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
+}