# Yahoo! UI Library

### attribute 3.0.0

Yahoo! UI Library > attribute > State.js (source view)
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        /**
         * 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;
            }
        };

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