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// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.
'use strict';
const {
ArrayPrototypeSlice,
Boolean,
Error,
ErrorCaptureStackTrace,
MathMin,
NumberIsNaN,
ObjectCreate,
ObjectDefineProperty,
ObjectDefineProperties,
ObjectGetPrototypeOf,
ObjectSetPrototypeOf,
Promise,
PromiseReject,
PromiseResolve,
ReflectOwnKeys,
String,
Symbol,
SymbolFor,
SymbolAsyncIterator
} = primordials;
const kRejection = SymbolFor('nodejs.rejection');
let spliceOne;
const {
hideStackFrames,
kEnhanceStackBeforeInspector,
codes
} = require('internal/errors');
const {
ERR_INVALID_ARG_TYPE,
ERR_OUT_OF_RANGE,
ERR_UNHANDLED_ERROR
} = codes;
const {
inspect
} = require('internal/util/inspect');
const {
validateAbortSignal
} = require('internal/validators');
const kCapture = Symbol('kCapture');
const kErrorMonitor = Symbol('events.errorMonitor');
const kMaxEventTargetListeners = Symbol('events.maxEventTargetListeners');
const kMaxEventTargetListenersWarned =
Symbol('events.maxEventTargetListenersWarned');
let DOMException;
const lazyDOMException = hideStackFrames((message, name) => {
if (DOMException === undefined)
DOMException = internalBinding('messaging').DOMException;
return new DOMException(message, name);
});
/**
* Creates a new `EventEmitter` instance.
* @param {{ captureRejections?: boolean; }} [opts]
* @returns {EventEmitter}
*/
function EventEmitter(opts) {
EventEmitter.init.call(this, opts);
}
module.exports = EventEmitter;
module.exports.once = once;
module.exports.on = on;
module.exports.getEventListeners = getEventListeners;
// Backwards-compat with node 0.10.x
EventEmitter.EventEmitter = EventEmitter;
EventEmitter.usingDomains = false;
EventEmitter.captureRejectionSymbol = kRejection;
ObjectDefineProperty(EventEmitter, 'captureRejections', {
get() {
return EventEmitter.prototype[kCapture];
},
set(value) {
if (typeof value !== 'boolean') {
throw new ERR_INVALID_ARG_TYPE('EventEmitter.captureRejections',
'boolean', value);
}
EventEmitter.prototype[kCapture] = value;
},
enumerable: true
});
EventEmitter.errorMonitor = kErrorMonitor;
// The default for captureRejections is false
ObjectDefineProperty(EventEmitter.prototype, kCapture, {
value: false,
writable: true,
enumerable: false
});
EventEmitter.prototype._events = undefined;
EventEmitter.prototype._eventsCount = 0;
EventEmitter.prototype._maxListeners = undefined;
// By default EventEmitters will print a warning if more than 10 listeners are
// added to it. This is a useful default which helps finding memory leaks.
let defaultMaxListeners = 10;
let isEventTarget;
function checkListener(listener) {
if (typeof listener !== 'function') {
throw new ERR_INVALID_ARG_TYPE('listener', 'Function', listener);
}
}
ObjectDefineProperty(EventEmitter, 'defaultMaxListeners', {
enumerable: true,
get: function() {
return defaultMaxListeners;
},
set: function(arg) {
if (typeof arg !== 'number' || arg < 0 || NumberIsNaN(arg)) {
throw new ERR_OUT_OF_RANGE('defaultMaxListeners',
'a non-negative number',
arg);
}
defaultMaxListeners = arg;
}
});
ObjectDefineProperties(EventEmitter, {
kMaxEventTargetListeners: {
value: kMaxEventTargetListeners,
enumerable: false,
configurable: false,
writable: false,
},
kMaxEventTargetListenersWarned: {
value: kMaxEventTargetListenersWarned,
enumerable: false,
configurable: false,
writable: false,
}
});
/**
* Sets the max listeners.
* @param {number} n
* @param {EventTarget[] | EventEmitter[]} [eventTargets]
* @returns {void}
*/
EventEmitter.setMaxListeners =
function(n = defaultMaxListeners, ...eventTargets) {
if (typeof n !== 'number' || n < 0 || NumberIsNaN(n))
throw new ERR_OUT_OF_RANGE('n', 'a non-negative number', n);
if (eventTargets.length === 0) {
defaultMaxListeners = n;
} else {
if (isEventTarget === undefined)
isEventTarget = require('internal/event_target').isEventTarget;
for (let i = 0; i < eventTargets.length; i++) {
const target = eventTargets[i];
if (isEventTarget(target)) {
target[kMaxEventTargetListeners] = n;
target[kMaxEventTargetListenersWarned] = false;
} else if (typeof target.setMaxListeners === 'function') {
target.setMaxListeners(n);
} else {
throw new ERR_INVALID_ARG_TYPE(
'eventTargets',
['EventEmitter', 'EventTarget'],
target);
}
}
}
};
EventEmitter.init = function(opts) {
if (this._events === undefined ||
this._events === ObjectGetPrototypeOf(this)._events) {
this._events = ObjectCreate(null);
this._eventsCount = 0;
}
this._maxListeners = this._maxListeners || undefined;
if (opts?.captureRejections) {
if (typeof opts.captureRejections !== 'boolean') {
throw new ERR_INVALID_ARG_TYPE('options.captureRejections',
'boolean', opts.captureRejections);
}
this[kCapture] = Boolean(opts.captureRejections);
} else {
// Assigning the kCapture property directly saves an expensive
// prototype lookup in a very sensitive hot path.
this[kCapture] = EventEmitter.prototype[kCapture];
}
};
function addCatch(that, promise, type, args) {
if (!that[kCapture]) {
return;
}
// Handle Promises/A+ spec, then could be a getter
// that throws on second use.
try {
const then = promise.then;
if (typeof then === 'function') {
then.call(promise, undefined, function(err) {
// The callback is called with nextTick to avoid a follow-up
// rejection from this promise.
process.nextTick(emitUnhandledRejectionOrErr, that, err, type, args);
});
}
} catch (err) {
that.emit('error', err);
}
}
function emitUnhandledRejectionOrErr(ee, err, type, args) {
if (typeof ee[kRejection] === 'function') {
ee[kRejection](err, type, ...args);
} else {
// We have to disable the capture rejections mechanism, otherwise
// we might end up in an infinite loop.
const prev = ee[kCapture];
// If the error handler throws, it is not catcheable and it
// will end up in 'uncaughtException'. We restore the previous
// value of kCapture in case the uncaughtException is present
// and the exception is handled.
try {
ee[kCapture] = false;
ee.emit('error', err);
} finally {
ee[kCapture] = prev;
}
}
}
/**
* Increases the max listeners of the event emitter.
* @param {number} n
* @returns {EventEmitter}
*/
EventEmitter.prototype.setMaxListeners = function setMaxListeners(n) {
if (typeof n !== 'number' || n < 0 || NumberIsNaN(n)) {
throw new ERR_OUT_OF_RANGE('n', 'a non-negative number', n);
}
this._maxListeners = n;
return this;
};
function _getMaxListeners(that) {
if (that._maxListeners === undefined)
return EventEmitter.defaultMaxListeners;
return that._maxListeners;
}
/**
* Returns the current max listener value for the event emitter.
* @returns {number}
*/
EventEmitter.prototype.getMaxListeners = function getMaxListeners() {
return _getMaxListeners(this);
};
// Returns the length and line number of the first sequence of `a` that fully
// appears in `b` with a length of at least 4.
function identicalSequenceRange(a, b) {
for (let i = 0; i < a.length - 3; i++) {
// Find the first entry of b that matches the current entry of a.
const pos = b.indexOf(a[i]);
if (pos !== -1) {
const rest = b.length - pos;
if (rest > 3) {
let len = 1;
const maxLen = MathMin(a.length - i, rest);
// Count the number of consecutive entries.
while (maxLen > len && a[i + len] === b[pos + len]) {
len++;
}
if (len > 3) {
return [len, i];
}
}
}
}
return [0, 0];
}
function enhanceStackTrace(err, own) {
let ctorInfo = '';
try {
const { name } = this.constructor;
if (name !== 'EventEmitter')
ctorInfo = ` on ${name} instance`;
} catch {}
const sep = `\nEmitted 'error' event${ctorInfo} at:\n`;
const errStack = err.stack.split('\n').slice(1);
const ownStack = own.stack.split('\n').slice(1);
const [ len, off ] = identicalSequenceRange(ownStack, errStack);
if (len > 0) {
ownStack.splice(off + 1, len - 2,
' [... lines matching original stack trace ...]');
}
return err.stack + sep + ownStack.join('\n');
}
/**
* Synchronously calls each of the listeners registered
* for the event.
* @param {string | symbol} type
* @param {...any} [args]
* @returns {boolean}
*/
EventEmitter.prototype.emit = function emit(type, ...args) {
let doError = (type === 'error');
const events = this._events;
if (events !== undefined) {
if (doError && events[kErrorMonitor] !== undefined)
this.emit(kErrorMonitor, ...args);
doError = (doError && events.error === undefined);
} else if (!doError)
return false;
// If there is no 'error' event listener then throw.
if (doError) {
let er;
if (args.length > 0)
er = args[0];
if (er instanceof Error) {
try {
const capture = {};
ErrorCaptureStackTrace(capture, EventEmitter.prototype.emit);
ObjectDefineProperty(er, kEnhanceStackBeforeInspector, {
value: enhanceStackTrace.bind(this, er, capture),
configurable: true
});
} catch {}
// Note: The comments on the `throw` lines are intentional, they show
// up in Node's output if this results in an unhandled exception.
throw er; // Unhandled 'error' event
}
let stringifiedEr;
const { inspect } = require('internal/util/inspect');
try {
stringifiedEr = inspect(er);
} catch {
stringifiedEr = er;
}
// At least give some kind of context to the user
const err = new ERR_UNHANDLED_ERROR(stringifiedEr);
err.context = er;
throw err; // Unhandled 'error' event
}
const handler = events[type];
if (handler === undefined)
return false;
if (typeof handler === 'function') {
const result = handler.apply(this, args);
// We check if result is undefined first because that
// is the most common case so we do not pay any perf
// penalty
if (result !== undefined && result !== null) {
addCatch(this, result, type, args);
}
} else {
const len = handler.length;
const listeners = arrayClone(handler);
for (let i = 0; i < len; ++i) {
const result = listeners[i].apply(this, args);
// We check if result is undefined first because that
// is the most common case so we do not pay any perf
// penalty.
// This code is duplicated because extracting it away
// would make it non-inlineable.
if (result !== undefined && result !== null) {
addCatch(this, result, type, args);
}
}
}
return true;
};
function _addListener(target, type, listener, prepend) {
let m;
let events;
let existing;
checkListener(listener);
events = target._events;
if (events === undefined) {
events = target._events = ObjectCreate(null);
target._eventsCount = 0;
} else {
// To avoid recursion in the case that type === "newListener"! Before
// adding it to the listeners, first emit "newListener".
if (events.newListener !== undefined) {
target.emit('newListener', type,
listener.listener ? listener.listener : listener);
// Re-assign `events` because a newListener handler could have caused the
// this._events to be assigned to a new object
events = target._events;
}
existing = events[type];
}
if (existing === undefined) {
// Optimize the case of one listener. Don't need the extra array object.
events[type] = listener;
++target._eventsCount;
} else {
if (typeof existing === 'function') {
// Adding the second element, need to change to array.
existing = events[type] =
prepend ? [listener, existing] : [existing, listener];
// If we've already got an array, just append.
} else if (prepend) {
existing.unshift(listener);
} else {
existing.push(listener);
}
// Check for listener leak
m = _getMaxListeners(target);
if (m > 0 && existing.length > m && !existing.warned) {
existing.warned = true;
// No error code for this since it is a Warning
// eslint-disable-next-line no-restricted-syntax
const w = new Error('Possible EventEmitter memory leak detected. ' +
`${existing.length} ${String(type)} listeners ` +
`added to ${inspect(target, { depth: -1 })}. Use ` +
'emitter.setMaxListeners() to increase limit');
w.name = 'MaxListenersExceededWarning';
w.emitter = target;
w.type = type;
w.count = existing.length;
process.emitWarning(w);
}
}
return target;
}
/**
* Adds a listener to the event emitter.
* @param {string | symbol} type
* @param {Function} listener
* @returns {EventEmitter}
*/
EventEmitter.prototype.addListener = function addListener(type, listener) {
return _addListener(this, type, listener, false);
};
EventEmitter.prototype.on = EventEmitter.prototype.addListener;
/**
* Adds the `listener` function to the beginning of
* the listeners array.
* @param {string | symbol} type
* @param {Function} listener
* @returns {EventEmitter}
*/
EventEmitter.prototype.prependListener =
function prependListener(type, listener) {
return _addListener(this, type, listener, true);
};
function onceWrapper() {
if (!this.fired) {
this.target.removeListener(this.type, this.wrapFn);
this.fired = true;
if (arguments.length === 0)
return this.listener.call(this.target);
return this.listener.apply(this.target, arguments);
}
}
function _onceWrap(target, type, listener) {
const state = { fired: false, wrapFn: undefined, target, type, listener };
const wrapped = onceWrapper.bind(state);
wrapped.listener = listener;
state.wrapFn = wrapped;
return wrapped;
}
/**
* Adds a one-time `listener` function to the event emitter.
* @param {string | symbol} type
* @param {Function} listener
* @returns {EventEmitter}
*/
EventEmitter.prototype.once = function once(type, listener) {
checkListener(listener);
this.on(type, _onceWrap(this, type, listener));
return this;
};
/**
* Adds a one-time `listener` function to the beginning of
* the listeners array.
* @param {string | symbol} type
* @param {Function} listener
* @returns {EventEmitter}
*/
EventEmitter.prototype.prependOnceListener =
function prependOnceListener(type, listener) {
checkListener(listener);
this.prependListener(type, _onceWrap(this, type, listener));
return this;
};
/**
* Removes the specified `listener` from the listeners array.
* @param {string | symbol} type
* @param {Function} listener
* @returns {EventEmitter}
*/
EventEmitter.prototype.removeListener =
function removeListener(type, listener) {
checkListener(listener);
const events = this._events;
if (events === undefined)
return this;
const list = events[type];
if (list === undefined)
return this;
if (list === listener || list.listener === listener) {
if (--this._eventsCount === 0)
this._events = ObjectCreate(null);
else {
delete events[type];
if (events.removeListener)
this.emit('removeListener', type, list.listener || listener);
}
} else if (typeof list !== 'function') {
let position = -1;
for (let i = list.length - 1; i >= 0; i--) {
if (list[i] === listener || list[i].listener === listener) {
position = i;
break;
}
}
if (position < 0)
return this;
if (position === 0)
list.shift();
else {
if (spliceOne === undefined)
spliceOne = require('internal/util').spliceOne;
spliceOne(list, position);
}
if (list.length === 1)
events[type] = list[0];
if (events.removeListener !== undefined)
this.emit('removeListener', type, listener);
}
return this;
};
EventEmitter.prototype.off = EventEmitter.prototype.removeListener;
/**
* Removes all listeners from the event emitter. (Only
* removes listeners for a specific event name if specified
* as `type`).
* @param {string | symbol} [type]
* @returns {EventEmitter}
*/
EventEmitter.prototype.removeAllListeners =
function removeAllListeners(type) {
const events = this._events;
if (events === undefined)
return this;
// Not listening for removeListener, no need to emit
if (events.removeListener === undefined) {
if (arguments.length === 0) {
this._events = ObjectCreate(null);
this._eventsCount = 0;
} else if (events[type] !== undefined) {
if (--this._eventsCount === 0)
this._events = ObjectCreate(null);
else
delete events[type];
}
return this;
}
// Emit removeListener for all listeners on all events
if (arguments.length === 0) {
for (const key of ReflectOwnKeys(events)) {
if (key === 'removeListener') continue;
this.removeAllListeners(key);
}
this.removeAllListeners('removeListener');
this._events = ObjectCreate(null);
this._eventsCount = 0;
return this;
}
const listeners = events[type];
if (typeof listeners === 'function') {
this.removeListener(type, listeners);
} else if (listeners !== undefined) {
// LIFO order
for (let i = listeners.length - 1; i >= 0; i--) {
this.removeListener(type, listeners[i]);
}
}
return this;
};
function _listeners(target, type, unwrap) {
const events = target._events;
if (events === undefined)
return [];
const evlistener = events[type];
if (evlistener === undefined)
return [];
if (typeof evlistener === 'function')
return unwrap ? [evlistener.listener || evlistener] : [evlistener];
return unwrap ?
unwrapListeners(evlistener) : arrayClone(evlistener);
}
/**
* Returns a copy of the array of listeners for the event name
* specified as `type`.
* @param {string | symbol} type
* @returns {Function[]}
*/
EventEmitter.prototype.listeners = function listeners(type) {
return _listeners(this, type, true);
};
/**
* Returns a copy of the array of listeners and wrappers for
* the event name specified as `type`.
* @param {string | symbol} type
* @returns {Function[]}
*/
EventEmitter.prototype.rawListeners = function rawListeners(type) {
return _listeners(this, type, false);
};
/**
* Returns the number of listeners listening to the event name
* specified as `type`.
* @deprecated since v3.2.0
* @param {EventEmitter} emitter
* @param {string | symbol} type
* @returns {number}
*/
EventEmitter.listenerCount = function(emitter, type) {
if (typeof emitter.listenerCount === 'function') {
return emitter.listenerCount(type);
}
return listenerCount.call(emitter, type);
};
EventEmitter.prototype.listenerCount = listenerCount;
/**
* Returns the number of listeners listening to event name
* specified as `type`.
* @param {string | symbol} type
* @returns {number}
*/
function listenerCount(type) {
const events = this._events;
if (events !== undefined) {
const evlistener = events[type];
if (typeof evlistener === 'function') {
return 1;
} else if (evlistener !== undefined) {
return evlistener.length;
}
}
return 0;
}
/**
* Returns an array listing the events for which
* the emitter has registered listeners.
* @returns {any[]}
*/
EventEmitter.prototype.eventNames = function eventNames() {
return this._eventsCount > 0 ? ReflectOwnKeys(this._events) : [];
};
function arrayClone(arr) {
// At least since V8 8.3, this implementation is faster than the previous
// which always used a simple for-loop
switch (arr.length) {
case 2: return [arr[0], arr[1]];
case 3: return [arr[0], arr[1], arr[2]];
case 4: return [arr[0], arr[1], arr[2], arr[3]];
case 5: return [arr[0], arr[1], arr[2], arr[3], arr[4]];
case 6: return [arr[0], arr[1], arr[2], arr[3], arr[4], arr[5]];
}
return ArrayPrototypeSlice(arr);
}
function unwrapListeners(arr) {
const ret = arrayClone(arr);
for (let i = 0; i < ret.length; ++i) {
const orig = ret[i].listener;
if (typeof orig === 'function')
ret[i] = orig;
}
return ret;
}
/**
* Returns a copy of the array of listeners for the event name
* specified as `type`.
* @param {EventEmitter | EventTarget} emitterOrTarget
* @param {string | symbol} type
* @returns {Function[]}
*/
function getEventListeners(emitterOrTarget, type) {
// First check if EventEmitter
if (typeof emitterOrTarget.listeners === 'function') {
return emitterOrTarget.listeners(type);
}
// Require event target lazily to avoid always loading it
const { isEventTarget, kEvents } = require('internal/event_target');
if (isEventTarget(emitterOrTarget)) {
const root = emitterOrTarget[kEvents].get(type);
const listeners = [];
let handler = root?.next;
while (handler?.listener !== undefined) {
listeners.push(handler.listener);
handler = handler.next;
}
return listeners;
}
throw new ERR_INVALID_ARG_TYPE('emitter',
['EventEmitter', 'EventTarget'],
emitterOrTarget);
}
/**
* Creates a `Promise` that is fulfilled when the emitter
* emits the given event.
* @param {EventEmitter} emitter
* @param {string} name
* @param {{ signal: AbortSignal; }} [options]
* @returns {Promise}
*/
async function once(emitter, name, options = {}) {
const signal = options?.signal;
validateAbortSignal(signal, 'options.signal');
if (signal?.aborted)
throw lazyDOMException('The operation was aborted', 'AbortError');
return new Promise((resolve, reject) => {
const errorListener = (err) => {
emitter.removeListener(name, resolver);
if (signal != null) {
eventTargetAgnosticRemoveListener(
signal,
'abort',
abortListener,
{ once: true });
}
reject(err);
};
const resolver = (...args) => {
if (typeof emitter.removeListener === 'function') {
emitter.removeListener('error', errorListener);
}
if (signal != null) {
eventTargetAgnosticRemoveListener(
signal,
'abort',
abortListener,
{ once: true });
}
resolve(args);
};
eventTargetAgnosticAddListener(emitter, name, resolver, { once: true });
if (name !== 'error') {
addErrorHandlerIfEventEmitter(emitter, errorListener, { once: true });
}
function abortListener() {
if (typeof emitter.removeListener === 'function') {
emitter.removeListener(name, resolver);
emitter.removeListener('error', errorListener);
} else {
eventTargetAgnosticRemoveListener(
emitter,
name,
resolver,
{ once: true });
eventTargetAgnosticRemoveListener(
emitter,
'error',
errorListener,
{ once: true });
}
reject(lazyDOMException('The operation was aborted', 'AbortError'));
}
if (signal != null) {
signal.addEventListener('abort', abortListener, { once: true });
}
});
}
const AsyncIteratorPrototype = ObjectGetPrototypeOf(
ObjectGetPrototypeOf(async function* () {}).prototype);
function createIterResult(value, done) {
return { value, done };
}
function addErrorHandlerIfEventEmitter(emitter, handler, flags) {
if (typeof emitter.on === 'function') {
eventTargetAgnosticAddListener(emitter, 'error', handler, flags);
}
}
function eventTargetAgnosticRemoveListener(emitter, name, listener, flags) {
if (typeof emitter.removeListener === 'function') {
emitter.removeListener(name, listener);
} else if (typeof emitter.removeEventListener === 'function') {
emitter.removeEventListener(name, listener, flags);
} else {
throw new ERR_INVALID_ARG_TYPE('emitter', 'EventEmitter', emitter);
}
}
function eventTargetAgnosticAddListener(emitter, name, listener, flags) {
if (typeof emitter.on === 'function') {
if (flags?.once) {
emitter.once(name, listener);
} else {
emitter.on(name, listener);
}
} else if (typeof emitter.addEventListener === 'function') {
// EventTarget does not have `error` event semantics like Node
// EventEmitters, we do not listen to `error` events here.
emitter.addEventListener(name, (arg) => { listener(arg); }, flags);
} else {
throw new ERR_INVALID_ARG_TYPE('emitter', 'EventEmitter', emitter);
}
}
/**
* Returns an `AsyncIterator` that iterates `event` events.
* @param {EventEmitter} emitter
* @param {string | symbol} event
* @param {{ signal: AbortSignal; }} [options]
* @returns {AsyncIterator}
*/
function on(emitter, event, options) {
const signal = options?.signal;
validateAbortSignal(signal, 'options.signal');
if (signal?.aborted) {
throw lazyDOMException('The operation was aborted', 'AbortError');
}
const unconsumedEvents = [];
const unconsumedPromises = [];
let error = null;
let finished = false;
const iterator = ObjectSetPrototypeOf({
next() {
// First, we consume all unread events
const value = unconsumedEvents.shift();
if (value) {
return PromiseResolve(createIterResult(value, false));
}
// Then we error, if an error happened
// This happens one time if at all, because after 'error'
// we stop listening
if (error) {
const p = PromiseReject(error);
// Only the first element errors
error = null;
return p;
}
// If the iterator is finished, resolve to done
if (finished) {
return PromiseResolve(createIterResult(undefined, true));
}
// Wait until an event happens
return new Promise(function(resolve, reject) {
unconsumedPromises.push({ resolve, reject });
});
},
return() {
eventTargetAgnosticRemoveListener(emitter, event, eventHandler);
eventTargetAgnosticRemoveListener(emitter, 'error', errorHandler);
if (signal) {
eventTargetAgnosticRemoveListener(
signal,
'abort',
abortListener,
{ once: true });
}
finished = true;
for (const promise of unconsumedPromises) {
promise.resolve(createIterResult(undefined, true));
}
return PromiseResolve(createIterResult(undefined, true));
},
throw(err) {
if (!err || !(err instanceof Error)) {
throw new ERR_INVALID_ARG_TYPE('EventEmitter.AsyncIterator',
'Error', err);
}
error = err;
eventTargetAgnosticRemoveListener(emitter, event, eventHandler);
eventTargetAgnosticRemoveListener(emitter, 'error', errorHandler);
},
[SymbolAsyncIterator]() {
return this;
}
}, AsyncIteratorPrototype);
eventTargetAgnosticAddListener(emitter, event, eventHandler);
if (event !== 'error') {
addErrorHandlerIfEventEmitter(emitter, errorHandler);
}
if (signal) {
eventTargetAgnosticAddListener(
signal,
'abort',
abortListener,
{ once: true });
}
return iterator;
function abortListener() {
errorHandler(lazyDOMException('The operation was aborted', 'AbortError'));
}
function eventHandler(...args) {
const promise = unconsumedPromises.shift();
if (promise) {
promise.resolve(createIterResult(args, false));
} else {
unconsumedEvents.push(args);
}
}
function errorHandler(err) {
finished = true;
const toError = unconsumedPromises.shift();
if (toError) {
toError.reject(err);
} else {
// The next time we call next()
error = err;
}
iterator.return();
}
}
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