Possibility to correlate ast nodes to line and column number in visitor

[ghost]

Hello,

Thank you for the amazing work on swc, wanted to ask if it's possible to get line column number corresponding to nodes when travering the ast generated by swc.

[ghost]

well, i found the methods to convert Span to location in the rust code, these are not exposed to the web assembly version currently i guess.

[kdy1]

Currently, it's true. There's no api for it.

I'm considering something like babelify which will return babel ast to javascript.
Related to: #1465

[ghost]

@kdy1 ah, understood. It makes sense better to have one proper API than a bunch of them.

If it is very very straightforward could you maybe write a sample snippet or so how I could expose let's say resolveSpan to resolve Spans on AST returned from parseSync. I could build the wasm module myself with the changes and use it until the official solution is in. I'm very new to rust and swc and is still trying to figure out the codebase.

[ghost]

@kdy1 actually nevermind my last request, i have already figured it out and it works perfectly. Thanks again for the awesome work on SWC!!.

[sam-goodwin]

@jiby-gh Mind sharing your solution? I also need to map Spans to line/column.

[gb-jos]

@sam-goodwin its was a while ago, but I believe what I used was node.span.lo.0

[sam-goodwin]

Thanks for the quick reply, I actually figured it out. The entrypoint to the plugin is passed a TransformPluginProgramMetadata which contains a PluginSourceMapProxy which can be used to map a BytePos such as span.lo() to a line_col

#[plugin_transform]
pub fn my_plugin(mut program: Program, meta: TransformPluginProgramMetadata) -> Program {
  // you need this
  let source_map = meta.source_map;

  // then, given a span
  let span = ??
 
  // map it to a line_col
  let line_col = source_map.lookup_char_pos(span.lo());
  line_col.line; // 1-based line
  line_col.col_display; // 0-based column

  program
}