Macro abortable_parser::peek

macro_rules! peek {
    ($i:expr, $f:ident!( $( $args:tt )* ) ) => { ... };
    ($i:expr, $f:ident( $( $args:tt )* ) ) => { ... };
    ($i:expr, $f:ident) => { ... };
}

Checks the given matcher without consuming the input.

let tok = peek!(iter, text_token!("foo"));