regular-expressions.js

/**
 * @fileoverview Common utils for regular expressions.
 * @author Josh Goldberg
 * @author Toru Nagashima
 */

"use strict";

const { RegExpValidator } = require("@eslint-community/regexpp");

const REGEXPP_LATEST_ECMA_VERSION = 2024;

/**
 * Checks if the given regular expression pattern would be valid with the `u` flag.
 * @param {number} ecmaVersion ECMAScript version to parse in.
 * @param {string} pattern The regular expression pattern to verify.
 * @returns {boolean} `true` if the pattern would be valid with the `u` flag.
 * `false` if the pattern would be invalid with the `u` flag or the configured
 * ecmaVersion doesn't support the `u` flag.
 */
function isValidWithUnicodeFlag(ecmaVersion, pattern) {
    if (ecmaVersion <= 5) { // ecmaVersion <= 5 doesn't support the 'u' flag
        return false;
    }

    const validator = new RegExpValidator({
        ecmaVersion: Math.min(ecmaVersion, REGEXPP_LATEST_ECMA_VERSION)
    });

    try {
        validator.validatePattern(pattern, void 0, void 0, { unicode: /* uFlag = */ true });
    } catch {
        return false;
    }

    return true;
}

module.exports = {
    isValidWithUnicodeFlag,
    REGEXPP_LATEST_ECMA_VERSION
};