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-- Maps - association of unique object with a value.
-- Copyright (C) 2019-2020 Tristan Gingold
--
-- 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, see <gnu.org/licenses>.
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;
-- Value associated to the object. Could be modified but not used
-- for comparision.
type Value_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;
-- Initial value of the object. Called when an object is created.
with function Build_Value (Obj : Object_Type) return Value_Type;
-- Return True iff OBJ is the object corresponding to PARAMS.
with function Equal (Obj : Object_Type; Params : Params_Type)
return Boolean;
package Dyn_Maps 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 its index.
-- Otherwise create it.
-- The index is doesn't change over the lifetime of the map.
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;
-- Get/Set the value.
function Get_Value (Inst : Instance; Index : Index_Type) return Value_Type;
procedure Set_Value
(Inst : in out Instance; Index : Index_Type; Val : Value_Type);
private
type Element_Wrapper is record
Hash : Hash_Value_Type;
Next : Index_Type := No_Index;
Obj : Object_Type;
Val : Value_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_Maps;
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