list.js

/* global RUNTIME_CHECKS, define */

(function () {
	'use strict';

	/**
	 * Maintains a list of items. The idea is to stay as true as possible to the native Array interface, but to augment its usefulness by triggering events whenever the list is updated, as well as adding convenience functions for mutating the List in place.
	 *
	 * The exported List constructor can be used as-is, in which case a generic List will be created. This is a quite common use case. Alternatively, a List "subclass" constructor can be created by calling `List.withProperties(...)`. This second approach provides the possibility to add custom _calculated_ properties to the list. See {@link module:bff/list#withProperties} for more details.
	 *
	 * @exports bff/list
	 */
	function moduleFactory(extend, eventEmitter, Record) {
		var ADDED_EVENT = 'added';
		var REPLACED_EVENT = 'replaced';
		var REMOVED_EVENT = 'removed';
		/**
		 * @event module:bff/list#item:added
		 * @arg {any} item - The item that was added to the List.
		 * @arg {number} index - The position withing the List where the item was added.
		 * @arg {module:bff/list} list - The List to which the item was added.
		 */
		var ITEM_ADDED_EVENT = 'item:added';
		/**
		 * @event module:bff/list#item:replaced
		 * @arg {any} newItem - The item that was added to the List.
		 * @arg {any} oldItem - The item that was removed from the List.
		 * @arg {number} index - The position withing the List where the item was replaced.
		 * @arg {module:bff/list} list - The List in which the item was replaced.
		 */
		var ITEM_REPLACED_EVENT = 'item:replaced';
		/**
		 * @event module:bff/list#item:removed
		 * @arg {any} item - The item that was removed from the List.
		 * @arg {number} index - The position withing the List where the item was removed.
		 * @arg {module:bff/list} list - The List from which the item was removed.
		 */
		var ITEM_REMOVED_EVENT = 'item:removed';
		/**
		 * @event module:bff/list#change:length
		 * @arg {number} newLength - The current length of the List.
		 * @arg {number} oldLength - The previous length of the List.
		 * @arg {module:bff/list} list - The List whose length has changed.
		 */
		var CHANGE_LENGTH_EVENT = 'change:length';

		// "Private event"
		var PRECHANGE_LENGTH_EVENT = 'prechange:length';

		var PRECHANGE_EVENT = 'prechange';
		var CHANGE_EVENT = 'change';

		/**
		 * @callback module:bff/list~forEachCallback
		 * @param {any} item - Current List item.
		 * @param {number} index - Item position in List.
		 * @param {module:bff/list} list - List being iterated over.
		 */

		/**
		 * @callback module:bff/list~mapCallback
		 * @param {any} item - Current List item.
		 * @param {number} index - Item position in List.
		 * @param {module:bff/list} list - List being iterated over.
		 * @returns {any} Transformed object.
		 */

		/**
		 * @callback module:bff/list~predicateCallback
		 * @param {any} item - Current List item.
		 * @param {number} index - Item position in List.
		 * @param {module:bff/list} list - List being iterated over.
		 * @returns {boolean} true if the item passes the test, false otherwise
		 */

		/**
		 * @callback module:bff/list~reduceCallback
		 * @param {any} previousItem - The value previously returned in the last invocation of the callback, or initialValue, if supplied. Usually an aggregate of previous items.
		 * @param {any} item - Current List item being processed.
		 * @param {number} index - Item position in List.
		 * @param {module:bff/list} list - List being iterated over.
		 * @returns {any} The aggregated value.
		 */

		/**
		 * Compares _itemA_ and _itemB_ arguments according to some sorting criterion. Should return -1 if _itemA_ comes before _itemB_, 0 if _itemA_ is equal to _itemB_, 1 if _itemB_ comes before _itemA_.
		 * @callback module:bff/list~compareFunction
		 * @param {any} itemA - A list item.
		 * @param {any} itemB - Another list item.
		 * @returns {number}.
		 */

		var ITEM_EVENT_TOKEN_MATCHER = /item:/;

		function isEmitter(obj) { return !!(obj && obj.addEventListener); } // Quack!

		function reemitItemEvent(self, item, strippedEventName, eventName) {
			self.listenTo(item, strippedEventName, function reemitItemEvent() {
				self.emitArgsAsArray(eventName, arguments);
			});
		}

		function onItemAdded(self, item, index) {
			if (!isEmitter(item)) {
				self.emit(ITEM_ADDED_EVENT, item, index, self);
				return;
			}

			for (var eventName in self.__private.reEmittingEvents) {
				var strippedEventName = eventName.replace(ITEM_EVENT_TOKEN_MATCHER, '');
				reemitItemEvent(self, item, strippedEventName, eventName);
			}

			item.emit(ADDED_EVENT, item, index, self);
		}

		function onItemRemoved(self, item, index) {
			if (!isEmitter(item)) {
				self.emit(ITEM_REMOVED_EVENT, item, index, self);
				return;
			}

			item.emit(REMOVED_EVENT, item, index, self);
			self.stopListening(item);
		}

		function onItemReplaced(self, newItem, oldItem, index) {
			if (newItem === oldItem) { return; }

			isEmitter(oldItem) ?
				oldItem.emit(REPLACED_EVENT, newItem, oldItem, index, self) :
				self.emit(ITEM_REPLACED_EVENT, newItem, oldItem, index, self);
		}

		function makeSetter(index) {
			// TODO: Investigate if this is really a good idea, performance wise
			return function setter(val) { this.splice(index, 1, val); };
		}

		function makeGetter(index) {
			return function getter() { return this.__private.array[index]; };
		}

		function delegate(funcName) {
			return function () {
				return this.__private.array[funcName].apply(this.__private.array, arguments);
			};
		}

		function delegateCreator(funcName) {
			return function () {
				return new this.constructor(this.__private.array[funcName].apply(this.__private.array, arguments));
			};
		}

		function triggerPrechangeLengthEvent(self) {
			self.emit(PRECHANGE_EVENT, 'length', self.length, self);
			self.emit(PRECHANGE_LENGTH_EVENT, self.length, self);
		}

		function triggerChangeLengthEvent(self, prevLength) {
			if (self.length === prevLength) { return; }
			self.emit(CHANGE_EVENT, 'length', self.length, prevLength, self);
			self.emit(CHANGE_LENGTH_EVENT, self.length, prevLength, self);
		}

		/**
		 * @alias module:bff/list
		 */
		var listFunctions = {};

		/**
		 * Add one or more items to the end of the List. Mirrors Array.push behavior.
		 * @instance
		 * @arg {...any} item - Each item argument will be pushed onto the List.
		 * @emits module:bff/list#change:length
		 * @emits module:bff/list#item:added
		 * @returns {number} Updated List length
		 */
		listFunctions.push = function () {
			var nItems = arguments.length;
			if (nItems === 0) { return this.length; }

			var prevLength = this.length;
			triggerPrechangeLengthEvent(this);

			var privArray = this.__private.array;
			privArray.push.apply(privArray, arguments);
			for (var i = prevLength; i < privArray.length; ++i) {
				onItemAdded(this, privArray[i], i);
			}

			triggerChangeLengthEvent(this, prevLength);

			return this.length;
		};

		/**
		 * Add one or more items to the beginning of the List. Mirrors Array.unshift behavior.
		 * @instance
		 * @arg {...any} item - Each item argument will be pushed onto the List.
		 * @emits module:bff/list#change:length
		 * @emits module:bff/list#item:added
		 * @returns {Number} Updated List length
		 */
		listFunctions.unshift = function () {
			var nItems = arguments.length;
			if (nItems === 0) { return this.length; }

			var prevLength = this.length;
			triggerPrechangeLengthEvent(this);

			var privArray = this.__private.array;
			privArray.unshift.apply(privArray, arguments);
			for (var i = 0; i < nItems; ++i) {
				onItemAdded(this, privArray[i], i);
			}

			triggerChangeLengthEvent(this, prevLength);

			return this.length;
		};

		/**
		 * Remove and return one item from the end of the List. Mirrors Array.pop behavior.
		 * @instance
		 * @emits module:bff/list#change:length
		 * @emits module:bff/list#item:removed
		 * @returns {any} Removed item
		 */
		listFunctions.pop = function () {
			if (this.length === 0) { return undefined; }

			var prevLength = this.length;
			triggerPrechangeLengthEvent(this);

			var privArray = this.__private.array;
			var poppedItem = privArray.pop.apply(privArray, arguments);
			onItemRemoved(this, poppedItem, this.length);

			triggerChangeLengthEvent(this, prevLength);

			return poppedItem;
		};

		/**
		 * Remove and return one item from the beginning of the List. Mirrors Array.shift behavior.
		 * @instance
		 * @emits module:bff/list#change:length
		 * @emits module:bff/list#item:removed
		 * @returns {any} Removed item
		 */
		listFunctions.shift = function () {
			if (this.length === 0) { return undefined; }

			var prevLength = this.length;
			triggerPrechangeLengthEvent(this);

			var privArray = this.__private.array;
			var shiftedItem = privArray.shift.apply(privArray, arguments);
			onItemRemoved(this, shiftedItem, 0);

			triggerChangeLengthEvent(this, prevLength);

			return shiftedItem;
		};

		/**
		 * Changes the content of the List by removing existing items and/or adding new items. Mirrors Array.splice behavior.
		 * @instance
		 * @arg {number} start - Index at which to start changing the array. If greater than the length of the array, actual starting index will be set to the length of the array. If negative, will begin that many items from the end.
		 * @arg {number} nItemsToRemove - An integer indicating the number of old array items to remove. If nItemsToRemove is greater than the number of items left in the array starting at start, then all of the items through the end of the array will be deleted.
		 * @arg {...any} [itemToAdd] - Item that will be added to the array, starting at the index specified in the first argument.
		 * @emits module:bff/list#change:length
		 * @emits module:bff/list#item:added
		 * @emits module:bff/list#item:replaced
		 * @emits module:bff/list#item:removed
		 * @returns {any[]} Array of removed items
		 */
		listFunctions.splice = function (start, nItemsToRemove) {
			if (RUNTIME_CHECKS) {
				if (arguments.length < 2) { throw '"start" and "nItemsToRemove" arguments are mandatory'; }
				if (typeof start !== 'number') { throw '"start" argument must be a number'; }
				if (typeof nItemsToRemove !== 'number') { throw '"nItemsToRemove" argument must be a number'; }
			}

			var i;
			var oldLength = this.length;

			if (start < 0) {
				start = oldLength + start;
			}
			nItemsToRemove = Math.min(nItemsToRemove, oldLength - start);

			var nItemsToAdd = arguments.length - 2;
			var nItemsToReplace = Math.min(nItemsToAdd, nItemsToRemove);
			var nItemsAffected = Math.max(nItemsToAdd, nItemsToRemove);

			var prevLength = this.length;
			triggerPrechangeLengthEvent(this);

			var privArray = this.__private.array;
			var deletedItems = privArray.splice.apply(privArray, arguments);

			for (i = 0; i < nItemsAffected; ++i) {
				if (i < nItemsToAdd) {
					onItemAdded(this, privArray[start + i], start + i);
				}
				if (i < nItemsToReplace) {
					onItemReplaced(this, privArray[start + i], deletedItems[i], start + i);
				}
				if (i < nItemsToRemove) {
					onItemRemoved(this, deletedItems[i], start + i);
				}
			}

			triggerChangeLengthEvent(this, prevLength);

			return deletedItems;
		};

		[
			/**
			 * Executes the given function once per List item. Mirrors Array.forEach behavior.
			 * @func forEach
			 * @instance
			 * @arg {module:bff/list~forEachCallback} callback - The function that will be called once per List item.
			 * @arg {any} [thisArg] - Value to use as "this" when executing callback.
			 */
			'forEach',
			/**
			 * Mirrors Array.every behavior.
			 * @func every
			 * @instance
			 * @arg {module:bff/list~predicateCallback} predicate - Executed once per List item.
			 * @arg {any} [thisArg] - Value to use as "this" when executing callback.
			 * @returns {boolean} true if all items passes the predicate test, false otherwise.
			 */
			'every',
			/**
			 * Mirrors Array.some behavior.
			 * @func some
			 * @instance
			 * @arg {module:bff/list~predicateCallback} predicate - Executed once per List item.
			 * @arg {any} [thisArg] - Value to use as "this" when executing callback.
			 * @returns {boolean} true if at least one item passes the predicate test, false otherwise.
			 */
			'some',
			/**
			 * Mirrors Array.indexOf behavior.
			 * @func indexOf
			 * @instance
			 * @arg {any} searchItem - The item to locate within the List.
			 * @arg {number} [fromIndex] - The index to start the search at. If the index is greater than or equal to the List's length, -1 is returned, which means the List will not be searched. If the provided index value is a negative number, it is taken as the offset from the end of the List.
			 * @returns {number} The first index at which a given item can be found in the List, or -1 if it is not present.
			 */
			'indexOf',
			/**
			 * @func lastIndexOf
			 * @instance
			 * @arg {any} searchItem - The item to locate within the List.
			 * @arg {number} [fromIndex] - The index at which to start searching backwards. Defaults to the List's length minus one, i.e. the whole List will be searched. If the index is greater than or equal to the length of the List, the whole List will be searched. If negative, it is taken as the offset from the end of the List. Mirrors Array.lastIndexOf behavior.
			 * @returns {number} The last index at which a given item can be found in the List, or -1 if it is not present.
			 */
			'lastIndexOf',
			/**
			 * @func join
			 * @instance
			 * @arg {string} [separator] - Specifies a string to separate each item of the List. If omitted, the List items are separated with a comma. Mirrors Array.join behavior.
			 * @returns {string} The stringified List items, joined by the 'separator' string argument.
			 */
			'join',
			/**
			 * Applies a function against an accumulator and each value of the List (from left-to-right) to reduce it to a single value. Mirrors Array.reduce behavior.
			 * @func reduce
			 * @instance
			 * @arg {module:bff/list~reduceCallback} callback - The function that will be called once per List item.
			 * @arg {any} initialValue - Value to use as the first argument to the first call of the callback.
			 * @returns {any} Aggregated value
			 */
			'reduce',
			/**
			 * Applies a function against an accumulator and each value of the List (from right-to-left) to reduce it to a single value. Mirrors Array.reduceRight behavior.
			 * @func reduceRight
			 * @instance
			 * @arg {module:bff/list~reduceCallback} callback - The function that will be called once per List item.
			 * @arg {any} initialValue - Value to use as the first argument to the first call of the callback.
			 * @returns {any} Aggregated value
			 */
			'reduceRight'
		].forEach(function (funcName) {
			listFunctions[funcName] = Array.prototype[funcName];
		});

		[
			/**
			 * Sorts the items of the List in place. The sort is not necessarily stable. The default sort order is according to string Unicode code points, unless a custom comparator finction is provided. Mirrors the behavior of Array.sort. No events are emitted by this operation.
			 * @func sort
			 * @instance
			 * @arg {module:bff/list~compareFunction} [comparator] - A function that specifies the ordering of two arbitrary List items. Called multiple times in order to produce a total ordering of the items.
			 * @returns {List} The sorted list.
			 */
			'sort',
			/**
			 * Reverses the List in place. Mirros the behavior of Array.reverse. No events are emitted by this operation.
			 * @func reverse
			 * @instance
			 */
			'reverse'
		].forEach(function (funcName) {
			listFunctions[funcName] = delegate(funcName);
		});

		[
			/**
			 * Creates a new List with all items that pass the test implemented by the predicate function test. The original list is unchanged. Mirrors the behavior of Array.filter.
			 * @func filter
			 * @instance
			 * @arg {module:bff/list~predicateCallback} predicate - Executed once per List item.
			 * @returns {List} The new List.
			 */
			'filter',
			/**
			 * Creates a new List from the range of current items specified by the begin and end arguments. Mirrors the behavior of Array.slice.
			 * @func slice
			 * @instance
			 * @arg {number} [begin] Index that specifies the beginning of the range. Inclusive. A negative index will
			 *     be relative to the end of the List instead of the beginning.
			 * @arg {number} [end] Index that specifies the end of the range. Exclusive. A negative index will
			 *     be relative to the end of the List instead of the beginning.
			 * @returns {List} The new List.
			 */
			'slice',
			/**
			 * Creates a new List with the results of calling a provided callback function on every element in the List. Mirrors the behavior of Array.map.
			 * @func map
			 * @instance
			 * @arg {module:bff/module~mapCallback} callback - Executed once per List item.
			 * @arg {any} [thisArg] - Value to use as "this" when executing callback.
			 * @returns {List} The new List.
			 */
			'map'
		].forEach(function (funcName) {
			listFunctions[funcName] = delegateCreator(funcName);
		});

		/**
		 * Returns a new List comprised of the List on which it is called joined with the List(s), Array(s) and/or value(s) provided as arguments. Mirrors the behavior of Array.concat.
		 * @instance
		 * @arg {...any} value - A List, Array or value that will be concatenated with the original List. Lists and Arrays will be deconstructed and each item added to the new List.
		 * @returns {List} The new List.
		 */
		listFunctions.concat = function () {
			for (var i = 0, n = arguments.length; i < n; ++i) {
				var argument = arguments[i];
				if (!(argument instanceof Array) && argument.length !== undefined) {
					arguments[i] = argument.toArray();
				}
			}
			return new this.constructor(this.__private.array.concat.apply(this.__private.array, arguments));
		};

		/**
		 * Mutates the List by removing all items that does not pass the predicate function test.
		 * @instance
		 * @arg {module:bff/list~predicateCallback} predicate - Called once per List item to determine whether the item should be removed.
		 * @arg {any} [thisArg] - Value to use as "this" when executing predicate callback.
		 * @emits module:bff/list#change:length
		 * @emits module:bff/list#item:removed
		 * @returns {List} The filtered List.
		 */
		listFunctions.filterMut = function (predicate, thisArg) {
			if (RUNTIME_CHECKS) {
				if (typeof predicate !== 'function') { throw '"predicate" argument must be a function'; }
			}

			var removeCount = 0;
			for (var i = this.length - 1; i >= -1; --i) {
				if (i > -1 && !predicate.call(thisArg, this[i], i, this)) {
					removeCount++;
				} else if (removeCount) {
					this.splice(i + 1, removeCount);
					removeCount = 0;
				}
			}
			return this;
		};

		/**
		 * Mutates the List by removing all occurances of the provided item.
		 * @instance
		 * @arg {any} item - The item to remove from the list.
		 * @emits module:bff/list#change:length
		 * @emits module:bff/list#item:removed
		 * @returns {List} The List, without any occurances of 'item'.
		 */
		listFunctions.remove = function (item) {
			return this.filterMut(function (listItem) { return item !== listItem; });
		};

		/**
		 * Mutates the List by removing all items.
		 * @instance
		 * @emits module:bff/list#change:length
		 * @emits module:bff/list#item:removed
		 * @returns {List} The List, now empty.
		 */
		listFunctions.clear = function () {
			return this.splice(0, this.length);
		};

		/**
		 * Mutates the List by adding the items comprising the provided List or Array to the end of the List.
		 * @instance
		 * @arg {module:bff/list|Array} items - The items that will be appended to the List.
		 * @emits module:bff/list#change:length
		 * @emits module:bff/list#item:added
		 * @returns {List} The List, with new items appended.
		 */
		listFunctions.pushAll = function (items) {
			if (RUNTIME_CHECKS && (!items || items.length === undefined)) {
				throw '"items" argument must have a length property';
			}
			items.length && this.push.apply(this, items);
			return this.length;
		};

		/**
		 * Mutates the List by removing all elements outside of range specified by the begin and end arguments.
		 * @instance
		 * @arg {number} [begin] Index that specifies the beginning of the range. Inclusive. A negative index will be relative to the end of the List instead of the beginning.
		 * @arg {number} [end] Index that specifies the end of the range. Exclusive. A negative index will be relative to the end of the List instead of the beginning.
		 * @emits module:bff/list#change:length
		 * @emits module:bff/list#item:removed
		 * @returns {List} The List, sans the items outside of the specified range.
		 */
		listFunctions.sliceMut = function (begin, end) {
			if (RUNTIME_CHECKS) {
				if (arguments.length < 2) { throw '"begin" and "end" arguments are mandatory'; }
				if (typeof begin !== 'number') { throw '"begin" argument must be a number'; }
				if (typeof end !== 'number') { throw '"end" argument must be a number'; }
			}

			var length = this.length;

			end = (typeof end !== 'undefined') ? end : length;

			// Handle negative value for "begin"
			var start = begin || 0;
			start = (start >= 0) ? start : Math.max(0, length + start);

			// Handle negative value for "end"
			var upTo = ((typeof end === 'number') ? Math.min(end, length) : length) - 1;
			end < 0 && (upTo = length + end);

			// Actual expected size of the slice
			var size = upTo - start;

			if (size !== length) {
				this.splice(0, start);
				this.splice(upTo, length - upTo);
			}

			return this;
		};

		/**
		 * Replaces all items in the List with new items, generated by the callback function.
		 * @instance
		 * @arg {module:bff/module~mapCallback} callback - Executed once per List item to produce new items.
		 * @arg {any} [thisArg] - Value to use as "this" when executing callback.
		 * @emits module:bff/list#item:replaced
		 * @returns {List} The List, with all items updated.
		 */
		listFunctions.mapMut = function (callback, thisArg) {
			if (RUNTIME_CHECKS && typeof callback !== 'function') { throw '"callback" argument must be a function'; }

			for (var i = 0, length = this.length; i < length; ++i) {
				this[i] = callback.call(thisArg, this[i], i, this);
			}
			return this;
		};

		/**
		 * Returns the first item in the List that passes the predicate function test, or undefined if no item passes.
		 * @instance
		 * @arg {module:bff/list~predicateCallback} predicate - Called once per List item to in order to find a matching item.
		 * @returns {any|undefined} The matching item, if any.
		 */
		listFunctions.find = function (predicate, thisArg) {
			if (RUNTIME_CHECKS && typeof predicate !== 'function') { throw '"predicate" argument must be a function'; }

			for (var i = 0, length = this.length; i < length; ++i) {
				if (predicate.call(thisArg, this[i], i, this)) { return this[i]; }
			}
		};

		/**
		 * Returns the index of the first item in the List that passes the predicate function test, or -1 if no item passes.
		 * @instance
		 * @arg {module:bff/list~predicateCallback} predicate - Called once per List item to in order to find a matching item.
		 * @returns {number} The position of the matching item, or -1 if none matches.
		 */
		listFunctions.findIndex = function (predicate, thisArg) {
			if (RUNTIME_CHECKS && typeof predicate !== 'function') { throw '"predicate" argument must be a function'; }

			for (var i = 0, length = this.length; i < length; ++i) {
				if (predicate.call(thisArg, this[i], i, this)) { return i; }
			}
			return -1;
		};

		/**
		 * Returns whether the provided item is part of the List.
		 * @instance
		 * @arg {any} item
		 * @arg {number} [fromIndex] - The index to start the search at. If the index is greater than or equal to the List's length, -1 is returned, which means the List will not be searched. If the provided index value is a negative number, it is taken as the offset from the end of the List.
		 * @returns {boolean} True if the item is part of the List, false otherwise.
		 */
		listFunctions.includes = function (item, fromIndex) {
			if (RUNTIME_CHECKS && arguments.length > 1 && typeof fromIndex !== 'number') {
				throw '"fromIndex" number must be a number';
			}

			fromIndex = fromIndex || 0;
			var index = this.__private.array.indexOf(item);
			return index !== -1 && index >= fromIndex;
		};

		/**
		 * Returns an newly created Array, containing all the items of the List. List properties are not copied to the Array object. The items are copied shallowly.
		 * @instance
		 * @returns {Array}
		 */
		listFunctions.toArray = function () {
			return this.__private.array.slice();
		};

		/**
		 * Returns a newly created Array representation of the List, containing deep copies of all the List's items, but not its properties.
		 * @instance
		 * @returns {Array}
		 */
		listFunctions.toJSON = function () {
			var jsonObj = new Array(this.length);
			for (var i = 0, n = jsonObj.length; i < n; ++i) {
				var item = this[i];
				jsonObj[i] = item instanceof Object ?
						(item.toJSON ? item.toJSON() : JSON.parse(JSON.stringify(item))) : item;
			}
			return jsonObj;
		};

		/**
		 * Returns a newly created Object containing the List's deep copied properties.
		 * @instance
		 * @returns {Object}
		 */
		listFunctions.propertiesToJSON = function () {
			return Record.prototype.toJSON.call(this);
		};

		/**
		 * Augmented version of {@link bff/event-emitter#addEventListener} that provides the option to listen to events emitted from any item in the List. To add a listener to an item event, prepend the event name with 'item:'. For instance, to listen for the 'change' event on all the list items (even ones added after the listener was created), add a listener for the 'item:change' event.
		 * @instance
		 * @arg {string} - Identifier string for the event.
		 */
		listFunctions.addEventListener = function (eventName) {
			if (RUNTIME_CHECKS && typeof eventName !== 'string') {
				throw '"eventName" argument must be a string';
			}

			if (!ITEM_EVENT_TOKEN_MATCHER.test(eventName) || this.__private.reEmittingEvents[eventName]) { return; }
			this.__private.reEmittingEvents[eventName] = true;

			var strippedEventName = eventName.replace(ITEM_EVENT_TOKEN_MATCHER, '');
			for (var i = 0, n = this.length; i < n; ++i) {
				var item = this[i];
				isEmitter(item) && reemitItemEvent(this, item, strippedEventName, eventName);
			}
		};

		/**
		 * Augmented version of {@link bff/event-emitter#removeEventListener} that provides functionality for removing "item" event listeners, e.g. for stop listening to events like "items:change".
		 * @instance
		 * @arg {string} - Identifier string for the event.
		 */
		listFunctions.removeEventListener = function (eventName) {
			if (RUNTIME_CHECKS && typeof eventName !== 'string') {
				throw '"eventName" argument must be a string';
			}

			if (!ITEM_EVENT_TOKEN_MATCHER.test(eventName)) { return; }

			// Check if we still need to re-emit this event
			var listeners = this.__private.listeners[eventName];
			if (listeners && listeners.length) { return; }

			delete this.__private.reEmittingEvents[eventName];
			var strippedEventName = eventName.replace(ITEM_EVENT_TOKEN_MATCHER, '');
			this.stopListening(undefined, strippedEventName);
		};

		extend(listFunctions, eventEmitter, { 'function': 'merge' });

		/**
		 * @instance
		 * @returns {string} A human readable string representation of the List.
		 */
		listFunctions.toString = function () {
			return JSON.stringify(this, undefined, 2);
		};

		function withProperties(schema) {
			for (var propName in schema) {
				var propertySchema = schema[propName];

				if (RUNTIME_CHECKS && !propertySchema.getter) {
					throw 'List property ' + propName + ' must have a custom getter function';
				}
				if (RUNTIME_CHECKS && propertySchema.setter) {
					throw 'List property ' + propName + ' may not have a setter';
				}

				propertySchema.setter = false;
			}

			extend(schema, {
				length: {
					getter: function () { return this.__private.array.length; },
					setter: false,
				},
				first: {
					getter: function () { return this[0]; },
					setter: false,
				},
				last: {
					getter: function () { return this[this.length - 1]; },
					setter: false,
				}
			});

			var RecordSubclass = Record.withProperties(schema, true);

			function List(items) {
				if (RUNTIME_CHECKS && arguments.length > 0 && (!items || items.length === undefined)) {
					throw '"items" argument must have a length property';
				}

				this.__private || Object.defineProperty(this, '__private', { writable: true, value: {}, });
				this.__private.array = [];
				this.__private.reEmittingEvents = {};

				this.listenTo(this, CHANGE_LENGTH_EVENT, function (length, prevLength) {
					var diff = length - prevLength;
					var i;
					if (diff > 0) {
						for (i = prevLength; i < length; ++i) {
							Object.defineProperty(this, i, {
								enumerable: true,
								configurable: true,
								get: makeGetter(i),
								set: makeSetter(i),
							});
						}
					} else {
						for (i = length; i < prevLength; ++i) {
							delete this[i];
						}
					}
				});

				// We don't want to send any arguments to the record constructor,
				// none of the properties we added has any setters!
				RecordSubclass.call(this);

				items = items || [];

				items.length && this.pushAll(items);
			}

			List.prototype = Object.create(RecordSubclass.prototype);
			List.prototype.constructor = List;

			extend(List.prototype, listFunctions);

			return List;
		}

		/**
		 * Creates a new List, with an optional list or array of initial items.
		 * @constructor
		 * @alias module:bff/list
		 * @mixes bff/event-emitter
		 * @mixes bff/event-listener
		 * @arg {(Array|List)} [items] - Items that will be added to the List on creation.
		 */
		var List = withProperties({});

		/**
		 * Creates a new List constructor function, that will create List instances with the property schema
		 * provided to this function
		 * @func
		 * @static
		 * @arg {Object} schema - An object describing the properties that will be part of all new instances created by the returned constructor function. The property descriptions should be on the same format at the schema specified for {@link module:bff/record.withProperties}, with the only exception that setters are not allowed.
		 * @returns {function} New constructor function based on the provided schema.
		 */
		List.withProperties = withProperties;

		return List;

	}

	// Expose, based on environment
	if (typeof define === 'function' && define.amd) { // AMD
		define([ './extend', './event-emitter', './record' ], moduleFactory);
	} else if (typeof exports === 'object') { // Node, CommonJS-like
		module.exports = moduleFactory(require('./extend'), require('./event-emitter'), require('./record'));
	} else { // Browser globals
		var bff = window.bff = window.bff || {};
		bff.List = moduleFactory(bff.extend, bff.eventEmitter, bff.Record);
	}

}());