1  'use strict';
  2  
  3  Object.defineProperty(exports, "__esModule", {
  4      value: true
  5  });
  6  
  7  var _once = require('./internal/once');
  8  
  9  var _once2 = _interopRequireDefault(_once);
 10  
 11  var _onlyOnce = require('./internal/onlyOnce');
 12  
 13  var _onlyOnce2 = _interopRequireDefault(_onlyOnce);
 14  
 15  var _wrapAsync = require('./internal/wrapAsync');
 16  
 17  var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
 18  
 19  var _awaitify = require('./internal/awaitify');
 20  
 21  var _awaitify2 = _interopRequireDefault(_awaitify);
 22  
 23  function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
 24  
 25  /**
 26   * Runs the `tasks` array of functions in series, each passing their results to
 27   * the next in the array. However, if any of the `tasks` pass an error to their
 28   * own callback, the next function is not executed, and the main `callback` is
 29   * immediately called with the error.
 30   *
 31   * @name waterfall
 32   * @static
 33   * @memberOf module:ControlFlow
 34   * @method
 35   * @category Control Flow
 36   * @param {Array} tasks - An array of [async functions]{@link AsyncFunction}
 37   * to run.
 38   * Each function should complete with any number of `result` values.
 39   * The `result` values will be passed as arguments, in order, to the next task.
 40   * @param {Function} [callback] - An optional callback to run once all the
 41   * functions have completed. This will be passed the results of the last task's
 42   * callback. Invoked with (err, [results]).
 43   * @returns undefined
 44   * @example
 45   *
 46   * async.waterfall([
 47   *     function(callback) {
 48   *         callback(null, 'one', 'two');
 49   *     },
 50   *     function(arg1, arg2, callback) {
 51   *         // arg1 now equals 'one' and arg2 now equals 'two'
 52   *         callback(null, 'three');
 53   *     },
 54   *     function(arg1, callback) {
 55   *         // arg1 now equals 'three'
 56   *         callback(null, 'done');
 57   *     }
 58   * ], function (err, result) {
 59   *     // result now equals 'done'
 60   * });
 61   *
 62   * // Or, with named functions:
 63   * async.waterfall([
 64   *     myFirstFunction,
 65   *     mySecondFunction,
 66   *     myLastFunction,
 67   * ], function (err, result) {
 68   *     // result now equals 'done'
 69   * });
 70   * function myFirstFunction(callback) {
 71   *     callback(null, 'one', 'two');
 72   * }
 73   * function mySecondFunction(arg1, arg2, callback) {
 74   *     // arg1 now equals 'one' and arg2 now equals 'two'
 75   *     callback(null, 'three');
 76   * }
 77   * function myLastFunction(arg1, callback) {
 78   *     // arg1 now equals 'three'
 79   *     callback(null, 'done');
 80   * }
 81   */
 82  function waterfall(tasks, callback) {
 83      callback = (0, _once2.default)(callback);
 84      if (!Array.isArray(tasks)) return callback(new Error('First argument to waterfall must be an array of functions'));
 85      if (!tasks.length) return callback();
 86      var taskIndex = 0;
 87  
 88      function nextTask(args) {
 89          var task = (0, _wrapAsync2.default)(tasks[taskIndex++]);
 90          task(...args, (0, _onlyOnce2.default)(next));
 91      }
 92  
 93      function next(err, ...args) {
 94          if (err === false) return;
 95          if (err || taskIndex === tasks.length) {
 96              return callback(err, ...args);
 97          }
 98          nextTask(args);
 99      }
100  
101      nextTask([]);
102  }
103  
104  exports.default = (0, _awaitify2.default)(waterfall);
105  module.exports = exports['default'];