/**
+ * The State class maintains state for a collection of named items, with
+ * a varying number of properties defined.
+ *
+ * It avoids the need to create a separate class for the item, and separate instances
+ * of these classes for each item, by storing the state in a 2 level hash table,
+ * improving performance when the number of items is likely to be large.
+ *
+ * @constructor
+ * @class State
+ */
+ Y.State = function() {
+ /**
+ * Hash of attributes
+ * @property data
+ */
+ this.data = {};
+ };
+
+ Y.State.prototype = {
+
+ /**
+ * Adds a property to an item.
+ *
+ * @method add
+ * @param name {String} The name of the item.
+ * @param key {String} The name of the property.
+ * @param val {Any} The value of the property.
+ */
+ add : function(name, key, val) {
+ var d = this.data;
+ d[key] = d[key] || {};
+ d[key][name] = val;
+ },
+
+ /**
+ * Adds multiple properties to an item.
+ *
+ * @method addAll
+ * @param name {String} The name of the item.
+ * @param o {Object} A hash of property/value pairs.
+ */
+ addAll: function(name, o) {
+ var key;
+ for (key in o) {
+ if (o.hasOwnProperty(key)) {
+ this.add(name, key, o[key]);
+ }
+ }
+ },
+
+ /**
+ * Removes a property from an item.
+ *
+ * @method remove
+ * @param name {String} The name of the item.
+ * @param key {String} The property to remove.
+ */
+ remove: function(name, key) {
+ var d = this.data;
+ if (d[key] && (name in d[key])) {
+ delete d[key][name];
+ }
+ },
+
+ /**
+ * Removes multiple properties from an item, or remove the item completely.
+ *
+ * @method removeAll
+ * @param name {String} The name of the item.
+ * @param o {Object|Array} Collection of properties to delete. If not provided, the entire item is removed.
+ */
+ removeAll: function(name, o) {
+ var d = this.data;
+
+ Y.each(o || d, function(v, k) {
+ if(Y.Lang.isString(k)) {
+ this.remove(name, k);
+ } else {
+ this.remove(name, v);
+ }
+ }, this);
+ },
+
+ /**
+ * For a given item, returns the value of the property requested, or undefined if not found.
+ *
+ * @method get
+ * @param name {String} The name of the item
+ * @param key {String} Optional. The property value to retrieve.
+ * @return {Any} The value of the supplied property.
+ */
+ get: function(name, key) {
+ var d = this.data;
+ return (d[key] && name in d[key]) ? d[key][name] : undefined;
+ },
+
+ /**
+ * For the given item, returns a disposable object with all of the
+ * item's property/value pairs.
+ *
+ * @method getAll
+ * @param name {String} The name of the item
+ * @return {Object} An object with property/value pairs for the item.
+ */
+ getAll : function(name) {
+ var d = this.data, o;
+
+ Y.each(d, function(v, k) {
+ if (name in d[k]) {
+ o = o || {};
+ o[k] = v[name];
+ }
+ }, this);
+
+ return o;
+ }
+ };
+