mirror of
https://github.com/tildearrow/furnace.git
synced 2024-11-18 18:45:10 +00:00
65 lines
2.3 KiB
OCaml
65 lines
2.3 KiB
OCaml
(*
|
|
* Copyright (c) 1997-1999 Massachusetts Institute of Technology
|
|
* Copyright (c) 2003, 2007-14 Matteo Frigo
|
|
* Copyright (c) 2003, 2007-14 Massachusetts Institute of Technology
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*
|
|
*)
|
|
|
|
(*************************************************************
|
|
* Functional associative table
|
|
*************************************************************)
|
|
|
|
(*
|
|
* this module implements a functional associative table.
|
|
* The table is parametrized by an equality predicate and
|
|
* a hash function, with the restriction that (equal a b) ==>
|
|
* hash a == hash b.
|
|
* The table is purely functional and implemented using a binary
|
|
* search tree (not balanced for now)
|
|
*)
|
|
|
|
type ('a, 'b) elem =
|
|
Leaf
|
|
| Node of int * ('a, 'b) elem * ('a, 'b) elem * ('a * 'b) list
|
|
|
|
let empty = Leaf
|
|
|
|
let lookup hash equal key table =
|
|
let h = hash key in
|
|
let rec look = function
|
|
Leaf -> None
|
|
| Node (hash_key, left, right, this_list) ->
|
|
if (hash_key < h) then look left
|
|
else if (hash_key > h) then look right
|
|
else let rec loop = function
|
|
[] -> None
|
|
| (a, b) :: rest -> if (equal key a) then Some b else loop rest
|
|
in loop this_list
|
|
in look table
|
|
|
|
let insert hash key value table =
|
|
let h = hash key in
|
|
let rec ins = function
|
|
Leaf -> Node (h, Leaf, Leaf, [(key, value)])
|
|
| Node (hash_key, left, right, this_list) ->
|
|
if (hash_key < h) then
|
|
Node (hash_key, ins left, right, this_list)
|
|
else if (hash_key > h) then
|
|
Node (hash_key, left, ins right, this_list)
|
|
else
|
|
Node (hash_key, left, right, (key, value) :: this_list)
|
|
in ins table
|