polyfill-service/polyfills/_Iterator/polyfill.js

A polyfill combinator

// A modification of https://github.com/medikoo/es6-iterator
// Copyright (C) 2013-2015 Mariusz Nowak (www.medikoo.com)

var Iterator = (function () { // eslint-disable-line no-unused-vars
	var clear = function () {
		this.length = 0;
		return this;
	};
	var callable = function (fn) {
		if (typeof fn !== 'function') throw new TypeError(fn + " is not a function");
		return fn;
	};

	var Iterator = function (list, context) {
		if (!(this instanceof Iterator)) {
			return new Iterator(list, context);
		}
		Object.defineProperties(this, {
			__list__: {
				writable: true,
				value: list
			},
			__context__: {
				writable: true,
				value: context
			},
			__nextIndex__: {
				writable: true,
				value: 0
			}
		});
		if (!context) return;
		callable(context.on);
		context.on('_add', this._onAdd.bind(this));
		context.on('_delete', this._onDelete.bind(this));
		context.on('_clear', this._onClear.bind(this));
	};

	Object.defineProperties(Iterator.prototype, Object.assign({
		constructor: {
			value: Iterator,
			configurable: true,
			enumerable: false,
			writable: true
		},
		_next: {
			value: function () {
				var i;
				if (!this.__list__) return;
				if (this.__redo__) {
					i = this.__redo__.shift();
					if (i !== undefined) return i;
				}
				if (this.__nextIndex__ < this.__list__.length) return this.__nextIndex__++;
				this._unBind();
			},
			configurable: true,
			enumerable: false,
			writable: true
		},
		next: {
			value: function () {
				return this._createResult(this._next());
			},
			configurable: true,
			enumerable: false,
			writable: true
		},
		_createResult: {
			value: function (i) {
				if (i === undefined) return {
					done: true,
					value: undefined
				};
				return {
					done: false,
					value: this._resolve(i)
				};
			},
			configurable: true,
			enumerable: false,
			writable: true
		},
		_resolve: {
			value: function (i) {
				return this.__list__[i];
			},
			configurable: true,
			enumerable: false,
			writable: true
		},
		_unBind: {
			value: function () {
				this.__list__ = null;
				delete this.__redo__;
				if (!this.__context__) return;
				this.__context__.off('_add', this._onAdd.bind(this));
				this.__context__.off('_delete', this._onDelete.bind(this));
				this.__context__.off('_clear', this._onClear.bind(this));
				this.__context__ = null;
			},
			configurable: true,
			enumerable: false,
			writable: true
		},
		toString: {
			value: function () {
				return '[object Iterator]';
			},
			configurable: true,
			enumerable: false,
			writable: true
		}
	}, {
		_onAdd: {
			value: function (index) {
				if (index >= this.__nextIndex__) return;
				++this.__nextIndex__;
				if (!this.__redo__) {
					Object.defineProperty(this, '__redo__', {
						value: [index],
						configurable: true,
						enumerable: false,
						writable: false
					});
					return;
				}
				this.__redo__.forEach(function (redo, i) {
					if (redo >= index) this.__redo__[i] = ++redo;
				}, this);
				this.__redo__.push(index);
			},
			configurable: true,
			enumerable: false,
			writable: true
		},
		_onDelete: {
			value: function (index) {
				var i;
				if (index >= this.__nextIndex__) return;
				--this.__nextIndex__;
				if (!this.__redo__) return;
				i = this.__redo__.indexOf(index);
				if (i !== -1) this.__redo__.splice(i, 1);
				this.__redo__.forEach(function (redo, i) {
					if (redo > index) this.__redo__[i] = --redo;
				}, this);
			},
			configurable: true,
			enumerable: false,
			writable: true
		},
		_onClear: {
			value: function () {
				if (this.__redo__) clear.call(this.__redo__);
				this.__nextIndex__ = 0;
			},
			configurable: true,
			enumerable: false,
			writable: true
		}
	}));

	Object.defineProperty(Iterator.prototype, Symbol.iterator, {
		value: function () {
			return this;
		},
		configurable: true,
		enumerable: false,
		writable: true
	});
	Object.defineProperty(Iterator.prototype, Symbol.toStringTag, {
		value: 'Iterator',
		configurable: false,
		enumerable: false,
		writable: true
	});

	return Iterator;
}());