Function parseString

lib/FileSystemInfo.js:957–1054

(str)

 * @throws {Error} on a malformed escape sequence, like the JS parser would
 */
const parseString = (str) => {
	const q = str[0];

	if (q !== '"' && q !== "'" && q !== "`") {
		return null;
	}

	const template = q === "`";
	const inner = str.slice(1, -1);
	const len = inner.length;
	let result = "";
	let i = 0;

	while (i < len) {
		const ch = inner[i];
		if (ch !== "\\") {
			// Template value normalizes raw <CR> and <CRLF> to <LF>
			if (template && ch === "\r") {
				result += "\n";
				i += inner[i + 1] === "\n" ? 2 : 1;
			} else {
				result += ch;
				i++;
			}
			continue;
		}

		i++;
		if (i >= len) throw new Error("Unterminated escape sequence");
		const esc = inner[i];

		if (esc === "x") {
			const hex = inner.slice(i + 1, i + 3);
			if (!/^[0-9a-fA-F]{2}$/.test(hex)) {
				throw new Error("Invalid hexadecimal escape sequence");
			}
			result += String.fromCharCode(Number.parseInt(hex, 16));
			i += 3;
		} else if (esc === "u") {
			if (inner[i + 1] === "{") {
				// \u{N...}
				const closeIdx = inner.indexOf("}", i + 2);
				const codeStr = closeIdx === -1 ? "" : inner.slice(i + 2, closeIdx);
				const code = Number.parseInt(codeStr, 16);
				if (!/^[0-9a-fA-F]+$/.test(codeStr) || code > 0x10ffff) {
					throw new Error("Invalid Unicode escape sequence");
				}
				result += String.fromCodePoint(code);
				i = closeIdx + 1;
			} else {
				// \uNNNN
				const hex = inner.slice(i + 1, i + 5);
				if (!/^[0-9a-fA-F]{4}$/.test(hex)) {
					throw new Error("Invalid Unicode escape sequence");
				}
				result += String.fromCharCode(Number.parseInt(hex, 16));
				i += 5;
			}