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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_Interning;
-- 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 Interning is
package Implementation is new Dyn_Interning
(Params_Type => Params_Type,
Object_Type => Object_Type,
Hash => Hash,
Build => Build,
Equal => Equal);
subtype Index_Type is Implementation.Index_Type;
-- Re-export (some) operators of Index_Type.
-- FIXME: is there a better way to do this ?
function "<=" (L, R : Index_Type) return Boolean
renames Implementation."<=";
function "+" (L, R : Index_Type) return Index_Type
renames Implementation."+";
-- Initialize. Required before any other operation.
procedure Init;
-- If there is already an existing object for PARAMS, return it.
-- Otherwise create it.
function Get (Params : Params_Type) return Object_Type;
-- Get the number of elements in the table.
function Last_Index 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 (Index : Index_Type) return Object_Type;
No_Index : constant Index_Type := Implementation.No_Index;
First_Index : constant Index_Type := Implementation.First_Index;
end Interning;
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