| 1 | module Array = ArrayLabels |
| 2 | |
| 3 | module type TREE = sig |
| 4 | type ('k, 'v) t |
| 5 | |
| 6 | val empty : ('k, 'v) t |
| 7 | |
| 8 | val set : ('k, 'v) t -> k:'k -> v:'v -> ('k, 'v) t |
| 9 | |
| 10 | val get : ('k, 'v) t -> k:'k -> 'v option |
| 11 | |
| 12 | val member : ('k, 'v) t -> k:'k -> bool |
| 13 | end |
| 14 | |
| 15 | module BinaryTree : TREE = struct |
| 16 | type ('k, 'v) t = |
| 17 | | Node of 'k * 'v * ('k, 'v) t * ('k, 'v) t |
| 18 | | Leaf |
| 19 | |
| 20 | let empty = Leaf |
| 21 | |
| 22 | let rec set t ~k ~v = |
| 23 | match t with |
| 24 | | Leaf -> Node (k, v, Leaf, Leaf) |
| 25 | | Node (k', v', l, r) when k < k' -> Node (k', v', set l ~k ~v, r) |
| 26 | | Node (k', v', l, r) when k > k' -> Node (k', v', l, set r ~k ~v) |
| 27 | | Node (k, _, l, r) -> Node (k, v, l, r) |
| 28 | |
| 29 | let rec get t ~k = |
| 30 | match t with |
| 31 | | Leaf -> None |
| 32 | | Node (k', _, l, _) when k < k' -> get l ~k |
| 33 | | Node (k', _, _, r) when k > k' -> get r ~k |
| 34 | | Node (_, v, _, _) -> Some v |
| 35 | |
| 36 | let rec member t ~k = |
| 37 | match t with |
| 38 | | Leaf -> false |
| 39 | | Node (k', _, l, _) when k < k' -> member l ~k |
| 40 | | Node (k', _, _, r) when k > k' -> member r ~k |
| 41 | | Node _ -> true |
| 42 | end |
| 43 | |
| 44 | let () = |
| 45 | let tree_a = BinaryTree.empty in |
| 46 | let tree_a = BinaryTree.set tree_a ~k:"k1" ~v:"v1" in |
| 47 | let tree_a = BinaryTree.set tree_a ~k:"k2" ~v:"v2" in |
| 48 | assert (BinaryTree.member tree_a ~k:"k1"); |
| 49 | assert (BinaryTree.member tree_a ~k:"k2"); |
| 50 | assert (Some "v1" = BinaryTree.get tree_a ~k:"k1"); |
| 51 | assert (Some "v2" = BinaryTree.get tree_a ~k:"k2"); |
| 52 | let tree_b = |
| 53 | Array.fold_left |
| 54 | (Sys.argv) |
| 55 | ~init:BinaryTree.empty |
| 56 | ~f:(fun t k -> BinaryTree.set t ~k ~v:()) |
| 57 | in |
| 58 | Printf.printf "%B\n" (BinaryTree.member tree_b ~k:"a") |