/* Iterating through multibyte strings: macros for multi-byte encodings. Copyright (C) 2001, 2005, 2007, 2009-2013 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . */ /* Written by Bruno Haible . */ /* The macros in this file implement forward iteration through a multi-byte string. With these macros, an iteration loop that looks like char *iter; for (iter = buf; iter < buf + buflen; iter++) { do_something (*iter); } becomes mbi_iterator_t iter; for (mbi_init (iter, buf, buflen); mbi_avail (iter); mbi_advance (iter)) { do_something (mbi_cur_ptr (iter), mb_len (mbi_cur (iter))); } The benefit of these macros over plain use of mbrtowc is: - Handling of invalid multibyte sequences is possible without making the code more complicated, while still preserving the invalid multibyte sequences. mbi_iterator_t is a type usable for variable declarations. mbi_init (iter, startptr, length) initializes the iterator, starting at startptr and crossing length bytes. mbi_avail (iter) returns true if there are more multibyte characters available before the end of string is reached. In this case, mbi_cur (iter) is initialized to the next multibyte character. mbi_advance (iter) advances the iterator by one multibyte character. mbi_cur (iter) returns the current multibyte character, of type mbchar_t. All the macros defined in mbchar.h can be used on it. mbi_cur_ptr (iter) return a pointer to the beginning of the current multibyte character. mbi_reloc (iter, ptrdiff) relocates iterator when the string is moved by ptrdiff bytes. mbi_copy (&destiter, &srciter) copies srciter to destiter. Here are the function prototypes of the macros. extern void mbi_init (mbi_iterator_t iter, const char *startptr, size_t length); extern bool mbi_avail (mbi_iterator_t iter); extern void mbi_advance (mbi_iterator_t iter); extern mbchar_t mbi_cur (mbi_iterator_t iter); extern const char * mbi_cur_ptr (mbi_iterator_t iter); extern void mbi_reloc (mbi_iterator_t iter, ptrdiff_t ptrdiff); extern void mbi_copy (mbi_iterator_t *new, const mbi_iterator_t *old); */ #ifndef _MBITER_H #define _MBITER_H 1 #include #include #include #include /* Tru64 with Desktop Toolkit C has a bug: must be included before . BSD/OS 4.1 has a bug: and must be included before . */ #include #include #include #include "mbchar.h" _GL_INLINE_HEADER_BEGIN #ifndef MBITER_INLINE # define MBITER_INLINE _GL_INLINE #endif struct mbiter_multi { const char *limit; /* pointer to end of string */ bool in_shift; /* true if next byte may not be interpreted as ASCII */ mbstate_t state; /* if in_shift: current shift state */ bool next_done; /* true if mbi_avail has already filled the following */ struct mbchar cur; /* the current character: const char *cur.ptr pointer to current character The following are only valid after mbi_avail. size_t cur.bytes number of bytes of current character bool cur.wc_valid true if wc is a valid wide character wchar_t cur.wc if wc_valid: the current character */ }; MBITER_INLINE void mbiter_multi_next (struct mbiter_multi *iter) { if (iter->next_done) return; if (iter->in_shift) goto with_shift; /* Handle most ASCII characters quickly, without calling mbrtowc(). */ if (is_basic (*iter->cur.ptr)) { /* These characters are part of the basic character set. ISO C 99 guarantees that their wide character code is identical to their char code. */ iter->cur.bytes = 1; iter->cur.wc = *iter->cur.ptr; iter->cur.wc_valid = true; } else { assert (mbsinit (&iter->state)); iter->in_shift = true; with_shift: iter->cur.bytes = mbrtowc (&iter->cur.wc, iter->cur.ptr, iter->limit - iter->cur.ptr, &iter->state); if (iter->cur.bytes == (size_t) -1) { /* An invalid multibyte sequence was encountered. */ iter->cur.bytes = 1; iter->cur.wc_valid = false; /* Whether to set iter->in_shift = false and reset iter->state or not is not very important; the string is bogus anyway. */ } else if (iter->cur.bytes == (size_t) -2) { /* An incomplete multibyte character at the end. */ iter->cur.bytes = iter->limit - iter->cur.ptr; iter->cur.wc_valid = false; /* Whether to set iter->in_shift = false and reset iter->state or not is not important; the string end is reached anyway. */ } else { if (iter->cur.bytes == 0) { /* A null wide character was encountered. */ iter->cur.bytes = 1; assert (*iter->cur.ptr == '\0'); assert (iter->cur.wc == 0); } iter->cur.wc_valid = true; /* When in the initial state, we can go back treating ASCII characters more quickly. */ if (mbsinit (&iter->state)) iter->in_shift = false; } } iter->next_done = true; } MBITER_INLINE void mbiter_multi_reloc (struct mbiter_multi *iter, ptrdiff_t ptrdiff) { iter->cur.ptr += ptrdiff; iter->limit += ptrdiff; } MBITER_INLINE void mbiter_multi_copy (struct mbiter_multi *new_iter, const struct mbiter_multi *old_iter) { new_iter->limit = old_iter->limit; if ((new_iter->in_shift = old_iter->in_shift)) memcpy (&new_iter->state, &old_iter->state, sizeof (mbstate_t)); else memset (&new_iter->state, 0, sizeof (mbstate_t)); new_iter->next_done = old_iter->next_done; mb_copy (&new_iter->cur, &old_iter->cur); } /* Iteration macros. */ typedef struct mbiter_multi mbi_iterator_t; #define mbi_init(iter, startptr, length) \ ((iter).cur.ptr = (startptr), (iter).limit = (iter).cur.ptr + (length), \ (iter).in_shift = false, memset (&(iter).state, '\0', sizeof (mbstate_t)), \ (iter).next_done = false) #define mbi_avail(iter) \ ((iter).cur.ptr < (iter).limit && (mbiter_multi_next (&(iter)), true)) #define mbi_advance(iter) \ ((iter).cur.ptr += (iter).cur.bytes, (iter).next_done = false) /* Access to the current character. */ #define mbi_cur(iter) (iter).cur #define mbi_cur_ptr(iter) (iter).cur.ptr /* Relocation. */ #define mbi_reloc(iter, ptrdiff) mbiter_multi_reloc (&iter, ptrdiff) /* Copying an iterator. */ #define mbi_copy mbiter_multi_copy _GL_INLINE_HEADER_END #endif /* _MBITER_H */