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Diffstat (limited to 'src/common/tuklib_mbstr_width.c')
-rw-r--r-- | src/common/tuklib_mbstr_width.c | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/src/common/tuklib_mbstr_width.c b/src/common/tuklib_mbstr_width.c new file mode 100644 index 00000000..3c38990f --- /dev/null +++ b/src/common/tuklib_mbstr_width.c @@ -0,0 +1,64 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file tuklib_mstr_width.c +/// \brief Calculate width of a multibyte string +// +// Author: Lasse Collin +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "tuklib_mbstr.h" + +#if defined(HAVE_MBRTOWC) && defined(HAVE_WCWIDTH) +# include <wchar.h> +#endif + + +extern size_t +tuklib_mbstr_width(const char *str, size_t *bytes) +{ + const size_t len = strlen(str); + if (bytes != NULL) + *bytes = len; + +#if !(defined(HAVE_MBRTOWC) && defined(HAVE_WCWIDTH)) + // In single-byte mode, the width of the string is the same + // as its length. + return len; + +#else + mbstate_t state; + memset(&state, 0, sizeof(state)); + + size_t width = 0; + size_t i = 0; + + // Convert one multibyte character at a time to wchar_t + // and get its width using wcwidth(). + while (i < len) { + wchar_t wc; + const size_t ret = mbrtowc(&wc, str + i, len - i, &state); + if (ret < 1 || ret > len) + return (size_t)-1; + + i += ret; + + const int wc_width = wcwidth(wc); + if (wc_width < 0) + return (size_t)-1; + + width += wc_width; + } + + // Require that the string ends in the initial shift state. + // This way the caller can be combine the string with other + // strings without needing to worry about the shift states. + if (!mbsinit(&state)) + return (size_t)-1; + + return width; +#endif +} |