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(*
Copyright (c) 2000
Cambridge University Technical Services Limited
Modified David C.J. Matthews 2008
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*)
structure UniversalArray :>
sig
type universal = Universal.universal;
type 'a tag = 'a Universal.tag;
type univArray;
val univArray: int -> univArray;
val update: univArray * 'a tag * string * 'a -> unit;
val sub: univArray * 'a tag * string -> 'a option;
val delete: univArray * 'a tag * string -> unit;
val fold: (string * universal * 'a -> 'a) -> 'a -> univArray-> 'a;
end =
struct
open HashArray;
open Universal;
type universal = universal
type 'a tag = 'a tag;
datatype univArray = Table of universal list hash
fun univArray n = Table (hash n);
fun op sub (Table tab, t:'a tag, name:string) : 'a option =
let
fun search [] = NONE
| search (H::T) = if tagIs t H then SOME (tagProject t H) else search T;
in
case HashArray.sub (tab, name) of
NONE => NONE
| SOME t => search t
end;
fun update (Table tab, t:'a tag, name:string, v:'a) : unit =
let
val u = tagInject t v;
(* If there is already an entry we add it to the list,
otherwise we start a new list. *)
fun search [] = [u]
| search (H::T) = if tagIs t H then u :: T else H :: search T;
val newList =
case HashArray.sub (tab, name) of
SOME v => search v
| NONE => [u]
in
HashArray.update (tab, name, newList)
end;
fun delete (Table tab, t:'a tag, name:string) : unit =
let
fun search [] = []
| search (H::T) = if tagIs t H then T else H :: search T;
in
case HashArray.sub (tab, name) of
SOME l => HashArray.update (tab, name, search l)
| NONE => ()
end;
fun fold f init (Table t) =
HashArray.fold (fn (s, l, i) => List.foldl (fn (x,y) => f(s, x, y)) i l) init t
end (* UniversalArray *);
|
