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-- Type interning - set of unique objects.
-- Copyright (C) 2019 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 Hash; use Hash;
with Dyn_Maps;
-- 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 No_Value_Type is null record;
function Build_No_Value (Obj : Object_Type) return No_Value_Type;
package Map is new Dyn_Maps
(Params_Type => Params_Type,
Object_Type => Object_Type,
Value_Type => No_Value_Type,
Hash => Hash,
Build => Build,
Build_Value => Build_No_Value,
Equal => Equal);
subtype Instance is Map.Instance;
-- Initialize. Required before any other operation.
procedure Init (Inst : out Instance) renames Map.Init;
procedure Free (Inst : in out Instance) renames Map.Free;
-- Export Index_Type...
subtype Index_Type is Map.Index_Type;
function "+" (L, R : Index_Type) return Index_Type renames Map."+";
function ">" (L, R : Index_Type) return Boolean renames Map.">";
function "<=" (L, R : Index_Type) return Boolean renames Map."<=";
No_Index : constant Index_Type := Map.No_Index;
First_Index : constant Index_Type := Map.First_Index;
-- 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)
renames Map.Get_Index;
-- Get the number of elements in the table.
function Last_Index (Inst : Instance) return Index_Type
renames Map.Last_Index;
-- 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
renames Map.Get_By_Index;
end Dyn_Interning;
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