Allow application bytecode transformation over plain byte arrays

[Sanne]

We need Hibernate ORM to apply its own bytecode transformation logic on the user's JPA model.

The API we have in ORM is this one:

• https://github.com/hibernate/hibernate-orm/blob/159bc99a36d86988b61b88ba91eec82cac044e1c/hibernate-core/src/main/java/org/hibernate/bytecode/enhance/spi/Enhancer.java#L16-L29

while Shamrock expects a Function<String, Function<ClassVisitor, ClassVisitor>> function; I don't see an easy way to adapt to this.

Would be nice to also expose the option to register a processor which works on plain byte[] rather than ASM class visitors?

[dmlloyd]

I believe you could adapt it by returning a Function which returns a subclass of ClassWriter, which calls your transform at visitEnd and then uses a ClassReader initialized with the resultant class bytes to accept the passed-in ClassVisitor.

[Sanne]

interesting idea! but visitEnd() is final :(

I'll play with that.

[dmlloyd]

Ah, in that case you should create a ClassVisitor subclass whose delegate is a ClassWriter. Same idea though.

[Sanne]

Prototyped an alternative based on David's suggestion:

• 75a73ca#diff-210528c8e74ac93e8d59665d67cbb046

I'll close this issue.