'use strict';
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var d = require('d')
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, callable = require('es5-ext/object/valid-callable')
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, apply = Function.prototype.apply, call = Function.prototype.call
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, create = Object.create, defineProperty = Object.defineProperty
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, defineProperties = Object.defineProperties
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, hasOwnProperty = Object.prototype.hasOwnProperty
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, descriptor = { configurable: true, enumerable: false, writable: true }
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, on, once, off, emit, methods, descriptors, base;
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on = function (type, listener) {
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var data;
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callable(listener);
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if (!hasOwnProperty.call(this, '__ee__')) {
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data = descriptor.value = create(null);
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defineProperty(this, '__ee__', descriptor);
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descriptor.value = null;
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} else {
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data = this.__ee__;
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}
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if (!data[type]) data[type] = listener;
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else if (typeof data[type] === 'object') data[type].push(listener);
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else data[type] = [data[type], listener];
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return this;
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};
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once = function (type, listener) {
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var once, self;
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callable(listener);
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self = this;
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on.call(this, type, once = function () {
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off.call(self, type, once);
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apply.call(listener, this, arguments);
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});
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once.__eeOnceListener__ = listener;
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return this;
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};
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off = function (type, listener) {
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var data, listeners, candidate, i;
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callable(listener);
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if (!hasOwnProperty.call(this, '__ee__')) return this;
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data = this.__ee__;
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if (!data[type]) return this;
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listeners = data[type];
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if (typeof listeners === 'object') {
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for (i = 0; (candidate = listeners[i]); ++i) {
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if ((candidate === listener) ||
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(candidate.__eeOnceListener__ === listener)) {
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if (listeners.length === 2) data[type] = listeners[i ? 0 : 1];
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else listeners.splice(i, 1);
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}
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}
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} else {
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if ((listeners === listener) ||
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(listeners.__eeOnceListener__ === listener)) {
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delete data[type];
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}
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}
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return this;
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};
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emit = function (type) {
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var i, l, listener, listeners, args;
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if (!hasOwnProperty.call(this, '__ee__')) return;
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listeners = this.__ee__[type];
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if (!listeners) return;
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if (typeof listeners === 'object') {
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l = arguments.length;
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args = new Array(l - 1);
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for (i = 1; i < l; ++i) args[i - 1] = arguments[i];
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listeners = listeners.slice();
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for (i = 0; (listener = listeners[i]); ++i) {
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apply.call(listener, this, args);
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}
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} else {
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switch (arguments.length) {
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case 1:
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call.call(listeners, this);
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break;
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case 2:
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call.call(listeners, this, arguments[1]);
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break;
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case 3:
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call.call(listeners, this, arguments[1], arguments[2]);
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break;
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default:
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l = arguments.length;
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args = new Array(l - 1);
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for (i = 1; i < l; ++i) {
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args[i - 1] = arguments[i];
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}
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apply.call(listeners, this, args);
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}
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}
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};
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methods = {
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on: on,
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once: once,
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off: off,
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emit: emit
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};
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descriptors = {
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on: d(on),
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once: d(once),
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off: d(off),
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emit: d(emit)
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};
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base = defineProperties({}, descriptors);
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module.exports = exports = function (o) {
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return (o == null) ? create(base) : defineProperties(Object(o), descriptors);
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};
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exports.methods = methods;
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