Library

The formatter is also a Rust library.

cargo add rdlfmt --no-default-features

let formatted = rdlfmt::format(source)?;

format returns Result<String, FormatError>. The error carries the parse diagnostics, each with a byte range into the input, so a caller can report them against its own source map.

rdlfmt::syntax exposes the layer underneath, if you want the tree rather than the text: lex for the token stream, parse for a lossless rowan concrete syntax tree with every comment and directive still in it, and SyntaxNode/SyntaxToken to walk it.

The cli feature is on by default and pulls in clap and friends for the binary. The library half depends on none of them, so default-features = false drops the lot and leaves logos and rowan.

Full API documentation is on docs.rs.

cargo run --example dump-cst -- regs.rdl

is the quickest way to see what the tree looks like.