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/**
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* Expose `Emitter`.
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*/
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if (typeof module !== 'undefined') {
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module.exports = Emitter;
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}
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/**
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* Initialize a new `Emitter`.
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*
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* @api public
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*/
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function Emitter(obj) {
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if (obj) return mixin(obj);
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};
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/**
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* Mixin the emitter properties.
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*
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* @param {Object} obj
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* @return {Object}
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* @api private
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*/
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function mixin(obj) {
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for (var key in Emitter.prototype) {
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obj[key] = Emitter.prototype[key];
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}
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return obj;
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}
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/**
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* Listen on the given `event` with `fn`.
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*
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* @param {String} event
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* @param {Function} fn
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* @return {Emitter}
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* @api public
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*/
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Emitter.prototype.on =
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Emitter.prototype.addEventListener = function(event, fn){
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this._callbacks = this._callbacks || {};
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(this._callbacks['$' + event] = this._callbacks['$' + event] || [])
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.push(fn);
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return this;
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};
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/**
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* Adds an `event` listener that will be invoked a single
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* time then automatically removed.
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*
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* @param {String} event
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* @param {Function} fn
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* @return {Emitter}
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* @api public
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*/
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Emitter.prototype.once = function(event, fn){
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function on() {
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this.off(event, on);
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fn.apply(this, arguments);
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}
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on.fn = fn;
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this.on(event, on);
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return this;
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};
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/**
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* Remove the given callback for `event` or all
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* registered callbacks.
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*
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* @param {String} event
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* @param {Function} fn
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* @return {Emitter}
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* @api public
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*/
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Emitter.prototype.off =
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Emitter.prototype.removeListener =
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Emitter.prototype.removeAllListeners =
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Emitter.prototype.removeEventListener = function(event, fn){
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this._callbacks = this._callbacks || {};
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// all
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if (0 == arguments.length) {
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this._callbacks = {};
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return this;
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}
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// specific event
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var callbacks = this._callbacks['$' + event];
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if (!callbacks) return this;
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// remove all handlers
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if (1 == arguments.length) {
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delete this._callbacks['$' + event];
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return this;
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}
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// remove specific handler
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var cb;
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for (var i = 0; i < callbacks.length; i++) {
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cb = callbacks[i];
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if (cb === fn || cb.fn === fn) {
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callbacks.splice(i, 1);
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break;
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}
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}
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// Remove event specific arrays for event types that no
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// one is subscribed for to avoid memory leak.
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if (callbacks.length === 0) {
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delete this._callbacks['$' + event];
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}
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return this;
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};
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/**
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* Emit `event` with the given args.
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*
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* @param {String} event
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* @param {Mixed} ...
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* @return {Emitter}
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*/
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Emitter.prototype.emit = function(event){
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this._callbacks = this._callbacks || {};
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var args = new Array(arguments.length - 1)
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, callbacks = this._callbacks['$' + event];
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for (var i = 1; i < arguments.length; i++) {
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args[i - 1] = arguments[i];
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}
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if (callbacks) {
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callbacks = callbacks.slice(0);
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for (var i = 0, len = callbacks.length; i < len; ++i) {
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callbacks[i].apply(this, args);
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}
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}
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return this;
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};
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/**
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* Return array of callbacks for `event`.
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*
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* @param {String} event
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* @return {Array}
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* @api public
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*/
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Emitter.prototype.listeners = function(event){
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this._callbacks = this._callbacks || {};
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return this._callbacks['$' + event] || [];
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};
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/**
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* Check if this emitter has `event` handlers.
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*
|
* @param {String} event
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* @return {Boolean}
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* @api public
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*/
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Emitter.prototype.hasListeners = function(event){
|
return !! this.listeners(event).length;
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};
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