/*
Copyright (c) 2011, Yahoo! Inc. All rights reserved.
Code licensed under the BSD License:
http://developer.yahoo.com/yui/license.html
version: 2.9.0
*/
var Y = YAHOO,
    Y_DOM = YAHOO.util.Dom, 
    EMPTY_ARRAY = [],
    Y_UA = Y.env.ua,
    Y_Lang = Y.lang,
    Y_DOC = document,
    Y_DOCUMENT_ELEMENT = Y_DOC.documentElement,

    Y_DOM_inDoc = Y_DOM.inDocument, 
    Y_mix = Y_Lang.augmentObject,
    Y_guid = Y_DOM.generateId,

    Y_getDoc = function(element) {
        var doc = Y_DOC;
        if (element) {
            doc = (element.nodeType === 9) ? element : // element === document
                element.ownerDocument || // element === DOM node
                element.document || // element === window
                Y_DOC; // default
        }

        return doc;
    },
    
    Y_Array = function(o, startIdx) {
        var l, a, start = startIdx || 0;

        // IE errors when trying to slice HTMLElement collections
        try {
            return Array.prototype.slice.call(o, start);
        } catch (e) {
            a = [];
            l = o.length;
            for (; start < l; start++) {
                a.push(o[start]);
            }
            return a;
        }
    },

    Y_DOM_allById = function(id, root) {
        root = root || Y_DOC;
        var nodes = [],
            ret = [],
            i,
            node;

        if (root.querySelectorAll) {
            ret = root.querySelectorAll('[id="' + id + '"]');
        } else if (root.all) {
            nodes = root.all(id);

            if (nodes) {
                // root.all may return HTMLElement or HTMLCollection.
                // some elements are also HTMLCollection (FORM, SELECT).
                if (nodes.nodeName) {
                    if (nodes.id === id) { // avoid false positive on name
                        ret.push(nodes);
                        nodes = EMPTY_ARRAY; // done, no need to filter
                    } else { //  prep for filtering
                        nodes = [nodes];
                    }
                }

                if (nodes.length) {
                    // filter out matches on node.name
                    // and element.id as reference to element with id === 'id'
                    for (i = 0; node = nodes[i++];) {
                        if (node.id === id  || 
                                (node.attributes && node.attributes.id &&
                                node.attributes.id.value === id)) { 
                            ret.push(node);
                        }
                    }
                }
            }
        } else {
            ret = [Y_getDoc(root).getElementById(id)];
        }

        return ret;
    };

/**
 * The selector-native module provides support for native querySelector
 * @module dom
 * @submodule selector-native
 * @for Selector
 */

/**
 * Provides support for using CSS selectors to query the DOM 
 * @class Selector 
 * @static
 * @for Selector
 */

var COMPARE_DOCUMENT_POSITION = 'compareDocumentPosition',
    OWNER_DOCUMENT = 'ownerDocument',

Selector = {
    _foundCache: [],

    useNative: true,

    _compare: ('sourceIndex' in Y_DOCUMENT_ELEMENT) ?
        function(nodeA, nodeB) {
            var a = nodeA.sourceIndex,
                b = nodeB.sourceIndex;

            if (a === b) {
                return 0;
            } else if (a > b) {
                return 1;
            }

            return -1;

        } : (Y_DOCUMENT_ELEMENT[COMPARE_DOCUMENT_POSITION] ?
        function(nodeA, nodeB) {
            if (nodeA[COMPARE_DOCUMENT_POSITION](nodeB) & 4) {
                return -1;
            } else {
                return 1;
            }
        } :
        function(nodeA, nodeB) {
            var rangeA, rangeB, compare;
            if (nodeA && nodeB) {
                rangeA = nodeA[OWNER_DOCUMENT].createRange();
                rangeA.setStart(nodeA, 0);
                rangeB = nodeB[OWNER_DOCUMENT].createRange();
                rangeB.setStart(nodeB, 0);
                compare = rangeA.compareBoundaryPoints(1, rangeB); // 1 === Range.START_TO_END
            }

            return compare;
        
    }),

    _sort: function(nodes) {
        if (nodes) {
            nodes = Y_Array(nodes, 0, true);
            if (nodes.sort) {
                nodes.sort(Selector._compare);
            }
        }

        return nodes;
    },

    _deDupe: function(nodes) {
        var ret = [],
            i, node;

        for (i = 0; (node = nodes[i++]);) {
            if (!node._found) {
                ret[ret.length] = node;
                node._found = true;
            }
        }

        for (i = 0; (node = ret[i++]);) {
            node._found = null;
            node.removeAttribute('_found');
        }

        return ret;
    },

    /**
     * Retrieves a set of nodes based on a given CSS selector. 
     * @method query
     *
     * @param {string} selector The CSS Selector to test the node against.
     * @param {HTMLElement} root optional An HTMLElement to start the query from. Defaults to Y.config.doc
     * @param {Boolean} firstOnly optional Whether or not to return only the first match.
     * @return {Array} An array of nodes that match the given selector.
     * @static
     */
    query: function(selector, root, firstOnly, skipNative) {
        if (root && typeof root == 'string') {
            root = Y_DOM.get(root);
            if (!root) {
                return (firstOnly) ? null : [];
            }
        } else {
            root = root || Y_DOC;
        }

        var ret = [],
            useNative = (Selector.useNative && Y_DOC.querySelector && !skipNative),
            queries = [[selector, root]],
            query,
            result,
            i,
            fn = (useNative) ? Selector._nativeQuery : Selector._bruteQuery;

        if (selector && fn) {
            // split group into seperate queries
            if (!skipNative && // already done if skipping
                    (!useNative || root.tagName)) { // split native when element scoping is needed
                queries = Selector._splitQueries(selector, root);
            }

            for (i = 0; (query = queries[i++]);) {
                result = fn(query[0], query[1], firstOnly);
                if (!firstOnly) { // coerce DOM Collection to Array
                    result = Y_Array(result, 0, true);
                }
                if (result) {
                    ret = ret.concat(result);
                }
            }

            if (queries.length > 1) { // remove dupes and sort by doc order 
                ret = Selector._sort(Selector._deDupe(ret));
            }
        }

        return (firstOnly) ? (ret[0] || null) : ret;

    },

    // allows element scoped queries to begin with combinator
    // e.g. query('> p', document.body) === query('body > p')
    _splitQueries: function(selector, node) {
        var groups = selector.split(','),
            queries = [],
            prefix = '',
            i, len;

        if (node) {
            // enforce for element scoping
            if (node.tagName) {
                node.id = node.id || Y_guid();
                prefix = '[id="' + node.id + '"] ';
            }

            for (i = 0, len = groups.length; i < len; ++i) {
                selector =  prefix + groups[i];
                queries.push([selector, node]);
            }
        }

        return queries;
    },

    _nativeQuery: function(selector, root, one) {
        if (Y_UA.webkit && selector.indexOf(':checked') > -1 &&
                (Selector.pseudos && Selector.pseudos.checked)) { // webkit (chrome, safari) fails to find "selected"
            return Selector.query(selector, root, one, true); // redo with skipNative true to try brute query
        }
        try {
            return root['querySelector' + (one ? '' : 'All')](selector);
        } catch(e) { // fallback to brute if available
            return Selector.query(selector, root, one, true); // redo with skipNative true
        }
    },

    filter: function(nodes, selector) {
        var ret = [],
            i, node;

        if (nodes && selector) {
            for (i = 0; (node = nodes[i++]);) {
                if (Selector.test(node, selector)) {
                    ret[ret.length] = node;
                }
            }
        } else {
        }

        return ret;
    },

    test: function(node, selector, root) {
        var ret = false,
            groups = selector.split(','),
            useFrag = false,
            parent,
            item,
            items,
            frag,
            i, j, group;

        if (node && node.tagName) { // only test HTMLElements

            // we need a root if off-doc
            if (!root && !Y_DOM_inDoc(node)) {
                parent = node.parentNode;
                if (parent) { 
                    root = parent;
                } else { // only use frag when no parent to query
                    frag = node[OWNER_DOCUMENT].createDocumentFragment();
                    frag.appendChild(node);
                    root = frag;
                    useFrag = true;
                }
            }
            root = root || node[OWNER_DOCUMENT];

            if (!node.id) {
                node.id = Y_guid();
            }
            for (i = 0; (group = groups[i++]);) { // TODO: off-dom test
                group += '[id="' + node.id + '"]';
                items = Selector.query(group, root);

                for (j = 0; item = items[j++];) {
                    if (item === node) {
                        ret = true;
                        break;
                    }
                }
                if (ret) {
                    break;
                }
            }

            if (useFrag) { // cleanup
                frag.removeChild(node);
            }
        }

        return ret;
    }

};

YAHOO.util.Selector = Selector;
/**
 * The selector module provides helper methods allowing CSS2 Selectors to be used with DOM elements.
 * @module dom
 * @submodule selector-css2
 * @for Selector
 */

/**
 * Provides helper methods for collecting and filtering DOM elements.
 */

var PARENT_NODE = 'parentNode',
    TAG_NAME = 'tagName',
    ATTRIBUTES = 'attributes',
    COMBINATOR = 'combinator',
    PSEUDOS = 'pseudos',

    SelectorCSS2 = {
        _reRegExpTokens: /([\^\$\?\[\]\*\+\-\.\(\)\|\\])/, // TODO: move?
        SORT_RESULTS: true,
        _children: function(node, tag) {
            var ret = node.children,
                i,
                children = [],
                childNodes,
                child;

            if (node.children && tag && node.children.tags) {
                children = node.children.tags(tag);
            } else if ((!ret && node[TAG_NAME]) || (ret && tag)) { // only HTMLElements have children
                childNodes = ret || node.childNodes;
                ret = [];
                for (i = 0; (child = childNodes[i++]);) {
                    if (child.tagName) {
                        if (!tag || tag === child.tagName) {
                            ret.push(child);
                        }
                    }
                }
            }

            return ret || [];
        },

        _re: {
            //attr: /(\[.*\])/g,
            attr: /(\[[^\]]*\])/g,
            //esc: /\\[:\[][\w\d\]]*/gi,
            esc: /\\[:\[\]\(\)#\.\'\>+~"]/gi,
            //pseudos: /:([\-\w]+(?:\(?:['"]?(.+)['"]?\))*)/i
            pseudos: /(\([^\)]*\))/g
        },

        /**
         * Mapping of shorthand tokens to corresponding attribute selector 
         * @property shorthand
         * @type object
         */
        shorthand: {
            //'\\#([^\\s\\\\(\\[:]*)': '[id=$1]',
            '\\#(-?[_a-z]+[-\\w\\uE000]*)': '[id=$1]',
            //'\\#([^\\s\\\.:\\[\\]]*)': '[id=$1]',
            //'\\.([^\\s\\\\(\\[:]*)': '[className=$1]'
            '\\.(-?[_a-z]+[-\\w\\uE000]*)': '[className~=$1]'
        },

        /**
         * List of operators and corresponding boolean functions. 
         * These functions are passed the attribute and the current node's value of the attribute.
         * @property operators
         * @type object
         */
        operators: {
            '': function(node, attr) { return !!node.getAttribute(attr); }, // Just test for existence of attribute
            //'': '.+',
            //'=': '^{val}$', // equality
            '~=': '(?:^|\\s+){val}(?:\\s+|$)', // space-delimited
            '|=': '^{val}(?:-|$)' // optional hyphen-delimited
        },

        pseudos: {
           'first-child': function(node) { 
                return Selector._children(node[PARENT_NODE])[0] === node; 
            } 
        },

        _bruteQuery: function(selector, root, firstOnly) {
            var ret = [],
                nodes = [],
                tokens = Selector._tokenize(selector),
                token = tokens[tokens.length - 1],
                rootDoc = Y_getDoc(root),
                child,
                id,
                className,
                tagName;


            // if we have an initial ID, set to root when in document
            /*
            if (tokens[0] && rootDoc === root &&  
                    (id = tokens[0].id) &&
                    rootDoc.getElementById(id)) {
                root = rootDoc.getElementById(id);
            }
            */

            if (token) {
                // prefilter nodes
                id = token.id;
                className = token.className;
                tagName = token.tagName || '*';

                if (root.getElementsByTagName) { // non-IE lacks DOM api on doc frags
                    // try ID first, unless no root.all && root not in document
                    // (root.all works off document, but not getElementById)
                    // TODO: move to allById?
                    if (id && (root.all || (root.nodeType === 9 || Y_DOM_inDoc(root)))) {
                        nodes = Y_DOM_allById(id, root);
                    // try className
                    } else if (className) {
                        nodes = root.getElementsByClassName(className);
                    } else { // default to tagName
                        nodes = root.getElementsByTagName(tagName);
                    }

                } else { // brute getElementsByTagName('*')
                    child = root.firstChild;
                    while (child) {
                        if (child.tagName) { // only collect HTMLElements
                            nodes.push(child);
                        }
                        child = child.nextSilbing || child.firstChild;
                    }
                }
                if (nodes.length) {
                    ret = Selector._filterNodes(nodes, tokens, firstOnly);
                }
            }

            return ret;
        },
        
        _filterNodes: function(nodes, tokens, firstOnly) {
            var i = 0,
                j,
                len = tokens.length,
                n = len - 1,
                result = [],
                node = nodes[0],
                tmpNode = node,
                getters = Selector.getters,
                operator,
                combinator,
                token,
                path,
                pass,
                //FUNCTION = 'function',
                value,
                tests,
                test;

            //do {
            for (i = 0; (tmpNode = node = nodes[i++]);) {
                n = len - 1;
                path = null;
                
                testLoop:
                while (tmpNode && tmpNode.tagName) {
                    token = tokens[n];
                    tests = token.tests;
                    j = tests.length;
                    if (j && !pass) {
                        while ((test = tests[--j])) {
                            operator = test[1];
                            if (getters[test[0]]) {
                                value = getters[test[0]](tmpNode, test[0]);
                            } else {
                                value = tmpNode[test[0]];
                                // use getAttribute for non-standard attributes
                                if (value === undefined && tmpNode.getAttribute) {
                                    value = tmpNode.getAttribute(test[0]);
                                }
                            }

                            if ((operator === '=' && value !== test[2]) ||  // fast path for equality
                                (typeof operator !== 'string' && // protect against String.test monkey-patch (Moo)
                                operator.test && !operator.test(value)) ||  // regex test
                                (!operator.test && // protect against RegExp as function (webkit)
                                        typeof operator === 'function' && !operator(tmpNode, test[0], test[2]))) { // function test

                                // skip non element nodes or non-matching tags
                                if ((tmpNode = tmpNode[path])) {
                                    while (tmpNode &&
                                        (!tmpNode.tagName ||
                                            (token.tagName && token.tagName !== tmpNode.tagName))
                                    ) {
                                        tmpNode = tmpNode[path]; 
                                    }
                                }
                                continue testLoop;
                            }
                        }
                    }

                    n--; // move to next token
                    // now that we've passed the test, move up the tree by combinator
                    if (!pass && (combinator = token.combinator)) {
                        path = combinator.axis;
                        tmpNode = tmpNode[path];

                        // skip non element nodes
                        while (tmpNode && !tmpNode.tagName) {
                            tmpNode = tmpNode[path]; 
                        }

                        if (combinator.direct) { // one pass only
                            path = null; 
                        }

                    } else { // success if we made it this far
                        result.push(node);
                        if (firstOnly) {
                            return result;
                        }
                        break;
                    }
                }
            }// while (tmpNode = node = nodes[++i]);
            node = tmpNode = null;
            return result;
        },

        combinators: {
            ' ': {
                axis: 'parentNode'
            },

            '>': {
                axis: 'parentNode',
                direct: true
            },


            '+': {
                axis: 'previousSibling',
                direct: true
            }
        },

        _parsers: [
            {
                name: ATTRIBUTES,
                //re: /^\[(-?[a-z]+[\w\-]*)+([~\|\^\$\*!=]=?)?['"]?([^\]]*?)['"]?\]/i,
                re: /^\uE003(-?[a-z]+[\w\-]*)+([~\|\^\$\*!=]=?)?['"]?([^\uE004'"]*)['"]?\uE004/i,
                fn: function(match, token) {
                    var operator = match[2] || '',
                        operators = Selector.operators,
                        escVal = (match[3]) ? match[3].replace(/\\/g, '') : '',
                        test;

                    // add prefiltering for ID and CLASS
                    if ((match[1] === 'id' && operator === '=') ||
                            (match[1] === 'className' &&
                            Y_DOCUMENT_ELEMENT.getElementsByClassName &&
                            (operator === '~=' || operator === '='))) {
                        token.prefilter = match[1];


                        match[3] = escVal; 

                        // escape all but ID for prefilter, which may run through QSA (via Dom.allById)
                        token[match[1]] = (match[1] === 'id') ? match[3] : escVal;

                    }

                    // add tests
                    if (operator in operators) {
                        test = operators[operator];
                        if (typeof test === 'string') {
                            match[3] = escVal.replace(Selector._reRegExpTokens, '\\$1');
                            test = new RegExp(test.replace('{val}', match[3]));
                        }
                        match[2] = test;
                    }
                    if (!token.last || token.prefilter !== match[1]) {
                        return match.slice(1);
                    }
                }

            },
            {
                name: TAG_NAME,
                re: /^((?:-?[_a-z]+[\w-]*)|\*)/i,
                fn: function(match, token) {
                    var tag = match[1].toUpperCase();
                    token.tagName = tag;

                    if (tag !== '*' && (!token.last || token.prefilter)) {
                        return [TAG_NAME, '=', tag];
                    }
                    if (!token.prefilter) {
                        token.prefilter = 'tagName';
                    }
                }
            },
            {
                name: COMBINATOR,
                re: /^\s*([>+~]|\s)\s*/,
                fn: function(match, token) {
                }
            },
            {
                name: PSEUDOS,
                re: /^:([\-\w]+)(?:\uE005['"]?([^\uE005]*)['"]?\uE006)*/i,
                fn: function(match, token) {
                    var test = Selector[PSEUDOS][match[1]];
                    if (test) { // reorder match array and unescape special chars for tests
                        if (match[2]) {
                            match[2] = match[2].replace(/\\/g, '');
                        }
                        return [match[2], test]; 
                    } else { // selector token not supported (possibly missing CSS3 module)
                        return false;
                    }
                }
            }
            ],

        _getToken: function(token) {
            return {
                tagName: null,
                id: null,
                className: null,
                attributes: {},
                combinator: null,
                tests: []
            };
        },

        /**
            Break selector into token units per simple selector.
            Combinator is attached to the previous token.
         */
        _tokenize: function(selector) {
            selector = selector || '';
            selector = Selector._replaceShorthand(Y_Lang.trim(selector)); 
            var token = Selector._getToken(),     // one token per simple selector (left selector holds combinator)
                query = selector, // original query for debug report
                tokens = [],    // array of tokens
                found = false,  // whether or not any matches were found this pass
                match,         // the regex match
                test,
                i, parser;

            /*
                Search for selector patterns, store, and strip them from the selector string
                until no patterns match (invalid selector) or we run out of chars.

                Multiple attributes and pseudos are allowed, in any order.
                for example:
                    'form:first-child[type=button]:not(button)[lang|=en]'
            */

            outer:
            do {
                found = false; // reset after full pass

                for (i = 0; (parser = Selector._parsers[i++]);) {
                    if ( (match = parser.re.exec(selector)) ) { // note assignment
                        if (parser.name !== COMBINATOR ) {
                            token.selector = selector;
                        }
                        selector = selector.replace(match[0], ''); // strip current match from selector
                        if (!selector.length) {
                            token.last = true;
                        }

                        if (Selector._attrFilters[match[1]]) { // convert class to className, etc.
                            match[1] = Selector._attrFilters[match[1]];
                        }

                        test = parser.fn(match, token);
                        if (test === false) { // selector not supported
                            found = false;
                            break outer;
                        } else if (test) {
                            token.tests.push(test);
                        }

                        if (!selector.length || parser.name === COMBINATOR) {
                            tokens.push(token);
                            token = Selector._getToken(token);
                            if (parser.name === COMBINATOR) {
                                token.combinator = Selector.combinators[match[1]];
                            }
                        }
                        found = true;


                    }
                }
            } while (found && selector.length);

            if (!found || selector.length) { // not fully parsed
                tokens = [];
            }
            return tokens;
        },

        _replaceShorthand: function(selector) {
            var shorthand = Selector.shorthand,
                esc = selector.match(Selector._re.esc), // pull escaped colon, brackets, etc. 
                attrs,
                pseudos,
                re, i, len;

            if (esc) {
                selector = selector.replace(Selector._re.esc, '\uE000');
            }

            attrs = selector.match(Selector._re.attr);
            pseudos = selector.match(Selector._re.pseudos);

            if (attrs) {
                selector = selector.replace(Selector._re.attr, '\uE001');
            }

            if (pseudos) {
                selector = selector.replace(Selector._re.pseudos, '\uE002');
            }


            for (re in shorthand) {
                if (shorthand.hasOwnProperty(re)) {
                    selector = selector.replace(new RegExp(re, 'gi'), shorthand[re]);
                }
            }

            if (attrs) {
                for (i = 0, len = attrs.length; i < len; ++i) {
                    selector = selector.replace(/\uE001/, attrs[i]);
                }
            }

            if (pseudos) {
                for (i = 0, len = pseudos.length; i < len; ++i) {
                    selector = selector.replace(/\uE002/, pseudos[i]);
                }
            }

            selector = selector.replace(/\[/g, '\uE003');
            selector = selector.replace(/\]/g, '\uE004');

            selector = selector.replace(/\(/g, '\uE005');
            selector = selector.replace(/\)/g, '\uE006');

            if (esc) {
                for (i = 0, len = esc.length; i < len; ++i) {
                    selector = selector.replace('\uE000', esc[i]);
                }
            }

            return selector;
        },

        _attrFilters: {
            'class': 'className',
            'for': 'htmlFor'
        },

        getters: {
            href: function(node, attr) {
                return Y_DOM.getAttribute(node, attr);
            }
        }
    };

Y_mix(Selector, SelectorCSS2, true);
Selector.getters.src = Selector.getters.rel = Selector.getters.href;

// IE wants class with native queries
if (Selector.useNative && Y_DOC.querySelector) {
    Selector.shorthand['\\.([^\\s\\\\(\\[:]*)'] = '[class~=$1]';
}

/**
 * The selector css3 module provides support for css3 selectors.
 * @module dom
 * @submodule selector-css3
 * @for Selector
 */

/*
    an+b = get every _a_th node starting at the _b_th
    0n+b = no repeat ("0" and "n" may both be omitted (together) , e.g. "0n+1" or "1", not "0+1"), return only the _b_th element
    1n+b =  get every element starting from b ("1" may may be omitted, e.g. "1n+0" or "n+0" or "n")
    an+0 = get every _a_th element, "0" may be omitted 
*/

Selector._reNth = /^(?:([\-]?\d*)(n){1}|(odd|even)$)*([\-+]?\d*)$/;

Selector._getNth = function(node, expr, tag, reverse) {
    Selector._reNth.test(expr);
    var a = parseInt(RegExp.$1, 10), // include every _a_ elements (zero means no repeat, just first _a_)
        n = RegExp.$2, // "n"
        oddeven = RegExp.$3, // "odd" or "even"
        b = parseInt(RegExp.$4, 10) || 0, // start scan from element _b_
        result = [],
        siblings = Selector._children(node.parentNode, tag),
        op;

    if (oddeven) {
        a = 2; // always every other
        op = '+';
        n = 'n';
        b = (oddeven === 'odd') ? 1 : 0;
    } else if ( isNaN(a) ) {
        a = (n) ? 1 : 0; // start from the first or no repeat
    }

    if (a === 0) { // just the first
        if (reverse) {
            b = siblings.length - b + 1; 
        }

        if (siblings[b - 1] === node) {
            return true;
        } else {
            return false;
        }

    } else if (a < 0) {
        reverse = !!reverse;
        a = Math.abs(a);
    }

    if (!reverse) {
        for (var i = b - 1, len = siblings.length; i < len; i += a) {
            if ( i >= 0 && siblings[i] === node ) {
                return true;
            }
        }
    } else {
        for (var i = siblings.length - b, len = siblings.length; i >= 0; i -= a) {
            if ( i < len && siblings[i] === node ) {
                return true;
            }
        }
    }
    return false;
};

Y_mix(Selector.pseudos, {
    'root': function(node) {
        return node === node.ownerDocument.documentElement;
    },

    'nth-child': function(node, expr) {
        return Selector._getNth(node, expr);
    },

    'nth-last-child': function(node, expr) {
        return Selector._getNth(node, expr, null, true);
    },

    'nth-of-type': function(node, expr) {
        return Selector._getNth(node, expr, node.tagName);
    },
     
    'nth-last-of-type': function(node, expr) {
        return Selector._getNth(node, expr, node.tagName, true);
    },
     
    'last-child': function(node) {
        var children = Selector._children(node.parentNode);
        return children[children.length - 1] === node;
    },

    'first-of-type': function(node) {
        return Selector._children(node.parentNode, node.tagName)[0] === node;
    },
     
    'last-of-type': function(node) {
        var children = Selector._children(node.parentNode, node.tagName);
        return children[children.length - 1] === node;
    },
     
    'only-child': function(node) {
        var children = Selector._children(node.parentNode);
        return children.length === 1 && children[0] === node;
    },

    'only-of-type': function(node) {
        var children = Selector._children(node.parentNode, node.tagName);
        return children.length === 1 && children[0] === node;
    },

    'empty': function(node) {
        return node.childNodes.length === 0;
    },

    'not': function(node, expr) {
        return !Selector.test(node, expr);
    },

    'contains': function(node, expr) {
        var text = node.innerText || node.textContent || '';
        return text.indexOf(expr) > -1;
    },

    'checked': function(node) {
        return (node.checked === true || node.selected === true);
    },

    enabled: function(node) {
        return (node.disabled !== undefined && !node.disabled);
    },

    disabled: function(node) {
        return (node.disabled);
    }
});

Y_mix(Selector.operators, {
    '^=': '^{val}', // Match starts with value
    '!=': function(node, attr, val) { return node[attr] !== val; }, // Match starts with value
    '$=': '{val}$', // Match ends with value
    '*=': '{val}' // Match contains value as substring 
});

Selector.combinators['~'] = {
    axis: 'previousSibling'
};
YAHOO.register("selector", YAHOO.util.Selector, {version: "2.9.0", build: "2800"});