isInstanceOf() now works with interfaces
parent
c3b00ab9b7
commit
56c13b757b
72
lib/class.js
72
lib/class.js
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@ -27,10 +27,9 @@ var util = require( './util' );
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/**
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* Stores class metadata internally (ensures data is encapsulated)
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*
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* The data in this object is hashed on the class object itself. Therefore, to
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* look up an item, you would provide the class itself as the property.
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* The data in this object is hashed a class id.
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*
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* @type {Object.<Object, { implemented: Array.<string> }>}
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* @type {Object.<number, { implemented: Array.<string> }>}
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*/
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var class_meta = {};
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@ -76,7 +75,7 @@ exports.implement = function()
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}
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var class_new = exports.extend( dest );
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getMeta( class_new ).implemented = implemented;
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getMeta( class_new.__cid ).implemented = implemented;
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return class_new;
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};
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@ -149,8 +148,9 @@ exports.isInstanceOf = function( type, instance )
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// if no metadata is available, then our remaining checks cannot be
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// performed
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if ( !( meta = getMeta( type ) ) )
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if ( !instance.__cid || !( meta = getMeta( instance.__cid ) ) )
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{
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console.log( instance );
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return false;
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}
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@ -203,6 +203,8 @@ function Class() {};
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*/
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var extend = ( function( extending )
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{
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var class_id = 0;
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/**
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* Mimics class inheritance
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*
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@ -274,18 +276,20 @@ var extend = ( function( extending )
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// set up the new class
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var new_class = createCtor( abstract_methods );
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setupProps( new_class, abstract_methods );
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attachPropInit( prototype, properties );
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new_class.prototype = prototype;
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new_class.constructor = new_class;
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// important: call after setting prototype
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setupProps( new_class, abstract_methods, ++class_id );
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// lock down the new class (if supported) to ensure that we can't add
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// members at runtime
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util.freeze( new_class );
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// create internal metadata for the new class
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createMeta( new_class );
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createMeta( new_class, base.prototype.__cid );
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// we're done with the extension process
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extending = false;
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@ -360,13 +364,15 @@ var extend = ( function( extending )
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*
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* @param {Function} func function (class) to set up
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* @param {Array.<string>} abstract_methods list of abstract method names
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* @param {number} class_id unique id to assign to class
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*
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* @return {undefined}
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*/
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function setupProps( func, abstract_methods )
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function setupProps( func, abstract_methods, class_id )
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{
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attachAbstract( func, abstract_methods );
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attachExtend( func );
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attachId( func, class_id );
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}
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@ -466,6 +472,25 @@ function attachExtend( func )
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}
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/**
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* Attaches the unique id to the class and its prototype
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*
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* The unique identifier is used internally to match a class and its instances
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* with the class metadata. Exposing the id breaks encapsulation to a degree,
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* but is a lesser evil when compared to exposing all metadata.
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*
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* @param {Function} func function (class) to attach method to
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* @param {number} id id to assign
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*
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* @return {undefined}
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*/
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function attachId( func, id )
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{
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util.defineSecureProp( func, '__cid', id );
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util.defineSecureProp( func.prototype, '__cid', id );
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}
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/**
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* Attaches partially applied isInstanceOf() method to class instance
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*
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@ -488,15 +513,30 @@ function attachInstanceOf( instance )
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/**
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* Initializes class metadata for the given class
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*
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* @param {Class} obj class to initialize metadata for
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* @param {Class} func class to initialize metadata for
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*
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* @return {undefined}
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*/
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function createMeta( obj )
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function createMeta( func, parent_id )
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{
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class_meta[ obj ] = {
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implemented: [],
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};
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var id = func.__cid,
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parent_meta = ( ( parent_id ) ? getMeta( parent_id) : undefined );
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// copy the parent prototype's metadata if it exists (inherit metadata)
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if ( parent_meta )
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{
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// todo: deep (1) util.clone() when available
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class_meta[ id ] = {
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implemented: util.clone( parent_meta.implemented ),
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};
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}
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else
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{
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// create empty
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class_meta[ id ] = {
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implemented: [],
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};
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}
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}
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@ -506,12 +546,12 @@ function createMeta( obj )
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* Since a reference is returned (rather than a copy), the returned object can
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* be modified to alter the metadata.
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*
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* @param {Class} obj class to retrieve metadata for
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* @param {number} id id of class to retrieve metadata for
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*
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* @return {Object}
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*/
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function getMeta( obj )
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function getMeta( id )
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{
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return class_meta[ obj ];
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return class_meta[ id ];
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}
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@ -77,3 +77,21 @@ assert.ok(
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"Abstract methods list contains names of implemented methods"
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);
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// concrete implementation so that we can instantiate it
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var ConcreteFoo = Foo.extend(
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{
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foo: function() {},
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foo2: function() {},
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}),
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concrete_inst = new ConcreteFoo();
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assert.ok(
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( concrete_inst.isInstanceOf( Type )
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&& concrete_inst.isInstanceOf( Type2 )
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),
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"Instances of classes implementing interfaces are considered to be " +
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"instances of the implemented interfaces"
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);
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@ -132,3 +132,15 @@ assert.equal(
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"Class instance contains isA() alias for isInstanceOf() partially applied function"
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);
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assert.ok(
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( Foo.__cid !== undefined ),
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"Class id available via class"
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);
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assert.ok(
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( Foo.prototype.__cid !== undefined ),
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"Class id available via class prototype"
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);
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