1 files changed, 97 insertions, 0 deletions
diff --git a/stdlib/map.ml b/stdlib/map.ml
new file mode 100644
index 000000000..40ebdfaef
--- /dev/null
+++ b/stdlib/map.ml
@@ -0,0 +1,97 @@
+module type OrderedType =
+  sig
+    type t
+    val compare: t -> t -> int
+  end
+
+module type S =
+  sig
+    type key
+    type 'a t
+    val empty: 'a t
+    val add: key -> 'a -> 'a t -> 'a t
+    val find: key -> 'a t -> 'a
+    val iter: (key -> 'a -> 'b) -> 'a t -> unit
+    val fold: (key -> 'a -> 'b -> 'b) -> 'a t -> 'b -> 'b
+  end
+
+module Make(Ord: OrderedType) = struct
+
+    type key = Ord.t
+
+    type 'a t =
+        Empty
+      | Node of 'a t * key * 'a * 'a t * int
+
+    let empty = Empty
+
+    let height = function
+        Empty -> 0
+      | Node(_,_,_,_,h) -> h
+
+    let new l x d r =
+      let hl = height l and hr = height r in
+      Node(l, x, d, r, (if hl >= hr then hl + 1 else hr + 1))
+
+    let bal l x d r =
+      let hl = match l with Empty -> 0 | Node(_,_,_,_,h) -> h in
+      let hr = match r with Empty -> 0 | Node(_,_,_,_,h) -> h in
+      if hl > hr + 2 then begin
+        match l with
+          Empty -> invalid_arg "Set.bal"
+        | Node(ll, lv, ld, lr, _) ->
+            if height ll >= height lr then
+              new ll lv ld (new lr x d r)
+            else begin
+              match lr with
+                Empty -> invalid_arg "Set.bal"
+              | Node(lrl, lrv, lrd, lrr, _)->
+                  new (new ll lv ld lrl) lrv lrd (new lrr x d r)
+            end
+      end else if hr > hl + 2 then begin
+        match r with
+          Empty -> invalid_arg "Set.bal"
+        | Node(rl, rv, rd, rr, _) ->
+            if height rr >= height rl then
+              new (new l x d rl) rv rd rr
+            else begin
+              match rl with
+                Empty -> invalid_arg "Set.bal"
+              | Node(rll, rlv, rld, rlr, _) ->
+                  new (new l x d rll) rlv rld (new rlr rv rd rr)
+            end
+      end else
+        Node(l, x, d, r, (if hl >= hr then hl + 1 else hr + 1))
+
+    let rec add x data = function
+        Empty ->
+          Node(Empty, x, data, Empty, 1)
+      | Node(l, v, d, r, h) as t ->
+          let c = Ord.compare x v in
+          if c = 0 then
+            Node(l, x, data, r, h)
+          else if c < 0 then
+            bal (add x data l) v d r
+          else
+            bal l v d (add x data r)
+
+    let rec find x = function
+        Empty ->
+          raise Not_found
+      | Node(l, v, d, r, _) ->
+          let c = Ord.compare x v in
+          if c = 0 then d
+          else find x (if c < 0 then l else r)
+
+    let rec iter f = function
+        Empty -> ()
+      | Node(l, v, d, r, _) ->
+          iter f l; f v d; iter f r
+
+    let rec fold f m accu =
+      match m with
+        Empty -> accu
+      | Node(l, v, d, r, _) ->
+          fold f l (f v d (fold f r accu))
+
+end