How to get source-code text from boa_ast::Span?

[tyilo]

I have some code that parses a JS file and then processes the AST. As part of this I have a boa_ast::Span that I would like to resolve to the corresponding source-code text (as UTF-16).

How would I do that?

The code looks something like:

function process_ast(interner: &Interner, ast: impl VisitWith) -> Span {
    let mut visitor = ...;
    _  = ast.visit_with(&mut visitor);
   visitor.span
}

let source = Source::from_filepath(...).unwrap();
let mut interner = Interner::new();
let mut parser = Parser::new(source);
let script = parser.parse_module(&Scope::global(), &mut interner).unwrap();

let span = process_ast(&interner, script);

// Now I want to get the UTF16-text of the returned span
let s = ???;

[jedel1043]

Maybe something like

let (ast, source_text) = parser.parse_module_with_source(&Scope::global(), &mut interner).unwrap();
let span = process_ast(&interner, ast);
let s = source_text.get_code_points_from_span(span);

[jedel1043]

Interesting. I'm wondering why you're using boa_ast instead of something like swc_ecma_ast though. Do you plan to integrate with boa_engine in the future?

[jedel1043]

I say this because our parser and ast are pretty much tied to the engine to enable more optimizations, but if your tool only requires parsing it would be better to use a more general library such as swc to parse and analyze the AST.

[tyilo]

No reason in particular. I might take a look at swc, thanks!

[tyilo]

I used boa in another Rust project where I needed to evaluate some JS and pass in some Rust objects, so I was just familiar with boa.

[tyilo]

I have now changed my code to use swc instead of boa.