/*
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* Element Traversal methods from Juriy Zaytsev (kangax)
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* used to emulate Prototype up/down/previous/next methods
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*/
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(function(D){
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// TODO: all of this needs tests
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var match = D.match, select = D.select, root = document.documentElement,
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// Use the Element Traversal API if available.
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nextElement = 'nextElementSibling',
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previousElement = 'previousElementSibling',
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parentElement = 'parentElement';
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// Fall back to the DOM Level 1 API.
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if (!(nextElement in root)) nextElement = 'nextSibling';
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if (!(previousElement in root)) previousElement = 'previousSibling';
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if (!(parentElement in root)) parentElement = 'parentNode';
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function walkElements(property, element, expr) {
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var i = 0, isIndex = typeof expr == 'number';
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if (typeof expr == 'undefined') {
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isIndex = true;
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expr = 0;
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}
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while ((element = element[property])) {
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if (element.nodeType != 1) continue;
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if (isIndex) {
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++i;
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if (i == expr) return element;
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} else if (match(element, expr)) {
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return element;
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}
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}
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return null;
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}
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/**
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* @method up
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* @param {HTMLElement} element element to walk from
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* @param {String | Number} expr CSS expression or an index
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* @return {HTMLElement | null}
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*/
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function up(element, expr) {
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return walkElements(parentElement, element, expr);
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}
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/**
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* @method next
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* @param {HTMLElement} element element to walk from
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* @param {String | Number} expr CSS expression or an index
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* @return {HTMLElement | null}
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*/
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function next(element, expr) {
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return walkElements(nextElement, element, expr);
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}
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/**
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* @method previous
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* @param {HTMLElement} element element to walk from
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* @param {String | Number} expr CSS expression or an index
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* @return {HTMLElement | null}
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*/
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function previous(element, expr) {
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return walkElements(previousElement, element, expr);
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}
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/**
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* @method down
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* @param {HTMLElement} element element to walk from
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* @param {String | Number} expr CSS expression or an index
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* @return {HTMLElement | null}
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*/
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function down(element, expr) {
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var isIndex = typeof expr == 'number', descendants, index, descendant;
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if (expr === null) {
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element = element.firstChild;
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while (element && element.nodeType != 1) element = element[nextElement];
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return element;
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}
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if (!isIndex && match(element, expr) || isIndex && expr === 0) return element;
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descendants = select('*', element);
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if (isIndex) return descendants[expr] || null;
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index = 0;
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while ((descendant = descendants[index]) && !match(descendant, expr)) { ++index; }
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return descendant || null;
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}
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D.up = up;
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D.down = down;
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D.next = next;
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D.previous = previous;
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})(NW.Dom);
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