LearningSalesForceCommerceCloud/storefront-reference-architecture/cartridges/modules/server/EventEmitter.js

/* eslint-disable */

/*

The MIT License (MIT)

Copyright (c) 2014 Arnout Kazemier

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';

//
// We store our EE objects in a plain object whose properties are event names.
// If `Object.create(null)` is not supported we prefix the event names with a
// `~` to make sure that the built-in object properties are not overridden or
// used as an attack vector.
// We also assume that `Object.create(null)` is available when the event name
// is an ES6 Symbol.
//
var prefix = typeof Object.create !== 'function' ? '~' : false;

/**
 * Representation of a single EventEmitter function.
 *
 * @param {Function} fn Event handler to be called.
 * @param {Mixed} context Context for function execution.
 * @param {Boolean} [once=false] Only emit once
 * @api private
 */
function EE(fn, context, once) {
  this.fn = fn;
  this.context = context;
  this.once = once || false;
}

/**
 * Minimal EventEmitter interface that is molded against the Node.js
 * EventEmitter interface.
 *
 * @constructor
 * @api public
 */
function EventEmitter() { /* Nothing to set */ }

/**
 * Holds the assigned EventEmitters by name.
 *
 * @type {Object}
 * @private
 */
EventEmitter.prototype._events = undefined;

/**
 * Return a list of assigned event listeners.
 *
 * @param {String} event The events that should be listed.
 * @param {Boolean} exists We only need to know if there are listeners.
 * @returns {Array|Boolean}
 * @api public
 */
EventEmitter.prototype.listeners = function listeners(event, exists) {
  var evt = prefix ? prefix + event : event
    , available = this._events && this._events[evt];

  if (exists) {
        return !!available;
  }
  if (!available) {
      return [];
  }
  if (available.fn) {
      return [available.fn];
  }

  for (var i = 0, l = available.length, ee = new Array(l); i < l; i++) {
    ee[i] = available[i].fn;
  }

  return ee;
};

/**
 * Emit an event to all registered event listeners.
 *
 * @param {String} event The name of the event.
 * @returns {Boolean} Indication if we've emitted an event.
 * @api public
 */
EventEmitter.prototype.emit = function emit(event, a1, a2, a3, a4, a5) {
  var evt = prefix ? prefix + event : event;

  if (!this._events || !this._events[evt]) {
      return false;
  }

  var listeners = this._events[evt]
    , len = arguments.length
    , args
    , i;

  if ('function' === typeof listeners.fn) {
    if (listeners.once) {
        this.removeListener(event, listeners.fn, undefined, true);
    }

    switch (len) {
      case 1: return listeners.fn.call(listeners.context), true;
      case 2: return listeners.fn.call(listeners.context, a1), true;
      case 3: return listeners.fn.call(listeners.context, a1, a2), true;
      case 4: return listeners.fn.call(listeners.context, a1, a2, a3), true;
      case 5: return listeners.fn.call(listeners.context, a1, a2, a3, a4), true;
      case 6: return listeners.fn.call(listeners.context, a1, a2, a3, a4, a5), true;
    }

    for (i = 1, args = new Array(len - 1); i < len; i++) {
      args[i - 1] = arguments[i];
    }

    listeners.fn.apply(listeners.context, args);
  } else {
    var length = listeners.length
      , j;

    for (i = 0; i < length; i++) {
      if (listeners[i].once) {
          this.removeListener(event, listeners[i].fn, undefined, true);
      }

      switch (len) {
        case 1: listeners[i].fn.call(listeners[i].context); break;
        case 2: listeners[i].fn.call(listeners[i].context, a1); break;
        case 3: listeners[i].fn.call(listeners[i].context, a1, a2); break;
        default:
          if (!args) {
              for (j = 1, args = new Array(len - 1); j < len; j++) {
                args[j - 1] = arguments[j];
              }
          }

          listeners[i].fn.apply(listeners[i].context, args);
      }
    }
  }

  return true;
};

/**
 * Register a new EventListener for the given event.
 *
 * @param {String} event Name of the event.
 * @param {Function} fn Callback function.
 * @param {Mixed} [context=this] The context of the function.
 * @api public
 */
EventEmitter.prototype.on = function on(event, fn, context) {
  var listener = new EE(fn, context || this)
    , evt = prefix ? prefix + event : event;

  if (!this._events) {
      this._events = prefix ? {} : Object.create(null);
  }
  if (!this._events[evt]) {
      this._events[evt] = listener;
  } else {
    if (!this._events[evt].fn) {
        this._events[evt].push(listener);
    } else {
        this._events[evt] = [
            this._events[evt], listener
        ];
    }
  }

  return this;
};

/**
 * Add an EventListener that's only called once.
 *
 * @param {String} event Name of the event.
 * @param {Function} fn Callback function.
 * @param {Mixed} [context=this] The context of the function.
 * @api public
 */
EventEmitter.prototype.once = function once(event, fn, context) {
  var listener = new EE(fn, context || this, true)
    , evt = prefix ? prefix + event : event;

  if (!this._events) {
      this._events = prefix ? {} : Object.create(null);
  }
  if (!this._events[evt]) {
      this._events[evt] = listener;
  } else {
    if (!this._events[evt].fn) {
        this._events[evt].push(listener);
    } else {
        this._events[evt] = [
            this._events[evt], listener
        ];
    }
  }

  return this;
};

/**
 * Remove event listeners.
 *
 * @param {String} event The event we want to remove.
 * @param {Function} fn The listener that we need to find.
 * @param {Mixed} context Only remove listeners matching this context.
 * @param {Boolean} once Only remove once listeners.
 * @api public
 */
EventEmitter.prototype.removeListener = function removeListener(event, fn, context, once) {
  var evt = prefix ? prefix + event : event;

  if (!this._events || !this._events[evt]) {
      return this;
  }

  var listeners = this._events[evt]
    , events = [];

  if (fn) {
    if (listeners.fn) {
      if (listeners.fn !== fn ||
        (once && !listeners.once) ||
        (context && listeners.context !== context)) {
        events.push(listeners);
      }
    } else {
      for (var i = 0, length = listeners.length; i < length; i++) {
        if (listeners[i].fn !== fn ||
            (once && !listeners[i].once) ||
            (context && listeners[i].context !== context)) {
            events.push(listeners[i]);
        }
      }
    }
  }

  //
  // Reset the array, or remove it completely if we have no more listeners.
  //
  if (events.length) {
    this._events[evt] = events.length === 1 ? events[0] : events;
  } else {
    delete this._events[evt];
  }

  return this;
};

/**
 * Remove all listeners or only the listeners for the specified event.
 *
 * @param {String} event The event want to remove all listeners for.
 * @api public
 */
EventEmitter.prototype.removeAllListeners = function removeAllListeners(event) {
  if (!this._events) {
      return this;
  }

  if (event) {
      delete this._events[prefix ? prefix + event : event];
  }
  else {
      this._events = prefix ? {} : Object.create(null);
  }

  return this;
};

//
// Alias methods names because people roll like that.
//
EventEmitter.prototype.off = EventEmitter.prototype.removeListener;
EventEmitter.prototype.addListener = EventEmitter.prototype.on;

//
// This function doesn't apply anymore.
//
EventEmitter.prototype.setMaxListeners = function setMaxListeners() {
  return this;
};

//
// Expose the prefix.
//
EventEmitter.prefixed = prefix;

//
// Expose the module.
//
module.exports = EventEmitter;

/* eslint-enable */