------------------------------------------------------------------------------ -- -- -- 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 -- -- . -- -- -- -- 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;