text: /**
   * Copyright 2017 The AMP HTML Authors. All Rights Reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS-IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  'use strict';
  
  const {Parser} = require('htmlparser2');
  const {DomHandler, NodeWithChildren} = require('domhandler');
  const {appendAll} = require('./NodeUtils');
  const serialize = require('dom-serializer');
  
  /**
   * HTML parser and serializer. DOM nodes use htmlparser2 API with custom extensions
   * required by transformers.
   */
  class TreeParser {
    constructor(options) {
      this.options = options;
    }
  
    /**
     * Parses an HTML string.
     *
     * @param {string} html
     * @returns {Node} root node
     */
    parse(html) {
      return new Promise((resolve, reject) => {
        const handler = new DomHandler((error, dom) => {
          if (error) {
            reject(error);
          } else {
            const root = new NodeWithChildren('root', []);
            appendAll(root, dom);
            resolve(root);
          }
        }, this.options);
        const parser = new Parser(handler);
        parser.write(html);
        parser.end();
      });
    }
  
    /**
     * Serializes a tree to an HTML string.
     *
     * @param {Tree} tree
     */
    serialize(node) {
      return serialize(node, {});
    }
  }
  
  module.exports = new TreeParser({
    normalizeWhitespace: true,
  });
  