push.rs

// push() method for a singly-linked list in Rust?!

use std::rc::Rc;

#[derive(Debug, PartialEq)]
enum List<T> {
    Nil,
    Cons(Rc<(T, List<T>)>)
}

impl<T> List<T> {
    fn push_front(&mut self, value: T) {
        let mut tmp = List::Nil;
        std::mem::swap(&mut tmp, self);
        *self = List::Cons(Rc::new((value, tmp)));
    }
}

#[test]
fn push_tests() {
    let mut my_list = List::Nil;
    my_list.push_front("world");
    my_list.push_front("hello");
    assert_eq!(my_list,
        List::Cons(Rc::new(("hello",
            List::Cons(Rc::new(("world", List::Nil)))))));
}