nstdlib-nightly/lib/events.mjs

Node.js standard library converted to runtime-agnostic ES modules.

// Source: https://github.com/nodejs/node/blob/65eff1eb/lib/events.js

import * as __hoisted_async_hooks__ from "nstdlib/lib/async_hooks";
import * as __hoisted_internal_event_target__ from "nstdlib/lib/internal/event_target";
import * as __hoisted_internal_util__ from "nstdlib/lib/internal/util";
import * as __hoisted_internal_fixed_queue__ from "nstdlib/lib/internal/fixed_queue";
import * as __hoisted_internal_events_symbols__ from "nstdlib/lib/internal/events/symbols";
import { kEmptyObject } from "nstdlib/lib/internal/util";
import {
  inspect,
  identicalSequenceRange,
} from "nstdlib/lib/internal/util/inspect";
import {
  AbortError,
  codes as __codes__,
  genericNodeError,
  kEnhanceStackBeforeInspector,
} from "nstdlib/lib/internal/errors";
import {
  validateInteger,
  validateAbortSignal,
  validateBoolean,
  validateFunction,
  validateNumber,
  validateObject,
  validateString,
} from "nstdlib/lib/internal/validators";
import { addAbortListener } from "nstdlib/lib/internal/events/abort_listener";
let _module_exports_ = {};
export { _module_exports_ as default };
// 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.

const kRejection = Symbol.for("nodejs.rejection");

let spliceOne;
let FixedQueue;
let kFirstEventParam;
let kResistStopPropagation;

const { ERR_INVALID_ARG_TYPE, ERR_INVALID_THIS, ERR_UNHANDLED_ERROR } =
  __codes__;

const kCapture = Symbol("kCapture");
const kErrorMonitor = Symbol("events.errorMonitor");
const kShapeMode = Symbol("shapeMode");
const kMaxEventTargetListeners = Symbol("events.maxEventTargetListeners");
const kMaxEventTargetListenersWarned = Symbol(
  "events.maxEventTargetListenersWarned",
);
const kWatermarkData = Symbol.for("nodejs.watermarkData");

let EventEmitterAsyncResource;
// The EventEmitterAsyncResource has to be initialized lazily because event.js
// is loaded so early in the bootstrap process, before async_hooks is available.
//
// This implementation was adapted straight from addaleax's
// eventemitter-asyncresource MIT-licensed userland module.
// https://github.com/addaleax/eventemitter-asyncresource
function lazyEventEmitterAsyncResource() {
  if (EventEmitterAsyncResource === undefined) {
    const { AsyncResource } = __hoisted_async_hooks__;

    const kEventEmitter = Symbol("kEventEmitter");
    const kAsyncResource = Symbol("kAsyncResource");
    class EventEmitterReferencingAsyncResource extends AsyncResource {
      /**
       * @param {EventEmitter} ee
       * @param {string} [type]
       * @param {{
       *   triggerAsyncId?: number,
       *   requireManualDestroy?: boolean,
       * }} [options]
       */
      constructor(ee, type, options) {
        super(type, options);
        this[kEventEmitter] = ee;
      }

      /**
       * @type {EventEmitter}
       */
      get eventEmitter() {
        if (this[kEventEmitter] === undefined)
          throw new ERR_INVALID_THIS("EventEmitterReferencingAsyncResource");
        return this[kEventEmitter];
      }
    }

    EventEmitterAsyncResource = class EventEmitterAsyncResource extends (
      EventEmitter
    ) {
      /**
       * @param {{
       *   name?: string,
       *   triggerAsyncId?: number,
       *   requireManualDestroy?: boolean,
       * }} [options]
       */
      constructor(options = undefined) {
        let name;
        if (typeof options === "string") {
          name = options;
          options = undefined;
        } else {
          if (new.target === EventEmitterAsyncResource) {
            validateString(options?.name, "options.name");
          }
          name = options?.name || new.target.name;
        }
        super(options);

        this[kAsyncResource] = new EventEmitterReferencingAsyncResource(
          this,
          name,
          options,
        );
      }

      /**
       * @param {symbol,string} event
       * @param  {...any} args
       * @returns {boolean}
       */
      emit(event, ...args) {
        if (this[kAsyncResource] === undefined)
          throw new ERR_INVALID_THIS("EventEmitterAsyncResource");
        const { asyncResource } = this;
        Array.prototype.unshift.call(args, super.emit, this, event);
        return ReflectApply(asyncResource.runInAsyncScope, asyncResource, args);
      }

      /**
       * @returns {void}
       */
      emitDestroy() {
        if (this[kAsyncResource] === undefined)
          throw new ERR_INVALID_THIS("EventEmitterAsyncResource");
        this.asyncResource.emitDestroy();
      }

      /**
       * @type {number}
       */
      get asyncId() {
        if (this[kAsyncResource] === undefined)
          throw new ERR_INVALID_THIS("EventEmitterAsyncResource");
        return this.asyncResource.asyncId();
      }

      /**
       * @type {number}
       */
      get triggerAsyncId() {
        if (this[kAsyncResource] === undefined)
          throw new ERR_INVALID_THIS("EventEmitterAsyncResource");
        return this.asyncResource.triggerAsyncId();
      }

      /**
       * @type {EventEmitterReferencingAsyncResource}
       */
      get asyncResource() {
        if (this[kAsyncResource] === undefined)
          throw new ERR_INVALID_THIS("EventEmitterAsyncResource");
        return this[kAsyncResource];
      }
    };
  }
  return EventEmitterAsyncResource;
}

/**
 * Creates a new `EventEmitter` instance.
 * @param {{ captureRejections?: boolean; }} [opts]
 * @constructs {EventEmitter}
 */
function EventEmitter(opts) {
  EventEmitter.init.call(this, opts);
}
_module_exports_ = EventEmitter;
_module_exports_.addAbortListener = addAbortListener;
_module_exports_.once = once;
_module_exports_.on = on;
_module_exports_.getEventListeners = getEventListeners;
_module_exports_.getMaxListeners = getMaxListeners;
// Backwards-compat with node 0.10.x
EventEmitter.EventEmitter = EventEmitter;

EventEmitter.usingDomains = false;

EventEmitter.captureRejectionSymbol = kRejection;
Object.defineProperty(EventEmitter, "captureRejections", {
  __proto__: null,
  get() {
    return EventEmitter.prototype[kCapture];
  },
  set(value) {
    validateBoolean(value, "EventEmitter.captureRejections");

    EventEmitter.prototype[kCapture] = value;
  },
  enumerable: true,
});

Object.defineProperty(EventEmitter, "EventEmitterAsyncResource", {
  __proto__: null,
  enumerable: true,
  get: lazyEventEmitterAsyncResource,
  set: undefined,
  configurable: true,
});

EventEmitter.errorMonitor = kErrorMonitor;

// The default for captureRejections is false
Object.defineProperty(EventEmitter.prototype, kCapture, {
  __proto__: null,
  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) {
  validateFunction(listener, "listener");
}

Object.defineProperty(EventEmitter, "defaultMaxListeners", {
  __proto__: null,
  enumerable: true,
  get: function () {
    return defaultMaxListeners;
  },
  set: function (arg) {
    validateNumber(arg, "defaultMaxListeners", 0);
    defaultMaxListeners = arg;
  },
});

Object.defineProperties(EventEmitter, {
  kMaxEventTargetListeners: {
    __proto__: null,
    value: kMaxEventTargetListeners,
    enumerable: false,
    configurable: false,
    writable: false,
  },
  kMaxEventTargetListenersWarned: {
    __proto__: null,
    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
) {
  validateNumber(n, "setMaxListeners", 0);
  if (eventTargets.length === 0) {
    defaultMaxListeners = n;
  } else {
    if (isEventTarget === undefined)
      isEventTarget = __hoisted_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,
        );
      }
    }
  }
};

// If you're updating this function definition, please also update any
// re-definitions, such as the one in the Domain module (lib/domain.js).
EventEmitter.init = function (opts) {
  if (
    this._events === undefined ||
    this._events === Object.getPrototypeOf(this)._events
  ) {
    this._events = { __proto__: null };
    this._eventsCount = 0;
    this[kShapeMode] = false;
  } else {
    this[kShapeMode] = true;
  }

  this._maxListeners = this._maxListeners || undefined;

  if (opts?.captureRejections) {
    validateBoolean(opts.captureRejections, "options.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 catchable 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) {
  validateNumber(n, "setMaxListeners", 0);
  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);
};

function enhanceStackTrace(err, own) {
  let ctorInfo = "";
  try {
    const { name } = this.constructor;
    if (name !== "EventEmitter") ctorInfo = ` on ${name} instance`;
  } catch {
    // Continue regardless of error.
  }
  const sep = `\nEmitted 'error' event${ctorInfo} at:\n`;

  const errStack = Array.prototype.slice.call(
    String.prototype.split.call(err.stack, "\n"),
    1,
  );
  const ownStack = Array.prototype.slice.call(
    String.prototype.split.call(own.stack, "\n"),
    1,
  );

  const { len, offset } = identicalSequenceRange(ownStack, errStack);
  if (len > 0) {
    Array.prototype.splice.call(
      ownStack,
      offset + 1,
      len - 2,
      "    [... lines matching original stack trace ...]",
    );
  }

  return err.stack + sep + Array.prototype.join.call(ownStack, "\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 = {};
        Error.captureStackTrace(capture, EventEmitter.prototype.emit);
        Object.defineProperty(er, kEnhanceStackBeforeInspector, {
          __proto__: null,
          value: Function.prototype.bind.call(
            enhanceStackTrace,
            this,
            er,
            capture,
          ),
          configurable: true,
        });
      } catch {
        // Continue regardless of error.
      }

      // 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;
    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 = { __proto__: 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);

      // 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
      const w = genericNodeError(
        `Possible EventEmitter memory leak detected. ${existing.length} ${String(type)} listeners ` +
          `added to ${inspect(target, { depth: -1 })}. MaxListeners is ${m}. Use emitter.setMaxListeners() to increase limit`,
        {
          name: "MaxListenersExceededWarning",
          emitter: target,
          type: type,
          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) {
    this._eventsCount -= 1;

    if (this[kShapeMode]) {
      events[type] = undefined;
    } else if (this._eventsCount === 0) {
      this._events = { __proto__: 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 = __hoisted_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 = { __proto__: null };
      this._eventsCount = 0;
    } else if (events[type] !== undefined) {
      if (--this._eventsCount === 0) this._events = { __proto__: null };
      else delete events[type];
    }
    this[kShapeMode] = false;
    return this;
  }

  // Emit removeListener for all listeners on all events
  if (arguments.length === 0) {
    for (const key of Reflect.ownKeys(events)) {
      if (key === "removeListener") continue;
      this.removeAllListeners(key);
    }
    this.removeAllListeners("removeListener");
    this._events = { __proto__: null };
    this._eventsCount = 0;
    this[kShapeMode] = false;
    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 Function.prototype.call.call(listenerCount, emitter, type);
};

EventEmitter.prototype.listenerCount = listenerCount;

/**
 * Returns the number of listeners listening to event name
 * specified as `type`.
 * @param {string | symbol} type
 * @param {Function} listener
 * @returns {number}
 */
function listenerCount(type, listener) {
  const events = this._events;

  if (events !== undefined) {
    const evlistener = events[type];

    if (typeof evlistener === "function") {
      if (listener != null) {
        return listener === evlistener || listener === evlistener.listener
          ? 1
          : 0;
      }

      return 1;
    } else if (evlistener !== undefined) {
      if (listener != null) {
        let matching = 0;

        for (let i = 0, l = evlistener.length; i < l; i++) {
          if (
            evlistener[i] === listener ||
            evlistener[i].listener === listener
          ) {
            matching++;
          }
        }

        return matching;
      }

      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 ? Reflect.ownKeys(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 Array.prototype.slice.call(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 } = __hoisted_internal_event_target__;
  if (isEventTarget(emitterOrTarget)) {
    const root = emitterOrTarget[kEvents].get(type);
    const listeners = [];
    let handler = root?.next;
    while (handler?.listener !== undefined) {
      const listener = handler.listener?.deref
        ? handler.listener.deref()
        : handler.listener;
      listeners.push(listener);
      handler = handler.next;
    }
    return listeners;
  }
  throw new ERR_INVALID_ARG_TYPE(
    "emitter",
    ["EventEmitter", "EventTarget"],
    emitterOrTarget,
  );
}

/**
 * Returns the max listeners set.
 * @param {EventEmitter | EventTarget} emitterOrTarget
 * @returns {number}
 */
function getMaxListeners(emitterOrTarget) {
  if (typeof emitterOrTarget?.getMaxListeners === "function") {
    return _getMaxListeners(emitterOrTarget);
  } else if (emitterOrTarget?.[kMaxEventTargetListeners]) {
    return emitterOrTarget[kMaxEventTargetListeners];
  }

  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 | symbol} name
 * @param {{ signal: AbortSignal; }} [options]
 * @returns {Promise}
 */
async function once(emitter, name, options = kEmptyObject) {
  validateObject(options, "options");
  const signal = options?.signal;
  validateAbortSignal(signal, "options.signal");
  if (signal?.aborted)
    throw new AbortError(undefined, { cause: signal?.reason });
  return new Promise((resolve, reject) => {
    const errorListener = (err) => {
      emitter.removeListener(name, resolver);
      if (signal != null) {
        eventTargetAgnosticRemoveListener(signal, "abort", abortListener);
      }
      reject(err);
    };
    const resolver = (...args) => {
      if (typeof emitter.removeListener === "function") {
        emitter.removeListener("error", errorListener);
      }
      if (signal != null) {
        eventTargetAgnosticRemoveListener(signal, "abort", abortListener);
      }
      resolve(args);
    };

    kResistStopPropagation ??=
      __hoisted_internal_event_target__.kResistStopPropagation;
    const opts = {
      __proto__: null,
      once: true,
      [kResistStopPropagation]: true,
    };
    eventTargetAgnosticAddListener(emitter, name, resolver, opts);
    if (name !== "error" && typeof emitter.once === "function") {
      // EventTarget does not have `error` event semantics like Node
      // EventEmitters, we listen to `error` events only on EventEmitters.
      emitter.once("error", errorListener);
    }
    function abortListener() {
      eventTargetAgnosticRemoveListener(emitter, name, resolver);
      eventTargetAgnosticRemoveListener(emitter, "error", errorListener);
      reject(new AbortError(undefined, { cause: signal?.reason }));
    }
    if (signal != null) {
      eventTargetAgnosticAddListener(signal, "abort", abortListener, {
        __proto__: null,
        once: true,
        [kResistStopPropagation]: true,
      });
    }
  });
}

const AsyncIteratorPrototype = Object.getPrototypeOf(
  Object.getPrototypeOf(async function* () {}).prototype,
);

function createIterResult(value, done) {
  return { value, done };
}

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") {
    emitter.addEventListener(name, listener, 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;
 *    close?: string[];
 *    highWaterMark?: number,
 *    lowWaterMark?: number
 *   }} [options]
 * @returns {AsyncIterator}
 */
function on(emitter, event, options = kEmptyObject) {
  // Parameters validation
  validateObject(options, "options");
  const signal = options.signal;
  validateAbortSignal(signal, "options.signal");
  if (signal?.aborted)
    throw new AbortError(undefined, { cause: signal?.reason });
  // Support both highWaterMark and highWatermark for backward compatibility
  const highWatermark =
    options.highWaterMark ?? options.highWatermark ?? Number.MAX_SAFE_INTEGER;
  validateInteger(highWatermark, "options.highWaterMark", 1);
  // Support both lowWaterMark and lowWatermark for backward compatibility
  const lowWatermark = options.lowWaterMark ?? options.lowWatermark ?? 1;
  validateInteger(lowWatermark, "options.lowWaterMark", 1);

  // Preparing controlling queues and variables
  FixedQueue ??= __hoisted_internal_fixed_queue__;
  const unconsumedEvents = new FixedQueue();
  const unconsumedPromises = new FixedQueue();
  let paused = false;
  let error = null;
  let finished = false;
  let size = 0;

  const iterator = Object.setPrototypeOf(
    {
      next() {
        // First, we consume all unread events
        if (size) {
          const value = unconsumedEvents.shift();
          size--;
          if (paused && size < lowWatermark) {
            emitter.resume();
            paused = false;
          }
          return Promise.resolve(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 = Promise.reject(error);
          // Only the first element errors
          error = null;
          return p;
        }

        // If the iterator is finished, resolve to done
        if (finished) return closeHandler();

        // Wait until an event happens
        return new Promise(function (resolve, reject) {
          unconsumedPromises.push({ resolve, reject });
        });
      },

      return() {
        return closeHandler();
      },

      throw(err) {
        if (!err || !(err instanceof Error)) {
          throw new ERR_INVALID_ARG_TYPE(
            "EventEmitter.AsyncIterator",
            "Error",
            err,
          );
        }
        errorHandler(err);
      },
      [SymbolAsyncIterator]() {
        return this;
      },
      [kWatermarkData]: {
        /**
         * The current queue size
         */
        get size() {
          return size;
        },
        /**
         * The low watermark. The emitter is resumed every time size is lower than it
         */
        get low() {
          return lowWatermark;
        },
        /**
         * The high watermark. The emitter is paused every time size is higher than it
         */
        get high() {
          return highWatermark;
        },
        /**
         * It checks whether the emitter is paused by the watermark controller or not
         */
        get isPaused() {
          return paused;
        },
      },
    },
    AsyncIteratorPrototype,
  );

  // Adding event handlers
  const { addEventListener, removeAll } = listenersController();
  kFirstEventParam ??= __hoisted_internal_events_symbols__.kFirstEventParam;
  addEventListener(
    emitter,
    event,
    options[kFirstEventParam]
      ? eventHandler
      : function (...args) {
          return eventHandler(args);
        },
  );
  if (event !== "error" && typeof emitter.on === "function") {
    addEventListener(emitter, "error", errorHandler);
  }
  const closeEvents = options?.close;
  if (closeEvents?.length) {
    for (let i = 0; i < closeEvents.length; i++) {
      addEventListener(emitter, closeEvents[i], closeHandler);
    }
  }

  const abortListenerDisposable = signal
    ? addAbortListener(signal, abortListener)
    : null;

  return iterator;

  function abortListener() {
    errorHandler(new AbortError(undefined, { cause: signal?.reason }));
  }

  function eventHandler(value) {
    if (unconsumedPromises.isEmpty()) {
      size++;
      if (!paused && size > highWatermark) {
        paused = true;
        emitter.pause();
      }
      unconsumedEvents.push(value);
    } else unconsumedPromises.shift().resolve(createIterResult(value, false));
  }

  function errorHandler(err) {
    if (unconsumedPromises.isEmpty()) error = err;
    else unconsumedPromises.shift().reject(err);

    closeHandler();
  }

  function closeHandler() {
    abortListenerDisposable?.[Symbol.for("nodejs.dispose")]();
    removeAll();
    finished = true;
    const doneResult = createIterResult(undefined, true);
    while (!unconsumedPromises.isEmpty()) {
      unconsumedPromises.shift().resolve(doneResult);
    }

    return Promise.resolve(doneResult);
  }
}

function listenersController() {
  const listeners = [];

  return {
    addEventListener(emitter, event, handler, flags) {
      eventTargetAgnosticAddListener(emitter, event, handler, flags);
      Array.prototype.push.call(listeners, [emitter, event, handler, flags]);
    },
    removeAll() {
      while (listeners.length > 0) {
        ReflectApply(
          eventTargetAgnosticRemoveListener,
          undefined,
          Array.prototype.pop.call(listeners),
        );
      }
    },
  };
}

export { EventEmitter };
export { once };
export { on };
export { getEventListeners };
export { getMaxListeners };