Function charsToCharClassContent

lib/util/compileBooleanMatcher.js:34–65

(chars)

 * @returns {string} optimized character class content (without the brackets)
 */
const charsToCharClassContent = (chars) => {
	if (chars.length === 0) return "";
	if (chars.length === 1) return quoteMetaInCharClass(chars[0]);

	// Sort by char code
	const sorted = [...chars].sort((a, b) => a.charCodeAt(0) - b.charCodeAt(0));

	/** @type {string[]} */
	const parts = [];
	let rangeStart = sorted[0];
	let rangeEnd = sorted[0];

	for (let i = 1; i < sorted.length; i++) {
		const char = sorted[i];
		const prevCode = rangeEnd.charCodeAt(0);
		const currCode = char.charCodeAt(0);

		if (currCode === prevCode + 1) {
			// Extend the range
			rangeEnd = char;
		} else {
			// Flush the current range
			parts.push(formatRange(rangeStart, rangeEnd));
			rangeStart = char;
			rangeEnd = char;
		}
	}
	// Flush the last range
	parts.push(formatRange(rangeStart, rangeEnd));

	return parts.join("");
};

/**
 * Formats a range of characters for use in a character class