Converting MethodHandle into reflective Method instance

[Eric Bodden]

Hi all.

The Lookup class contains an "unreflect" method which converts Method
objects into MethodHandles. I am lookingo for something that does just
the opposite and I wonder if the JDK provides this functionality or if
otherwise you would accept a patch from us such that it did.

Our motivation for this is as follows. We are trying to extend the
AspectJ compiler such that it allows the runtime to match method-call,
field-set and field-get pointcuts against invokedynamic instructions,
so that effectively a pointcut such as call(* foo()) would match also
if "foo" is called via invokedynamic.

Our current design for this is as follows:
We wrap all original bootstrap methods into a wrapper which (a)
invokes the original bootstrap code, (b) retrieves the method handle
returned by that bootstrap code and matches it against all pointcuts
of all aspects and if any pointcuts do match then (c) returns a
modified method handle that implements the intended advice-execution
logic.

Steps (a) and (c) seem to work quite smoothly but (b) is giving us
trouble. This is because, to match AspectJ pointcuts at runtime, we
would like to use ajc's weaving API:
http://eclipse.org/aspectj/doc/next/weaver-api/org/aspectj/weaver/tools/PointcutExpression.html#matchesMethodCall(java.lang.reflect.Method,
java.lang.Class)
This API requires jva.lang.reflect objects and has no knowledge of
MethodHandles. Hence the need for a converter.

I do realize that not every kind of MethodHandle may actually *have*
an appropriate Method object, as not every MethodHandle actually
points to a method. But it would be great to have a getMethod() method
for those that do, or a getField() method for those that represent
field accesses.

Any pointers in this direction would be appreciated. Also, if you
think that what I am after will *not* be possible for some reason, it
would be great if you could let me know that, too.

Best wishes,
Eric Bodden
-- 
Eric Bodden, Ph.D., http://sse.ec-spride.de/ http://bodden.de/
Head of Secure Software Engineering Group at EC SPRIDE
Tel: +49 6151 16-75422    Fax: +49 6151 16-72051
Room 3.2.14, Mornewegstr. 30, 64293 Darmstadt