1Nasgen is a tool for processing Java classes that implement native
2JavaScript objects. It does so by looking for the
3com.oracle.nashorn.objects.annotations.ScriptClass annotation and other
4annotations in that package.
5
6For each  class "C", nasgen instruments the original class and generates
7two additional classes: a "C$Prototype" class for the JavaScript
8prototype object, and a "C$Constructor" class for the JavaScript
9constructor function.
10
11Each class instrumented or generated by nasgen contains a private static
12"$nasgenmap$" field of type com.oracle.nashorn.runtime.PropertyMap and
13static initializer block to initialize the field to the object's
14JavaScript properties.
15
16Members annotated with @Function, @Property, @Getter, and @Setter are
17mapped to the $Constructor, $Prototype, or main class, depending on the
18value of the annotation's 'where' field. By default, @Property, @Getter,
19and @Setter belong to the main class while @Function methods without
20explicit 'where' field belong to the $Prototype class. The @Constructor
21annotation marks a method to be invoked as JavaScript constructor.
22
23Nasgen enforces all @Function/@Getter/@Setter/@Constructor annotated
24methods to be declared as static. Static final @Property fields remain
25in the main class while other @Property fields are moved to respective
26classes depending on the annotation's 'where' value. For functions
27mapped to the $Prototype or $Constructor class, nasgen also generates
28getters and setters prefixed by G$ and S$, respectively.
29
30Nasgen-generated classes are hidden from normal ClassLoaders by giving
31them a ".clazz" file name extension instead of the standard ".class"
32extension. This allows script classes to be loaded independently by each
33Nashorn context through the com.oracle.nashorn.runtime.StructureLoader
34class loader.
35