Initial draft of a public API to navigate and manipulate VHDL syntax

[Schottkyc137]

No description provided.

[skaupper]

Regarding your comment here:
As far as I understand, you want to find a better way of generating AstNodes which are basically the user API. If you represent every variant of NodeKind with the macros from the ast_syntax_gen crate the file would get rather extensive.

If you say, you want to generate them from some description you are also considering providing the description using some kind of text file (e.g. JSON, YAML, whatever), am I right?
Contrary to the grammar, each token would get a name associated with it but in the end it would still be a representation of the original grammar.

Sure, the AstNodes shouldn't be as much of a pain as some of the parsing routines, but most productions are pretty straight forward as well. If you want a description to generate the AstNodes couldn't a lot of the productions be generated from the very same description if you get them into some kind of regular structure? signal_declaration etc. are some pretty trivial examples.

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That's how I could imagine a description using YAML. It's basically the same as your macro approach but in a separate file and probably more readable? Is that the direction you imagined, or am I way off? :)

# `SignalDeclaration` is a sequence of nodes and tokens 
# with an optional alternative and an optional sequence
SignalDeclaration:
  sequence:
    - keyword: Signal
    - node: IdentifierList
    - token: Colon
    - node: SubtypeIndication
    - optional: true
      alternative: 
        - keyword: Register
        - keyword: Bus
    - optional: true 
      sequence:
        - token: ColonEq
        - node: Expression
    - token: SemiColon

# `IdentifierList` is a repeated node of `Identifier`s, 
# separated by a `Comma` token
IdentifierList:
  repeat: "+"
  separate_by: 
    token: Comma
  sequence:
    - token: Identifier

# Provide the implementations for these nodes manually
SubtypeIndication:
  raw: true
Expression: 
  raw: true