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-- Type interning - set of unique objects.
-- Copyright (C) 2019 Tristan Gingold
--
-- GHDL 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, or (at your option) any later
-- version.
--
-- GHDL 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 GHDL; see the file COPYING. If not, write to the Free
-- Software Foundation, 59 Temple Place - Suite 330, Boston, MA
-- 02111-1307, USA.
with Types; use Types;
with Hash; use Hash;
with Dyn_Tables;
-- This generic package provides a factory to build unique objects.
-- Get will return an existing object or create a new one.
generic
-- Parameters of the object to be created.
type Params_Type (<>) is private;
-- Object to be built and stored.
type Object_Type is private;
-- Reduce PARAMS to a small value.
-- The required property is: Hash(P1) /= Hash(P2) => P1 /= P2.
with function Hash (Params : Params_Type) return Hash_Value_Type;
-- Create an object from PARAMS.
with function Build (Params : Params_Type) return Object_Type;
-- Return True iff OBJ is the object corresponding to PARAMS.
with function Equal (Obj : Object_Type; Params : Params_Type)
return Boolean;
package Dyn_Interning is
type Instance is limited private;
-- Initialize. Required before any other operation.
procedure Init (Inst : out Instance);
procedure Free (Inst : in out Instance);
type Index_Type is new Uns32;
No_Index : constant Index_Type := 0;
First_Index : constant Index_Type := 1;
-- If there is already an existing object for PARAMS, return it.
-- Otherwise create it.
procedure Get
(Inst : in out Instance; Params : Params_Type; Res : out Object_Type);
-- Likewise, but return its index.
procedure Get_Index
(Inst : in out Instance; Params : Params_Type; Idx : out Index_Type);
-- Get the number of elements in the table.
function Last_Index (Inst : Instance) return Index_Type;
-- Get an element by index. The index has no real meaning, but the
-- current implementation allocates index incrementally.
function Get_By_Index (Inst : Instance; Index : Index_Type)
return Object_Type;
private
type Element_Wrapper is record
Hash : Hash_Value_Type;
Next : Index_Type := No_Index;
Obj : Object_Type;
end record;
package Wrapper_Tables is new Dyn_Tables
(Table_Index_Type => Index_Type,
Table_Component_Type => Element_Wrapper,
Table_Low_Bound => No_Index + 1);
type Hash_Array is array (Hash_Value_Type range <>) of Index_Type;
type Hash_Array_Acc is access Hash_Array;
Initial_Size : constant Hash_Value_Type := 1024;
type Instance is record
Els : Wrapper_Tables.Instance;
Size : Hash_Value_Type;
Hash_Table : Hash_Array_Acc;
end record;
end Dyn_Interning;
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