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df399c5255
It's a new function split from tuklib_mbstr_width(). It's useful with partial strings that aren't terminated with \0.
87 lines
2.0 KiB
C
87 lines
2.0 KiB
C
// SPDX-License-Identifier: 0BSD
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///////////////////////////////////////////////////////////////////////////////
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//
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/// \file tuklib_mbstr_width.c
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/// \brief Calculate width of a multibyte string
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//
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// Author: Lasse Collin
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//
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///////////////////////////////////////////////////////////////////////////////
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#include "tuklib_mbstr.h"
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#include <string.h>
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#ifdef HAVE_MBRTOWC
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# include <wchar.h>
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#endif
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extern size_t
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tuklib_mbstr_width(const char *str, size_t *bytes)
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{
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const size_t len = strlen(str);
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if (bytes != NULL)
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*bytes = len;
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return tuklib_mbstr_width_mem(str, len);
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}
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extern size_t
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tuklib_mbstr_width_mem(const char *str, size_t len)
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{
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#ifndef HAVE_MBRTOWC
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// In single-byte mode, the width of the string is the same
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// as its length.
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(void)str;
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return len;
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#else
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mbstate_t state;
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memset(&state, 0, sizeof(state));
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size_t width = 0;
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size_t i = 0;
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// Convert one multibyte character at a time to wchar_t
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// and get its width using wcwidth().
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while (i < len) {
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wchar_t wc;
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const size_t ret = mbrtowc(&wc, str + i, len - i, &state);
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if (ret < 1 || ret > len - i)
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return (size_t)-1;
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i += ret;
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#ifdef HAVE_WCWIDTH
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const int wc_width = wcwidth(wc);
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if (wc_width < 0)
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return (size_t)-1;
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width += (size_t)wc_width;
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#else
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// Without wcwidth() (like in a native Windows build),
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// assume that one multibyte char == one column. With
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// UTF-8, this is less bad than one byte == one column.
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// This way quite a few languages will be handled correctly
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// in practice; CJK chars will be very wrong though.
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++width;
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#endif
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}
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// It's good to check that the string ended in the initial state.
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// However, in practice this is redundant:
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//
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// - No one will use this code with character sets that have
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// locking shift states.
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//
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// - We already checked that mbrtowc() didn't return (size_t)-2
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// which would indicate a partial multibyte character.
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if (!mbsinit(&state))
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return (size_t)-1;
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return width;
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#endif
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}
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