stdio-common/grouping_iterator.c

   1 /* Iterator for inserting thousands separators into numbers.
   2    Copyright (C) 2022-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <grouping_iterator.h>
  20
  21 #include <assert.h>
  22 #include <limits.h>
  23 #include <locale/localeinfo.h>
  24 #include <stdint.h>
  25 #include <string.h>
  26
  27 /* Initializes *IT with no grouping information for a string of length
  28    DIGITS, and return false to indicate no grouping.  */
  29 bool
  30 __grouping_iterator_init_none (struct grouping_iterator *it,
  31                                unsigned int digits)
  32 {
  33   memset (it, 0, sizeof (*it));
  34   it->remaining_in_current_group = digits;
  35   it->remaining = digits;
  36   return false;
  37 }
  38
  39 static bool
  40 grouping_iterator_setup (struct grouping_iterator *it, unsigned int digits,
  41                          const char *grouping)
  42 {
  43   /* We treat all negative values like CHAR_MAX.  */
  44
  45   if (*grouping == CHAR_MAX || *grouping <= 0)
  46     /* No grouping should be done.  */
  47     return __grouping_iterator_init_none (it, digits);
  48
  49   unsigned int remaining_to_group = digits;
  50   unsigned int non_repeating_groups = 0;
  51   unsigned int groups = 0;
  52   while (true)
  53     {
  54       non_repeating_groups += *grouping;
  55       if (remaining_to_group <= (unsigned int) *grouping)
  56         break;
  57
  58       ++groups;
  59       remaining_to_group -= *grouping++;
  60
  61       if (*grouping == CHAR_MAX
  62 #if CHAR_MIN < 0
  63           || *grouping < 0
  64 #endif
  65           )
  66           /* No more grouping should be done.  */
  67         break;
  68       else if (*grouping == 0)
  69         {
  70           /* Same grouping repeats.  */
  71           --grouping;
  72           non_repeating_groups -= *grouping; /* Over-counted.  */
  73           unsigned int repeats = (remaining_to_group - 1) / *grouping;
  74           groups += repeats;
  75           remaining_to_group -= repeats * *grouping;
  76           break;
  77         }
  78     }
  79
  80   it->remaining_in_current_group = remaining_to_group;
  81   it->remaining = digits;
  82   it->groupings = grouping;
  83   it->non_repeating_groups = non_repeating_groups;
  84   it->separators = groups;
  85   return it->separators > 0;
  86 }
  87
  88 /* Returns the appropriate grouping item in LOC depending on CATEGORY
  89    (which must be LC_MONETARY or LC_NUMERIC).  */
  90 static const char *
  91 get_grouping (int category, locale_t loc)
  92 {
  93   return _nl_lookup (loc, category,
  94                      category == LC_MONETARY ? MON_GROUPING : GROUPING);
  95 }
  96
  97
  98 bool
  99 __grouping_iterator_init (struct grouping_iterator *it,
 100                           int category, locale_t loc, unsigned int digits)
 101 {
 102   if (digits <= 1)
 103     return __grouping_iterator_init_none (it, digits);
 104   else
 105     return grouping_iterator_setup (it, digits, get_grouping (category, loc));
 106 }
 107
 108 bool
 109 __grouping_iterator_next (struct grouping_iterator *it)
 110 {
 111   assert (it->remaining > 0);
 112   --it->remaining;
 113
 114   if (it->remaining_in_current_group > 0)
 115     {
 116       --it->remaining_in_current_group;
 117       return false;
 118     }
 119
 120   /* If we are in the non-repeating part, switch group.  */
 121   if (it->remaining < it->non_repeating_groups)
 122     --it->groupings;
 123
 124   it->remaining_in_current_group = *it->groupings - 1;
 125   return true;
 126 }