Function qFactory

test/angular/1.4/angular.js:15044–15396

* Constructs a promise manager. * * @param {function(function)} nextTick Function for executing functions in the next turn. * @param {function(...*)} exceptionHandler Function into which unexpected exceptions are passed for * debugging purposes. * @returns {object} Promise manager.

(nextTick, exceptionHandler)

 * @returns {object} Promise manager.
 */
function qFactory(nextTick, exceptionHandler) {
  var $qMinErr = minErr('$q', TypeError);
  function callOnce(self, resolveFn, rejectFn) {
    var called = false;
    function wrap(fn) {
      return function(value) {
        if (called) return;
        called = true;
        fn.call(self, value);
      };
    }

    return [wrap(resolveFn), wrap(rejectFn)];
  }

  /**
   * @ngdoc method
   * @name ng.$q#defer
   * @kind function
   *
   * @description
   * Creates a `Deferred` object which represents a task which will finish in the future.
   *
   * @returns {Deferred} Returns a new instance of deferred.
   */
  var defer = function() {
    return new Deferred();
  };

  function Promise() {
    this.$$state = { status: 0 };
  }

  extend(Promise.prototype, {
    then: function(onFulfilled, onRejected, progressBack) {
      if (isUndefined(onFulfilled) && isUndefined(onRejected) && isUndefined(progressBack)) {
        return this;
      }
      var result = new Deferred();

      this.$$state.pending = this.$$state.pending || [];
      this.$$state.pending.push([result, onFulfilled, onRejected, progressBack]);
      if (this.$$state.status > 0) scheduleProcessQueue(this.$$state);

      return result.promise;
    },

    "catch": function(callback) {
      return this.then(null, callback);
    },

    "finally": function(callback, progressBack) {
      return this.then(function(value) {
        return handleCallback(value, true, callback);
      }, function(error) {
        return handleCallback(error, false, callback);
      }, progressBack);
    }