maint/gnulib/lib/mbuiter.h

/* */
This source file includes following definitions.
mbuiter_multi_next
mbuiter_multi_reloc
mbuiter_multi_copy
   1 /* Iterating through multibyte strings: macros for multi-byte encodings.
   2    Copyright (C) 2001, 2005, 2007, 2009-2021 Free Software Foundation, Inc.
   3 
   4    This file is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation; either version 3 of the
   7    License, or (at your option) any later version.
   8 
   9    This file is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU Lesser General Public License for more details.
  13 
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16 
  17 /* Written by Bruno Haible <bruno@clisp.org>.  */
  18 
  19 /* The macros in this file implement forward iteration through a
  20    multi-byte string, without knowing its length a-priori.
  21 
  22    With these macros, an iteration loop that looks like
  23 
  24       char *iter;
  25       for (iter = buf; *iter != '\0'; iter++)
  26         {
  27           do_something (*iter);
  28         }
  29 
  30    becomes
  31 
  32       mbui_iterator_t iter;
  33       for (mbui_init (iter, buf); mbui_avail (iter); mbui_advance (iter))
  34         {
  35           do_something (mbui_cur_ptr (iter), mb_len (mbui_cur (iter)));
  36         }
  37 
  38    The benefit of these macros over plain use of mbrtowc is:
  39    - Handling of invalid multibyte sequences is possible without
  40      making the code more complicated, while still preserving the
  41      invalid multibyte sequences.
  42 
  43    Compared to mbiter.h, the macros here don't need to know the string's
  44    length a-priori.  The downside is that at each step, the look-ahead
  45    that guards against overrunning the terminating '\0' is more expensive.
  46    The mbui_* macros are therefore suitable when there is a high probability
  47    that only the first few multibyte characters need to be inspected.
  48    Whereas the mbi_* macros are better if usually the iteration runs
  49    through the entire string.
  50 
  51    mbui_iterator_t
  52      is a type usable for variable declarations.
  53 
  54    mbui_init (iter, startptr)
  55      initializes the iterator, starting at startptr.
  56 
  57    mbui_avail (iter)
  58      returns true if there are more multibyte characters available before
  59      the end of string is reached. In this case, mbui_cur (iter) is
  60      initialized to the next multibyte character.
  61 
  62    mbui_advance (iter)
  63      advances the iterator by one multibyte character.
  64 
  65    mbui_cur (iter)
  66      returns the current multibyte character, of type mbchar_t.  All the
  67      macros defined in mbchar.h can be used on it.
  68 
  69    mbui_cur_ptr (iter)
  70      return a pointer to the beginning of the current multibyte character.
  71 
  72    mbui_reloc (iter, ptrdiff)
  73      relocates iterator when the string is moved by ptrdiff bytes.
  74 
  75    mbui_copy (&destiter, &srciter)
  76      copies srciter to destiter.
  77 
  78    Here are the function prototypes of the macros.
  79 
  80    extern void          mbui_init (mbui_iterator_t iter, const char *startptr);
  81    extern bool          mbui_avail (mbui_iterator_t iter);
  82    extern void          mbui_advance (mbui_iterator_t iter);
  83    extern mbchar_t      mbui_cur (mbui_iterator_t iter);
  84    extern const char *  mbui_cur_ptr (mbui_iterator_t iter);
  85    extern void          mbui_reloc (mbui_iterator_t iter, ptrdiff_t ptrdiff);
  86    extern void          mbui_copy (mbui_iterator_t *new, const mbui_iterator_t *old);
  87  */
  88 
  89 #ifndef _MBUITER_H
  90 #define _MBUITER_H 1
  91 
  92 #include <assert.h>
  93 #include <stdbool.h>
  94 #include <stddef.h>
  95 #include <stdlib.h>
  96 #include <string.h>
  97 #include <wchar.h>
  98 
  99 #include "mbchar.h"
 100 #include "strnlen1.h"
 101 
 102 #ifndef _GL_INLINE_HEADER_BEGIN
 103  #error "Please include config.h first."
 104 #endif
 105 _GL_INLINE_HEADER_BEGIN
 106 #ifndef MBUITER_INLINE
 107 # define MBUITER_INLINE _GL_INLINE
 108 #endif
 109 
 110 struct mbuiter_multi
 111 {
 112   bool in_shift;        /* true if next byte may not be interpreted as ASCII */
 113   mbstate_t state;      /* if in_shift: current shift state */
 114   bool next_done;       /* true if mbui_avail has already filled the following */
 115   struct mbchar cur;    /* the current character:
 116         const char *cur.ptr             pointer to current character
 117         The following are only valid after mbui_avail.
 118         size_t cur.bytes                number of bytes of current character
 119         bool cur.wc_valid               true if wc is a valid wide character
 120         wchar_t cur.wc                  if wc_valid: the current character
 121         */
 122 };
 123 
 124 MBUITER_INLINE void
 125 mbuiter_multi_next (struct mbuiter_multi *iter)
     /*  */
 126 {
 127   if (iter->next_done)
 128     return;
 129   if (iter->in_shift)
 130     goto with_shift;
 131   /* Handle most ASCII characters quickly, without calling mbrtowc().  */
 132   if (is_basic (*iter->cur.ptr))
 133     {
 134       /* These characters are part of the basic character set.  ISO C 99
 135          guarantees that their wide character code is identical to their
 136          char code.  */
 137       iter->cur.bytes = 1;
 138       iter->cur.wc = *iter->cur.ptr;
 139       iter->cur.wc_valid = true;
 140     }
 141   else
 142     {
 143       assert (mbsinit (&iter->state));
 144       iter->in_shift = true;
 145     with_shift:
 146       iter->cur.bytes = mbrtowc (&iter->cur.wc, iter->cur.ptr,
 147                                  strnlen1 (iter->cur.ptr, MB_CUR_MAX),
 148                                  &iter->state);
 149       if (iter->cur.bytes == (size_t) -1)
 150         {
 151           /* An invalid multibyte sequence was encountered.  */
 152           iter->cur.bytes = 1;
 153           iter->cur.wc_valid = false;
 154           /* Whether to set iter->in_shift = false and reset iter->state
 155              or not is not very important; the string is bogus anyway.  */
 156         }
 157       else if (iter->cur.bytes == (size_t) -2)
 158         {
 159           /* An incomplete multibyte character at the end.  */
 160           iter->cur.bytes = strlen (iter->cur.ptr);
 161           iter->cur.wc_valid = false;
 162           /* Whether to set iter->in_shift = false and reset iter->state
 163              or not is not important; the string end is reached anyway.  */
 164         }
 165       else
 166         {
 167           if (iter->cur.bytes == 0)
 168             {
 169               /* A null wide character was encountered.  */
 170               iter->cur.bytes = 1;
 171               assert (*iter->cur.ptr == '\0');
 172               assert (iter->cur.wc == 0);
 173             }
 174           iter->cur.wc_valid = true;
 175 
 176           /* When in the initial state, we can go back treating ASCII
 177              characters more quickly.  */
 178           if (mbsinit (&iter->state))
 179             iter->in_shift = false;
 180         }
 181     }
 182   iter->next_done = true;
 183 }
 184 
 185 MBUITER_INLINE void
 186 mbuiter_multi_reloc (struct mbuiter_multi *iter, ptrdiff_t ptrdiff)
     /*  */
 187 {
 188   iter->cur.ptr += ptrdiff;
 189 }
 190 
 191 MBUITER_INLINE void
 192 mbuiter_multi_copy (struct mbuiter_multi *new_iter, const struct mbuiter_multi *old_iter)
     /*  */
 193 {
 194   if ((new_iter->in_shift = old_iter->in_shift))
 195     memcpy (&new_iter->state, &old_iter->state, sizeof (mbstate_t));
 196   else
 197     memset (&new_iter->state, 0, sizeof (mbstate_t));
 198   new_iter->next_done = old_iter->next_done;
 199   mb_copy (&new_iter->cur, &old_iter->cur);
 200 }
 201 
 202 /* Iteration macros.  */
 203 typedef struct mbuiter_multi mbui_iterator_t;
 204 #define mbui_init(iter, startptr) \
 205   ((iter).cur.ptr = (startptr), \
 206    (iter).in_shift = false, memset (&(iter).state, '\0', sizeof (mbstate_t)), \
 207    (iter).next_done = false)
 208 #define mbui_avail(iter) \
 209   (mbuiter_multi_next (&(iter)), !mb_isnul ((iter).cur))
 210 #define mbui_advance(iter) \
 211   ((iter).cur.ptr += (iter).cur.bytes, (iter).next_done = false)
 212 
 213 /* Access to the current character.  */
 214 #define mbui_cur(iter) (iter).cur
 215 #define mbui_cur_ptr(iter) (iter).cur.ptr
 216 
 217 /* Relocation.  */
 218 #define mbui_reloc(iter, ptrdiff) mbuiter_multi_reloc (&iter, ptrdiff)
 219 
 220 /* Copying an iterator.  */
 221 #define mbui_copy mbuiter_multi_copy
 222 
 223 _GL_INLINE_HEADER_END
 224 
 225 #endif /* _MBUITER_H */
/* */
root/maint/gnulib/lib/mbuiter.h

INCLUDED FROM

DEFINITIONS
