = grouping;
  72
  73       /* Check first group.  */
  74       while (cp >= begin)
  75         {
  76 #ifdef USE_WIDE_CHAR
  77           if (*cp == thousands)
  78             break;
  79 #else
  80           if (cp[thousands_len - 1] == *thousands)
  81             {
  82               for (cnt = 1; thousands[cnt] != '\0'; ++cnt)
  83                 if (thousands[cnt] != cp[thousands_len - 1 - cnt])
  84                   break;
  85               if (thousands[cnt] == '\0')
  86                 break;
  87             }
  88 #endif
  89           --cp;
  90         }
  91
  92       /* We allow the representation to contain no grouping at all even if
  93          the locale specifies we can have grouping.  */
  94       if (cp < begin)
  95         return end;
  96
  97       if (end - cp == (int) *gp + 1)
  98         {
  99           /* This group matches the specification.  */
 100
 101           const STRING_TYPE *new_end;
 102
 103           if (cp < begin)
 104             /* There is just one complete group.  We are done.  */
 105             return end;
 106
 107           /* CP points to a thousands separator character.  The preceding
 108              remainder of the string from BEGIN to NEW_END is the part we
 109              will consider if there is a grouping error in this trailing
 110              portion from CP to END.  */
 111           new_end = cp - 1;
 112
 113           /* Loop while the grouping is correct.  */
 114           while (1)
 115             {
 116               /* Get the next grouping rule.  */
 117               ++gp;
 118               if (*gp == 0)
 119                 /* If end is reached use last rule.  */
 120                 --gp;
 121
 122               /* Skip the thousands separator.  */
 123               --cp;
 124
 125               if (*gp == CHAR_MAX
 126 #if CHAR_MIN < 0
 127                   || *gp < 0
 128 #endif
 129                   )
 130                 {
 131                   /* No more thousands separators are allowed to follow.  */
 132                   while (cp >= begin)
 133                     {
 134 #ifdef USE_WIDE_CHAR
 135                       if (*cp == thousands)
 136                         break;
 137 #else
 138                       for (cnt = 0; thousands[cnt] != '\0'; ++cnt)
 139                         if (thousands[cnt] != cp[thousands_len - cnt - 1])
 140                           break;
 141                       if (thousands[cnt] == '\0')
 142                         break;
 143 #endif
 144                       --cp;
 145                     }
 146
 147                   if (cp < begin)
 148                     /* OK, only digits followed.  */
 149                     return end;
 150                 }
 151               else
 152                 {
 153                   /* Check the next group.  */
 154                   const STRING_TYPE *group_end = cp;
 155
 156                   while (cp >= begin)
 157                     {
 158 #ifdef USE_WIDE_CHAR
 159                       if (*cp == thousands)
 160                         break;
 161 #else
 162                       for (cnt = 0; thousands[cnt] != '\0'; ++cnt)
 163                         if (thousands[cnt] != cp[thousands_len - cnt - 1])
 164                           break;
 165                       if (thousands[cnt] == '\0')
 166                         break;
 167 #endif
 168                       --cp;
 169                     }
 170
 171                   if (cp < begin && group_end - cp <= (int) *gp)
 172                     /* Final group is correct.  */
 173                     return end;
 174
 175                   if (cp < begin || group_end - cp != (int) *gp)
 176                     /* Incorrect group.  Punt.  */
 177                     break;
 178                 }
 179             }
 180
 181           /* The trailing portion of the string starting at NEW_END
 182              contains a grouping error.  So we will look for a correctly
 183              grouped number in the preceding portion instead.  */
 184           end = new_end;
 185         }
 186       else
 187         {
 188           /* Even the first group was wrong; determine maximum shift.  */
 189           if (end - cp > (int) *gp + 1)
 190             end = cp + (int) *gp + 1;
 191           else if (cp < begin)
 192             /* This number does not fill the first group, but is correct.  */
 193             return end;
 194           else
 195             /* CP points to a thousands separator character.  */
 196             end = cp;
 197         }
 198     }
 199
 200   return MAX (begin, end);
 201 }