102 lines
2.3 KiB
OCaml
102 lines
2.3 KiB
OCaml
(* This file was originally part of lwt-dllist, which is licensed
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under MIT: https://github.com/ocsigen/lwt/blob/master/LICENSE.md. *)
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type 'a t = {
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mutable prev : 'a t;
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mutable next : 'a t;
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}
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type 'a node = {
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mutable node_prev : 'a t;
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mutable node_next : 'a t;
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mutable node_active : bool;
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node_data : 'a;
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}
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(* XXX: technically [.node_next]/[.node_prev] *are* mutated in [remove] but they are [Obj.magic]'d
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into ['a t] first.*)
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[@@warning "-69"]
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external seq_of_node : 'a node -> 'a t = "%identity"
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external node_of_seq : 'a t -> 'a node = "%identity"
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let create () =
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let rec seq = { prev = seq; next = seq } in
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seq
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let is_empty seq = seq.next == seq
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let remove node =
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if node.node_active then begin
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node.node_active <- false;
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let seq = seq_of_node node in
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seq.prev.next <- seq.next;
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seq.next.prev <- seq.prev
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end
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let add_l data seq =
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let node = { node_prev = seq; node_next = seq.next; node_data = data; node_active = true } in
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seq.next.prev <- seq_of_node node;
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seq.next <- seq_of_node node;
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node
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let add_r data seq =
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let node = { node_prev = seq.prev; node_next = seq; node_data = data; node_active = true } in
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seq.prev.next <- seq_of_node node;
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seq.prev <- seq_of_node node;
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node
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let take_l seq =
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if is_empty seq then raise Not_found;
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begin
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let node = node_of_seq seq.next in
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remove node;
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node.node_data
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end
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let take_r seq =
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if is_empty seq then raise Not_found;
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begin
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let node = node_of_seq seq.prev in
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remove node;
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node.node_data
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end
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let fold_r f seq acc =
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let rec loop curr acc =
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if curr == seq then
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acc
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else
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let node = node_of_seq curr in
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if node.node_active then
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loop node.node_prev (f node.node_data acc)
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else
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loop node.node_prev acc
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in
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loop seq.prev acc
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let find f seq =
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let rec loop curr =
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if curr == seq then
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raise Not_found
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else
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let node = node_of_seq curr in
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if node.node_active && f node.node_data then
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node.node_data
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else
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loop node.node_next
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in
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loop seq.next
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let exists f seq =
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let rec loop curr =
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if curr == seq then
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false
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else
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let node = node_of_seq curr in
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if node.node_active && f node.node_data then
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true
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else
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loop node.node_next
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in
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loop seq.next
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