const ATTR_REGEX = /[&"<]/g;
const CONTENT_REGEX = /[&<]/g;

/**
 * Note: this method is performance sensitive and has been optimized
 * https://github.com/sveltejs/svelte/pull/5701
 * @param {unknown} value
 * @returns {string}
 */
export function escape(value, is_attr = false) {
	const str = String(value);
	const pattern = is_attr ? ATTR_REGEX : CONTENT_REGEX;
	pattern.lastIndex = 0;
	let escaped = '';
	let last = 0;
	while (pattern.test(str)) {
		const i = pattern.lastIndex - 1;
		const ch = str[i];
		escaped += str.substring(last, i) + (ch === '&' ? '&amp;' : ch === '"' ? '&quot;' : '&lt;');
		last = i + 1;
	}
	return escaped + str.substring(last);
}