Kampfkarren/full-moon

how to extract preceding comment from a statement?

wez opened this issue · 6 comments

wez commented

I don't see an obvious way from the API docs to to access the comments from the ast for something like this:

---@class Foo
---@field name string the name of the Foo
local Foo = {}

what's the recommended way to be able to extract the uninterrupted sequence of comments that precedes an ast node?

Kampfkarren commented

Does leading_trivia() do what you want?

wez commented

I don't know what it does?

wez commented

and by that I mean, the docs don't specify what leading trivia is, or its scope:
https://docs.rs/full_moon/latest/full_moon/tokenizer/struct.TokenReference.html#method.leading_trivia

can you clarify the behavior? What is exactly is trivia in this context?

Kampfkarren commented

Oh, surrounding_trivia() will work too. https://docs.rs/full_moon/latest/full_moon/node/trait.Node.html#method.surrounding_trivia

Trivia is whitespace and comments, anything that doesn't have a node on its own.

wez commented

I see, so parse() will yield an Ast, and from there ast.nodes() will yield each node, and node.surrounding_trivia() will get the before/after tokens.

JohnnyMorganz commented

Yup, that's correct. The preceding comment of each statement is attached as leading trivia of the first token in the statement. Generally, it can be accessed using node.surrounding_trivia() on the Node trait that each specialised node implements.

You can also treat each statement node individually if you wish. For the example in OP, you have a LocalAssignment, and the two comments are leading trivia on the LocalAssignment::local_token()

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