base/js/Base.js

Base.js revision 793e508bd277c48d6a09b91bb99064b4046eda7a
   /**
    * The base module provides the Base class, which objects requiring managed attributes
    * and custom event support can extend. The base module also provides two ways to reuse
    * code - An augmentable PluginHost interface which provides plugin support
    * (which is augmented to the Base class) and Base.build which provides a way to
    * build custom classes using extensions.
    *
    * @module base
    */

   /**
    * The base-base submodule provides the Base class and augmentable PluginHost implementation,
    * without the extension support provided by Base.build.
    *
    * @module base
    * @submodule base-base
    */
   var O = Y.Object,
       DOT = ".",
       DESTROY = "destroy",
       INIT = "init",
       INITIALIZED = "initialized",
       DESTROYED = "destroyed",
       INITIALIZER = "initializer",
       OBJECT_CONSTRUCTOR = Object.prototype.constructor,
       DEEP = "deep",
       SHALLOW = "shallow",
       VALUE = "value",
       DESTRUCTOR = "destructor";

   /**
    * <p>
    * Provides a base class for which objects requiring managed attributes and
    * custom event support can extend. The Base class also handles the chaining of
    * initializer and destructor methods across the hierarchy as part of object construction
    * and destruction. Additionally, attributes configured through the static
    * <a href="#property_Base.ATTRS">ATTRS</a> property for each class in the hierarchy will be
    * initialized by Base.
    * </p>
    *
    * <p>The static <a href="#property_Base.NAME">NAME</a> property of each class extending
    * from Base will be used as the identifier for the class, and is used by Base to prefix
    * all events fired by instances of that class.</p>
    *
    * @class Base
    * @constructor
    * @uses Attribute, Plugin.Host
    *
    * @param {Object} config Object literal of configuration property name/value pairs
    */
   function Base() {
       Y.log('constructor called', 'life', 'base');

       Y.Attribute.call(this);
       Y.Plugin.Host.call(this);

       this._silentInit = this._silentInit || false;
       if (this._lazyAddAttrs !== false) { this._lazyAddAttrs = true; }

       this.init.apply(this, arguments);
   }

   /**
    * The list of properties which can be configured for
    * each attribute (e.g. setter, getter, writeOnce, readOnly etc.)
    *
    * @property Base._ATTR_CFG
    * @type Array
    * @static
    * @private
    */
   Base._ATTR_CFG = Y.Attribute._ATTR_CFG.concat("cloneDefaultValue");

   /**
    * <p>
    * The string to be used to identify instances of
    * this class, for example in prefixing events.
    * </p>
    * <p>
    * Classes extending Base, should define their own
    * static NAME property, which should be camelCase by
    * convention (e.g. MyClass.NAME = "myClass";).
    * </p>
    * @property Base.NAME
    * @type String
    * @static
    */
   Base.NAME = 'base';

   /**
    * Object literal defining the set of attributes which
    * will be available for instances of this class, and
    * how they are configured. See Attribute's <a href="Attribute.html#method_addAttr">addAttr</a>
    * method for a description of configuration options available
    * for each attribute.
    *
    * @property Base.ATTRS
    * @type Object
    * @static
    */
   Base.ATTRS = {
       /**
        * Flag indicating whether or not this object
        * has been through the init lifecycle phase.
        *
        * @attribute initialized
        * @readonly
        * @default false
        * @type boolean
        */
       initialized: {
           readOnly:true,
           value:false
       },

       /**
        * Flag indicating whether or not this object
        * has been through the destroy lifecycle phase.
        *
        * @attribute destroyed
        * @readonly
        * @default false
        * @type boolean
        */
       destroyed: {
           readOnly:true,
           value:false
       }
   };

   Base.prototype = {

       /**
        * Init lifecycle method, invoked during construction.
        * Fires the init event prior to setting up attributes and
        * invoking initializers for the class hierarchy.
        *
        * @method init
        * @final
        * @chainable
        * @param {Object} config Object literal of configuration property name/value pairs
        * @return {Base} A reference to this object
        */
       init: function(config) {
           Y.log('init called', 'life', 'base');

           /**
            * The string used to identify the class of this object.
            *
            * @deprecated Use this.constructor.NAME
            * @property name
            * @type String
            */
           this._yuievt.config.prefix = this.name = this.constructor.NAME;

           /**
            * <p>
            * Lifecycle event for the init phase, fired prior to initialization.
            * Invoking the preventDefault() method on the event object provided
            * to subscribers will prevent initialization from occuring.
            * </p>
            * <p>
            * Subscribers to the "after" momemt of this event, will be notified
            * after initialization of the object is complete (and therefore
            * cannot prevent initialization).
            * </p>
            *
            * @event init
            * @preventable _defInitFn
            * @param {Event.Facade} e Event object, with a cfg property which
            * refers to the configuration object literal passed to the constructor.
            */
           if (!this._silentInit) {
               this.publish(INIT, {
                   queuable:false,
                   defaultFn:this._defInitFn
               });
           }

           if (config) {
               if (config.on) {
                   this.on(config.on);
               }
               if (config.after) {
                   this.after(config.after);
               }
           }

           if (!this._silentInit) {
               this.fire(INIT, {cfg: config});
           } else {
               this._defInitFn({cfg: config});
           }

           return this;
       },

       /**
        * <p>
        * Destroy lifecycle method. Fires the destroy
        * event, prior to invoking destructors for the
        * class hierarchy.
        * </p>
        * <p>
        * Subscribers to the destroy
        * event can invoke preventDefault on the event object, to prevent destruction
        * from proceeding.
        * </p>
        * @method destroy
        * @return {Base} A reference to this object
        * @final
        * @chainable
        */
       destroy: function() {
           Y.log('destroy called', 'life', 'base');

           /**
            * <p>
            * Lifecycle event for the destroy phase,
            * fired prior to destruction. Invoking the preventDefault
            * method on the event object provided to subscribers will
            * prevent destruction from proceeding.
            * </p>
            * <p>
            * Subscribers to the "after" moment of this event, will be notified
            * after destruction is complete (and as a result cannot prevent
            * destruction).
            * </p>
            * @event destroy
            * @preventable _defDestroyFn
            * @param {Event.Facade} e Event object
            */
           this.publish(DESTROY, {
               queuable:false,
               defaultFn: this._defDestroyFn
           });
           this.fire(DESTROY);
           return this;
       },

       /**
        * Default init event handler
        *
        * @method _defInitFn
        * @param {Event.Facade} e Event object, with a cfg property which
        * refers to the configuration object literal passed to the constructor.
        * @protected
        */
       _defInitFn : function(e) {
           this._initHierarchy(e.cfg);
           this._initPlugins(e.cfg);

           if (!this._silentInit) {
               this._set(INITIALIZED, true);
           } else {
               this._conf.add(INITIALIZED, VALUE, true);
           }
       },

       /**
        * Default destroy event handler
        *
        * @method _defDestroyFn
        * @param {Event.Facade} e Event object
        * @protected
        */
       _defDestroyFn : function(e) {
           this._destroyHierarchy();
           this._destroyPlugins();
           this._set(DESTROYED, true);
       },

       /**
        * Returns the class hierarchy for this object, with Base being the last class in the array.
        *
        * @method _getClasses
        * @protected
        * @return {Function[]} An array of classes (constructor functions), making up the class hierarchy for this object.
        * This value is cached the first time the method, or _getAttrCfgs, is invoked. Subsequent invocations return the
        * cached value.
        */
       _getClasses : function() {
           if (!this._classes) {
               this._initHierarchyData();
           }
           return this._classes;
       },

       /**
        * Returns an aggregated set of attribute configurations, by traversing the class hierarchy.
        *
        * @method _getAttrCfgs
        * @protected
        * @return {Object} The hash of attribute configurations, aggregated across classes in the hierarchy
        * This value is cached the first time the method, or _getClasses, is invoked. Subsequent invocations return
        * the cached value.
        */
       _getAttrCfgs : function() {
           if (!this._attrs) {
               this._initHierarchyData();
           }
           return this._attrs;
       },

       /**
        * A helper method used when processing ATTRS across the class hierarchy during
        * initialization. Returns a disposable object with the attributes defined for
        * the provided class, extracted from the set of all attributes passed in .
        *
        * @method _filterAttrCfs
        * @private
        *
        * @param {Function} clazz The class for which the desired attributes are required.
        * @param {Object} allCfgs The set of all attribute configurations for this instance.
        * Attributes will be removed from this set, if they belong to the filtered class, so
        * that by the time all classes are processed, allCfgs will be empty.
        *
        * @return {Object} The set of attributes belonging to the class passed in, in the form
        * of an object literal with name/cfg pairs.
        */
       _filterAttrCfgs : function(clazz, allCfgs) {
           var cfgs = null, attr, attrs = clazz.ATTRS;

           if (attrs) {
               for (attr in attrs) {
                   if (attrs.hasOwnProperty(attr) && allCfgs[attr]) {
                       cfgs = cfgs || {};
                       cfgs[attr] = allCfgs[attr];
                       delete allCfgs[attr];
                   }
               }
           }

           return cfgs;
       },

       /**
        * A helper method used by _getClasses and _getAttrCfgs, which determines both
        * the array of classes and aggregate set of attribute configurations
        * across the class hierarchy for the instance.
        *
        * @method _initHierarchyData
        * @private
        */
       _initHierarchyData : function() {
           var c = this.constructor,
               classes = [],
               attrs = [];

           while (c) {
               // Add to classes
               classes[classes.length] = c;

               // Add to attributes
               if (c.ATTRS) {
                   attrs[attrs.length] = c.ATTRS;
               }
               c = c.superclass ? c.superclass.constructor : null;
           }

           this._classes = classes;
           this._attrs = this._aggregateAttrs(attrs);
       },

       /**
        * A helper method, used by _initHierarchyData to aggregate
        * attribute configuration across the instances class hierarchy.
        *
        * The method will potect the attribute configuration value to protect the statically defined
        * default value in ATTRS if required (value is an object literal or array or the
        * attribute configuration has clone set to shallow or deep).
        *
        * @method _aggregateAttrs
        * @private
        * @param {Array} allAttrs An array of ATTRS definitions across classes in the hierarchy
        * (subclass first, Base last)
        * @return {Object} The aggregate set of ATTRS definitions for the instance
        */
       _aggregateAttrs : function(allAttrs) {
           var attr,
               attrs,
               cfg,
               val,
               path,
               i,
               clone,
               cfgProps = Base._ATTR_CFG,
               aggAttrs = {};

           if (allAttrs) {
               for (i = allAttrs.length-1; i >= 0; --i) {
                   attrs = allAttrs[i];

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

                           // Protect config passed in
                           cfg = Y.mix({}, attrs[attr], true, cfgProps);

                           val = cfg.value;
                           clone = cfg.cloneDefaultValue;

                           if (val) {
                               if ( (clone === undefined && (OBJECT_CONSTRUCTOR === val.constructor || L.isArray(val))) || clone === DEEP || clone === true) {
                                   Y.log('Cloning default value for attribute:' + attr, 'info', 'base');
                                   cfg.value = Y.clone(val);
                               } else if (clone === SHALLOW) {
                                   Y.log('Merging default value for attribute:' + attr, 'info', 'base');
                                   cfg.value = Y.merge(val);
                               }
                               // else if (clone === false), don't clone the static default value.
                               // It's intended to be used by reference.
                           }

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

                           if (path && aggAttrs[attr] && aggAttrs[attr].value) {
                               O.setValue(aggAttrs[attr].value, path, val);
                           } else if (!path){
                               if (!aggAttrs[attr]) {
                                   aggAttrs[attr] = cfg;
                               } else {
                                   Y.mix(aggAttrs[attr], cfg, true, cfgProps);
                               }
                           }
                       }
                   }
               }
           }

           return aggAttrs;
       },

       /**
        * Initializes the class hierarchy for the instance, which includes
        * initializing attributes for each class defined in the class's
        * static <a href="#property_Base.ATTRS">ATTRS</a> property and
        * invoking the initializer method on the prototype of each class in the hierarchy.
        *
        * @method _initHierarchy
        * @param {Object} userVals Object literal containing configuration name/value pairs
        * @private
        */
       _initHierarchy : function(userVals) {
           var lazy = this._lazyAddAttrs,
               constr,
               constrProto,
               ci,
               ei,
               el,
               classes = this._getClasses(),
               attrCfgs = this._getAttrCfgs();

           for (ci = classes.length-1; ci >= 0; ci--) {

               constr = classes[ci];
               constrProto = constr.prototype;

               if (constr._yuibuild && constr._yuibuild.exts && !constr._yuibuild.dynamic) {
                   for (ei = 0, el = constr._yuibuild.exts.length; ei < el; ei++) {
                       constr._yuibuild.exts[ei].apply(this, arguments);
                   }
               }

               this.addAttrs(this._filterAttrCfgs(constr, attrCfgs), userVals, lazy);

               if (constrProto.hasOwnProperty(INITIALIZER)) {
                   constrProto.initializer.apply(this, arguments);
               }
           }
       },

       /**
        * Destroys the class hierarchy for this instance by invoking
        * the descructor method on the prototype of each class in the hierarchy.
        *
        * @method _destroyHierarchy
        * @private
        */
       _destroyHierarchy : function() {
           var constr,
               constrProto,
               ci, cl,
               classes = this._getClasses();

           for (ci = 0, cl = classes.length; ci < cl; ci++) {
               constr = classes[ci];
               constrProto = constr.prototype;
               if (constrProto.hasOwnProperty(DESTRUCTOR)) {
                   constrProto.destructor.apply(this, arguments);
               }
           }
       },

       /**
        * Default toString implementation. Provides the constructor NAME
        * and the instance ID.
        *
        * @method toString
        * @return {String} String representation for this object
        */
       toString: function() {
           return this.constructor.NAME + "[" + Y.stamp(this) + "]";
       }
   };

   // Straightup augment, no wrapper functions
   Y.mix(Base, Y.Attribute, false, null, 1);
   Y.mix(Base, PluginHost, false, null, 1);

   /**
    * Alias for <a href="PluginHost.html#method_PluginHost.plug">PluginHost.plug</a>.
    *
    * @method Base.plug
    * @static
    */
   Base.plug = PluginHost.plug;

   /**
    * Alias for <a href="PluginHost.html#method_PluginHost.unplug">PluginHost.unplug</a>.
    *
    * @method Base.unplug
    * @static
    */
   Base.unplug = PluginHost.unplug;

   // Fix constructor
   Base.prototype.constructor = Base;

   Y.Base = Base;