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65 lines
2.4 KiB
OCaml
65 lines
2.4 KiB
OCaml
(*
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Copyright (c) 2013, Simon Cruanes
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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Redistributions of source code must retain the above copyright notice, this
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list of conditions and the following disclaimer. Redistributions in binary
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form must reproduce the above copyright notice, this list of conditions and the
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following disclaimer in the documentation and/or other materials provided with
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the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*)
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(** {1 Splay trees} *)
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(** See http://en.wikipedia.org/wiki/Splay_tree and
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Okasaki's "purely functional data structures" p46 *)
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type ('a, 'b) t = (('a, 'b) tree * ('a -> 'a -> int))
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(** A splay tree with the given comparison function *)
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and ('a, 'b) tree =
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| Empty
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| Node of (('a,'b) tree * 'a * 'b * ('a,'b) tree)
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(** A splay tree containing values of type 'a *)
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let empty ~cmp =
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(Empty, cmp)
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let is_empty (tree, _) =
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match tree with
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| Empty -> true
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| Node _ -> false
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let rec bigger ~cmp pivot tree =
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match tree with
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| Empty -> Empty
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| Node (a, x, x_val, b) ->
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if cmp x pivot <= 0
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then bigger ~cmp pivot b
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else match a with
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| Empty -> Node (Empty, x, x_val, b)
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| Node (a1, y, y_val, a2) ->
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if cmp y pivot <= 0
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then Node (bigger ~cmp pivot a2, x, x_val, b)
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else Node (bigger ~cmp pivot a1, y, y_val, Node (a2, x, x_val, b))
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let rec smaller ~cmp pivot tree =
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(** Insert the pair (key -> value) in the tree *)
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let insert (tree, cmp) k v =
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let tree' = Node (smaller ~cmp k tree, k, v, bigger ~cmp k tree) in
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tree', cmp
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