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-rw-r--r--src/common/tuklib_mbstr_width.c64
1 files changed, 64 insertions, 0 deletions
diff --git a/src/common/tuklib_mbstr_width.c b/src/common/tuklib_mbstr_width.c
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+++ b/src/common/tuklib_mbstr_width.c
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+///////////////////////////////////////////////////////////////////////////////
+//
+/// \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
+}