macro-match-tt.rs

use std::boxed::Box;

#[derive(Debug, PartialEq)]
enum N {
    V(Vec<Box<N>>),
    S(Box<N>),
    C(i32),
}

macro_rules! t {
    ( [ $( $n:tt ),+ ] ) => { Box::new(N::V( vec![ $( t!($n) ),+ ])) };

    ( ( $n:tt ) ) => { Box::new(N::S( t!($n) )) };

    ( $i:expr ) => { Box::new(N::C($i)) };
}

fn main() {
    let n = Box::new(N::V(vec![
                          Box::new(N::S(Box::new(N::C(1)))),
                          Box::new(N::S(Box::new(N::C(2)))),
                          Box::new(N::S(Box::new(N::C(3))))
    ]));

    let m = t! {
        [
            (1), (2), (3)
        ]
    };

    assert_eq!(n, m);
}