Use SWC for codemods?

[lgrammel]

Hi!

I'm thinking about exploring SWC/Rust for codemods and was wondering if that's a usecase that would make sense?

Right now, I'm using Babel + Recast, and in particular I'm curious if something like Recast (retaining most of the formatting during a codemod) is supported / would be easy to add?

Cheers, Lars

[kdy1]

I guess it makes sense, although I'm not sure what you mean by codemod.
Can you tell me what it is?

[kdy1]

All information related to original source code is stored at swc_common::SourceMap.
Span is a pointer for the data and has a document on it.

For the modification part, Fold will be useful. There are lots of transforms using Fold at /ecmascript/transforms so you can refer to it to see what can be done.

The codegen will require getting original line and column. You can do it with methods on the SourceMap. One example is lookup_char_pos.
After getting original line and column, you can print them carefully. (You can even just print original source code if it's not modifed.)

[lgrammel]

Thanks for the pointers! I'll see if I can get some trivial codemod working.

[0xdevalias]

@lgrammel Did you ever have any luck getting this going?

[lgrammel]

@0xdevalias never got around to explore this

[Viijay-Kr]

@lgrammel Did you get to explore this ? I am also in the pursuit of writing a codemods using SWC AST . Would love to see some explorations for reference