chowdown/dist/query/paginate.js

A JavaScript library that allows for the quick transformation of DOM documents into useful formats.

"use strict";

function _typeof(obj) { if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") { _typeof = function _typeof(obj) { return typeof obj; }; } else { _typeof = function _typeof(obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; }; } return _typeof(obj); }

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

function _defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } }

function _createClass(Constructor, protoProps, staticProps) { if (protoProps) _defineProperties(Constructor.prototype, protoProps); if (staticProps) _defineProperties(Constructor, staticProps); return Constructor; }

function _possibleConstructorReturn(self, call) { if (call && (_typeof(call) === "object" || typeof call === "function")) { return call; } return _assertThisInitialized(self); }

function _assertThisInitialized(self) { if (self === void 0) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return self; }

function _get(target, property, receiver) { if (typeof Reflect !== "undefined" && Reflect.get) { _get = Reflect.get; } else { _get = function _get(target, property, receiver) { var base = _superPropBase(target, property); if (!base) return; var desc = Object.getOwnPropertyDescriptor(base, property); if (desc.get) { return desc.get.call(receiver); } return desc.value; }; } return _get(target, property, receiver || target); }

function _superPropBase(object, property) { while (!Object.prototype.hasOwnProperty.call(object, property)) { object = _getPrototypeOf(object); if (object === null) break; } return object; }

function _getPrototypeOf(o) { _getPrototypeOf = Object.setPrototypeOf ? Object.getPrototypeOf : function _getPrototypeOf(o) { return o.__proto__ || Object.getPrototypeOf(o); }; return _getPrototypeOf(o); }

function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function"); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, writable: true, configurable: true } }); if (superClass) _setPrototypeOf(subClass, superClass); }

function _setPrototypeOf(o, p) { _setPrototypeOf = Object.setPrototypeOf || function _setPrototypeOf(o, p) { o.__proto__ = p; return o; }; return _setPrototypeOf(o, p); }

var FollowQuery = require('./follow');

var _require = require('lodash'),
    flatten = _require.flatten,
    last = _require.last,
    isFunction = _require.isFunction;
/**
 * When executed, this query will return a promise resolving to
 * the result of the inner query executed on multiple pages 
 * reachable from the original document.
 *
 * @class PaginateQuery
 * @extends Query
 */


var PaginateQuery =
/*#__PURE__*/
function (_FollowQuery) {
  _inherits(PaginateQuery, _FollowQuery);

  /**
   * Constructs a PaginateQuery given an inner query to execute on each document, 
   * a URI query to find the uri of the next document and a function that
   * determines when to stop paginating.
   *
   * Also takes an additional object of configuration options.
   * 
   * @param  {Query}  inner       A query pointing to a URI for a different document.
   * @param  {Query}  uri         The query to execute on the other document.
   * @param  {object} [options] An object of additional configuration options.
   */
  function PaginateQuery(inner, uri, max) {
    var options = arguments.length > 3 && arguments[3] !== undefined ? arguments[3] : {};

    _classCallCheck(this, PaginateQuery);

    options.max = max;
    return _possibleConstructorReturn(this, _getPrototypeOf(PaginateQuery).call(this, uri, inner, options));
  }
  /**
   * Configures the PaginateQuery given an object of configuration options.
   *
   * If the inner query and URI query are not already Query objects,
   * then Query objects will be created from them.
   *
   * If the given max value is NOT a function but a number,
   * a function will be created that will return false (to stop)
   * after max pages have been perused.
   *
   * If no merge function is provided, the lodash flatten function will
   * be used to merge results.
   * 
   * @param  {object}          options         An object of configuration options.
   * @param  {Query}           options.uri     A query pointing to a URI for a different document.
   * @param  {Query}           options.inner   The query to execute on the other document.
   * @param  {function|number} [options.max]   The function used to determine when to stop.
   * @param  {function}        [options.merge] The function used to merge the results.
   */


  _createClass(PaginateQuery, [{
    key: "configure",
    value: function configure(options) {
      _get(_getPrototypeOf(PaginateQuery.prototype), "configure", this).call(this, options);

      this.options.merge = this.options.merge || flatten;
      if (!isFunction(this.options.max)) this.options.max = function (count) {
        return count < (options.max || Infinity);
      };
    }
    /**
     * Executes the inner query on a document and recursively calls itself on the next document
     * located at the uri found in the current document. 
     * 
     * @param  {Document}     document The document containing the URI linking to the other document.
     * @param  {any[]}        [pages]  The results accumulator.
     * @return {Promise<any>} A promise containing the paginated results.
     */

  }, {
    key: "find",
    value: function find(document) {
      var _this = this;

      var pages = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : [];
      return this.options.inner.on(document).then(function (result) {
        return pages.push(result);
      }).then(function (count) {
        return _this.options.uri.on(document);
      }).then(function (uri) {
        return uri && _this.options.max(pages.length, pages) ? _this.next(uri).then(function (document) {
          return _this.find(document, pages);
        }) : pages;
      });
    }
    /**
     * Merges the results using the merge function provided
     * at query creation.
     * 
     * @param  {any[]} pages An array of the page results.
     * @return {any}   The merged page results.
     */

  }, {
    key: "build",
    value: function build(pages) {
      return this.options.merge(pages);
    }
  }]);

  return PaginateQuery;
}(FollowQuery);

module.exports = PaginateQuery;