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/**
* Returns an EventEmitter that proxies events from the given event emitter
* @param {any} eventEmitter
* @param {object} listeners - The listeners to proxy to
* @returns {any}
*/
module.exports = function createEventEmitterProxy (eventEmitter, listeners) {
let target = eventEmitter
const eventHandlers = listeners || {}
const proxy = /** @type {any} */ (new Proxy({}, {
get: (_, name) => {
// intercept listeners
if (name === 'on') return addListener
if (name === 'setTarget') return setTarget
if (name === 'proxyEventHandlers') return eventHandlers
return (/** @type {any} */ (target))[name]
},
set: (_, name, value) => {
target[name] = value
return true
},
}))
function setTarget (/** @type {EventEmitter} */ eventEmitter) {
target = eventEmitter
// migrate listeners
Object.keys(eventHandlers).forEach((name) => {
/** @type {Array<Function>} */ (eventHandlers[name]).forEach((handler) => target.on(name, handler))
})
}
/**
* Attaches a function to be called whenever the specified event is emitted
* @param {string} name
* @param {Function} handler
*/
function addListener (name, handler) {
if (!eventHandlers[name]) eventHandlers[name] = []
eventHandlers[name].push(handler)
target.on(name, handler)
}
if (listeners) proxy.setTarget(eventEmitter)
return proxy
}
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