Wed, 03 Jul 2013 13:41:18 -0300
8011629: Object.defineProperty performance issue
Reviewed-by: sundar, attila
Contributed-by: james.laskey@oracle.com
1 Nasgen is a tool for processing Java classes that implement native
2 JavaScript objects. It does so by looking for the
3 com.oracle.nashorn.objects.annotations.ScriptClass annotation and other
4 annotations in that package.
6 For each class "C", nasgen instruments the original class and generates
7 two additional classes: a "C$Prototype" class for the JavaScript
8 prototype object, and a "C$Constructor" class for the JavaScript
9 constructor function.
11 Each class instrumented or generated by nasgen contains a private static
12 "$nasgenmap$" field of type com.oracle.nashorn.runtime.PropertyMap and
13 static initializer block to initialize the field to the object's
14 JavaScript properties.
16 Members annotated with @Function, @Property, @Getter, and @Setter are
17 mapped to the $Constructor, $Prototype, or main class, depending on the
18 value of the annotation's 'where' field. By default, @Property, @Getter,
19 and @Setter belong to the main class while @Function methods without
20 explicit 'where' field belong to the $Prototype class. The @Constructor
21 annotation marks a method to be invoked as JavaScript constructor.
23 Nasgen enforces all @Function/@Getter/@Setter/@Constructor annotated
24 methods to be declared as static. Static final @Property fields remain
25 in the main class while other @Property fields are moved to respective
26 classes depending on the annotation's 'where' value. For functions
27 mapped to the $Prototype or $Constructor class, nasgen also generates
28 getters and setters prefixed by G$ and S$, respectively.
30 Nasgen-generated classes are hidden from normal ClassLoaders by giving
31 them a ".clazz" file name extension instead of the standard ".class"
32 extension. This allows script classes to be loaded independently by each
33 Nashorn context through the com.oracle.nashorn.runtime.StructureLoader
34 class loader.