1 files changed, 29 insertions, 0 deletions
diff --git a/text-util.c b/text-util.c
index 2b48719..4d3406b 100644
--- a/text-util.c
+++ b/text-util.c
@@ -1,5 +1,7 @@
 #include "text-util.h"
 #include "util.h"
+#include <wchar.h>
+#include <errno.h>
 
 bool text_range_valid(Filerange *r) {
 	return r->start != EPOS && r->end != EPOS && r->start <= r->end;
@@ -46,3 +48,30 @@ bool text_range_overlap(Filerange *r1, Filerange *r2) {
 bool text_range_contains(Filerange *r, size_t pos) {
 	return text_range_valid(r) && r->start <= pos && pos <= r->end;
 }
+
+int text_char_count(const char *data, size_t len) {
+	int count = 0;
+	mbstate_t ps = { 0 };
+	while (len > 0) {
+		wchar_t wc;
+		size_t wclen = mbrtowc(&wc, data, len, &ps);
+		if (wclen == (size_t)-1 && errno == EILSEQ) {
+			count++;
+			while (!ISUTF8(*data))
+				data++, len--;
+		} else if (wclen == (size_t)-2) {
+			break;
+                } else if (wclen == 0) {
+			count++;
+			data++;
+			len--;
+		} else {
+			int width = wcwidth(wc);
+			if (width != 0)
+				count++;
+			data += wclen;
+			len -= wclen;
+                }
+	}
+	return count;
+}