Add initial wide-character support

Adds support for the emoticon, hiragana, katakana and CJK unicode
blocks.

1 files changed, 32 insertions, 0 deletions

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;
+};