Rust Macro

macro_rules! test {
    (`patten`) => {`template`};
    (`patten`) => {`template`};
}

macro_rules! print_n_times {
    ($n:expr, $v:expr) => (
        for i in 0..$n {
            println!("{:?}", $v);
        }
    );
}

fn main() {
    print_n_times!(3, "hello");
}

macro_rules! my_vec {
    ($($v:expr), *) => (
        {
            let mut ret = vec![];
            $(
                ret.push($v);
            )*;
            ret
        }
    );
    ($($v:expr) *) => (
        {
            let mut ret = vec![];
            $(
                ret.push($v)
            );*;
            ret
        }
    );
}
fn main() {
    println!("{:?}", my_vec!(1, 2, 3));
    println!("{:?}", my_vec!(1 2 3));
}

macro_rules! print {
    (one) => {
        println!("{:?}", 1);
    };
    (two) => {
        println!("{:?}", 2);
    };
    ($($v:tt),*) => {
        $(
            print!($v);
        )*
    };
}
fn main() {
    print!(one, two, one);
}

macro_rules! v {
    (None) => {
        println!("{:?}", "None");
    };
    ($v:expr) => {
        println!("{:?}", $v);
    };
    ($($v:tt),*) => {
        println!("{:?}", "begin");
        $(
            v!($v);
        )*;
        println!("{:?}", "end");
    };
}
fn main() {
    v![1, 2, None];
}