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package container
Ring :: struct($T: typeid) {
next, prev: ^Ring(T),
value: T,
}
ring_init :: proc(r: ^$R/Ring) -> ^R {
r.prev, r.next = r, r;
return r;
}
ring_next :: proc(r: ^$R/Ring) -> ^R {
if r.next == nil {
return ring_init(r);
}
return r.next;
}
ring_prev :: proc(r: ^$R/Ring) -> ^R {
if r.prev == nil {
return ring_init(r);
}
return r.prev;
}
ring_move :: proc(r: ^$R/Ring, n: int) -> ^R {
r := r;
if r.next == nil {
return ring_init(r);
}
switch {
case n < 0:
for _ in n..<0 {
r = r.prev;
}
case n > 0:
for _ in 0..<n {
r = r.next;
}
}
return r;
}
ring_link :: proc(r, s: ^$R/Ring) -> ^R {
n := ring_next(r);
if s != nil {
p := ring_prev(s);
r.next = s;
s.prev = r;
n.prev = p;
p.next = n;
}
return n;
}
ring_unlink :: proc(r: ^$R/Ring, n: int) -> ^R {
if n <= 0 {
return nil;
}
return ring_link(r, ring_move(r, n+1));
}
ring_len :: proc(r: ^$R/Ring) -> int {
n := 0;
if r != nil {
n = 1;
for p := ring_next(r); p != r; p = p.next {
n += 1;
}
}
return n;
}
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