Yahoo! UI Library

(function(Y) {
/**
 * 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
 */

Y.namespace('Selector'); // allow native module to standalone

var COMPARE_DOCUMENT_POSITION = 'compareDocumentPosition',
    OWNER_DOCUMENT = 'ownerDocument',
    TMP_PREFIX = 'yui-tmp-',
    g_counter = 0;

var Selector = {
    _foundCache: [],

    useNative: true,

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

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

            return -1;

        } : (document.documentElement[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) {
        root = root || Y.config.doc;
        var ret = [],
            useNative = (Y.Selector.useNative && document.querySelector && !skipNative),
            queries = [[selector, root]],
            query,
            result,
            i,
            fn = (useNative) ? Y.Selector._nativeQuery : Y.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));
            }
        }

        Y.log('query: ' + selector + ' returning: ' + ret.length, 'info', 'Selector');
        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 = '#' + 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) {
        try {
            //Y.log('trying native query with: ' + selector, 'info', 'selector-native');
            return root['querySelector' + (one ? '' : 'All')](selector);
        } catch(e) { // fallback to brute if available
            //Y.log('native query error; reverting to brute query with: ' + selector, 'info', 'selector-native');
            return Y.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 (Y.Selector.test(node, selector)) {
                    ret[ret.length] = node;
                }
            }
        } else {
            Y.log('invalid filter input (nodes: ' + nodes +
                    ', selector: ' + selector + ')', 'warn', 'Selector');
        }

        return ret;
    },

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

        if (node && node.tagName) { // only test HTMLElements
            root = root || node.ownerDocument;

            if (!node.id) {
                node.id = TMP_PREFIX + g_counter++;
            }
            for (i = 0; (group = groups[i++]);) { // TODO: off-dom test
                group += '#' + node.id; // add ID for uniqueness
                item = Y.Selector.query(group, root, true);
                ret = (item === node);
                if (ret) {
                    break;
                }
            }
        }

        return ret;
    }
};

Y.mix(Y.Selector, Selector, true);

})(Y);