From 5d8a0a6ce5dbb12963323f97220767fcf7c08b5c Mon Sep 17 00:00:00 2001
From: Julian Hurst <julian.hurst@digdash.com>
Date: Thu, 20 Mar 2025 11:24:13 +0100
Subject: Add initial wide-character support

Adds support for the emoticon, hiragana, katakana and CJK unicode
blocks.
---
 .gitignore           |  1 +
 cmd/runewidth.ha     | 10 ++++++++++
 tests/runewidth.ha   |  9 +++++++++
 tui/widget/widget.ha |  4 ++--
 tui/width.ha         | 32 ++++++++++++++++++++++++++++++++
 5 files changed, 54 insertions(+), 2 deletions(-)
 create mode 100644 cmd/runewidth.ha
 create mode 100644 tests/runewidth.ha
 create mode 100644 tui/width.ha

diff --git a/.gitignore b/.gitignore
index 5f9fd69..2b08464 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,4 @@
 /list_nostyle
 /scrolllist
 /il
+/runewidth
diff --git a/cmd/runewidth.ha b/cmd/runewidth.ha
new file mode 100644
index 0000000..2e288e9
--- /dev/null
+++ b/cmd/runewidth.ha
@@ -0,0 +1,10 @@
+use fmt;
+use tui;
+
+export fn main() void = {
+	fmt::println(tui::runewidth('f'))!;
+	fmt::println(tui::runewidth('大'))!;
+	fmt::println(tui::runewidth('ぁ'))!;
+	fmt::println(tui::runewidth('😀'))!;
+	fmt::println(tui::strwidth("😀ぁ大f"))!;
+};
diff --git a/tests/runewidth.ha b/tests/runewidth.ha
new file mode 100644
index 0000000..5e570a5
--- /dev/null
+++ b/tests/runewidth.ha
@@ -0,0 +1,9 @@
+use tui;
+
+@test
+fn runewidth() void = {
+	assert(tui::runewidth('f') == 1);
+	assert(tui::runewidth('大') == 2);
+	assert(tui::runewidth('ぁ') == 2);
+	assert(tui::runewidth('😀') == 2);
+};
diff --git a/tui/widget/widget.ha b/tui/widget/widget.ha
index 05ade80..7c82dfa 100644
--- a/tui/widget/widget.ha
+++ b/tui/widget/widget.ha
@@ -234,11 +234,11 @@ fn truncate_to_size(w: *widget) []str = {
 		const line = w.buf.lines[i];
 		let item = match (w.sz) {
 		case let sz: tty::ttysize =>
-			const s = if (len(line) > sz.columns) strings::sub(line, 0z, sz.columns) else line;
+			const s = if (tui::strwidth(line) > sz.columns) strings::sub(line, 0z, sz.columns) else line;
 			yield strings::rpad(s, ' ', sz.columns);
 		case void =>
 			const wsz = tty::winsize(w.state.out)!;
-			const s = if (len(line) > wsz.columns) strings::sub(line, 0z, wsz.columns) else line;
+			const s = if (tui::strwidth(line) > wsz.columns) strings::sub(line, 0z, wsz.columns) else line;
 			yield strings::dup(s);
 		};
 		append(lines, item);
diff --git a/tui/width.ha b/tui/width.ha
new file mode 100644
index 0000000..6f9631c
--- /dev/null
+++ b/tui/width.ha
@@ -0,0 +1,32 @@
+use strings;
+
+export fn runewidth(r: rune) uint = {
+	let ru = r: u32;
+	// emoticons: https://en.wikipedia.org/wiki/Emoticons_(Unicode_block)
+	if (ru >= '\U0001F600' && ru <= '\U0001F64F') {
+		return 2;
+	};
+	// hiragana: https://en.wikipedia.org/wiki/Hiragana_%28Unicode_block%29
+	if (ru >= '\U00003040' && ru <= '\U0000309F') {
+		return 2;
+	};
+	// katakana: https://en.wikipedia.org/wiki/Katakana_(Unicode_block)
+	if (ru >= '\U000030A0' && ru <= '\U000030FF') {
+		return 2;
+	};
+	// CJK: https://en.wikipedia.org/wiki/CJK_Unified_Ideographs_(Unicode_block)
+	if (ru >= '\U00004E00' && ru <= '\U00009FFF') {
+		return 2;
+	};
+	return 1;
+};
+
+export fn strwidth(s: str) uint = {
+	const runes = strings::torunes(s);
+	defer free(runes);
+	let sum = 0u;
+	for (let r .. runes) {
+		sum += runewidth(r);
+	};
+	return sum;
+};
-- 
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