utf8: add utf8_strwidth()

I'm about to use this pattern more than once, so make it a common function.

Signed-off-by: Geoffrey Thomas <geofft@mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/utf8.c b/utf8.c
index dc3735364f..ddfdc5e2b8 100644
--- a/utf8.c
+++ b/utf8.c
@@ -246,6 +246,25 @@ int utf8_width(const char **start, size_t *remainder_p)
 	return git_wcwidth(ch);
 }
 
+/*
+ * Returns the total number of columns required by a null-terminated
+ * string, assuming that the string is utf8.  Returns strlen() instead
+ * if the string does not look like a valid utf8 string.
+ */
+int utf8_strwidth(const char *string)
+{
+	int width = 0;
+	const char *orig = string;
+
+	while (1) {
+		if (!string)
+			return strlen(orig);
+		if (!*string)
+			return width;
+		width += utf8_width(&string, NULL);
+	}
+}
+
 int is_utf8(const char *text)
 {
 	while (*text) {