Running the pipeline in reverse

[dennwc]

The DSL was designed and implemented to run in both forward (AST->UAST) and reverse (UAST->AST) modes. This allows converting the native AST returned by drivers to a canonical form (UAST) and back to the native AST. Assuming #352 is solved this will allows us to render UAST into the source files.

However, to make this possible all operations defined by the DSL are required to be reversible (ast == RevOp(Op(ast))). SDK closely follows this requirement, but some drivers don't.

We should revisit the drivers and make sure we can always run the transformation pipelines in reverse.

This will also allow us to have a better test coverage for drivers by runing the pipeline in both directions..

[sxiii]

@dennwc I wonder if current implementation of bblfsh are capable of doing something like:

Go -> Go native AST -> UAST -> C native AST -> C.

So in result that would allow do a Go to C code transpiling.

As I understood well if all drivers will allow to run pipelines in reverse than it would be possible?

Thanks