rangoo94/universal-lexer

const namedRegexp = require('named-js-regexp')

/**
 * As `named-js-regexp` library is changing RegExp object,
 * it's much slower than regular expressions.
 *
 * Instead of that, we use `named-js-regexp` library
 * only to find named properties,
 * and build object with standard regular expressions.
 *
 * @param {string} text
 * @param {string} [flags]
 * @returns {RegExp|NamedRegExp}
 */
function buildNamedRegularExpression (text, flags) {
  // Build named regular expression
  const enhancedRegex = namedRegexp(text, flags)

  // Find group indices
  const indices = enhancedRegex.groupsIndices

  // Build regular expression without named properties
  /** @type {RegExp|Object} */
  // eslint-disable-next-line
  const regex = eval(enhancedRegex.toString())

  // Build object which simulates regular expressions
  return {
    regex: regex,
    indices: indices
  }
}

module.exports = buildNamedRegularExpression