Function visibleWidth

packages/pi-tui/src/utils.ts:216–271

(str: string)

 * Calculate the visible width of a string in terminal columns.
 */
export function visibleWidth(str: string): number {
	if (str.length === 0) {
		return 0;
	}

	// Fast path: pure ASCII printable
	if (isPrintableAscii(str)) {
		return str.length;
	}

	// Check cache
	const cached = widthCache.get(str);
	if (cached !== undefined) {
		return cached;
	}

	// Normalize: tabs to 3 spaces, strip ANSI escape codes
	let clean = str;
	if (str.includes("\t")) {
		clean = clean.replace(/\t/g, "   ");
	}
	if (clean.includes("\x1b")) {
		// Strip supported ANSI/OSC/APC escape sequences in one pass.
		// This covers CSI styling/cursor codes, OSC hyperlinks and prompt markers,
		// and APC sequences like CURSOR_MARKER.
		let stripped = "";
		let i = 0;
		while (i < clean.length) {
			const ansi = extractAnsiCode(clean, i);
			if (ansi) {
				i += ansi.length;
				continue;
			}
			stripped += clean[i];
			i++;
		}
		clean = stripped;
	}

	// Calculate width
	let width = 0;
	for (const { segment } of graphemeSegmenter.segment(clean)) {
		width += graphemeWidth(segment);
	}

	// Cache result
	if (widthCache.size >= WIDTH_CACHE_SIZE) {
		const firstKey = widthCache.keys().next().value;
		if (firstKey !== undefined) {
			widthCache.delete(firstKey);
		}
	}
	widthCache.set(str, width);

	return width;
}

/**