91 lines
2.1 KiB
JavaScript
91 lines
2.1 KiB
JavaScript
(function(define) {
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define(
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'video/00_iterator.js',
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[],
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function() {
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'use strict';
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/**
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* Provides convenient way to work with iterable data.
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* @exports video/00_iterator.js
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* @constructor
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* @param {array} list Array to be iterated.
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*/
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var Iterator = function(list) {
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this.list = list;
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this.index = 0;
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this.size = this.list.length;
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this.lastIndex = this.list.length - 1;
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};
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Iterator.prototype = {
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/**
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* Checks validity of provided index for the iterator.
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* @access protected
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* @param {numebr} index
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* @return {boolean}
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*/
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_isValid: function(index) {
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return _.isNumber(index) && index < this.size && index >= 0;
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},
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/**
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* Returns next element.
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* @param {number} [index] Updates current position.
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* @return {any}
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*/
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next: function(index) {
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if (!(this._isValid(index))) {
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index = this.index;
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}
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this.index = (index >= this.lastIndex) ? 0 : index + 1;
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return this.list[this.index];
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},
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/**
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* Returns previous element.
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* @param {number} [index] Updates current position.
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* @return {any}
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*/
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prev: function(index) {
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if (!(this._isValid(index))) {
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index = this.index;
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}
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this.index = (index < 1) ? this.lastIndex : index - 1;
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return this.list[this.index];
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},
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/**
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* Returns last element in the list.
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* @return {any}
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*/
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last: function() {
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return this.list[this.lastIndex];
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},
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/**
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* Returns first element in the list.
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* @return {any}
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*/
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first: function() {
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return this.list[0];
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},
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/**
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* Returns `true` if current position is last for the iterator.
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* @return {boolean}
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*/
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isEnd: function() {
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return this.index === this.lastIndex;
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}
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};
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return Iterator;
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});
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}(RequireJS.define));
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