1///////////////////////////////////////////////////////////////////////////////
2//
3/// \file       tuklib_mstr_width.c
4/// \brief      Calculate width of a multibyte string
5//
6//  Author:     Lasse Collin
7//
8//  This file has been put into the public domain.
9//  You can do whatever you want with this file.
10//
11///////////////////////////////////////////////////////////////////////////////
12
13#include "tuklib_mbstr.h"
14
15#if defined(HAVE_MBRTOWC) && defined(HAVE_WCWIDTH)
16#	include <wchar.h>
17#endif
18
19
20extern size_t
21tuklib_mbstr_width(const char *str, size_t *bytes)
22{
23	const size_t len = strlen(str);
24	if (bytes != NULL)
25		*bytes = len;
26
27#if !(defined(HAVE_MBRTOWC) && defined(HAVE_WCWIDTH))
28	// In single-byte mode, the width of the string is the same
29	// as its length.
30	return len;
31
32#else
33	mbstate_t state;
34	memset(&state, 0, sizeof(state));
35
36	size_t width = 0;
37	size_t i = 0;
38
39	// Convert one multibyte character at a time to wchar_t
40	// and get its width using wcwidth().
41	while (i < len) {
42		wchar_t wc;
43		const size_t ret = mbrtowc(&wc, str + i, len - i, &state);
44		if (ret < 1 || ret > len)
45			return (size_t)-1;
46
47		i += ret;
48
49		const int wc_width = wcwidth(wc);
50		if (wc_width < 0)
51			return (size_t)-1;
52
53		width += wc_width;
54	}
55
56	// Require that the string ends in the initial shift state.
57	// This way the caller can be combine the string with other
58	// strings without needing to worry about the shift states.
59	if (!mbsinit(&state))
60		return (size_t)-1;
61
62	return width;
63#endif
64}
65