Generate code from the grammar constructs (Code Generation)

[multimeric]

Given a hermes Grammar and values for each terminal, is it possible to perform code generation? I ask because I'm interested in writing code that generates WDL (which uses a hermes grammar), but I can't see any easy or documented way to do this.

[scottfrazer]

Hey sorry! For some reason I wasn't even aware of issues being filed on this project!

I assume you probably don't need this anymore... but in case you do, I'm not sure I understand your use case. The only input needed for code generation is the grammar

[multimeric]

I kind of still do. I think I was hoping to do something like: generate a new task with name x, containing a list of declarations y, based on the grammar. Is this possible somehow?

[scottfrazer]

If I understand correctly:

Generate wdl_parser.py

$ hermes generate wdl.hgr

then example.py:

from wdl_parser import parse
tree = parse('''
    task y {
        Int i
        String s
    }
''')
print(tree.ast().dumps(indent=2))

$ python example.py
(Namespace:
  imports=[],
  body=[
    (Task:
      name=<string:2:10 identifier "eQ==">,
      declarations=[
        (Declaration:
          type=<string:3:9 type "SW50">,
          postfix=None,
          name=<string:3:13 identifier "aQ==">,
          expression=None
        ),
        (Declaration:
          type=<string:4:9 type "U3RyaW5n">,
          postfix=None,
          name=<string:4:16 identifier "cw==">,
          expression=None
        )
      ],
      sections=[]
    )
  ]
)

[multimeric]

Right, but I want to do the opposite of this. Here, you're parsing a WDL string to hermes data structures, but I want to provide hermes data structures and generate WDL using the grammar. Is this possible?

[scottfrazer]

It's possible in theory but there's no way to do this with the current code.

If you wanted to write it yourself, you could recursively walk the AST and output source code for each node.