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martinheideggermartinheidegger
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‎EventProxy.js‎

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'use strict'
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var EventEmitter = require('events').EventEmitter
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var inherits = require('inherits')
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module.exports = EventProxy
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function EventProxy (proxied) {
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this._listening = {}
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this._ownEvents = {}
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this._proxied = proxied
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}
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inherits(EventProxy, EventEmitter)
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Object.assign(EventProxy.prototype, {
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_initEventProxy: function (eventName) {
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if (this._ownEvents[eventName]) return
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// Already listening to proxied event
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if (this._listening[eventName] !== undefined) return
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var self = this
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var listener = function (payload) {
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self.emit(eventName, payload)
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}
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this._listening[eventName] = listener
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this._proxied.addListener(eventName, listener)
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},
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_exitEventProxy: function (eventName) {
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if (this._ownEvents[eventName]) return
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// Still listener for event given
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if (this.listenerCount(eventName) > 0) return
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var listener = this._listening[eventName]
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// Called without ever being added
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if (listener === undefined) return
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delete this._listening[eventName]
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this._proxied.removeListener(eventName, listener)
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},
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_exitAll: function () {
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for (var eventName of this._listening) {
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this._exitEventProxy(eventName)
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}
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},
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addListener: function (eventName, listener) {
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EventEmitter.prototype.addListener.call(this, eventName, listener)
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this._initEventProxy(eventName)
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return this
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},
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prependListener: function (eventName, listener) {
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EventEmitter.prototype.prependListener.call(this, eventName, listener)
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this._initEventProxy(eventName)
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return this
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},
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removeListener: function (eventName, listener) {
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EventEmitter.prototype.removeListener.call(this, eventName, listener)
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this._exitEventProxy(eventName)
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return this
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},
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removeAllListeners: function (eventName) {
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EventEmitter.prototype.removeAllListeners.call(this, eventName)
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if (arguments.length === 0) {
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this._exitAll()
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} else {
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this._exitEventProxy(eventName)
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}
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return this
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},
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once: function (eventName, listener) {
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var self = this
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var wrapper = function (payload) {
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listener(payload)
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self.removeListener(eventName, wrapper)
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}
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return this.addListener(eventName, wrapper)
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},
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prependOnceListener: function (eventName, listener) {
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var self = this
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var wrapper = function (payload) {
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listener(payload)
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self.removeListener(eventName, wrapper)
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}
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return this.prependListener(eventName, wrapper)
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},
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on: function (eventName, listener) {
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return this.addListener(eventName, listener)
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},
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off: function (eventName, listener) {
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return this.removeListener(eventName, listener)
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}
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})

‎EventProxy.test.js‎

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#!/usr/bin/env node
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const tape = require('tape')
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const events = require('events')
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const EventProxy = require('./EventProxy.js')
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tape('basic listening', function (t) {
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var target = new events.EventEmitter()
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var proxy = new EventProxy(target)
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t.equals(proxy.listenerCount('hello'), 0, 'By default no listener is added')
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target.addListener('hello', function () {})
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t.equals(proxy.listenerCount('hello'), 0, 'Just because a listener is added to the target doesnt mean there is a listener on the source')
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var addResult = proxy.addListener('holla', function (data) {
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t.equals(data, 'mundo', 'target event is passed to the proxy')
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t.end()
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})
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t.equals(addResult, proxy, 'Return type of ')
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t.equals(target.listenerCount('holla'), 1, 'There should be a listener on the target, after adding one to the proxy')
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target.emit('holla', 'mundo')
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})
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tape('once', function (t) {
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var target = new events.EventEmitter()
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var proxy = new EventProxy(target)
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var count = 0
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var addResult = proxy.once('hello', function (data) {
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t.equals(count, 0, 'event called once.')
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t.equals(data, 'world', 'data passed through')
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count += 1
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})
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t.equals(addResult, proxy, 'Result of once should be the proxy instance')
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t.equals(target.listenerCount('hello'), 1, 'Should have listener after once added')
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target.emit('hello', 'world')
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t.equals(target.listenerCount('hello'), 0, 'Should not have listener on target after once executed')
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t.equals(proxy.listenerCount('hello'), 0, 'Should not have listener on proxy after once executed')
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target.emit('hello', 'mundo')
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t.end()
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})
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tape('prepend once', function (t) {
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var target = new events.EventEmitter()
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var proxy = new EventProxy(target)
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var count = 0
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target.addListener('hello', function () {
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count += 1
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})
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proxy.addListener('hello', function () {
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count += 2
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})
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var addResult = proxy.prependOnceListener('hello', function (data) {
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t.equals(count, 1, 'event called once, before the listeners on proxy, after the listeners on target')
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t.equals(data, 'world', 'data passed through')
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count += 1
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})
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t.equals(addResult, proxy, 'Result of prepend once is proxy instance')
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target.emit('hello', 'world')
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target.emit('hello', 'mundo')
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t.equals(count, 7)
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t.end()
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})
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tape('remove all listeners', function (t) {
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var target = new events.EventEmitter()
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var proxy = new EventProxy(target)
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var count = 0
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target.addListener('hello', function () {
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count += 1
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})
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proxy.addListener('hello', function () {
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t.fail('Shouldnt be called because removed by removeAllListeners')
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})
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var removeResult = proxy.removeAllListeners('hello')
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t.equals(removeResult, proxy, 'Result of removeAllListeners is proxy instance')
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target.emit('hello', 'world')
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t.equals(count, 1, 'target listener is still called')
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t.end()
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})
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tape('own events', function (t) {
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var target = new events.EventEmitter()
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var proxy = new EventProxy(target)
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proxy._ownEvents['hello'] = true
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target.on('hello', function (data) {
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t.equals(data, 'world', 'target called with world')
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})
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var onResult = proxy.on('hello', function (data) {
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t.equals(data, 'mundo', 'proxy called with mundo, target not passed to proxy')
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})
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t.equals(onResult, proxy, 'result of on is proxy instance')
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target.emit('hello', 'world')
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proxy.emit('hello', 'mundo')
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t.end()
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})

‎PauseWrapper.js‎

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'use strict'
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var EventProxy = require('./EventProxy.js')
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var EventEmitter = require('events').EventEmitter
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var inherits = require('inherits')
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module.exports = PauseWrapper
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function PauseWrapper (proxied) {
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if (!(this instanceof PauseWrapper)) {
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return new PauseWrapper(proxied)
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}
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EventProxy.call(this, proxied)
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this._ownEvents['pause'] = true
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this._ownEvents['paused'] = true
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this._ownEvents['resume'] = true
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this.pauseable = true
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this._paused = false
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this._closed = false
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}
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inherits(PauseWrapper, EventProxy)
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Object.assign(PauseWrapper.prototype, {
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_onResume: function (handler) {
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if (this._closed) return
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if (this._paused || this.resuming) {
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return this._pauseStack.push(handler)
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}
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handler.call(this)
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},
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_onResumeCb: function (cb, handler) {
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var scope = this
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this._onResume(function () {
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handler.call(this, function (err, data) {
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scope._onResume(function () {
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if (!cb) return
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cb.call(scope, err, data)
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})
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})
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})
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},
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emit: function (eventName, payload) {
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if (eventName === 'close' || eventName === 'destroy') {
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this._closed = true
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return EventEmitter.prototype.emit.call(this, eventName, payload)
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}
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if (this._closed) {
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return
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}
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if (eventName === 'pause' || eventName === 'resume' || eventName === 'paused') {
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return EventEmitter.prototype.emit.call(this, eventName, payload)
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}
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var scope = this
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this._onResume(function () { EventEmitter.prototype.emit.call(scope, eventName, payload) })
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},
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setPaused: function (paused) {
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if (paused === this._paused) return false
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if (this._resuming) {
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var scope = this
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this._pauseStack.push(function () { scope.setPaused(paused) })
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return false
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}
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this._paused = paused
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if (paused) {
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this._pauseStack = []
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} else {
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while (this._pauseStack) {
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var pauseStack = this._pauseStack
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delete this._pauseStack
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while (pauseStack.length > 0) {
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var handler = pauseStack.shift()
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handler()
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}
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}
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}
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this.emit('paused', paused)
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if (paused) {
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this.emit('pause')
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} else {
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this.emit('resume')
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}
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return true
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},
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pause: function () {
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return this.setPaused(true)
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},
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resume: function () {
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return this.setPaused(false)
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}
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})
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Object.defineProperties(PauseWrapper.prototype, {
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paused: {
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get: function () {
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return this._paused
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},
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set: function (paused) {
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this.setPaused(paused)
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return this._paused
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}
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}
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})

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