Add option iter
[tiger.ml.git] / compiler / src / lib / tiger / tiger_map_red_black.ml
1 module List = ListLabels
2
3 type color = R | B
4 type ('k, 'v) t =
5 | Leaf
6 | Node of color * ('k * 'v) * ('k, 'v) t * ('k, 'v) t
7
8 let empty = Leaf
9
10 let set t ~k ~v =
11 let balance = function
12 | Leaf -> assert false
13 (* LL *) | Node (B, x, Node (R, lx, Node (R, llx, lll, llr), lr ), r ) -> Node (R, lx , Node (B, llx, lll, llr), Node (B, x , lr , r ))
14 (* LR *) | Node (B, x, Node (R, lx, ll , Node (R, lrx, lrl, lrr)), r ) -> Node (R, lrx, Node (B, lx , ll , lrl), Node (B, x , lrr, r ))
15 (* RL *) | Node (B, x, l , Node (R, rx, Node (R, rlx, rll, rlr), rr )) -> Node (R, rlx, Node (B, x , l , rll), Node (B, rx , rlr, rr ))
16 (* RR *) | Node (B, x, l , Node (R, rx, rl , Node (R, rrx, rrl, rrr))) -> Node (R, rx , Node (B, x , l , rl ), Node (B, rrx, rrl, rrr))
17 | node -> node (* Fragile pattern. Shall we reconsider? *)
18 in
19 let rec set t k v =
20 match t with
21 (* Because we recur, we cannot at this stage know if the following Node
22 * with Leaf children will end-up as root (in which case it should be
23 * black) or as the last node before leaves (in which case it should be
24 * red). We begin by assuming that it is the later and at the very end,
25 * before returning to the caller, force the actual root node (which is
26 * easy to identify at that point) to be black, regardless of what it
27 * already is.
28 *)
29 | Leaf -> Node (R, (k, v), Leaf, Leaf) (* Maybe root or last node, so R *)
30 | Node (c, ((k', _) as x), l, r) when k < k' -> balance (Node (c, x, set l k v, r))
31 | Node (c, ((k', _) as x), l, r) when k > k' -> balance (Node (c, x, l , set r k v))
32 | Node (c, _ , l, r) -> Node (c, (k, v), l, r)
33 in
34 match set t k v with
35 | Leaf -> assert false (* Can we GADT this away? *)
36 | Node (_, (k, v), l, r) -> Node (B, (k, v), l, r) (* Root is always Black *)
37
38 let rec get t ~k =
39 match t with
40 | Leaf -> None
41 | Node (_, (k', _), l, _) when k < k' -> get l ~k
42 | Node (_, (k', _), _, r) when k > k' -> get r ~k
43 | Node (_, (_ , v), _, _) -> Some v
44
45 let rec member t ~k =
46 match t with
47 | Leaf -> false
48 | Node (_, (k', _), l, _) when k < k' -> member l ~k
49 | Node (_, (k', _), _, r) when k > k' -> member r ~k
50 | Node (_, (_ , _), _, _) -> true
51
52 let to_edges t =
53 let rec to_edges_from node1 t =
54 match t with
55 | Leaf -> [(node1, `Leaf)]
56 | Node (c2, (k2, _), l, r) ->
57 let node2 = k2, c2 in
58 (node1, `Node node2) :: ((to_edges_from node2 l) @ (to_edges_from node2 r))
59 in
60 match t with
61 | Leaf ->
62 []
63 | Node (c, (k, _), l, r) ->
64 let node1 = k, c in
65 (to_edges_from node1 l) @ (to_edges_from node1 r)
66
67 let color_to_string = function
68 | B -> "black"
69 | R -> "red"
70
71 let to_dot t ~k_to_string =
72 let (dot_edges_and_nodes, _, _) =
73 List.fold_left
74 (to_edges t)
75 ~init:("", "\n", 0)
76 ~f:(fun (dot_edges_and_nodes, sep, leaves) ((k1, c1), node2_or_leaf) ->
77 let k1 = k_to_string k1 in
78 let k2, c2, leaves =
79 match node2_or_leaf with
80 | `Leaf ->
81 let leaves = succ leaves in
82 let label = Printf.sprintf "Leaf_%d" leaves in
83 (label, B, leaves)
84 | `Node (k2, c2) ->
85 let label = k_to_string k2 in
86 (label, c2, leaves)
87 in
88 let dot_edges_and_nodes =
89 Printf.sprintf
90 "%s%s %S -> %S;\n %S [color=%s,fontcolor=white,style=filled];\n %S [color=%s,fontcolor=white,style=filled];\n"
91 dot_edges_and_nodes
92 sep
93 k1 k2
94 k1 (color_to_string c1) (* Yes, it's redundant... *)
95 k2 (color_to_string c2)
96 in
97 let sep = "" in
98 (dot_edges_and_nodes, sep, leaves)
99 )
100 in
101 "digraph G {" ^ dot_edges_and_nodes ^ "}"
102
103 let of_list pairs =
104 List.fold_left pairs ~init:empty ~f:(fun t (k, v) -> set t ~k ~v)
105
106 let rec to_list = function
107 | Leaf ->
108 []
109 | Node (_, pair, left, right) ->
110 pair :: ((to_list left) @ (to_list right))
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