In this part, we will use the Truffle DSL to achieve the same result as we did in part 2, but with a fraction of the code.
The interesting part is the AdditionNode class.
The Truffle DSL annotation processor will generate a new class, AdditionNodeGen,
extending AdditionNode, that actually implements the execute*() methods.
You create instances of AdditionNodeGen by calling its static factory create() method,
and providing the two child nodes.
See the tests in ExecuteNodesDslTest
on how to use the generated AdditonNodeGen class.
A TypeSystem is sometimes required when using specializations,
to let the DSL know that it should treat certain types differently --
by default, it implements type checking with instanceof,
and type conversions just with Java casts.
Since our EasyScript implementation allows mixing of ints and doubles,
we need to inform the DSL of that fact.
We do that in the EasyScriptTypeSystem class,
which is used in the EasyScriptNode superclass
by using the @TypeSystemReference annotation
(the type system is inherited by subclasses,
so this way all EasyScript Nodes will have it without having to repeat it for each class).
Feel free to comment out the @TypeSystemReference line from EasyScriptNode --
you should see 2 out of 3 tests in
ExecuteNodesDslTest
fail.