Substring widthwise instead of runewise

1 files changed, 14 insertions, 0 deletions

diff --git a/tui/width.ha b/tui/width.ha
index 6f9631c..ed498e6 100644
--- a/tui/width.ha
+++ b/tui/width.ha
@@ -30,3 +30,17 @@ export fn strwidth(s: str) uint = {
 	};
 	return sum;
 };
+
+export fn subwidth(s: str, end: (size | strings::end)) str = {
+	const runes = strings::torunes(s);
+	defer free(runes);
+	let sum = 0u;
+	for (let i = 0z; i < len(runes); i += 1) {
+		const r = runes[i];
+		sum += runewidth(r);
+		if (sum > end: uint) {
+			return strings::sub(s, 0, i - 1);
+		};
+	};
+	return s;
+};