# all files / ol/events/ eventtarget.js

87.5% Statements 49/56
58.33% Branches 14/24
71.43% Functions 5/7
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     goog.provide('ol.events.EventTarget');

    goog.require('ol');
    goog.require('ol.Disposable');
    goog.require('ol.events');
    goog.require('ol.events.Event');

    /**
     * @classdesc
     * A simplified implementation of the W3C DOM Level 2 EventTarget interface.
     * @see {@link https://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113/events.html#Events-EventTarget}
     *
     * There are two important simplifications compared to the specification:
     *
     * 1. The handling of `useCapture` in `addEventListener` and
     *    `removeEventListener`. There is no real capture model.
     * 2. The handling of `stopPropagation` and `preventDefault` on `dispatchEvent`.
     *    There is no event target hierarchy. When a listener calls
     *    `stopPropagation` or `preventDefault` on an event object, it means that no
     *    more listeners after this one will be called. Same as when the listener
     *    returns false.
     *
     * @constructor
     * @extends {ol.Disposable}
     */
    ol.events.EventTarget = function() {

      ol.Disposable.call(this);

      /**
       * @private
       * @type {!Object.<string, number>}
       */
      this.pendingRemovals_ = {};

      /**
       * @private
       * @type {!Object.<string, number>}
       */
      this.dispatching_ = {};

      /**
       * @private
       * @type {!Object.<string, Array.<ol.EventsListenerFunctionType>>}
       */
      this.listeners_ = {};

    };
    ol.inherits(ol.events.EventTarget, ol.Disposable);

    /**
     * @param {string} type Type.
     * @param {ol.EventsListenerFunctionType} listener Listener.
     */
    ol.events.EventTarget.prototype.addEventListener = function(type, listener) {
      var listeners = this.listeners_[type];
      Eif (!listeners) {
        listeners = this.listeners_[type] = [];
      }
      Eif (listeners.indexOf(listener) === -1) {
        listeners.push(listener);
      }
    };

    /**
     * @param {{type: string,
     *     target: (EventTarget|ol.events.EventTarget|undefined)}|ol.events.Event|
     *     string} event Event or event type.
     * @return {boolean|undefined} `false` if anyone called preventDefault on the
     *     event object or if any of the listeners returned false.
     */
    ol.events.EventTarget.prototype.dispatchEvent = function(event) {
      var evt = typeof event === 'string' ? new ol.events.Event(event) : event;
      var type = evt.type;
      evt.target = this;
      var listeners = this.listeners_[type];
      var propagate;
      if (listeners) {
        Eif (!(type in this.dispatching_)) {
          this.dispatching_[type] = 0;
          this.pendingRemovals_[type] = 0;
        }
        ++this.dispatching_[type];
        for (var i = 0, ii = listeners.length; i < ii; ++i) {
          Iif (listeners[i].call(this, evt) === false || evt.propagationStopped) {
            propagate = false;
            break;
          }
        }
        --this.dispatching_[type];
        Eif (this.dispatching_[type] === 0) {
          var pendingRemovals = this.pendingRemovals_[type];
          delete this.pendingRemovals_[type];
          while (pendingRemovals--) {
            this.removeEventListener(type, ol.nullFunction);
          }
          delete this.dispatching_[type];
        }
        return propagate;
      }
    };

    /**
     * @inheritDoc
     */
    ol.events.EventTarget.prototype.disposeInternal = function() {
      ol.events.unlistenAll(this);
    };

    /**
     * Get the listeners for a specified event type. Listeners are returned in the
     * order that they will be called in.
     *
     * @param {string} type Type.
     * @return {Array.<ol.EventsListenerFunctionType>} Listeners.
     */
    ol.events.EventTarget.prototype.getListeners = function(type) {
      return this.listeners_[type];
    };

    /**
     * @param {string=} opt_type Type. If not provided,
     *     `true` will be returned if this EventTarget has any listeners.
     * @return {boolean} Has listeners.
     */
    ol.events.EventTarget.prototype.hasListener = function(opt_type) {
      return opt_type ?
        opt_type in this.listeners_ :
        Object.keys(this.listeners_).length > 0;
    };

    /**
     * @param {string} type Type.
     * @param {ol.EventsListenerFunctionType} listener Listener.
     */
    ol.events.EventTarget.prototype.removeEventListener = function(type, listener) {
      var listeners = this.listeners_[type];
      Eif (listeners) {
        var index = listeners.indexOf(listener);
        Iif (type in this.pendingRemovals_) {
          // make listener a no-op, and remove later in #dispatchEvent()
          listeners[index] = ol.nullFunction;
          ++this.pendingRemovals_[type];
        } else {
          listeners.splice(index, 1);
          Eif (listeners.length === 0) {
            delete this.listeners_[type];
          }
        }
      }
    };