417 lines
13 KiB
Ada
417 lines
13 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 . T A B L E --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 1998-2014, 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 GNAT.Heap_Sort_G;
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with System; use System;
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with System.Memory; use System.Memory;
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with Ada.Unchecked_Conversion;
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package body GNAT.Table is
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Min : constant Integer := Integer (Table_Low_Bound);
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-- Subscript of the minimum entry in the currently allocated table
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Max : Integer;
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-- Subscript of the maximum entry in the currently allocated table
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Length : Integer := 0;
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-- Number of entries in currently allocated table. The value of zero
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-- ensures that we initially allocate the table.
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Last_Val : Integer;
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-- Current value of Last
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-----------------------
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-- Local Subprograms --
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-----------------------
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procedure Reallocate;
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-- Reallocate the existing table according to the current value stored
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-- in Max. Works correctly to do an initial allocation if the table
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-- is currently null.
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pragma Warnings (Off);
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-- Turn off warnings. The following unchecked conversions are only used
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-- internally in this package, and cannot never result in any instances
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-- of improperly aliased pointers for the client of the package.
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function To_Address is new Ada.Unchecked_Conversion (Table_Ptr, Address);
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function To_Pointer is new Ada.Unchecked_Conversion (Address, Table_Ptr);
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pragma Warnings (On);
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--------------
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-- Allocate --
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--------------
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function Allocate (Num : Integer := 1) return Table_Index_Type is
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Old_Last : constant Integer := Last_Val;
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begin
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Last_Val := Last_Val + Num;
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if Last_Val > Max then
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Reallocate;
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end if;
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return Table_Index_Type (Old_Last + 1);
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end Allocate;
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------------
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-- Append --
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------------
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procedure Append (New_Val : Table_Component_Type) is
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begin
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Set_Item (Table_Index_Type (Last_Val + 1), New_Val);
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end Append;
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----------------
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-- Append_All --
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----------------
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procedure Append_All (New_Vals : Table_Type) is
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begin
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for J in New_Vals'Range loop
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Append (New_Vals (J));
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end loop;
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end Append_All;
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--------------------
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-- Decrement_Last --
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--------------------
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procedure Decrement_Last is
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begin
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Last_Val := Last_Val - 1;
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end Decrement_Last;
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--------------
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-- For_Each --
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--------------
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procedure For_Each is
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Quit : Boolean := False;
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begin
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for Index in Table_Low_Bound .. Table_Index_Type (Last_Val) loop
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Action (Index, Table (Index), Quit);
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exit when Quit;
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end loop;
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end For_Each;
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----------
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-- Free --
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----------
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procedure Free is
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begin
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Free (To_Address (Table));
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Table := null;
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Length := 0;
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end Free;
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--------------------
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-- Increment_Last --
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--------------------
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procedure Increment_Last is
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begin
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Last_Val := Last_Val + 1;
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if Last_Val > Max then
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Reallocate;
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end if;
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end Increment_Last;
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----------
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-- Init --
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----------
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procedure Init is
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Old_Length : constant Integer := Length;
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begin
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Last_Val := Min - 1;
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Max := Min + Table_Initial - 1;
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Length := Max - Min + 1;
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-- If table is same size as before (happens when table is never
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-- expanded which is a common case), then simply reuse it. Note
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-- that this also means that an explicit Init call right after
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-- the implicit one in the package body is harmless.
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if Old_Length = Length then
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return;
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-- Otherwise we can use Reallocate to get a table of the right size.
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-- Note that Reallocate works fine to allocate a table of the right
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-- initial size when it is first allocated.
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else
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Reallocate;
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end if;
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end Init;
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----------
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-- Last --
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----------
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function Last return Table_Index_Type is
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begin
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return Table_Index_Type (Last_Val);
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end Last;
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----------------
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-- Reallocate --
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----------------
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procedure Reallocate is
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New_Size : size_t;
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New_Length : Long_Long_Integer;
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begin
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if Max < Last_Val then
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pragma Assert (not Locked);
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-- Now increment table length until it is sufficiently large. Use
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-- the increment value or 10, which ever is larger (the reason
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-- for the use of 10 here is to ensure that the table does really
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-- increase in size (which would not be the case for a table of
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-- length 10 increased by 3% for instance). Do the intermediate
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-- calculation in Long_Long_Integer to avoid overflow.
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while Max < Last_Val loop
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New_Length :=
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Long_Long_Integer (Length) *
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(100 + Long_Long_Integer (Table_Increment)) / 100;
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Length := Integer'Max (Integer (New_Length), Length + 10);
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Max := Min + Length - 1;
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end loop;
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end if;
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New_Size :=
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size_t ((Max - Min + 1) *
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(Table_Type'Component_Size / Storage_Unit));
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if Table = null then
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Table := To_Pointer (Alloc (New_Size));
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elsif New_Size > 0 then
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Table :=
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To_Pointer (Realloc (Ptr => To_Address (Table),
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Size => New_Size));
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end if;
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if Length /= 0 and then Table = null then
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raise Storage_Error;
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end if;
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end Reallocate;
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-------------
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-- Release --
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-------------
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procedure Release is
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begin
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Length := Last_Val - Integer (Table_Low_Bound) + 1;
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Max := Last_Val;
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Reallocate;
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end Release;
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--------------
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-- Set_Item --
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--------------
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procedure Set_Item
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(Index : Table_Index_Type;
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Item : Table_Component_Type)
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is
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-- If Item is a value within the current allocation, and we are going to
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-- reallocate, then we must preserve an intermediate copy here before
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-- calling Increment_Last. Otherwise, if Table_Component_Type is passed
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-- by reference, we are going to end up copying from storage that might
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-- have been deallocated from Increment_Last calling Reallocate.
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subtype Allocated_Table_T is
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Table_Type (Table'First .. Table_Index_Type (Max + 1));
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-- A constrained table subtype one element larger than the currently
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-- allocated table.
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Allocated_Table_Address : constant System.Address :=
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Table.all'Address;
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-- Used for address clause below (we can't use non-static expression
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-- Table.all'Address directly in the clause because some older versions
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-- of the compiler do not allow it).
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Allocated_Table : Allocated_Table_T;
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pragma Import (Ada, Allocated_Table);
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pragma Suppress (Range_Check, On => Allocated_Table);
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for Allocated_Table'Address use Allocated_Table_Address;
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-- Allocated_Table represents the currently allocated array, plus one
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-- element (the supplementary element is used to have a convenient
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-- way of computing the address just past the end of the current
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-- allocation). Range checks are suppressed because this unit uses
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-- direct calls to System.Memory for allocation, and this can yield
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-- misaligned storage (and we cannot rely on the bootstrap compiler
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-- supporting specifically disabling alignment checks, so we need to
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-- suppress all range checks). It is safe to suppress this check here
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-- because we know that a (possibly misaligned) object of that type
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-- does actually exist at that address. ??? We should really improve
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-- the allocation circuitry here to
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-- guarantee proper alignment.
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Need_Realloc : constant Boolean := Integer (Index) > Max;
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-- True if this operation requires storage reallocation (which may
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-- involve moving table contents around).
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begin
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-- If we're going to reallocate, check whether Item references an
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-- element of the currently allocated table.
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if Need_Realloc
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and then Allocated_Table'Address <= Item'Address
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and then Item'Address <
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Allocated_Table (Table_Index_Type (Max + 1))'Address
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then
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-- If so, save a copy on the stack because Increment_Last will
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-- reallocate storage and might deallocate the current table.
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declare
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Item_Copy : constant Table_Component_Type := Item;
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begin
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Set_Last (Index);
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Table (Index) := Item_Copy;
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end;
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else
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-- Here we know that either we won't reallocate (case of Index < Max)
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-- or that Item is not in the currently allocated table.
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if Integer (Index) > Last_Val then
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Set_Last (Index);
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end if;
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Table (Index) := Item;
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end if;
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end Set_Item;
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--------------
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-- Set_Last --
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--------------
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procedure Set_Last (New_Val : Table_Index_Type) is
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begin
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if Integer (New_Val) < Last_Val then
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Last_Val := Integer (New_Val);
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else
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Last_Val := Integer (New_Val);
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if Last_Val > Max then
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Reallocate;
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end if;
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end if;
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end Set_Last;
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----------------
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-- Sort_Table --
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----------------
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procedure Sort_Table is
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Temp : Table_Component_Type;
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-- A temporary position to simulate index 0
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-- Local subprograms
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function Index_Of (Idx : Natural) return Table_Index_Type;
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-- Return index of Idx'th element of table
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function Lower_Than (Op1, Op2 : Natural) return Boolean;
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-- Compare two components
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procedure Move (From : Natural; To : Natural);
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-- Move one component
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package Heap_Sort is new GNAT.Heap_Sort_G (Move, Lower_Than);
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--------------
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-- Index_Of --
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--------------
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function Index_Of (Idx : Natural) return Table_Index_Type is
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J : constant Integer'Base := Table_Index_Type'Pos (First) + Idx - 1;
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begin
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return Table_Index_Type'Val (J);
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end Index_Of;
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----------
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-- Move --
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----------
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procedure Move (From : Natural; To : Natural) is
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begin
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if From = 0 then
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Table (Index_Of (To)) := Temp;
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elsif To = 0 then
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Temp := Table (Index_Of (From));
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else
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Table (Index_Of (To)) := Table (Index_Of (From));
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end if;
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end Move;
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----------------
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-- Lower_Than --
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----------------
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function Lower_Than (Op1, Op2 : Natural) return Boolean is
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begin
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if Op1 = 0 then
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return Lt (Temp, Table (Index_Of (Op2)));
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elsif Op2 = 0 then
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return Lt (Table (Index_Of (Op1)), Temp);
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else
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return Lt (Table (Index_Of (Op1)), Table (Index_Of (Op2)));
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end if;
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end Lower_Than;
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-- Start of processing for Sort_Table
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begin
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Heap_Sort.Sort (Natural (Last - First) + 1);
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end Sort_Table;
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begin
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Init;
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end GNAT.Table;
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