use std::cell::RefCell;

pub struct Entry<A,B> {
    key: A,
    value: B
}

pub struct alist<A,B> {
    eq_fn: extern "Rust" fn(A,A) -> bool,
    data: Box<RefCell<Vec<Entry<A,B>>>>,
}

pub fn alist_add<A:'static,B:'static>(lst: &alist<A,B>, k: A, v: B) {
    let mut data = lst.data.borrow_mut();
    (*data).push(Entry{key:k, value:v});
}

pub fn alist_get<A:Clone + 'static,
                 B:Clone + 'static>(
                 lst: &alist<A,B>,
                 k: A)
                 -> B {
    let eq_fn = lst.eq_fn;
    let data = lst.data.borrow();
    for entry in &(*data) {
        if eq_fn(entry.key.clone(), k.clone()) {
            return entry.value.clone();
        }
    }
    panic!();
}

#[inline]
pub fn new_int_alist<B:'static>() -> alist<isize, B> {
    fn eq_int(a: isize, b: isize) -> bool { a == b }
    return alist {
        eq_fn: eq_int,
        data: Box::new(RefCell::new(Vec::new())),
    };
}

#[inline]
pub fn new_int_alist_2<B:'static>() -> alist<isize, B> {
    #[inline]
    fn eq_int(a: isize, b: isize) -> bool { a == b }
    return alist {
        eq_fn: eq_int,
        data: Box::new(RefCell::new(Vec::new())),
    };
}