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/* Iterating through multibyte strings: macros for multi-byte encodings.
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Copyright (C) 2001, 2005, 2007, 2009, 2010 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* Written by Bruno Haible <bruno@clisp.org>. */
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/* The macros in this file implement forward iteration through a
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With these macros, an iteration loop that looks like
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for (iter = buf; iter < buf + buflen; iter++)
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for (mbi_init (iter, buf, buflen); mbi_avail (iter); mbi_advance (iter))
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do_something (mbi_cur_ptr (iter), mb_len (mbi_cur (iter)));
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The benefit of these macros over plain use of mbrtowc is:
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- Handling of invalid multibyte sequences is possible without
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making the code more complicated, while still preserving the
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invalid multibyte sequences.
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is a type usable for variable declarations.
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mbi_init (iter, startptr, length)
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initializes the iterator, starting at startptr and crossing length bytes.
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returns true if there are more multibyte chracters available before
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the end of string is reached. In this case, mbi_cur (iter) is
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initialized to the next multibyte chracter.
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advances the iterator by one multibyte character.
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returns the current multibyte character, of type mbchar_t. All the
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macros defined in mbchar.h can be used on it.
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return a pointer to the beginning of the current multibyte character.
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mbi_reloc (iter, ptrdiff)
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relocates iterator when the string is moved by ptrdiff bytes.
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mbi_copy (&destiter, &srciter)
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copies srciter to destiter.
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Here are the function prototypes of the macros.
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extern void mbi_init (mbi_iterator_t iter,
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const char *startptr, size_t length);
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extern bool mbi_avail (mbi_iterator_t iter);
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extern void mbi_advance (mbi_iterator_t iter);
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extern mbchar_t mbi_cur (mbi_iterator_t iter);
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extern const char * mbi_cur_ptr (mbi_iterator_t iter);
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extern void mbi_reloc (mbi_iterator_t iter, ptrdiff_t ptrdiff);
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extern void mbi_copy (mbi_iterator_t *new, const mbi_iterator_t *old);
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/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
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BSD/OS 4.1 has a bug: <stdio.h> and <time.h> must be included before
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const char *limit; /* pointer to end of string */
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bool in_shift; /* true if next byte may not be interpreted as ASCII */
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mbstate_t state; /* if in_shift: current shift state */
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bool next_done; /* true if mbi_avail has already filled the following */
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struct mbchar cur; /* the current character:
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const char *cur.ptr pointer to current character
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The following are only valid after mbi_avail.
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size_t cur.bytes number of bytes of current character
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bool cur.wc_valid true if wc is a valid wide character
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wchar_t cur.wc if wc_valid: the current character
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mbiter_multi_next (struct mbiter_multi *iter)
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/* Handle most ASCII characters quickly, without calling mbrtowc(). */
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if (is_basic (*iter->cur.ptr))
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/* These characters are part of the basic character set. ISO C 99
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guarantees that their wide character code is identical to their
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iter->cur.wc = *iter->cur.ptr;
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iter->cur.wc_valid = true;
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assert (mbsinit (&iter->state));
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iter->in_shift = true;
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iter->cur.bytes = mbrtowc (&iter->cur.wc, iter->cur.ptr,
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iter->limit - iter->cur.ptr, &iter->state);
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if (iter->cur.bytes == (size_t) -1)
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/* An invalid multibyte sequence was encountered. */
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iter->cur.wc_valid = false;
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/* Whether to set iter->in_shift = false and reset iter->state
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or not is not very important; the string is bogus anyway. */
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else if (iter->cur.bytes == (size_t) -2)
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/* An incomplete multibyte character at the end. */
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iter->cur.bytes = iter->limit - iter->cur.ptr;
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iter->cur.wc_valid = false;
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/* Whether to set iter->in_shift = false and reset iter->state
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or not is not important; the string end is reached anyway. */
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if (iter->cur.bytes == 0)
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/* A null wide character was encountered. */
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assert (*iter->cur.ptr == '\0');
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assert (iter->cur.wc == 0);
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iter->cur.wc_valid = true;
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/* When in the initial state, we can go back treating ASCII
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characters more quickly. */
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if (mbsinit (&iter->state))
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iter->in_shift = false;
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iter->next_done = true;
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mbiter_multi_reloc (struct mbiter_multi *iter, ptrdiff_t ptrdiff)
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iter->cur.ptr += ptrdiff;
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iter->limit += ptrdiff;
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mbiter_multi_copy (struct mbiter_multi *new_iter, const struct mbiter_multi *old_iter)
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new_iter->limit = old_iter->limit;
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if ((new_iter->in_shift = old_iter->in_shift))
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memcpy (&new_iter->state, &old_iter->state, sizeof (mbstate_t));
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memset (&new_iter->state, 0, sizeof (mbstate_t));
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new_iter->next_done = old_iter->next_done;
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mb_copy (&new_iter->cur, &old_iter->cur);
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/* Iteration macros. */
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typedef struct mbiter_multi mbi_iterator_t;
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#define mbi_init(iter, startptr, length) \
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((iter).cur.ptr = (startptr), (iter).limit = (iter).cur.ptr + (length), \
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(iter).in_shift = false, memset (&(iter).state, '\0', sizeof (mbstate_t)), \
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(iter).next_done = false)
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#define mbi_avail(iter) \
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((iter).cur.ptr < (iter).limit && (mbiter_multi_next (&(iter)), true))
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#define mbi_advance(iter) \
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((iter).cur.ptr += (iter).cur.bytes, (iter).next_done = false)
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/* Access to the current character. */
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#define mbi_cur(iter) (iter).cur
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#define mbi_cur_ptr(iter) (iter).cur.ptr
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#define mbi_reloc(iter, ptrdiff) mbiter_multi_reloc (&iter, ptrdiff)
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/* Copying an iterator. */
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#define mbi_copy mbiter_multi_copy
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#endif /* _MBITER_H */
added
removed
lib/mbiter.h
