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                                /*jshint maxlen:200*/

                                /**
                                 * The attribute module provides an augmentable Attribute implementation, which
                                 * adds configurable attributes and attribute change events to the class being
                                 * augmented. It also provides a State class, which is used internally by Attribute,
                                 * but can also be used independently to provide a name/property/value data structure to
                                 * store state.
                                 *
                                 * @module attribute
                                 */

                                /**
                                 * The attribute-core submodule provides the lightest level of attribute handling support
                                 * without Attribute change events, or lesser used methods such as reset(), modifyAttrs(),
                                 * and removeAttr().
                                 *
                                 * @module attribute
                                 * @submodule attribute-core
                                 */
                                var O = Y.Object,
                                    Lang = Y.Lang,

                                    DOT = ".",

                                    // Externally configurable props
                                    GETTER = "getter",
                                    SETTER = "setter",
                                    READ_ONLY = "readOnly",
                                    WRITE_ONCE = "writeOnce",
                                    INIT_ONLY = "initOnly",
                                    VALIDATOR = "validator",
                                    VALUE = "value",
                                    VALUE_FN = "valueFn",
                                    LAZY_ADD = "lazyAdd",

                                    // Used for internal state management
                                    ADDED = "added",
                                    BYPASS_PROXY = "_bypassProxy",
                                    INIT_VALUE = "initValue",
                                    LAZY = "lazy",

                                    INVALID_VALUE;

                                /**
                                 * <p>
                                 * AttributeCore provides the lightest level of configurable attribute support. It is designed to be
                                 * augmented on to a host class, and provides the host with the ability to configure
                                 * attributes to store and retrieve state, <strong>but without support for attribute change events</strong>.
                                 * </p>
                                 * <p>For example, attributes added to the host can be configured:</p>
                                 * <ul>
                                 *     <li>As read only.</li>
                                 *     <li>As write once.</li>
                                 *     <li>With a setter function, which can be used to manipulate
                                 *     values passed to Attribute's <a href="#method_set">set</a> method, before they are stored.</li>
                                 *     <li>With a getter function, which can be used to manipulate stored values,
                                 *     before they are returned by Attribute's <a href="#method_get">get</a> method.</li>
                                 *     <li>With a validator function, to validate values before they are stored.</li>
                                 * </ul>
                                 *
                                 * <p>See the <a href="#method_addAttr">addAttr</a> method, for the complete set of configuration
                                 * options available for attributes.</p>
                                 *
                                 * <p>Object/Classes based on AttributeCore can augment <a href="AttributeObservable.html">AttributeObservable</a>
                                 * (with true for overwrite) and <a href="AttributeExtras.html">AttributeExtras</a> to add attribute event and
                                 * additional, less commonly used attribute methods, such as `modifyAttr`, `removeAttr` and `reset`.</p>
                                 *
                                 * @class AttributeCore
                                 * @param attrs {Object} The attributes to add during construction (passed through to <a href="#method_addAttrs">addAttrs</a>).
                                 *        These can also be defined on the constructor being augmented with Attribute by defining the ATTRS property on the constructor.
                                 * @param values {Object} The initial attribute values to apply (passed through to <a href="#method_addAttrs">addAttrs</a>).
                                 *        These are not merged/cloned. The caller is responsible for isolating user provided values if required.
                                 * @param lazy {boolean} Whether or not to add attributes lazily (passed through to <a href="#method_addAttrs">addAttrs</a>).
                                 */
                                function AttributeCore(attrs, values, lazy) {
                                    // HACK: Fix #2531929
                                    // Complete hack, to make sure the first clone of a node value in IE doesn't doesn't hurt state - maintains 3.4.1 behavior.
                                    // Too late in the release cycle to do anything about the core problem.
                                    // The root issue is that cloning a Y.Node instance results in an object which barfs in IE, when you access it's properties (since 3.3.0).
                                    this._yuievt = null;

                                    this._initAttrHost(attrs, values, lazy);
                                }

                                /**
                                 * <p>The value to return from an attribute setter in order to prevent the set from going through.</p>
                                 *
                                 * <p>You can return this value from your setter if you wish to combine validator and setter
                                 * functionality into a single setter function, which either returns the massaged value to be stored or
                                 * AttributeCore.INVALID_VALUE to prevent invalid values from being stored.</p>
                                 *
                                 * @property INVALID_VALUE
                                 * @type Object
                                 * @static
                                 * @final
                                 */
                                AttributeCore.INVALID_VALUE = {};
                                INVALID_VALUE = AttributeCore.INVALID_VALUE;

                                /**
                                 * The list of properties which can be configured for
                                 * each attribute (e.g. setter, getter, writeOnce etc.).
                                 *
                                 * This property is used internally as a whitelist for faster
                                 * Y.mix operations.
                                 *
                                 * @property _ATTR_CFG
                                 * @type Array
                                 * @static
                                 * @protected
                                 */
                                AttributeCore._ATTR_CFG = [SETTER, GETTER, VALIDATOR, VALUE, VALUE_FN, WRITE_ONCE, READ_ONLY, LAZY_ADD, BYPASS_PROXY];

                                /**
                                 * Utility method to protect an attribute configuration hash, by merging the
                                 * entire object and the individual attr config objects.
                                 *
                                 * @method protectAttrs
                                 * @static
                                 * @param {Object} attrs A hash of attribute to configuration object pairs.
                                 * @return {Object} A protected version of the `attrs` argument.
                                 */
                                AttributeCore.protectAttrs = function (attrs) {
                                    if (attrs) {
                                        attrs = Y.merge(attrs);
                                        for (var attr in attrs) {
                                            if (attrs.hasOwnProperty(attr)) {
                                                attrs[attr] = Y.merge(attrs[attr]);
                                            }
                                        }
                                    }

                                    return attrs;
                                };

                                AttributeCore.prototype = {

                                    /**
                                     * Constructor logic for attributes. Initializes the host state, and sets up the inital attributes passed to the
                                     * constructor.
                                     *
                                     * @method _initAttrHost
                                     * @param attrs {Object} The attributes to add during construction (passed through to <a href="#method_addAttrs">addAttrs</a>).
                                     *        These can also be defined on the constructor being augmented with Attribute by defining the ATTRS property on the constructor.
                                     * @param values {Object} The initial attribute values to apply (passed through to <a href="#method_addAttrs">addAttrs</a>).
                                     *        These are not merged/cloned. The caller is responsible for isolating user provided values if required.
                                     * @param lazy {boolean} Whether or not to add attributes lazily (passed through to <a href="#method_addAttrs">addAttrs</a>).
                                     * @private
                                     */
                                    _initAttrHost : function(attrs, values, lazy) {
                                        this._state = new Y.State();
                                        this._initAttrs(attrs, values, lazy);
                                    },

                                    /**
                                     * <p>
                                     * Adds an attribute with the provided configuration to the host object.
                                     * </p>
                                     * <p>
                                     * The config argument object supports the following properties:
                                     * </p>
                                     *
                                     * <dl>
                                     *    <dt>value &#60;Any&#62;</dt>
                                     *    <dd>The initial value to set on the attribute</dd>
                                     *
                                     *    <dt>valueFn &#60;Function | String&#62;</dt>
                                     *    <dd>
                                     *    <p>A function, which will return the initial value to set on the attribute. This is useful
                                     *    for cases where the attribute configuration is defined statically, but needs to
                                     *    reference the host instance ("this") to obtain an initial value. If both the value and valueFn properties are defined,
                                     *    the value returned by the valueFn has precedence over the value property, unless it returns undefined, in which
                                     *    case the value property is used.</p>
                                     *
                                     *    <p>valueFn can also be set to a string, representing the name of the instance method to be used to retrieve the value.</p>
                                     *    </dd>
                                     *
                                     *    <dt>readOnly &#60;boolean&#62;</dt>
                                     *    <dd>Whether or not the attribute is read only. Attributes having readOnly set to true
                                     *        cannot be modified by invoking the set method.</dd>
                                     *
                                     *    <dt>writeOnce &#60;boolean&#62; or &#60;string&#62;</dt>
                                     *    <dd>
                                     *        Whether or not the attribute is "write once". Attributes having writeOnce set to true,
                                     *        can only have their values set once, be it through the default configuration,
                                     *        constructor configuration arguments, or by invoking set.
                                     *        <p>The writeOnce attribute can also be set to the string "initOnly",
                                     *         in which case the attribute can only be set during initialization
                                     *        (when used with Base, this means it can only be set during construction)</p>
                                     *    </dd>
                                     *
                                     *    <dt>setter &#60;Function | String&#62;</dt>
                                     *    <dd>
                                     *    <p>The setter function used to massage or normalize the value passed to the set method for the attribute.
                                     *    The value returned by the setter will be the final stored value. Returning
                                     *    <a href="#property_Attribute.INVALID_VALUE">Attribute.INVALID_VALUE</a>, from the setter will prevent
                                     *    the value from being stored.
                                     *    </p>
                                     *
                                     *    <p>setter can also be set to a string, representing the name of the instance method to be used as the setter function.</p>
                                     *    </dd>
                                     *
                                     *    <dt>getter &#60;Function | String&#62;</dt>
                                     *    <dd>
                                     *    <p>
                                     *    The getter function used to massage or normalize the value returned by the get method for the attribute.
                                     *    The value returned by the getter function is the value which will be returned to the user when they
                                     *    invoke get.
                                     *    </p>
                                     *
                                     *    <p>getter can also be set to a string, representing the name of the instance method to be used as the getter function.</p>
                                     *    </dd>
                                     *
                                     *    <dt>validator &#60;Function | String&#62;</dt>
                                     *    <dd>
                                     *    <p>
                                     *    The validator function invoked prior to setting the stored value. Returning
                                     *    false from the validator function will prevent the value from being stored.
                                     *    </p>
                                     *
                                     *    <p>validator can also be set to a string, representing the name of the instance method to be used as the validator function.</p>
                                     *    </dd>
                                     *
                                     *    <dt>lazyAdd &#60;boolean&#62;</dt>
                                     *    <dd>Whether or not to delay initialization of the attribute until the first call to get/set it.
                                     *    This flag can be used to over-ride lazy initialization on a per attribute basis, when adding multiple attributes through
                                     *    the <a href="#method_addAttrs">addAttrs</a> method.</dd>
                                     *
                                     * </dl>
                                     *
                                     * <p>The setter, getter and validator are invoked with the value and name passed in as the first and second arguments, and with
                                     * the context ("this") set to the host object.</p>
                                     *
                                     * <p>Configuration properties outside of the list mentioned above are considered private properties used internally by attribute,
                                     * and are not intended for public use.</p>
                                     *
                                     * @method addAttr
                                     *
                                     * @param {String} name The name of the attribute.
                                     * @param {Object} config An object with attribute configuration property/value pairs, specifying the configuration for the attribute.
                                     *
                                     * <p>
                                     * <strong>NOTE:</strong> The configuration object is modified when adding an attribute, so if you need
                                     * to protect the original values, you will need to merge the object.
                                     * </p>
                                     *
                                     * @param {boolean} lazy (optional) Whether or not to add this attribute lazily (on the first call to get/set).
                                     *
                                     * @return {Object} A reference to the host object.
                                     *
                                     * @chainable
                                     */
                                    addAttr : function(name, config, lazy) {

                                        Y.log('Adding attribute: ' + name, 'info', 'attribute');

                                        var host = this, // help compression
                                            state = host._state,
                                            data = state.data,
                                            value,
                                            added,
                                            hasValue;

                                        config = config || {};

                                        if (LAZY_ADD in config) {
                                            lazy = config[LAZY_ADD];
                                        }

                                        added = state.get(name, ADDED);

                                        if (lazy && !added) {
                                            state.data[name] = {
                                                lazy : config,
                                                added : true
                                            };
                                        } else {

                                            if (added && !config.isLazyAdd) { Y.log('Attribute: ' + name + ' already exists. Cannot add it again without removing it first', 'warn', 'attribute'); }

                                            if (!added || config.isLazyAdd) {

                                                hasValue = (VALUE in config);

                                                if (config.readOnly && !hasValue) { Y.log('readOnly attribute: ' + name + ', added without an initial value. Value will be set on initial call to set', 'warn', 'attribute');}

                                                if (hasValue) {

                                                    // We'll go through set, don't want to set value in config directly

                                                    // PERF TODO: VALIDATE: See if setting this to undefined is sufficient. We use to delete before.
                                                    // In certain code paths/use cases, undefined may not be the same as not present.
                                                    // If not, we can set it to some known fixed value (like INVALID_VALUE, say INITIALIZING_VALUE) for performance,
                                                    // to avoid a delete which seems to help a lot.

                                                    value = config.value;
                                                    config.value = undefined;
                                                }

                                                config.added = true;
                                                config.initializing = true;

                                                data[name] = config;

                                                if (hasValue) {
                                                    // Go through set, so that raw values get normalized/validated
                                                    host.set(name, value);
                                                }

                                                config.initializing = false;
                                            }
                                        }

                                        return host;
                                    },

                                    /**
                                     * Checks if the given attribute has been added to the host
                                     *
                                     * @method attrAdded
                                     * @param {String} name The name of the attribute to check.
                                     * @return {boolean} true if an attribute with the given name has been added, false if it hasn't.
                                     *         This method will return true for lazily added attributes.
                                     */
                                    attrAdded: function(name) {
                                        return !!(this._state.get(name, ADDED));
                                    },

                                    /**
                                     * Returns the current value of the attribute. If the attribute
                                     * has been configured with a 'getter' function, this method will delegate
                                     * to the 'getter' to obtain the value of the attribute.
                                     *
                                     * @method get
                                     *
                                     * @param {String} name The name of the attribute. If the value of the attribute is an Object,
                                     * dot notation can be used to obtain the value of a property of the object (e.g. <code>get("x.y.z")</code>)
                                     *
                                     * @return {Any} The value of the attribute
                                     */
                                    get : function(name) {
                                        return this._getAttr(name);
                                    },

                                    /**
                                     * Checks whether or not the attribute is one which has been
                                     * added lazily and still requires initialization.
                                     *
                                     * @method _isLazyAttr
                                     * @private
                                     * @param {String} name The name of the attribute
                                     * @return {boolean} true if it's a lazily added attribute, false otherwise.
                                     */
                                    _isLazyAttr: function(name) {
                                        return this._state.get(name, LAZY);
                                    },

                                    /**
                                     * Finishes initializing an attribute which has been lazily added.
                                     *
                                     * @method _addLazyAttr
                                     * @private
                                     * @param {Object} name The name of the attribute
                                     * @param {Object} [lazyCfg] Optional config hash for the attribute. This is added for performance
                                     * along the critical path, where the calling method has already obtained lazy config from state.
                                     */
                                    _addLazyAttr: function(name, lazyCfg) {
                                        var state = this._state;

                                        lazyCfg = lazyCfg || state.get(name, LAZY);

                                        if (lazyCfg) {

                                            // PERF TODO: For App's id override, otherwise wouldn't be
                                            // needed. It expects to find it in the cfg for it's
                                            // addAttr override. Would like to remove, once App override is
                                            // removed.
                                            state.data[name].lazy = undefined;

                                            lazyCfg.isLazyAdd = true;

                                            this.addAttr(name, lazyCfg);
                                        }
                                    },

                                    /**
                                     * Sets the value of an attribute.
                                     *
                                     * @method set
                                     * @chainable
                                     *
                                     * @param {String} name The name of the attribute. If the
                                     * current value of the attribute is an Object, dot notation can be used
                                     * to set the value of a property within the object (e.g. <code>set("x.y.z", 5)</code>).
                                     * @param {Any} value The value to set the attribute to.
                                     * @param {Object} [opts] Optional data providing the circumstances for the change.
                                     * @return {Object} A reference to the host object.
                                     */
                                    set : function(name, val, opts) {
                                        return this._setAttr(name, val, opts);
                                    },

                                    /**
                                     * Allows setting of readOnly/writeOnce attributes. See <a href="#method_set">set</a> for argument details.
                                     *
                                     * @method _set
                                     * @protected
                                     * @chainable
                                     *
                                     * @param {String} name The name of the attribute.
                                     * @param {Any} val The value to set the attribute to.
                                     * @param {Object} [opts] Optional data providing the circumstances for the change.
                                     * @return {Object} A reference to the host object.
                                     */
                                    _set : function(name, val, opts) {
                                        return this._setAttr(name, val, opts, true);
                                    },

                                    /**
                                     * Provides the common implementation for the public set and protected _set methods.
                                     *
                                     * See <a href="#method_set">set</a> for argument details.
                                     *
                                     * @method _setAttr
                                     * @protected
                                     * @chainable
                                     *
                                     * @param {String} name The name of the attribute.
                                     * @param {Any} value The value to set the attribute to.
                                     * @param {Object} [opts] Optional data providing the circumstances for the change.
                                     * @param {boolean} force If true, allows the caller to set values for
                                     * readOnly or writeOnce attributes which have already been set.
                                     *
                                     * @return {Object} A reference to the host object.
                                     */
                                    _setAttr : function(name, val, opts, force)  {
                                        var allowSet = true,
                                            state = this._state,
                                            stateProxy = this._stateProxy,
                                            tCfgs = this._tCfgs,
                                            cfg,
                                            initialSet,
                                            strPath,
                                            path,
                                            currVal,
                                            writeOnce,
                                            initializing;

                                        if (name.indexOf(DOT) !== -1) {
                                            strPath = name;

                                            path = name.split(DOT);
                                            name = path.shift();
                                        }

                                        // On Demand - Should be rare - handles out of order valueFn, setter, getter references
                                        if (tCfgs && tCfgs[name]) {
                                            this._addOutOfOrder(name, tCfgs[name]);
                                        }

                                        cfg = state.data[name] || {};

                                        if (cfg.lazy) {
                                            cfg = cfg.lazy;
                                            this._addLazyAttr(name, cfg);
                                        }

                                        initialSet = (cfg.value === undefined);

                                        if (stateProxy && name in stateProxy && !cfg._bypassProxy) {
                                            // TODO: Value is always set for proxy. Can we do any better? Maybe take a snapshot as the initial value for the first call to set?
                                            initialSet = false;
                                        }

                                        writeOnce = cfg.writeOnce;
                                        initializing = cfg.initializing;

                                        if (!initialSet && !force) {

                                            if (writeOnce) {
                                                Y.log('Set attribute:' + name + ', aborted; Attribute is writeOnce', 'warn', 'attribute');
                                                allowSet = false;
                                            }

                                            if (cfg.readOnly) {
                                                Y.log('Set attribute:' + name + ', aborted; Attribute is readOnly', 'warn', 'attribute');
                                                allowSet = false;
                                            }
                                        }

                                        if (!initializing && !force && writeOnce === INIT_ONLY) {
                                            Y.log('Set attribute:' + name + ', aborted; Attribute is writeOnce: "initOnly"', 'warn', 'attribute');
                                            allowSet = false;
                                        }

                                        if (allowSet) {
                                            // Don't need currVal if initialSet (might fail in custom getter if it always expects a non-undefined/non-null value)
                                            if (!initialSet) {
                                                currVal =  this.get(name);
                                            }

                                            if (path) {
                                               val = O.setValue(Y.clone(currVal), path, val);

                                               if (val === undefined) {
                                                   Y.log('Set attribute path:' + strPath + ', aborted; Path is invalid', 'warn', 'attribute');
                                                   allowSet = false;
                                               }
                                            }

                                            if (allowSet) {
                                                if (!this._fireAttrChange || initializing) {
                                                    this._setAttrVal(name, strPath, currVal, val, opts, cfg);
                                                } else {
                                                    // HACK - no real reason core needs to know about _fireAttrChange, but
                                                    // it adds fn hops if we want to break it out. Not sure it's worth it for this critical path
                                                    this._fireAttrChange(name, strPath, currVal, val, opts, cfg);
                                                }
                                            }
                                        }

                                        return this;
                                    },

                                    /**
                                     * Utility method used by get/set to add attributes
                                     * encountered out of order when calling addAttrs().
                                     *
                                     * For example, if:
                                     *
                                     *     this.addAttrs({
                                     *          foo: {
                                     *              setter: function() {
                                     *                 // make sure this bar is available when foo is added
                                     *                 this.get("bar");
                                     *              }
                                     *          },
                                     *          bar: {
                                     *              value: ...
                                     *          }
                                     *     });
                                     *
                                     * @method _addOutOfOrder
                                     * @private
                                     * @param name {String} attribute name
                                     * @param cfg {Object} attribute configuration
                                     */
                                    _addOutOfOrder : function(name, cfg) {

                                        var attrs = {};
                                        attrs[name] = cfg;

                                        delete this._tCfgs[name];

                                        // TODO: The original code went through addAttrs, so
                                        // sticking with it for this pass. Seems like we could
                                        // just jump straight to _addAttr() and get some perf
                                        // improvement.
                                        this._addAttrs(attrs, this._tVals);
                                    },

                                    /**
                                     * Provides the common implementation for the public get method,
                                     * allowing Attribute hosts to over-ride either method.
                                     *
                                     * See <a href="#method_get">get</a> for argument details.
                                     *
                                     * @method _getAttr
                                     * @protected
                                     * @chainable
                                     *
                                     * @param {String} name The name of the attribute.
                                     * @return {Any} The value of the attribute.
                                     */
                                    _getAttr : function(name) {
                                        var fullName = name,
                                            tCfgs = this._tCfgs,
                                            path,
                                            getter,
                                            val,
                                            attrCfg;

                                        if (name.indexOf(DOT) !== -1) {
                                            path = name.split(DOT);
                                            name = path.shift();
                                        }

                                        // On Demand - Should be rare - handles out of
                                        // order valueFn, setter, getter references
                                        if (tCfgs && tCfgs[name]) {
                                            this._addOutOfOrder(name, tCfgs[name]);
                                        }

                                        attrCfg = this._state.data[name] || {};

                                        // Lazy Init
                                        if (attrCfg.lazy) {
                                            attrCfg = attrCfg.lazy;
                                            this._addLazyAttr(name, attrCfg);
                                        }

                                        val = this._getStateVal(name, attrCfg);

                                        getter = attrCfg.getter;

                                        if (getter && !getter.call) {
                                            getter = this[getter];
                                        }

                                        val = (getter) ? getter.call(this, val, fullName) : val;
                                        val = (path) ? O.getValue(val, path) : val;

                                        return val;
                                    },

                                    /**
                                     * Gets the stored value for the attribute, from either the
                                     * internal state object, or the state proxy if it exits
                                     *
                                     * @method _getStateVal
                                     * @private
                                     * @param {String} name The name of the attribute
                                     * @param {Object} [cfg] Optional config hash for the attribute. This is added for performance along the critical path,
                                     * where the calling method has already obtained the config from state.
                                     *
                                     * @return {Any} The stored value of the attribute
                                     */
                                    _getStateVal : function(name, cfg) {
                                        var stateProxy = this._stateProxy;

                                        if (!cfg) {
                                            cfg = this._state.getAll(name) || {};
                                        }

                                        return (stateProxy && (name in stateProxy) && !(cfg._bypassProxy)) ? stateProxy[name] : cfg.value;
                                    },

                                    /**
                                     * Sets the stored value for the attribute, in either the
                                     * internal state object, or the state proxy if it exits
                                     *
                                     * @method _setStateVal
                                     * @private
                                     * @param {String} name The name of the attribute
                                     * @param {Any} value The value of the attribute
                                     */
                                    _setStateVal : function(name, value) {
                                        var stateProxy = this._stateProxy;
                                        if (stateProxy && (name in stateProxy) && !this._state.get(name, BYPASS_PROXY)) {
                                            stateProxy[name] = value;
                                        } else {
                                            this._state.add(name, VALUE, value);
                                        }
                                    },

                                    /**
                                     * Updates the stored value of the attribute in the privately held State object,
                                     * if validation and setter passes.
                                     *
                                     * @method _setAttrVal
                                     * @private
                                     * @param {String} attrName The attribute name.
                                     * @param {String} subAttrName The sub-attribute name, if setting a sub-attribute property ("x.y.z").
                                     * @param {Any} prevVal The currently stored value of the attribute.
                                     * @param {Any} newVal The value which is going to be stored.
                                     * @param {Object} [opts] Optional data providing the circumstances for the change.
                                     * @param {Object} [attrCfg] Optional config hash for the attribute. This is added for performance along the critical path,
                                     * where the calling method has already obtained the config from state.
                                     *
                                     * @return {Boolean} true if the new attribute value was stored, false if not.
                                     */
                                    _setAttrVal : function(attrName, subAttrName, prevVal, newVal, opts, attrCfg) {

                                        var host = this,
                                            allowSet = true,
                                            cfg = attrCfg || this._state.data[attrName] || {},
                                            validator = cfg.validator,
                                            setter = cfg.setter,
                                            initializing = cfg.initializing,
                                            prevRawVal = this._getStateVal(attrName, cfg),
                                            name = subAttrName || attrName,
                                            retVal,
                                            valid;

                                        if (validator) {
                                            if (!validator.call) {
                                                // Assume string - trying to keep critical path tight, so avoiding Lang check
                                                validator = this[validator];
                                            }
                                            if (validator) {
                                                valid = validator.call(host, newVal, name, opts);

                                                if (!valid && initializing) {
                                                    newVal = cfg.defaultValue;
                                                    valid = true; // Assume it's valid, for perf.
                                                }
                                            }
                                        }

                                        if (!validator || valid) {
                                            if (setter) {
                                                if (!setter.call) {
                                                    // Assume string - trying to keep critical path tight, so avoiding Lang check
                                                    setter = this[setter];
                                                }
                                                if (setter) {
                                                    retVal = setter.call(host, newVal, name, opts);

                                                    if (retVal === INVALID_VALUE) {
                                                        if (initializing) {
                                                            Y.log('Attribute: ' + attrName + ', setter returned Attribute.INVALID_VALUE for value:' + newVal + ', initializing to default value', 'warn', 'attribute');
                                                            newVal = cfg.defaultValue;
                                                        } else {
                                                            Y.log('Attribute: ' + attrName + ', setter returned Attribute.INVALID_VALUE for value:' + newVal, 'warn', 'attribute');
                                                            allowSet = false;
                                                        }
                                                    } else if (retVal !== undefined){
                                                        Y.log('Attribute: ' + attrName + ', raw value: ' + newVal + ' modified by setter to:' + retVal, 'info', 'attribute');
                                                        newVal = retVal;
                                                    }
                                                }
                                            }

                                            if (allowSet) {
                                                if(!subAttrName && (newVal === prevRawVal) && !Lang.isObject(newVal)) {
                                                    Y.log('Attribute: ' + attrName + ', value unchanged:' + newVal, 'warn', 'attribute');
                                                    allowSet = false;
                                                } else {
                                                    // Store value
                                                    if (!(INIT_VALUE in cfg)) {
                                                        cfg.initValue = newVal;
                                                    }
                                                    host._setStateVal(attrName, newVal);
                                                }
                                            }

                                        } else {
                                            Y.log('Attribute:' + attrName + ', Validation failed for value:' + newVal, 'warn', 'attribute');
                                            allowSet = false;
                                        }

                                        return allowSet;
                                    },

                                    /**
                                     * Sets multiple attribute values.
                                     *
                                     * @method setAttrs
                                     * @param {Object} attrs  An object with attributes name/value pairs.
                                     * @param {Object} [opts] Optional data providing the circumstances for the change.
                                     * @return {Object} A reference to the host object.
                                     * @chainable
                                     */
                                    setAttrs : function(attrs, opts) {
                                        return this._setAttrs(attrs, opts);
                                    },

                                    /**
                                     * Implementation behind the public setAttrs method, to set multiple attribute values.
                                     *
                                     * @method _setAttrs
                                     * @protected
                                     * @param {Object} attrs  An object with attributes name/value pairs.
                                     * @param {Object} [opts] Optional data providing the circumstances for the change
                                     * @return {Object} A reference to the host object.
                                     * @chainable
                                     */
                                    _setAttrs : function(attrs, opts) {
                                        var attr;
                                        for (attr in attrs) {
                                            if ( attrs.hasOwnProperty(attr) ) {
                                                this.set(attr, attrs[attr], opts);
                                            }
                                        }
                                        return this;
                                    },

                                    /**
                                     * Gets multiple attribute values.
                                     *
                                     * @method getAttrs
                                     * @param {String[]|Boolean} attrs Optional. An array of attribute names. If omitted, all attribute values are
                                     * returned. If set to true, all attributes modified from their initial values are returned.
                                     * @return {Object} An object with attribute name/value pairs.
                                     */
                                    getAttrs : function(attrs) {
                                        return this._getAttrs(attrs);
                                    },

                                    /**
                                     * Implementation behind the public getAttrs method, to get multiple attribute values.
                                     *
                                     * @method _getAttrs
                                     * @protected
                                     * @param {String[]|Boolean} attrs Optional. An array of attribute names. If omitted, all attribute values are
                                     * returned. If set to true, all attributes modified from their initial values are returned.
                                     * @return {Object} An object with attribute name/value pairs.
                                     */
                                    _getAttrs : function(attrs) {
                                        var obj = {},
                                            attr, i, len,
                                            modifiedOnly = (attrs === true);

                                        // TODO - figure out how to get all "added"
                                        if (!attrs || modifiedOnly) {
                                            attrs = O.keys(this._state.data);
                                        }

                                        for (i = 0, len = attrs.length; i < len; i++) {
                                            attr = attrs[i];

                                            if (!modifiedOnly || this._getStateVal(attr) != this._state.get(attr, INIT_VALUE)) {
                                                // Go through get, to honor cloning/normalization
                                                obj[attr] = this.get(attr);
                                            }
                                        }

                                        return obj;
                                    },

                                    /**
                                     * Configures a group of attributes, and sets initial values.
                                     *
                                     * <p>
                                     * <strong>NOTE:</strong> This method does not isolate the configuration object by merging/cloning.
                                     * The caller is responsible for merging/cloning the configuration object if required.
                                     * </p>
                                     *
                                     * @method addAttrs
                                     * @chainable
                                     *
                                     * @param {Object} cfgs An object with attribute name/configuration pairs.
                                     * @param {Object} values An object with attribute name/value pairs, defining the initial values to apply.
                                     * Values defined in the cfgs argument will be over-written by values in this argument unless defined as read only.
                                     * @param {boolean} lazy Whether or not to delay the intialization of these attributes until the first call to get/set.
                                     * Individual attributes can over-ride this behavior by defining a lazyAdd configuration property in their configuration.
                                     * See <a href="#method_addAttr">addAttr</a>.
                                     *
                                     * @return {Object} A reference to the host object.
                                     */
                                    addAttrs : function(cfgs, values, lazy) {
                                        if (cfgs) {
                                            this._tCfgs = cfgs;
                                            this._tVals = (values) ? this._normAttrVals(values) : null;
                                            this._addAttrs(cfgs, this._tVals, lazy);
                                            this._tCfgs = this._tVals = null;
                                        }

                                        return this;
                                    },

                                    /**
                                     * Implementation behind the public addAttrs method.
                                     *
                                     * This method is invoked directly by get if it encounters a scenario
                                     * in which an attribute's valueFn attempts to obtain the
                                     * value an attribute in the same group of attributes, which has not yet
                                     * been added (on demand initialization).
                                     *
                                     * @method _addAttrs
                                     * @private
                                     * @param {Object} cfgs An object with attribute name/configuration pairs.
                                     * @param {Object} values An object with attribute name/value pairs, defining the initial values to apply.
                                     * Values defined in the cfgs argument will be over-written by values in this argument unless defined as read only.
                                     * @param {boolean} lazy Whether or not to delay the intialization of these attributes until the first call to get/set.
                                     * Individual attributes can over-ride this behavior by defining a lazyAdd configuration property in their configuration.
                                     * See <a href="#method_addAttr">addAttr</a>.
                                     */
                                    _addAttrs : function(cfgs, values, lazy) {
                                        var tCfgs = this._tCfgs,
                                            tVals = this._tVals,
                                            attr,
                                            attrCfg,
                                            value;

                                        for (attr in cfgs) {
                                            if (cfgs.hasOwnProperty(attr)) {

                                                // Not Merging. Caller is responsible for isolating configs
                                                attrCfg = cfgs[attr];
                                                attrCfg.defaultValue = attrCfg.value;

                                                // Handle simple, complex and user values, accounting for read-only
                                                value = this._getAttrInitVal(attr, attrCfg, tVals);

                                                if (value !== undefined) {
                                                    attrCfg.value = value;
                                                }

                                                if (tCfgs[attr]) {
                                                    tCfgs[attr] = undefined;
                                                }

                                                this.addAttr(attr, attrCfg, lazy);
                                            }
                                        }
                                    },

                                    /**
                                     * Utility method to protect an attribute configuration
                                     * hash, by merging the entire object and the individual
                                     * attr config objects.
                                     *
                                     * @method _protectAttrs
                                     * @protected
                                     * @param {Object} attrs A hash of attribute to configuration object pairs.
                                     * @return {Object} A protected version of the attrs argument.
                                     * @deprecated Use `AttributeCore.protectAttrs()` or
                                     *   `Attribute.protectAttrs()` which are the same static utility method.
                                     */
                                    _protectAttrs : AttributeCore.protectAttrs,

                                    /**
                                     * Utility method to normalize attribute values. The base implementation
                                     * simply merges the hash to protect the original.
                                     *
                                     * @method _normAttrVals
                                     * @param {Object} valueHash An object with attribute name/value pairs
                                     *
                                     * @return {Object} An object literal with 2 properties - "simple" and "complex",
                                     * containing simple and complex attribute values respectively keyed
                                     * by the top level attribute name, or null, if valueHash is falsey.
                                     *
                                     * @private
                                     */
                                    _normAttrVals : function(valueHash) {
                                        var vals,
                                            subvals,
                                            path,
                                            attr,
                                            v, k;

                                        if (!valueHash) {
                                            return null;
                                        }

                                        vals = {};

                                        for (k in valueHash) {
                                            if (valueHash.hasOwnProperty(k)) {
                                                if (k.indexOf(DOT) !== -1) {
                                                    path = k.split(DOT);
                                                    attr = path.shift();

                                                    subvals = subvals || {};

                                                    v = subvals[attr] = subvals[attr] || [];
                                                    v[v.length] = {
                                                        path : path,
                                                        value: valueHash[k]
                                                    };
                                                } else {
                                                    vals[k] = valueHash[k];
                                                }
                                            }
                                        }

                                        return { simple:vals, complex:subvals };
                                    },

                                    /**
                                     * Returns the initial value of the given attribute from
                                     * either the default configuration provided, or the
                                     * over-ridden value if it exists in the set of initValues
                                     * provided and the attribute is not read-only.
                                     *
                                     * @param {String} attr The name of the attribute
                                     * @param {Object} cfg The attribute configuration object
                                     * @param {Object} initValues The object with simple and complex attribute name/value pairs returned from _normAttrVals
                                     *
                                     * @return {Any} The initial value of the attribute.
                                     *
                                     * @method _getAttrInitVal
                                     * @private
                                     */
                                    _getAttrInitVal : function(attr, cfg, initValues) {
                                        var val = cfg.value,
                                            valFn = cfg.valueFn,
                                            tmpVal,
                                            initValSet = false,
                                            readOnly = cfg.readOnly,
                                            simple,
                                            complex,
                                            i,
                                            l,
                                            path,
                                            subval,
                                            subvals;

                                        if (!readOnly && initValues) {
                                            // Simple Attributes
                                            simple = initValues.simple;
                                            if (simple && simple.hasOwnProperty(attr)) {
                                                val = simple[attr];
                                                initValSet = true;
                                            }
                                        }

                                        if (valFn && !initValSet) {
                                            if (!valFn.call) {
                                                valFn = this[valFn];
                                            }
                                            if (valFn) {
                                                tmpVal = valFn.call(this, attr);
                                                val = tmpVal;
                                            }
                                        }

                                        if (!readOnly && initValues) {

                                            // Complex Attributes (complex values applied, after simple, in case both are set)
                                            complex = initValues.complex;

                                            if (complex && complex.hasOwnProperty(attr) && (val !== undefined) && (val !== null)) {
                                                subvals = complex[attr];
                                                for (i = 0, l = subvals.length; i < l; ++i) {
                                                    path = subvals[i].path;
                                                    subval = subvals[i].value;
                                                    O.setValue(val, path, subval);
                                                }
                                            }
                                        }

                                        return val;
                                    },

                                    /**
                                     * Utility method to set up initial attributes defined during construction,
                                     * either through the constructor.ATTRS property, or explicitly passed in.
                                     *
                                     * @method _initAttrs
                                     * @protected
                                     * @param attrs {Object} The attributes to add during construction (passed through to <a href="#method_addAttrs">addAttrs</a>).
                                     *        These can also be defined on the constructor being augmented with Attribute by defining the ATTRS property on the constructor.
                                     * @param values {Object} The initial attribute values to apply (passed through to <a href="#method_addAttrs">addAttrs</a>).
                                     *        These are not merged/cloned. The caller is responsible for isolating user provided values if required.
                                     * @param lazy {boolean} Whether or not to add attributes lazily (passed through to <a href="#method_addAttrs">addAttrs</a>).
                                     */
                                    _initAttrs : function(attrs, values, lazy) {
                                        // ATTRS support for Node, which is not Base based
                                        attrs = attrs || this.constructor.ATTRS;

                                        var Base = Y.Base,
                                            BaseCore = Y.BaseCore,
                                            baseInst = (Base && Y.instanceOf(this, Base)),
                                            baseCoreInst = (!baseInst && BaseCore && Y.instanceOf(this, BaseCore));

                                        if (attrs && !baseInst && !baseCoreInst) {
                                            this.addAttrs(Y.AttributeCore.protectAttrs(attrs), values, lazy);
                                        }
                                    }
                                };

                                Y.AttributeCore = AttributeCore;