711 lines
20 KiB
Ada
711 lines
20 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- G N A T . D Y N A M I C _ H T A B L E S --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 2002-2015, AdaCore --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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with Ada.Unchecked_Deallocation;
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package body GNAT.Dynamic_HTables is
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-------------------
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-- Static_HTable --
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-------------------
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package body Static_HTable is
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type Table_Type is array (Header_Num) of Elmt_Ptr;
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type Instance_Data is record
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Table : Table_Type;
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Iterator_Index : Header_Num;
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Iterator_Ptr : Elmt_Ptr;
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Iterator_Started : Boolean := False;
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end record;
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function Get_Non_Null (T : Instance) return Elmt_Ptr;
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-- Returns Null_Ptr if Iterator_Started is False or if the Table is
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-- empty. Returns Iterator_Ptr if non null, or the next non null
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-- element in table if any.
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---------
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-- Get --
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---------
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function Get (T : Instance; K : Key) return Elmt_Ptr is
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Elmt : Elmt_Ptr;
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begin
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if T = null then
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return Null_Ptr;
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end if;
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Elmt := T.Table (Hash (K));
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loop
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if Elmt = Null_Ptr then
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return Null_Ptr;
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elsif Equal (Get_Key (Elmt), K) then
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return Elmt;
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else
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Elmt := Next (Elmt);
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end if;
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end loop;
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end Get;
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---------------
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-- Get_First --
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---------------
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function Get_First (T : Instance) return Elmt_Ptr is
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begin
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if T = null then
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return Null_Ptr;
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end if;
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T.Iterator_Started := True;
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T.Iterator_Index := T.Table'First;
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T.Iterator_Ptr := T.Table (T.Iterator_Index);
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return Get_Non_Null (T);
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end Get_First;
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--------------
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-- Get_Next --
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--------------
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function Get_Next (T : Instance) return Elmt_Ptr is
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begin
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if T = null or else not T.Iterator_Started then
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return Null_Ptr;
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end if;
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T.Iterator_Ptr := Next (T.Iterator_Ptr);
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return Get_Non_Null (T);
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end Get_Next;
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------------------
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-- Get_Non_Null --
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------------------
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function Get_Non_Null (T : Instance) return Elmt_Ptr is
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begin
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if T = null then
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return Null_Ptr;
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end if;
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while T.Iterator_Ptr = Null_Ptr loop
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if T.Iterator_Index = T.Table'Last then
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T.Iterator_Started := False;
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return Null_Ptr;
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end if;
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T.Iterator_Index := T.Iterator_Index + 1;
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T.Iterator_Ptr := T.Table (T.Iterator_Index);
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end loop;
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return T.Iterator_Ptr;
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end Get_Non_Null;
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------------
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-- Remove --
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------------
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procedure Remove (T : Instance; K : Key) is
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Index : constant Header_Num := Hash (K);
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Elmt : Elmt_Ptr;
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Next_Elmt : Elmt_Ptr;
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begin
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if T = null then
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return;
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end if;
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Elmt := T.Table (Index);
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if Elmt = Null_Ptr then
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return;
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elsif Equal (Get_Key (Elmt), K) then
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T.Table (Index) := Next (Elmt);
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else
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loop
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Next_Elmt := Next (Elmt);
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if Next_Elmt = Null_Ptr then
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return;
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elsif Equal (Get_Key (Next_Elmt), K) then
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Set_Next (Elmt, Next (Next_Elmt));
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return;
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else
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Elmt := Next_Elmt;
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end if;
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end loop;
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end if;
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end Remove;
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-----------
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-- Reset --
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-----------
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procedure Reset (T : in out Instance) is
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procedure Free is
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new Ada.Unchecked_Deallocation (Instance_Data, Instance);
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begin
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if T = null then
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return;
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end if;
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for J in T.Table'Range loop
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T.Table (J) := Null_Ptr;
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end loop;
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Free (T);
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end Reset;
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---------
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-- Set --
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---------
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procedure Set (T : in out Instance; E : Elmt_Ptr) is
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Index : Header_Num;
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begin
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if T = null then
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T := new Instance_Data;
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end if;
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Index := Hash (Get_Key (E));
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Set_Next (E, T.Table (Index));
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T.Table (Index) := E;
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end Set;
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end Static_HTable;
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-------------------
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-- Simple_HTable --
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-------------------
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package body Simple_HTable is
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procedure Free is new
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Ada.Unchecked_Deallocation (Element_Wrapper, Elmt_Ptr);
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---------
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-- Get --
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---------
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function Get (T : Instance; K : Key) return Element is
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Tmp : Elmt_Ptr;
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begin
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if T = Nil then
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return No_Element;
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end if;
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Tmp := Tab.Get (Tab.Instance (T), K);
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if Tmp = null then
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return No_Element;
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else
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return Tmp.E;
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end if;
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end Get;
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---------------
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-- Get_First --
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---------------
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function Get_First (T : Instance) return Element is
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Tmp : constant Elmt_Ptr := Tab.Get_First (Tab.Instance (T));
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begin
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if Tmp = null then
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return No_Element;
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else
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return Tmp.E;
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end if;
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end Get_First;
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-------------
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-- Get_Key --
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-------------
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function Get_Key (E : Elmt_Ptr) return Key is
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begin
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return E.K;
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end Get_Key;
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--------------
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-- Get_Next --
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--------------
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function Get_Next (T : Instance) return Element is
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Tmp : constant Elmt_Ptr := Tab.Get_Next (Tab.Instance (T));
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begin
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if Tmp = null then
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return No_Element;
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else
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return Tmp.E;
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end if;
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end Get_Next;
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----------
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-- Next --
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----------
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function Next (E : Elmt_Ptr) return Elmt_Ptr is
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begin
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return E.Next;
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end Next;
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------------
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-- Remove --
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------------
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procedure Remove (T : Instance; K : Key) is
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Tmp : Elmt_Ptr;
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begin
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Tmp := Tab.Get (Tab.Instance (T), K);
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if Tmp /= null then
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Tab.Remove (Tab.Instance (T), K);
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Free (Tmp);
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end if;
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end Remove;
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-----------
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-- Reset --
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-----------
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procedure Reset (T : in out Instance) is
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E1, E2 : Elmt_Ptr;
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begin
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E1 := Tab.Get_First (Tab.Instance (T));
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while E1 /= null loop
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E2 := Tab.Get_Next (Tab.Instance (T));
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Free (E1);
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E1 := E2;
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end loop;
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Tab.Reset (Tab.Instance (T));
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end Reset;
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---------
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-- Set --
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---------
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procedure Set (T : in out Instance; K : Key; E : Element) is
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Tmp : constant Elmt_Ptr := Tab.Get (Tab.Instance (T), K);
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begin
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if Tmp = null then
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Tab.Set (Tab.Instance (T), new Element_Wrapper'(K, E, null));
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else
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Tmp.E := E;
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end if;
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end Set;
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--------------
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-- Set_Next --
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--------------
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procedure Set_Next (E : Elmt_Ptr; Next : Elmt_Ptr) is
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begin
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E.Next := Next;
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end Set_Next;
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end Simple_HTable;
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------------------------
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-- Load_Factor_HTable --
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------------------------
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package body Load_Factor_HTable is
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Min_Size_Increase : constant := 5;
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-- The minimum increase expressed as number of buckets. This value is
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-- used to determine the new size of small tables and/or small growth
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-- percentages.
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procedure Attach
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(Elmt : not null Element_Ptr;
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Chain : not null Element_Ptr);
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-- Prepend an element to a bucket chain. Elmt is inserted after the
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-- dummy head of Chain.
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function Create_Buckets (Size : Positive) return Buckets_Array_Ptr;
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-- Allocate and initialize a new set of buckets. The buckets are created
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-- in the range Range_Type'First .. Range_Type'First + Size - 1.
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procedure Detach (Elmt : not null Element_Ptr);
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-- Remove an element from an arbitrary bucket chain
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function Find
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(Key : Key_Type;
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Chain : not null Element_Ptr) return Element_Ptr;
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-- Try to locate the element which contains a particular key within a
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-- bucket chain. If no such element exists, return No_Element.
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procedure Free is
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new Ada.Unchecked_Deallocation (Buckets_Array, Buckets_Array_Ptr);
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procedure Free is
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new Ada.Unchecked_Deallocation (Element, Element_Ptr);
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function Is_Empty_Chain (Chain : not null Element_Ptr) return Boolean;
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-- Determine whether a bucket chain contains only one element, namely
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-- the dummy head.
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------------
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-- Attach --
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------------
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procedure Attach
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(Elmt : not null Element_Ptr;
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Chain : not null Element_Ptr)
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is
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begin
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Chain.Next.Prev := Elmt;
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Elmt.Next := Chain.Next;
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Chain.Next := Elmt;
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Elmt.Prev := Chain;
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end Attach;
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--------------------
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-- Create_Buckets --
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--------------------
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function Create_Buckets (Size : Positive) return Buckets_Array_Ptr is
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Low_Bound : constant Range_Type := Range_Type'First;
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Buckets : Buckets_Array_Ptr;
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begin
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Buckets :=
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new Buckets_Array (Low_Bound .. Low_Bound + Range_Type (Size) - 1);
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-- Ensure that the dummy head of each bucket chain points to itself
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-- in both directions.
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for Index in Buckets'Range loop
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declare
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Bucket : Element renames Buckets (Index);
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begin
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Bucket.Prev := Bucket'Unchecked_Access;
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Bucket.Next := Bucket'Unchecked_Access;
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end;
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end loop;
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return Buckets;
|
||
|
|
end Create_Buckets;
|
||
|
|
|
||
|
|
------------------
|
||
|
|
-- Current_Size --
|
||
|
|
------------------
|
||
|
|
|
||
|
|
function Current_Size (T : Table) return Positive is
|
||
|
|
begin
|
||
|
|
-- The table should have been properly initialized during object
|
||
|
|
-- elaboration.
|
||
|
|
|
||
|
|
if T.Buckets = null then
|
||
|
|
raise Program_Error;
|
||
|
|
|
||
|
|
-- The size of the table is determined by the number of buckets
|
||
|
|
|
||
|
|
else
|
||
|
|
return T.Buckets'Length;
|
||
|
|
end if;
|
||
|
|
end Current_Size;
|
||
|
|
|
||
|
|
------------
|
||
|
|
-- Detach --
|
||
|
|
------------
|
||
|
|
|
||
|
|
procedure Detach (Elmt : not null Element_Ptr) is
|
||
|
|
begin
|
||
|
|
if Elmt.Prev /= null and Elmt.Next /= null then
|
||
|
|
Elmt.Prev.Next := Elmt.Next;
|
||
|
|
Elmt.Next.Prev := Elmt.Prev;
|
||
|
|
Elmt.Prev := null;
|
||
|
|
Elmt.Next := null;
|
||
|
|
end if;
|
||
|
|
end Detach;
|
||
|
|
|
||
|
|
--------------
|
||
|
|
-- Finalize --
|
||
|
|
--------------
|
||
|
|
|
||
|
|
procedure Finalize (T : in out Table) is
|
||
|
|
Bucket : Element_Ptr;
|
||
|
|
Elmt : Element_Ptr;
|
||
|
|
|
||
|
|
begin
|
||
|
|
-- Inspect the buckets and deallocate bucket chains
|
||
|
|
|
||
|
|
for Index in T.Buckets'Range loop
|
||
|
|
Bucket := T.Buckets (Index)'Unchecked_Access;
|
||
|
|
|
||
|
|
-- The current bucket chain contains an element other than the
|
||
|
|
-- dummy head.
|
||
|
|
|
||
|
|
while not Is_Empty_Chain (Bucket) loop
|
||
|
|
|
||
|
|
-- Skip the dummy head, remove and deallocate the element
|
||
|
|
|
||
|
|
Elmt := Bucket.Next;
|
||
|
|
Detach (Elmt);
|
||
|
|
Free (Elmt);
|
||
|
|
end loop;
|
||
|
|
end loop;
|
||
|
|
|
||
|
|
-- Deallocate the buckets
|
||
|
|
|
||
|
|
Free (T.Buckets);
|
||
|
|
end Finalize;
|
||
|
|
|
||
|
|
----------
|
||
|
|
-- Find --
|
||
|
|
----------
|
||
|
|
|
||
|
|
function Find
|
||
|
|
(Key : Key_Type;
|
||
|
|
Chain : not null Element_Ptr) return Element_Ptr
|
||
|
|
is
|
||
|
|
Elmt : Element_Ptr;
|
||
|
|
|
||
|
|
begin
|
||
|
|
-- Skip the dummy head, inspect the bucket chain for an element whose
|
||
|
|
-- key matches the requested key. Since each bucket chain is circular
|
||
|
|
-- the search must stop once the dummy head is encountered.
|
||
|
|
|
||
|
|
Elmt := Chain.Next;
|
||
|
|
while Elmt /= Chain loop
|
||
|
|
if Equal (Elmt.Key, Key) then
|
||
|
|
return Elmt;
|
||
|
|
end if;
|
||
|
|
|
||
|
|
Elmt := Elmt.Next;
|
||
|
|
end loop;
|
||
|
|
|
||
|
|
return No_Element;
|
||
|
|
end Find;
|
||
|
|
|
||
|
|
---------
|
||
|
|
-- Get --
|
||
|
|
---------
|
||
|
|
|
||
|
|
function Get (T : Table; Key : Key_Type) return Value_Type is
|
||
|
|
Bucket : Element_Ptr;
|
||
|
|
Elmt : Element_Ptr;
|
||
|
|
|
||
|
|
begin
|
||
|
|
-- Obtain the bucket chain where the (key, value) pair should reside
|
||
|
|
-- by calculating the proper hash location.
|
||
|
|
|
||
|
|
Bucket := T.Buckets (Hash (Key, Current_Size (T)))'Unchecked_Access;
|
||
|
|
|
||
|
|
-- Try to find an element whose key matches the requested key
|
||
|
|
|
||
|
|
Elmt := Find (Key, Bucket);
|
||
|
|
|
||
|
|
-- The hash table does not contain a matching (key, value) pair
|
||
|
|
|
||
|
|
if Elmt = No_Element then
|
||
|
|
return No_Value;
|
||
|
|
else
|
||
|
|
return Elmt.Val;
|
||
|
|
end if;
|
||
|
|
end Get;
|
||
|
|
|
||
|
|
----------------
|
||
|
|
-- Initialize --
|
||
|
|
----------------
|
||
|
|
|
||
|
|
procedure Initialize (T : in out Table) is
|
||
|
|
begin
|
||
|
|
pragma Assert (T.Buckets = null);
|
||
|
|
|
||
|
|
T.Buckets := Create_Buckets (Initial_Size);
|
||
|
|
T.Element_Count := 0;
|
||
|
|
end Initialize;
|
||
|
|
|
||
|
|
--------------------
|
||
|
|
-- Is_Empty_Chain --
|
||
|
|
--------------------
|
||
|
|
|
||
|
|
function Is_Empty_Chain (Chain : not null Element_Ptr) return Boolean is
|
||
|
|
begin
|
||
|
|
return Chain.Next = Chain and Chain.Prev = Chain;
|
||
|
|
end Is_Empty_Chain;
|
||
|
|
|
||
|
|
------------
|
||
|
|
-- Remove --
|
||
|
|
------------
|
||
|
|
|
||
|
|
procedure Remove (T : in out Table; Key : Key_Type) is
|
||
|
|
Bucket : Element_Ptr;
|
||
|
|
Elmt : Element_Ptr;
|
||
|
|
|
||
|
|
begin
|
||
|
|
-- Obtain the bucket chain where the (key, value) pair should reside
|
||
|
|
-- by calculating the proper hash location.
|
||
|
|
|
||
|
|
Bucket := T.Buckets (Hash (Key, Current_Size (T)))'Unchecked_Access;
|
||
|
|
|
||
|
|
-- Try to find an element whose key matches the requested key
|
||
|
|
|
||
|
|
Elmt := Find (Key, Bucket);
|
||
|
|
|
||
|
|
-- Remove and deallocate the (key, value) pair
|
||
|
|
|
||
|
|
if Elmt /= No_Element then
|
||
|
|
Detach (Elmt);
|
||
|
|
Free (Elmt);
|
||
|
|
end if;
|
||
|
|
end Remove;
|
||
|
|
|
||
|
|
---------
|
||
|
|
-- Set --
|
||
|
|
---------
|
||
|
|
|
||
|
|
procedure Set
|
||
|
|
(T : in out Table;
|
||
|
|
Key : Key_Type;
|
||
|
|
Val : Value_Type)
|
||
|
|
is
|
||
|
|
Curr_Size : constant Positive := Current_Size (T);
|
||
|
|
|
||
|
|
procedure Grow;
|
||
|
|
-- Grow the table to a new size according to the desired percentage
|
||
|
|
-- and relocate all existing elements to the new buckets.
|
||
|
|
|
||
|
|
----------
|
||
|
|
-- Grow --
|
||
|
|
----------
|
||
|
|
|
||
|
|
procedure Grow is
|
||
|
|
Buckets : Buckets_Array_Ptr;
|
||
|
|
Elmt : Element_Ptr;
|
||
|
|
Hash_Loc : Range_Type;
|
||
|
|
Old_Bucket : Element_Ptr;
|
||
|
|
Old_Buckets : Buckets_Array_Ptr := T.Buckets;
|
||
|
|
Size : Positive;
|
||
|
|
|
||
|
|
begin
|
||
|
|
-- Calculate the new size and allocate a new set of buckets. Note
|
||
|
|
-- that a table with a small size or a small growth percentage may
|
||
|
|
-- not always grow (for example, 10 buckets and 3% increase). In
|
||
|
|
-- that case, enforce a minimum increase.
|
||
|
|
|
||
|
|
Size :=
|
||
|
|
Positive'Max (Curr_Size * ((100 + Growth_Percentage) / 100),
|
||
|
|
Min_Size_Increase);
|
||
|
|
Buckets := Create_Buckets (Size);
|
||
|
|
|
||
|
|
-- Inspect the old buckets and transfer all elements by rehashing
|
||
|
|
-- all (key, value) pairs in the new buckets.
|
||
|
|
|
||
|
|
for Index in Old_Buckets'Range loop
|
||
|
|
Old_Bucket := Old_Buckets (Index)'Unchecked_Access;
|
||
|
|
|
||
|
|
-- The current bucket chain contains an element other than the
|
||
|
|
-- dummy head.
|
||
|
|
|
||
|
|
while not Is_Empty_Chain (Old_Bucket) loop
|
||
|
|
|
||
|
|
-- Skip the dummy head and find the new hash location
|
||
|
|
|
||
|
|
Elmt := Old_Bucket.Next;
|
||
|
|
Hash_Loc := Hash (Elmt.Key, Size);
|
||
|
|
|
||
|
|
-- Remove the element from the old buckets and insert it
|
||
|
|
-- into the new buckets. Note that there is no need to check
|
||
|
|
-- for duplicates because the hash table did not have any to
|
||
|
|
-- begin with.
|
||
|
|
|
||
|
|
Detach (Elmt);
|
||
|
|
Attach
|
||
|
|
(Elmt => Elmt,
|
||
|
|
Chain => Buckets (Hash_Loc)'Unchecked_Access);
|
||
|
|
end loop;
|
||
|
|
end loop;
|
||
|
|
|
||
|
|
-- Associate the new buckets with the table and reclaim the
|
||
|
|
-- storage occupied by the old buckets.
|
||
|
|
|
||
|
|
T.Buckets := Buckets;
|
||
|
|
|
||
|
|
Free (Old_Buckets);
|
||
|
|
end Grow;
|
||
|
|
|
||
|
|
-- Local variables
|
||
|
|
|
||
|
|
subtype LLF is Long_Long_Float;
|
||
|
|
|
||
|
|
Count : Natural renames T.Element_Count;
|
||
|
|
Bucket : Element_Ptr;
|
||
|
|
Hash_Loc : Range_Type;
|
||
|
|
|
||
|
|
-- Start of processing for Set
|
||
|
|
|
||
|
|
begin
|
||
|
|
-- Find the bucket where the (key, value) pair should be inserted by
|
||
|
|
-- computing the proper hash location.
|
||
|
|
|
||
|
|
Hash_Loc := Hash (Key, Curr_Size);
|
||
|
|
Bucket := T.Buckets (Hash_Loc)'Unchecked_Access;
|
||
|
|
|
||
|
|
-- Ensure that the key is not already present in the bucket in order
|
||
|
|
-- to avoid duplicates.
|
||
|
|
|
||
|
|
if Find (Key, Bucket) = No_Element then
|
||
|
|
Attach
|
||
|
|
(Elmt => new Element'(Key, Val, null, null),
|
||
|
|
Chain => Bucket);
|
||
|
|
Count := Count + 1;
|
||
|
|
|
||
|
|
-- Multiple insertions may cause long bucket chains and decrease
|
||
|
|
-- the performance of basic operations. If this is the case, grow
|
||
|
|
-- the table and rehash all existing elements.
|
||
|
|
|
||
|
|
if (LLF (Count) / LLF (Curr_Size)) > LLF (Load_Factor) then
|
||
|
|
Grow;
|
||
|
|
end if;
|
||
|
|
end if;
|
||
|
|
end Set;
|
||
|
|
end Load_Factor_HTable;
|
||
|
|
|
||
|
|
end GNAT.Dynamic_HTables;
|