attribute/js/Attribute.js

Attribute.js revision 9f7c20b894a93b0da425b8b9470043abefb6d7de
   /**
    * Managed Attribute Provider
    * @module attribute
    */

   var O = Y.Object,

       DOT = ".",
       CHANGE = "Change",
       GETTER = "getter",
       SETTER = "setter",
       VALUE = "value",
       ADDED = "added",
       INITIALIZING = "initializing",
       INIT_VALUE = "initValue",
       READ_ONLY = "readOnly",
       WRITE_ONCE = "writeOnce",
       VALIDATOR = "validator",
       PUBLISHED = "published",
       INVALID_VALUE,

       EventTarget = Y.EventTarget;

   /**
    * <p>
    * Attribute provides managed attribute support.
    * </p>
    * <p>
    * The class is designed to be augmented onto a host class,
    * and allows the host to support getter/setter methods for attributes,
    * initial configuration support and attribute change events.
    * </p>
    * <p>Attributes added to the host can:</p>
    * <ul>
    *     <li>Be defined as read-only.</li>
    *     <li>Be defined as write-once.</li>
    *     <li>Be defined with a setter function, used to manipulate
    *     values passed to Attribute's set method, before they are stored.</li>
    *     <li>Be defined with a validator function, to validate values before they are stored.</li>
    *     <li>Be defined with a getter function, which can be used to manipulate stored values,
    *     before they are returned by Attribute's get method.</li>
    * </ul>
    *
    * <p>See the <a href="#method_addAtt">addAttr</a> method, for details about how to add attributes with
    * a specific configuration</p>
    *
    * @class Attribute
    * @uses Event.Target
    */
   function Attribute() {
       Y.log('Attribute constructor called', 'info', 'attribute');

       this._ATTR_E_CFG = {queuable:false, defaultFn:this._defAttrChangeFn, silent:true};
       this._ATTR_E_FACADE = {};

       EventTarget.call(this, {emitFacade:true});
       this._conf = new Y.State();
   }

   Attribute.INVALID_VALUE = {};

   INVALID_VALUE = Attribute.INVALID_VALUE;

   Attribute.prototype = {
       /**
        * <p>
        * Adds an attribute with the provided configuration to the host object. Intended
        * to be used by the host object to setup it's set of available attributes.
        * </p>
        * <p>
        * The config argument object literal supports the following optional properties:
        * </p>
        * <dl>
        *    <dt>value &#60;Any&#62;</dt>
        *    <dd>The initial value to set on the attribute</dd>
        *    <dt>readOnly &#60;Boolean&#62;</dt>
        *    <dd>Whether or not the attribute is read only. Attributes having readOnly set to true
        *        cannot be set by invoking the set method.</dd>
        *    <dt>writeOnce &#60;Boolean&#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.</dd>
        *    <dt>setter &#60;Function&#62;</dt>
        *    <dd>The setter function to be invoked (within the context of the host object) before
        *        the attribute is stored by a call to the setter method. The value returned by the
        *        setter function will be the finally stored value.</dd>
        *    <dt>getter &#60;Function&#62;</dt>
        *    <dd>The getter function to be invoked (within the context of the host object) before
        *    the stored values is returned to a user invoking the getter method for the attribute.
        *    The value returned by the getter function is the final value which will be returned to the
        *    user when they invoke get.</dd>
        *    <dt>validator &#60;Function&#62;</dt>
        *    <dd>The validator function which is invoked prior to setting the stored value. Returning
        *    false from the validator function will prevent the value from being stored</dd>
        * </dl>
        *
        * @method addAttr
        *
        * @param {String} name The attribute key
        * @param {Object} config (optional) An object literal specifying the configuration for the attribute.
        * <strong>NOTE:</strong> The config object is modified when adding an attribute,
        * so if you need to protect the original values, you will need to merge or clone the object.
        *
        * @chainable
        */
       addAttr: function(name, config) {
           Y.log('Adding attribute: ' + name, 'info', 'attribute');

           if (!this.attrAdded(name)) {
               config = config || {};

               var value,
                   hasValue = (VALUE in config),
                   conf = this._conf;

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

               if(hasValue) {
                   // We'll go through set, don't want to set value in _conf directory
                   value = config.value;
                   delete config.value;
               }

               config[ADDED] = true;
               config[INITIALIZING] = true;

               conf.addAll(name, config);

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

               conf.remove(name, INITIALIZING);

           } else {
               Y.log('Attribute: ' + name + ' already exists. Cannot add it again without removing it first', 'warn', 'attribute');
           }

           return this;
       },

       /**
        * Tests 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.
        */
       attrAdded: function(name) {
           return !!(this._conf.get(name, ADDED));
       },

       /**
        * Removes an attribute.
        *
        * @method removeAttr
        * @param {String} name The attribute key
        */
       removeAttr: function(name) {
           this._conf.removeAll(name);
       },

       /**
        * 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.
        * The 'getter' will be passed the current value of the attribute
        * as the only argument.
        *
        * @method get
        *
        * @param {String} name The attribute whose value will be returned. 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 current value of the attribute
        */
       get : function(name) {

           var conf = this._conf,
               path,
               getter,
               val;

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

           val = conf.get(name, VALUE);
           getter = conf.get(name, GETTER);

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

           return val;
       },

       /**
        * Sets the value of an attribute.
        *
        * @method set
        * @chainable
        *
        * @param {String} name The name of the attribute. Note, if the
        * 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 apply to the attribute
        *
        * @param {Object} opts Optional event data. This object will be mixed into
        * the event facade passed as the first argument to subscribers
        * of attribute change events
        *
        * @return {Object} Reference to the host object
        */
       set : function(name, val, opts) {
           return this._setAttr(name, val, opts);
       },

       /**
        * Resets the given attribute or all attributes to the initial value.
        *
        * @method reset
        * @param {String} name optional An attribute to reset.  If omitted, all attributes are reset.
        * @chainable
        */
       reset : function(name) {
           if (name) {
               this._set(name, this._conf.get(name, INIT_VALUE));
           } else {
               var initVals = this._conf.data.initValue;
               Y.each(initVals, function(v, n) {
                   this._set(n, v);
               }, this);
           }
           return this;
       },

       /**
        * Allows setting of readOnly/writeOnce attributes.
        *
        * @method _set
        * @protected
        * @chainable
        *
        * @return {Object} Reference to the host object
        */
       _set : function(name, val, opts) {
           return this._setAttr(name, val, opts, true);
       },

       /**
        * Internal set implementation
        *
        * @method _setAttr
        * @protected
        * @chainable
        *
        * @param {String} name The name of the attribute. Note, if the
        * 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 apply to the attribute
        *
        * @param {Object} opts Optional event data. This object will be mixed into
        * the event facade passed as the first argument to subscribers
        * of attribute change events
        *
        * @param {boolean} force If true, allows the caller to set values for
        * readOnly or writeOnce attributes which have already been set.
        *
        * @return {Object} Reference to the host object
        */
       _setAttr : function(name, val, opts, force) {
           var allowSet = true,
               conf = this._conf,
               data = conf.data,
               initialSet,
               strPath,
               path,
               currVal;

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

           initialSet = (!data.value || !(name in data.value));

           if (!this.attrAdded(name)) {
               Y.log('Set attribute:' + name + ', aborted; Attribute is not configured', 'warn', 'attribute');
           } else {

               if (!initialSet && !force) {

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

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

               if (allowSet) {
                   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 (conf.get(name, INITIALIZING)) {
                           this._setAttrVal(name, strPath, currVal, val);
                       } else {
                           this._fireAttrChange(name, strPath, currVal, val, opts);
                       }
                   }
               }
           }

           return this;
       },

       /**
        * Utility method to help setup the event payload and
        * fire the attribute change event.
        *
        * @method _fireAttrChange
        * @private
        * @param {String} attrName The name of the attribute
        * @param {String} subAttrName The full path of the property being changed,
        * if this is a sub-attribute value being change. Otherwise null.
        * @param {Any} currVal The current value of the attribute
        * @param {Any} newVal The new value of the attribute
        * @param {Object} opts Any additional event data to mix into the attribute change event's event facade.
        */
       _fireAttrChange : function(attrName, subAttrName, currVal, newVal, opts) {
           var eventName = attrName + CHANGE,
               conf = this._conf,
               facade;

           if (!conf.get(attrName, PUBLISHED)) {
               this.publish(eventName, this._ATTR_E_CFG);
               conf.add(attrName, PUBLISHED, true);
           }

           facade = (opts) ? Y.merge(opts) : this._ATTR_E_FACADE;

           facade.type = eventName;
           facade.attrName = attrName;
           facade.subAttrName = subAttrName;
           facade.prevVal = currVal;
           facade.newVal = newVal;

           this.fire(facade);
       },

       /**
        * Default handler implementation for Attribute change events
        *
        * @private
        * @method _defAttrChangeFn
        * @param {Event.Facade} e The event object for the custom event
        */
       _defAttrChangeFn : function(e) {
           if (!this._setAttrVal(e.attrName, e.subAttrName, e.prevVal, e.newVal)) {
               Y.log('State not updated and stopImmediatePropagation called for attribute: ' + e.attrName + ' , value:' + e.newVal, 'warn', 'attribute');
               // Prevent "after" listeners from being invoked since nothing changed.
               e.stopImmediatePropagation();
           } else {
               e.newVal = this._conf.get(e.attrName, 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.
        *
        * @return {booolean} true if the new attribute value was stored, false if not.
        */
       _setAttrVal : function(attrName, subAttrName, prevVal, newVal) {

           var allowSet = true,
               conf = this._conf,
               validator  = conf.get(attrName, VALIDATOR),
               setter = conf.get(attrName, SETTER),
               retVal;

           if (!validator || validator.call(this, newVal)) {

               if (setter) {
                   retVal = setter.call(this, newVal);

                   if (retVal === INVALID_VALUE) {
                       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 === prevVal) {
                       Y.log('Attribute: ' + attrName + ', value unchanged:' + newVal, 'warn', 'attribute');
                       allowSet = false;
                   } else {
                       // Store value
                       if (conf.get(attrName, INIT_VALUE) === undefined) {
                           conf.add(attrName, INIT_VALUE, newVal);
                       }
                       conf.add(attrName, VALUE, 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  A hash of attributes: name/value pairs
        * @chainable
        */
       setAttrs : function(attrs) {
           for (var attr in attrs) {
               if ( attrs.hasOwnProperty(attr) ) {
                   this.set(attr, attrs[attr]);
               }
           }
           return this;
       },

       /**
        * Gets multiple attribute values.
        *
        * @method getAttrs
        * @param {Array | Boolean} attrs Optional. An array of attribute names, whose values are required. If omitted, all attribute values are
        * returned. If set to true, all attributes modified from their original values are returned.
        * @return {Object} A hash of attributes: name/value pairs
        */
       getAttrs : function(attrs) {
           var o = {}, i, l, attr, val,
               modifiedOnly = (attrs === true);

           attrs = (attrs && !modifiedOnly) ? attrs : O.keys(this._conf.data[VALUE]);

           for (i = 0, l = attrs.length; i < l; i++) {
               // Go through get, to honor cloning/normalization
               attr = attrs[i];
               val = this.get(attr);

               if (!modifiedOnly || this._conf.get(attr, VALUE) != this._conf.get(attr, INIT_VALUE)) {
                   o[attr] = this.get(attr);
               }
           }

           return o;
       },

       /**
        * Configures attributes, and sets initial values. This method does not
        * isolate configuration object by merging/cloning. The caller is responsible for
        * merging/cloning the configuration object when required.
        *
        * @method addAttrs
        * @chainable
        *
        * @param {Object} cfgs Name/value hash of attribute configuration literals.
        * @param {Object} values Name/value hash of initial values to apply. Values defined in the configuration hash will be over-written by the initial values hash unless read-only.
        */
       addAttrs : function(cfgs, values) {
           if (cfgs) {
               var attr,
                   attrCfg,
                   value;

               values = this._splitAttrVals(values);

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

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

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

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

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

       /**
        * Utility to split out regular attribute values
        * from complex attribute values, so that complex
        * attributes can be keyed by top level attribute name.
        *
        * @method _splitAttrValues
        * @param {Object} valueHash Name/value hash of initial values
        *
        * @return {Object} Object literal with 2 properties - "simple" and "complex",
        * containing simple and complex attribute values respectively keyed
        * by attribute the top level attribute name.
        * @private
        */
       _splitAttrVals : function(valueHash) {
           var vals = {},
               subvals = {},
               path,
               attr,
               v, k;

           for (k in valueHash) {
               if (valueHash.hasOwnProperty(k)) {
                   if (k.indexOf(DOT) !== -1) {
                       path = k.split(DOT);
                       attr = path.shift();
                       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 initValues
        * hash provided, if the attribute is not read-only.
        *
        * @param {String} attr Attribute name
        * @param {Object} cfg Default attribute configuration object literal
        * @param {Object} initValues Name/Value hash of initial attribute values from _splitAttrVals
        *
        * @return {Any} Initial value of the attribute.
        *
        * @method _getAttrInitVal
        * @private
        */
       _getAttrInitVal : function(attr, cfg, initValues) {

           var val = (cfg.valueFn) ? cfg.valueFn.call(this) : cfg.value,
               simple,
               complex,
               i,
               l,
               path,
               subval,
               subvals;

           if (!cfg[READ_ONLY] && initValues) {

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

               // Complex Attributes (complex values applied, after simple, incase both are set)
               complex = initValues.complex;
               if (complex && complex.hasOwnProperty(attr)) {
                   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;
       }
   };

   // Basic prototype augment - no lazy constructor invocation.
   Y.mix(Attribute, EventTarget, false, null, 1);

   Y.Attribute = Attribute;