Function syntax::ext::tt::transcribe::transcribe

pub fn transcribe(
    cx: &ExtCtxt, 
    interp: &FxHashMap<Ident, Rc<NamedMatch>>, 
    src: Vec<TokenTree>
) -> TokenStream

This can do Macro-By-Example transcription.

• interp is a map of meta-variables to the tokens (non-terminals) they matched in the invocation. We are assuming we already know there is a match.
• src is the RHS of the MBE, that is, the "example" we are filling in.

For example,

macro_rules! foo {
    ($id:ident) => { println!("{}", stringify!($id)); }
}

foo!(bar);

interp would contain $id => bar and src would contain println!("{}", stringify!($id));.

transcribe would return a TokenStream containing println!("{}", stringify!(bar));.

Along the way, we do some additional error checking.