    /**
     * @class Ext.ComponentQuery
     * @extends Object
     * @singleton
     *
     * Provides searching of Components within Ext.ComponentManager (globally) or a specific
     * Ext.container.Container on the document with a similar syntax to a CSS selector.
     *
     * Components can be retrieved by using their {@link Ext.Component xtype} with an optional . prefix
     *
     * - `component` or `.component`
     * - `gridpanel` or `.gridpanel`
     *
     * An itemId or id must be prefixed with a #
     *
     * - `#myContainer`
     *
     * Attributes must be wrapped in brackets
     *
     * - `component[autoScroll]`
     * - `panel[title="Test"]`
     *
     * Member expressions from candidate Components may be tested. If the expression returns a *truthy* value,
     * the candidate Component will be included in the query:
     *
     *     var disabledFields = myFormPanel.query("{isDisabled()}");
     *
     * Pseudo classes may be used to filter results in the same way as in {@link Ext.DomQuery DomQuery}:
     *
     *     // Function receives array and returns a filtered array.
     *     Ext.ComponentQuery.pseudos.invalid = function(items) {
     *         var i = 0, l = items.length, c, result = [];
     *         for (; i < l; i++) {
     *             if (!(c = items[i]).isValid()) {
     *                 result.push(c);
     *             }
     *         }
     *         return result;
     *     };
     *
     *     var invalidFields = myFormPanel.query('field:invalid');
     *     if (invalidFields.length) {
     *         invalidFields[0].getEl().scrollIntoView(myFormPanel.body);
     *         for (var i = 0, l = invalidFields.length; i < l; i++) {
     *             invalidFields[i].getEl().frame("red");
     *         }
     *     }
     *
     * Default pseudos include:
     *
     * - not
     *
     * Queries return an array of components.
     * Here are some example queries.
     *
     *     // retrieve all Ext.Panels in the document by xtype
     *     var panelsArray = Ext.ComponentQuery.query('panel');
     *
     *     // retrieve all Ext.Panels within the container with an id myCt
     *     var panelsWithinmyCt = Ext.ComponentQuery.query('#myCt panel');
     *
     *     // retrieve all direct children which are Ext.Panels within myCt
     *     var directChildPanel = Ext.ComponentQuery.query('#myCt > panel');
     *
     *     // retrieve all grids and trees
     *     var gridsAndTrees = Ext.ComponentQuery.query('gridpanel, treepanel');
     *
     * For easy access to queries based from a particular Container see the {@link Ext.container.Container#query},
     * {@link Ext.container.Container#down} and {@link Ext.container.Container#child} methods. Also see
     * {@link Ext.Component#up}.
     */
    Ext.define('Ext.ComponentQuery', {
        singleton: true,
        uses: ['Ext.ComponentManager']
    }, function() {

        var cq = this,

            // A function source code pattern with a placeholder which accepts an expression which yields a truth value when applied
            // as a member on each item in the passed array.
            filterFnPattern = [
                'var r = [],',
                    'i = 0,',
                    'it = items,',
                    'l = it.length,',
                    'c;',
                'for (; i < l; i++) {',
                    'c = it[i];',
                    'if (c.{0}) {',
                       'r.push(c);',
                    '}',
                '}',
                'return r;'
            ].join(''),

            filterItems = function(items, operation) {
                // Argument list for the operation is [ itemsArray, operationArg1, operationArg2...]
                // The operation's method loops over each item in the candidate array and
                // returns an array of items which match its criteria
                return operation.method.apply(this, [ items ].concat(operation.args));
            },

            getItems = function(items, mode) {
                var result = [],
                    i = 0,
                    length = items.length,
                    candidate,
                    deep = mode !== '>';

                for (; i < length; i++) {
                    candidate = items[i];
                    if (candidate.getRefItems) {
                        result = result.concat(candidate.getRefItems(deep));
                    }
                }
                return result;
            },

            getAncestors = function(items) {
                var result = [],
                    i = 0,
                    length = items.length,
                    candidate;
                for (; i < length; i++) {
                    candidate = items[i];
                    while (!!(candidate = (candidate.ownerCt || candidate.floatParent))) {
                        result.push(candidate);
                    }
                }
                return result;
            },

            // Filters the passed candidate array and returns only items which match the passed xtype
            filterByXType = function(items, xtype, shallow) {
                if (xtype === '*') {
                    return items.slice();
                }
                else {
                    var result = [],
                        i = 0,
                        length = items.length,
                        candidate;
                    for (; i < length; i++) {
                        candidate = items[i];
                        if (candidate.isXType(xtype, shallow)) {
                            result.push(candidate);
                        }
                    }
                    return result;
                }
            },

            // Filters the passed candidate array and returns only items which have the passed className
            filterByClassName = function(items, className) {
                var EA = Ext.Array,
                    result = [],
                    i = 0,
                    length = items.length,
                    candidate;
                for (; i < length; i++) {
                    candidate = items[i];
                    if (candidate.el ? candidate.el.hasCls(className) : EA.contains(candidate.initCls(), className)) {
                        result.push(candidate);
                    }
                }
                return result;
            },

            // Filters the passed candidate array and returns only items which have the specified property match
            filterByAttribute = function(items, property, operator, value) {
                var result = [],
                    i = 0,
                    length = items.length,
                    candidate;
                for (; i < length; i++) {
                    candidate = items[i];
                    if (!value ? !!candidate[property] : (String(candidate[property]) === value)) {
                        result.push(candidate);
                    }
                }
                return result;
            },

            // Filters the passed candidate array and returns only items which have the specified itemId or id
            filterById = function(items, id) {
                var result = [],
                    i = 0,
                    length = items.length,
                    candidate;
                for (; i < length; i++) {
                    candidate = items[i];
                    if (candidate.getItemId() === id) {
                        result.push(candidate);
                    }
                }
                return result;
            },

            // Filters the passed candidate array and returns only items which the named pseudo class matcher filters in
            filterByPseudo = function(items, name, value) {
                return cq.pseudos[name](items, value);
            },

            // Determines leading mode
            // > for direct child, and ^ to switch to ownerCt axis
            modeRe = /^(\s?([>\^])\s?|\s|$)/,

            // Matches a token with possibly (true|false) appended for the "shallow" parameter
            tokenRe = /^(#)?([\w\-]+|\*)(?:\((true|false)\))?/,

            matchers = [{
                // Checks for .xtype with possibly (true|false) appended for the "shallow" parameter
                re: /^\.([\w\-]+)(?:\((true|false)\))?/,
                method: filterByXType
            },{
                // checks for [attribute=value]
                re: /^(?:[\[](?:@)?([\w\-]+)\s?(?:(=|.=)\s?['"]?(.*?)["']?)?[\]])/,
                method: filterByAttribute
            }, {
                // checks for #cmpItemId
                re: /^#([\w\-]+)/,
                method: filterById
            }, {
                // checks for :<pseudo_class>(<selector>)
                re: /^\:([\w\-]+)(?:\(((?:\{[^\}]+\})|(?:(?!\{)[^\s>\/]*?(?!\})))\))?/,
                method: filterByPseudo
            }, {
                // checks for {<member_expression>}
                re: /^(?:\{([^\}]+)\})/,
                method: filterFnPattern
            }];

        /**
         * @class Ext.ComponentQuery.Query
         * @extends Object
         * @private
         */
        cq.Query = Ext.extend(Object, {
            constructor: function(cfg) {
                cfg = cfg || {};
                Ext.apply(this, cfg);
            },

            /**
             * @private
             * Executes this Query upon the selected root.
             * The root provides the initial source of candidate Component matches which are progressively
             * filtered by iterating through this Query's operations cache.
             * If no root is provided, all registered Components are searched via the ComponentManager.
             * root may be a Container who's descendant Components are filtered
             * root may be a Component with an implementation of getRefItems which provides some nested Components such as the
             * docked items within a Panel.
             * root may be an array of candidate Components to filter using this Query.
             */
            execute : function(root) {
                var operations = this.operations,
                    i = 0,
                    length = operations.length,
                    operation,
                    workingItems;

                // no root, use all Components in the document
                if (!root) {
                    workingItems = Ext.ComponentManager.all.getArray();
                }
                // Root is a candidate Array
                else if (Ext.isArray(root)) {
                    workingItems = root;
                }

                // We are going to loop over our operations and take care of them
                // one by one.
                for (; i < length; i++) {
                    operation = operations[i];

                    // The mode operation requires some custom handling.
                    // All other operations essentially filter down our current
                    // working items, while mode replaces our current working
                    // items by getting children from each one of our current
                    // working items. The type of mode determines the type of
                    // children we get. (e.g. > only gets direct children)
                    if (operation.mode === '^') {
                        workingItems = getAncestors(workingItems || [root]);
                    }
                    else if (operation.mode) {
                        workingItems = getItems(workingItems || [root], operation.mode);
                    }
                    else {
                        workingItems = filterItems(workingItems || getItems([root]), operation);
                    }

                    // If this is the last operation, it means our current working
                    // items are the final matched items. Thus return them!
                    if (i === length -1) {
                        return workingItems;
                    }
                }
                return [];
            },

            is: function(component) {
                var operations = this.operations,
                    components = Ext.isArray(component) ? component : [component],
                    originalLength = components.length,
                    lastOperation = operations[operations.length-1],
                    ln, i;

                components = filterItems(components, lastOperation);
                if (components.length === originalLength) {
                    if (operations.length > 1) {
                        for (i = 0, ln = components.length; i < ln; i++) {
                            if (Ext.Array.indexOf(this.execute(), components[i]) === -1) {
                                return false;
                            }
                        }
                    }
                    return true;
                }
                return false;
            }
        });

        Ext.apply(this, {

            // private cache of selectors and matching ComponentQuery.Query objects
            cache: {},

            // private cache of pseudo class filter functions
            pseudos: {
                not: function(components, selector){
                    var CQ = Ext.ComponentQuery,
                        i = 0,
                        length = components.length,
                        results = [],
                        index = -1,
                        component;

                    for(; i < length; ++i) {
                        component = components[i];
                        if (!CQ.is(component, selector)) {
                            results[++index] = component;
                        }
                    }
                    return results;
                }
            },

            /**
             * Returns an array of matched Components from within the passed root object.
             *
             * This method filters returned Components in a similar way to how CSS selector based DOM
             * queries work using a textual selector string.
             *
             * See class summary for details.
             *
             * @param {String} selector The selector string to filter returned Components
             * @param {Ext.container.Container} root The Container within which to perform the query.
             * If omitted, all Components within the document are included in the search.
             *
             * This parameter may also be an array of Components to filter according to the selector.</p>
             * @returns {[Ext.Component]} The matched Components.
             *
             * @member Ext.ComponentQuery
             */
            query: function(selector, root) {
                var selectors = selector.split(','),
                    length = selectors.length,
                    i = 0,
                    results = [],
                    noDupResults = [],
                    dupMatcher = {},
                    query, resultsLn, cmp;

                for (; i < length; i++) {
                    selector = Ext.String.trim(selectors[i]);
                    query = this.cache[selector];
                    if (!query) {
                        this.cache[selector] = query = this.parse(selector);
                    }
                    results = results.concat(query.execute(root));
                }

                // multiple selectors, potential to find duplicates
                // lets filter them out.
                if (length > 1) {
                    resultsLn = results.length;
                    for (i = 0; i < resultsLn; i++) {
                        cmp = results[i];
                        if (!dupMatcher[cmp.id]) {
                            noDupResults.push(cmp);
                            dupMatcher[cmp.id] = true;
                        }
                    }
                    results = noDupResults;
                }
                return results;
            },

            /**
             * Tests whether the passed Component matches the selector string.
             * @param {Ext.Component} component The Component to test
             * @param {String} selector The selector string to test against.
             * @return {Boolean} True if the Component matches the selector.
             * @member Ext.ComponentQuery
             */
            is: function(component, selector) {
                if (!selector) {
                    return true;
                }
                var query = this.cache[selector];
                if (!query) {
                    this.cache[selector] = query = this.parse(selector);
                }
                return query.is(component);
            },

            parse: function(selector) {
                var operations = [],
                    length = matchers.length,
                    lastSelector,
                    tokenMatch,
                    matchedChar,
                    modeMatch,
                    selectorMatch,
                    i, matcher, method;

                // We are going to parse the beginning of the selector over and
                // over again, slicing off the selector any portions we converted into an
                // operation, until it is an empty string.
                while (selector && lastSelector !== selector) {
                    lastSelector = selector;

                    // First we check if we are dealing with a token like #, * or an xtype
                    tokenMatch = selector.match(tokenRe);

                    if (tokenMatch) {
                        matchedChar = tokenMatch[1];

                        // If the token is prefixed with a # we push a filterById operation to our stack
                        if (matchedChar === '#') {
                            operations.push({
                                method: filterById,
                                args: [Ext.String.trim(tokenMatch[2])]
                            });
                        }
                        // If the token is prefixed with a . we push a filterByClassName operation to our stack
                        // FIXME: Not enabled yet. just needs \. adding to the tokenRe prefix
                        else if (matchedChar === '.') {
                            operations.push({
                                method: filterByClassName,
                                args: [Ext.String.trim(tokenMatch[2])]
                            });
                        }
                        // If the token is a * or an xtype string, we push a filterByXType
                        // operation to the stack.
                        else {
                            operations.push({
                                method: filterByXType,
                                args: [Ext.String.trim(tokenMatch[2]), Boolean(tokenMatch[3])]
                            });
                        }

                        // Now we slice of the part we just converted into an operation
                        selector = selector.replace(tokenMatch[0], '');
                    }

                    // If the next part of the query is not a space or > or ^, it means we
                    // are going to check for more things that our current selection
                    // has to comply to.
                    while (!(modeMatch = selector.match(modeRe))) {
                        // Lets loop over each type of matcher and execute it
                        // on our current selector.
                        for (i = 0; selector && i < length; i++) {
                            matcher = matchers[i];
                            selectorMatch = selector.match(matcher.re);
                            method = matcher.method;

                            // If we have a match, add an operation with the method
                            // associated with this matcher, and pass the regular
                            // expression matches are arguments to the operation.
                            if (selectorMatch) {
                                operations.push({
                                    method: Ext.isString(matcher.method)
                                        // Turn a string method into a function by formatting the string with our selector matche expression
                                        // A new method is created for different match expressions, eg {id=='textfield-1024'}
                                        // Every expression may be different in different selectors.
                                        ? Ext.functionFactory('items', Ext.String.format.apply(Ext.String, [method].concat(selectorMatch.slice(1))))
                                        : matcher.method,
                                    args: selectorMatch.slice(1)
                                });
                                selector = selector.replace(selectorMatch[0], '');
                                break; // Break on match
                            }
                            //<debug>
                            // Exhausted all matches: It's an error
                            if (i === (length - 1)) {
                                Ext.Error.raise('Invalid ComponentQuery selector: "' + arguments[0] + '"');
                            }
                            //</debug>
                        }
                    }

                    // Now we are going to check for a mode change. This means a space
                    // or a > to determine if we are going to select all the children
                    // of the currently matched items, or a ^ if we are going to use the
                    // ownerCt axis as the candidate source.
                    if (modeMatch[1]) { // Assignment, and test for truthiness!
                        operations.push({
                            mode: modeMatch[2]||modeMatch[1]
                        });
                        selector = selector.replace(modeMatch[0], '');
                    }
                }

                //  Now that we have all our operations in an array, we are going
                // to create a new Query using these operations.
                return new cq.Query({
                    operations: operations
                });
            }
        });
    });