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(*
Copyright (c) 2000
Cambridge University Technical Services Limited
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
*)
(*
Title: Table of printing functions for user-defined types.
Author: Dave Matthews, Cambridge University Computer Laboratory
Copyright Cambridge University 1990
*)
(* implicitly imports Boot.Misc, Boot.PrettyPrinter, StructVals and Address *)
(*
The original purpose of this module was to allow for type-dependent
print functions to be installed by the user. That requires a special
mechanism to allow a function to be installed in a child database without
needing to be able to write to the top-level database containing the
compiler.
This has been extended to deal with SML97 overloading for both functions
and literal constants and also for ref-like types which support pointer
equality even though these cases are intended only for the implementors
of libraries which would probably be in the top-level database.
*)
functor PRINT_TABLE (
structure CODETREE:
sig
type machineWord;
type codetree
end;
(*****************************************************************************)
(* STRUCTVALS *)
(*****************************************************************************)
structure STRUCTVALS :
sig
type typeId;
type typeConstrs
val sameTypeId: typeId * typeId -> bool;
val tcIdentifier: typeConstrs -> typeId
end;
(*****************************************************************************)
(* PRETTY *)
(*****************************************************************************)
structure PRETTY : PRETTYSIG
):
(*****************************************************************************)
(* PRINTTABLE export signature *)
(*****************************************************************************)
sig
type typeConstrs
type codetree
val addOverload: string * typeConstrs * codetree -> unit
val getOverloads: string -> (typeConstrs * codetree) list
val getOverload: string * typeConstrs * (unit->codetree) -> codetree
structure Sharing:
sig
type typeConstrs = typeConstrs
type codetree = codetree
end
end =
(*****************************************************************************)
(* PRINTTABLE functor body *)
(*****************************************************************************)
struct
open STRUCTVALS;
type pretty = PRETTY.pretty
open CODETREE
type overloadEntry = string * typeConstrs * codetree;
(* Create a ref to hold the list *)
val overloadTable : overloadEntry list ref = ref []
(* The most recent ref refers to the current level of the hierarchy,
so is the one we should update. *)
fun addOverload (name, cons, overload) =
let
(* Remove any existing occurrences of the type. The only reason
is to allow any existing function to be garbage-collected. *)
fun filter [] = []
| filter ((this as (n, t, _)) :: rest) =
if n = name andalso
sameTypeId (tcIdentifier cons, tcIdentifier t)
then filter rest
else this :: filter rest
in
overloadTable := (name, cons, overload) :: filter (!overloadTable)
end
(* Return all the overloads for a particular identifier. *)
fun getOverloads name =
let
fun searchList [] = []
| searchList ((n,t,v)::rest) =
if name = n then (t, v) :: searchList rest else searchList rest
in
searchList (! overloadTable)
end;
(* Return the first matching overload or call mkDefault. *)
fun getOverload(name, constr, mkDefault) =
let
fun searchList [] = mkDefault()
| searchList ((n,t,v)::rest) =
if name = n andalso
sameTypeId (tcIdentifier constr, tcIdentifier t)
then v else searchList rest
in
searchList (! overloadTable)
end;
structure Sharing =
struct
type codetree = codetree
and typeConstrs = typeConstrs
end
end;
|
