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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- G N A T . T A B L E --
-- --
-- B o d y --
-- --
-- Copyright (C) 1998-2014, AdaCore --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with GNAT.Heap_Sort_G;
with System; use System;
with System.Memory; use System.Memory;
with Ada.Unchecked_Conversion;
package body GNAT.Table is
Min : constant Integer := Integer (Table_Low_Bound);
-- Subscript of the minimum entry in the currently allocated table
Max : Integer;
-- Subscript of the maximum entry in the currently allocated table
Length : Integer := 0;
-- Number of entries in currently allocated table. The value of zero
-- ensures that we initially allocate the table.
Last_Val : Integer;
-- Current value of Last
-----------------------
-- Local Subprograms --
-----------------------
procedure Reallocate;
-- Reallocate the existing table according to the current value stored
-- in Max. Works correctly to do an initial allocation if the table
-- is currently null.
pragma Warnings (Off);
-- Turn off warnings. The following unchecked conversions are only used
-- internally in this package, and cannot never result in any instances
-- of improperly aliased pointers for the client of the package.
function To_Address is new Ada.Unchecked_Conversion (Table_Ptr, Address);
function To_Pointer is new Ada.Unchecked_Conversion (Address, Table_Ptr);
pragma Warnings (On);
--------------
-- Allocate --
--------------
function Allocate (Num : Integer := 1) return Table_Index_Type is
Old_Last : constant Integer := Last_Val;
begin
Last_Val := Last_Val + Num;
if Last_Val > Max then
Reallocate;
end if;
return Table_Index_Type (Old_Last + 1);
end Allocate;
------------
-- Append --
------------
procedure Append (New_Val : Table_Component_Type) is
begin
Set_Item (Table_Index_Type (Last_Val + 1), New_Val);
end Append;
----------------
-- Append_All --
----------------
procedure Append_All (New_Vals : Table_Type) is
begin
for J in New_Vals'Range loop
Append (New_Vals (J));
end loop;
end Append_All;
--------------------
-- Decrement_Last --
--------------------
procedure Decrement_Last is
begin
Last_Val := Last_Val - 1;
end Decrement_Last;
--------------
-- For_Each --
--------------
procedure For_Each is
Quit : Boolean := False;
begin
for Index in Table_Low_Bound .. Table_Index_Type (Last_Val) loop
Action (Index, Table (Index), Quit);
exit when Quit;
end loop;
end For_Each;
----------
-- Free --
----------
procedure Free is
begin
Free (To_Address (Table));
Table := null;
Length := 0;
end Free;
--------------------
-- Increment_Last --
--------------------
procedure Increment_Last is
begin
Last_Val := Last_Val + 1;
if Last_Val > Max then
Reallocate;
end if;
end Increment_Last;
----------
-- Init --
----------
procedure Init is
Old_Length : constant Integer := Length;
begin
Last_Val := Min - 1;
Max := Min + Table_Initial - 1;
Length := Max - Min + 1;
-- If table is same size as before (happens when table is never
-- expanded which is a common case), then simply reuse it. Note
-- that this also means that an explicit Init call right after
-- the implicit one in the package body is harmless.
if Old_Length = Length then
return;
-- Otherwise we can use Reallocate to get a table of the right size.
-- Note that Reallocate works fine to allocate a table of the right
-- initial size when it is first allocated.
else
Reallocate;
end if;
end Init;
----------
-- Last --
----------
function Last return Table_Index_Type is
begin
return Table_Index_Type (Last_Val);
end Last;
----------------
-- Reallocate --
----------------
procedure Reallocate is
New_Size : size_t;
New_Length : Long_Long_Integer;
begin
if Max < Last_Val then
pragma Assert (not Locked);
-- Now increment table length until it is sufficiently large. Use
-- the increment value or 10, which ever is larger (the reason
-- for the use of 10 here is to ensure that the table does really
-- increase in size (which would not be the case for a table of
-- length 10 increased by 3% for instance). Do the intermediate
-- calculation in Long_Long_Integer to avoid overflow.
while Max < Last_Val loop
New_Length :=
Long_Long_Integer (Length) *
(100 + Long_Long_Integer (Table_Increment)) / 100;
Length := Integer'Max (Integer (New_Length), Length + 10);
Max := Min + Length - 1;
end loop;
end if;
New_Size :=
size_t ((Max - Min + 1) *
(Table_Type'Component_Size / Storage_Unit));
if Table = null then
Table := To_Pointer (Alloc (New_Size));
elsif New_Size > 0 then
Table :=
To_Pointer (Realloc (Ptr => To_Address (Table),
Size => New_Size));
end if;
if Length /= 0 and then Table = null then
raise Storage_Error;
end if;
end Reallocate;
-------------
-- Release --
-------------
procedure Release is
begin
Length := Last_Val - Integer (Table_Low_Bound) + 1;
Max := Last_Val;
Reallocate;
end Release;
--------------
-- Set_Item --
--------------
procedure Set_Item
(Index : Table_Index_Type;
Item : Table_Component_Type)
is
-- If Item is a value within the current allocation, and we are going to
-- reallocate, then we must preserve an intermediate copy here before
-- calling Increment_Last. Otherwise, if Table_Component_Type is passed
-- by reference, we are going to end up copying from storage that might
-- have been deallocated from Increment_Last calling Reallocate.
subtype Allocated_Table_T is
Table_Type (Table'First .. Table_Index_Type (Max + 1));
-- A constrained table subtype one element larger than the currently
-- allocated table.
Allocated_Table_Address : constant System.Address :=
Table.all'Address;
-- Used for address clause below (we can't use non-static expression
-- Table.all'Address directly in the clause because some older versions
-- of the compiler do not allow it).
Allocated_Table : Allocated_Table_T;
pragma Import (Ada, Allocated_Table);
pragma Suppress (Range_Check, On => Allocated_Table);
for Allocated_Table'Address use Allocated_Table_Address;
-- Allocated_Table represents the currently allocated array, plus one
-- element (the supplementary element is used to have a convenient
-- way of computing the address just past the end of the current
-- allocation). Range checks are suppressed because this unit uses
-- direct calls to System.Memory for allocation, and this can yield
-- misaligned storage (and we cannot rely on the bootstrap compiler
-- supporting specifically disabling alignment checks, so we need to
-- suppress all range checks). It is safe to suppress this check here
-- because we know that a (possibly misaligned) object of that type
-- does actually exist at that address. ??? We should really improve
-- the allocation circuitry here to
-- guarantee proper alignment.
Need_Realloc : constant Boolean := Integer (Index) > Max;
-- True if this operation requires storage reallocation (which may
-- involve moving table contents around).
begin
-- If we're going to reallocate, check whether Item references an
-- element of the currently allocated table.
if Need_Realloc
and then Allocated_Table'Address <= Item'Address
and then Item'Address <
Allocated_Table (Table_Index_Type (Max + 1))'Address
then
-- If so, save a copy on the stack because Increment_Last will
-- reallocate storage and might deallocate the current table.
declare
Item_Copy : constant Table_Component_Type := Item;
begin
Set_Last (Index);
Table (Index) := Item_Copy;
end;
else
-- Here we know that either we won't reallocate (case of Index < Max)
-- or that Item is not in the currently allocated table.
if Integer (Index) > Last_Val then
Set_Last (Index);
end if;
Table (Index) := Item;
end if;
end Set_Item;
--------------
-- Set_Last --
--------------
procedure Set_Last (New_Val : Table_Index_Type) is
begin
if Integer (New_Val) < Last_Val then
Last_Val := Integer (New_Val);
else
Last_Val := Integer (New_Val);
if Last_Val > Max then
Reallocate;
end if;
end if;
end Set_Last;
----------------
-- Sort_Table --
----------------
procedure Sort_Table is
Temp : Table_Component_Type;
-- A temporary position to simulate index 0
-- Local subprograms
function Index_Of (Idx : Natural) return Table_Index_Type;
-- Return index of Idx'th element of table
function Lower_Than (Op1, Op2 : Natural) return Boolean;
-- Compare two components
procedure Move (From : Natural; To : Natural);
-- Move one component
package Heap_Sort is new GNAT.Heap_Sort_G (Move, Lower_Than);
--------------
-- Index_Of --
--------------
function Index_Of (Idx : Natural) return Table_Index_Type is
J : constant Integer'Base := Table_Index_Type'Pos (First) + Idx - 1;
begin
return Table_Index_Type'Val (J);
end Index_Of;
----------
-- Move --
----------
procedure Move (From : Natural; To : Natural) is
begin
if From = 0 then
Table (Index_Of (To)) := Temp;
elsif To = 0 then
Temp := Table (Index_Of (From));
else
Table (Index_Of (To)) := Table (Index_Of (From));
end if;
end Move;
----------------
-- Lower_Than --
----------------
function Lower_Than (Op1, Op2 : Natural) return Boolean is
begin
if Op1 = 0 then
return Lt (Temp, Table (Index_Of (Op2)));
elsif Op2 = 0 then
return Lt (Table (Index_Of (Op1)), Temp);
else
return Lt (Table (Index_Of (Op1)), Table (Index_Of (Op2)));
end if;
end Lower_Than;
-- Start of processing for Sort_Table
begin
Heap_Sort.Sort (Natural (Last - First) + 1);
end Sort_Table;
begin
Init;
end GNAT.Table;