#[path="support/slot_pool.rs"] mod slot_pool;
use slot_pool::SlotPool;
struct Node { val:i64, prev:usize, next:usize }

fn insert_after(pool: &mut SlotPool<Node>, p: usize, v: i64) -> usize {
    let next = pool.items[p].next;
    let n = pool.alloc(Node { val: v, prev: p, next });
    pool.items[next].prev = n;
    pool.items[p].next = n;
    n
}
fn remove(pool: &mut SlotPool<Node>, n: usize) {
    let (prev, next) = (pool.items[n].prev, pool.items[n].next);
    pool.items[prev].next = next;
    pool.items[next].prev = prev;
    pool.free(n);
}
fn is_end(n: usize, head: usize) -> bool { n == head }

fn values(pool:&SlotPool<Node>,head:usize)->Vec<i64> {
    let mut out=vec![]; let mut at=pool.items[head].next;
    while !is_end(at,head) { out.push(pool.items[at].val); at=pool.items[at].next; assert!(out.len()<100); }
    out
}
fn main() {
    let mut pool=SlotPool::new();let head=pool.alloc(Node {val:0,prev:0,next:0});
    let mut tail=head;let mut handles=vec![];
    for v in [10,20,30,40,50] { tail=insert_after(&mut pool,tail,v);handles.push(tail); }
    assert_eq!(values(&pool,head),[10,20,30,40,50]); assert_eq!(pool.items.len(),6);
    remove(&mut pool,handles[1]); remove(&mut pool,handles[3]);
    assert_eq!(values(&pool,head),[10,30,50]);
    tail=insert_after(&mut pool,tail,7); insert_after(&mut pool,tail,8);
    assert_eq!(values(&pool,head),[10,30,50,7,8]);assert_eq!(pool.items.len(),6);
}