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289 lines
7.6 KiB
289 lines
7.6 KiB
'use strict'; |
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var has = Object.prototype.hasOwnProperty; |
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// |
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// We store our EE objects in a plain object whose properties are event names. |
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// If `Object.create(null)` is not supported we prefix the event names with a |
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// `~` to make sure that the built-in object properties are not overridden or |
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// used as an attack vector. |
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// We also assume that `Object.create(null)` is available when the event name |
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// is an ES6 Symbol. |
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// |
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var prefix = typeof Object.create !== 'function' ? '~' : false; |
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/** |
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* Representation of a single EventEmitter function. |
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* |
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* @param {Function} fn Event handler to be called. |
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* @param {Mixed} context Context for function execution. |
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* @param {Boolean} [once=false] Only emit once |
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* @api private |
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*/ |
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function EE(fn, context, once) { |
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this.fn = fn; |
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this.context = context; |
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this.once = once || false; |
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} |
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/** |
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* Minimal EventEmitter interface that is molded against the Node.js |
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* EventEmitter interface. |
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* |
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* @constructor |
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* @api public |
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*/ |
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function EventEmitter() { /* Nothing to set */ } |
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/** |
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* Hold the assigned EventEmitters by name. |
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* |
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* @type {Object} |
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* @private |
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*/ |
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EventEmitter.prototype._events = undefined; |
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/** |
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* Return an array listing the events for which the emitter has registered |
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* listeners. |
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* |
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* @returns {Array} |
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* @api public |
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*/ |
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EventEmitter.prototype.eventNames = function eventNames() { |
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var events = this._events |
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, names = [] |
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, name; |
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if (!events) return names; |
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for (name in events) { |
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if (has.call(events, name)) names.push(prefix ? name.slice(1) : name); |
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} |
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if (Object.getOwnPropertySymbols) { |
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return names.concat(Object.getOwnPropertySymbols(events)); |
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} |
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return names; |
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}; |
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/** |
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* Return a list of assigned event listeners. |
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* |
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* @param {String} event The events that should be listed. |
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* @param {Boolean} exists We only need to know if there are listeners. |
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* @returns {Array|Boolean} |
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* @api public |
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*/ |
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EventEmitter.prototype.listeners = function listeners(event, exists) { |
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var evt = prefix ? prefix + event : event |
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, available = this._events && this._events[evt]; |
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if (exists) return !!available; |
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if (!available) return []; |
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if (available.fn) return [available.fn]; |
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for (var i = 0, l = available.length, ee = new Array(l); i < l; i++) { |
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ee[i] = available[i].fn; |
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} |
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return ee; |
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}; |
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/** |
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* Emit an event to all registered event listeners. |
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* |
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* @param {String} event The name of the event. |
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* @returns {Boolean} Indication if we've emitted an event. |
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* @api public |
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*/ |
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EventEmitter.prototype.emit = function emit(event, a1, a2, a3, a4, a5) { |
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var evt = prefix ? prefix + event : event; |
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if (!this._events || !this._events[evt]) return false; |
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var listeners = this._events[evt] |
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, len = arguments.length |
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, args |
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, i; |
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if ('function' === typeof listeners.fn) { |
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if (listeners.once) this.removeListener(event, listeners.fn, undefined, true); |
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switch (len) { |
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case 1: return listeners.fn.call(listeners.context), true; |
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case 2: return listeners.fn.call(listeners.context, a1), true; |
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case 3: return listeners.fn.call(listeners.context, a1, a2), true; |
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case 4: return listeners.fn.call(listeners.context, a1, a2, a3), true; |
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case 5: return listeners.fn.call(listeners.context, a1, a2, a3, a4), true; |
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case 6: return listeners.fn.call(listeners.context, a1, a2, a3, a4, a5), true; |
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} |
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for (i = 1, args = new Array(len -1); i < len; i++) { |
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args[i - 1] = arguments[i]; |
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} |
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listeners.fn.apply(listeners.context, args); |
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} else { |
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var length = listeners.length |
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, j; |
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for (i = 0; i < length; i++) { |
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if (listeners[i].once) this.removeListener(event, listeners[i].fn, undefined, true); |
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switch (len) { |
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case 1: listeners[i].fn.call(listeners[i].context); break; |
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case 2: listeners[i].fn.call(listeners[i].context, a1); break; |
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case 3: listeners[i].fn.call(listeners[i].context, a1, a2); break; |
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default: |
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if (!args) for (j = 1, args = new Array(len -1); j < len; j++) { |
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args[j - 1] = arguments[j]; |
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} |
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listeners[i].fn.apply(listeners[i].context, args); |
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} |
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} |
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} |
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return true; |
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}; |
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/** |
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* Register a new EventListener for the given event. |
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* |
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* @param {String} event Name of the event. |
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* @param {Function} fn Callback function. |
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* @param {Mixed} [context=this] The context of the function. |
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* @api public |
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*/ |
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EventEmitter.prototype.on = function on(event, fn, context) { |
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var listener = new EE(fn, context || this) |
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, evt = prefix ? prefix + event : event; |
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if (!this._events) this._events = prefix ? {} : Object.create(null); |
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if (!this._events[evt]) this._events[evt] = listener; |
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else { |
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if (!this._events[evt].fn) this._events[evt].push(listener); |
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else this._events[evt] = [ |
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this._events[evt], listener |
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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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* Add an EventListener that's only called once. |
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* |
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* @param {String} event Name of the event. |
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* @param {Function} fn Callback function. |
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* @param {Mixed} [context=this] The context of the function. |
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* @api public |
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*/ |
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EventEmitter.prototype.once = function once(event, fn, context) { |
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var listener = new EE(fn, context || this, true) |
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, evt = prefix ? prefix + event : event; |
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if (!this._events) this._events = prefix ? {} : Object.create(null); |
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if (!this._events[evt]) this._events[evt] = listener; |
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else { |
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if (!this._events[evt].fn) this._events[evt].push(listener); |
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else this._events[evt] = [ |
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this._events[evt], listener |
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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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* Remove event listeners. |
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* |
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* @param {String} event The event we want to remove. |
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* @param {Function} fn The listener that we need to find. |
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* @param {Mixed} context Only remove listeners matching this context. |
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* @param {Boolean} once Only remove once listeners. |
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* @api public |
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*/ |
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EventEmitter.prototype.removeListener = function removeListener(event, fn, context, once) { |
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var evt = prefix ? prefix + event : event; |
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if (!this._events || !this._events[evt]) return this; |
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var listeners = this._events[evt] |
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, events = []; |
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if (fn) { |
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if (listeners.fn) { |
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if ( |
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listeners.fn !== fn |
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|| (once && !listeners.once) |
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|| (context && listeners.context !== context) |
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) { |
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events.push(listeners); |
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} |
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} else { |
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for (var i = 0, length = listeners.length; i < length; i++) { |
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if ( |
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listeners[i].fn !== fn |
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|| (once && !listeners[i].once) |
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|| (context && listeners[i].context !== context) |
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) { |
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events.push(listeners[i]); |
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} |
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} |
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} |
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} |
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// |
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// Reset the array, or remove it completely if we have no more listeners. |
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// |
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if (events.length) { |
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this._events[evt] = events.length === 1 ? events[0] : events; |
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} else { |
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delete this._events[evt]; |
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} |
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return this; |
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}; |
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/** |
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* Remove all listeners or only the listeners for the specified event. |
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* |
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* @param {String} event The event want to remove all listeners for. |
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* @api public |
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*/ |
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EventEmitter.prototype.removeAllListeners = function removeAllListeners(event) { |
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if (!this._events) return this; |
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if (event) delete this._events[prefix ? prefix + event : event]; |
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else this._events = prefix ? {} : Object.create(null); |
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return this; |
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}; |
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// |
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// Alias methods names because people roll like that. |
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// |
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EventEmitter.prototype.off = EventEmitter.prototype.removeListener; |
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EventEmitter.prototype.addListener = EventEmitter.prototype.on; |
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// |
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// This function doesn't apply anymore. |
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// |
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EventEmitter.prototype.setMaxListeners = function setMaxListeners() { |
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return this; |
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}; |
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// |
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// Expose the prefix. |
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// |
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EventEmitter.prefixed = prefix; |
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// |
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// Expose the module. |
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// |
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if ('undefined' !== typeof module) { |
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module.exports = EventEmitter; |
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}
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