Go parser

[zkat]

We should have a nice golang parser for kdl. Hopefully we can also add it to the org!

[gcapizzi]

giving a go (heh) at this using https://github.com/alecthomas/participle, not sure I'll get anywhere, wish me luck! 😅

[zkat]

Good luck!

[gcapizzi]

Alright, I'm a bit stuck.

participle is quite rigid in terms of the ASTs that it can generate. In particular, it maps variants as structs with multiple fields, only one of which has a value. For example, to allow interleaved values and properties as arguments, we would have to add an Argument struct with Value and a Property fields. Same for the Value type.

It would be a lot nicer to have separate Values and Properties lists (just like in the Rust parser), but I don't think there's a good way to do this in participle 😞

I could try to handwrite a lexer and a parser, but I've never done it and I'm not sure I'd get to the bottom of it 😅
Alternatively, we could parse with participle and then convert the AST into the one we like. This would mean three passes though (lexing + parsing + "fixing" the AST).

I was also thinking that a tags-based solutions would be pretty nice (that's what the json package does for example). I don't think that would save us from building a more traditional AST-producing parser though (the json package has one, which produces map[string]interface{}s).

Thoughts?

[zkat]

I have never done Go so I don't really know what the best thing would be.

I will say, though, that I don't think parsing speed is that important as an initial goal, so "fixing" the AST seems ok to me?

[danderson]

I just came across KDL, and as it happens it's exactly what I needed for a Go project of mine, for which I was in the middle of writing a parser for a custom language. I'm going to retool that to parse KDL instead.

I can't promise I'll get anywhere, so please don't view this as me planting a flag or anything, just broadcasting in case anyone else is interested in collaborating.

[binhonglee]

I got started working on this like yesterday so it only works on really small selection of cases. I've never worked on a parser before either, open to suggestions / PR etc.

https://github.com/binhonglee/kdl-go

[zhengpd]

Both https://github.com/binhonglee/kdlgo and https://github.com/danderson/go-kdl are inactive since 2021. Are they abandoned?

[danderson]

In my case, yes, sorry. I lost my use-case for KDL, and the time to build the library. My vague memory is that I had a pretty solid lexer, but no parser yet.

[Frixuu]

No unmarshalling/marshalling yet, but I have somewhat of a working parser at https://github.com/Frixuu/KDLGo. Like above, I'm just putting it out there etc. etc. 😉