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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT RUN-TIME COMPONENTS                         --

--                                                                          --

--                A D A . S T R E A M S . S T R E A M _ I O                 --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 1992-2011, Free Software Foundation, Inc.         --

--                                                                          --

-- This specification is derived from the Ada Reference Manual for use with --

-- GNAT. The copyright notice above, and the license provisions that follow --

-- apply solely to the  contents of the part following the private keyword. --

--                                                                          --

-- 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 Ada.IO_Exceptions;

with System.File_Control_Block;

package Ada.Streams.Stream_IO is

   type Stream_Access is access all Root_Stream_Type'Class;

   type File_Type is limited private;

   type File_Mode is (In_File, Out_File, Append_File);

   --  The following representation clause allows the use of unchecked

   --  conversion for rapid translation between the File_Mode type

   --  used in this package and System.File_IO.

   for File_Mode use

     (In_File     => 0,  -- System.File_IO.File_Mode'Pos (In_File)

      Out_File    => 2,  -- System.File_IO.File_Mode'Pos (Out_File)

      Append_File => 3); -- System.File_IO.File_Mode'Pos (Append_File)

   type Count is new Stream_Element_Offset

     range 0 .. Stream_Element_Offset'Last;

   subtype Positive_Count is Count range 1 .. Count'Last;

   --  Index into file, in stream elements

   ---------------------

   -- File Management --

   ---------------------

   procedure Create

     (File : in out File_Type;

      Mode : File_Mode := Out_File;

      Name : String := "";

      Form : String := "");

   procedure Open

     (File : in out File_Type;

      Mode : File_Mode;

      Name : String;

      Form : String := "");

   procedure Close  (File : in out File_Type);

   procedure Delete (File : in out File_Type);

   procedure Reset  (File : in out File_Type; Mode : File_Mode);

   procedure Reset  (File : in out File_Type);

   function Mode (File : File_Type) return File_Mode;

   function Name (File : File_Type) return String;

   function Form (File : File_Type) return String;

   function Is_Open     (File : File_Type) return Boolean;

   function End_Of_File (File : File_Type) return Boolean;

   function Stream (File : File_Type) return Stream_Access;

   -----------------------------

   -- Input-Output Operations --

   -----------------------------

   procedure Read

     (File : File_Type;

      Item : out Stream_Element_Array;

      Last : out Stream_Element_Offset;

      From : Positive_Count);

   procedure Read

     (File : File_Type;

      Item : out Stream_Element_Array;

      Last : out Stream_Element_Offset);

   procedure Write

     (File : File_Type;

      Item : Stream_Element_Array;

      To   : Positive_Count);

   procedure Write

     (File : File_Type;

      Item : Stream_Element_Array);

   ----------------------------------------

   -- Operations on Position within File --

   ----------------------------------------

   procedure Set_Index (File : File_Type; To : Positive_Count);

   function Index (File : File_Type) return Positive_Count;

   function Size  (File : File_Type) return Count;

   procedure Set_Mode (File : in out File_Type; Mode : File_Mode);

   --  Note: The parameter file is IN OUT in the RM, but this is clearly

   --  an oversight, and was intended to be IN, see AI95-00057.

   procedure Flush (File : File_Type);

   ----------------

   -- Exceptions --

   ----------------

   Status_Error : exception renames IO_Exceptions.Status_Error;

   Mode_Error   : exception renames IO_Exceptions.Mode_Error;

   Name_Error   : exception renames IO_Exceptions.Name_Error;

   Use_Error    : exception renames IO_Exceptions.Use_Error;

   Device_Error : exception renames IO_Exceptions.Device_Error;

   End_Error    : exception renames IO_Exceptions.End_Error;

   Data_Error   : exception renames IO_Exceptions.Data_Error;

private

   --  The following procedures have a File_Type formal of mode IN OUT because

   --  they may close the original file. The Close operation may raise an

   --  exception, but in that case we want any assignment to the formal to

   --  be effective anyway, so it must be passed by reference (or the caller

   --  will be left with a dangling pointer).

   pragma Export_Procedure

     (Internal  => Close,

      External  => "",

      Mechanism => Reference);

   pragma Export_Procedure

     (Internal  => Delete,

      External  => "",

      Mechanism => Reference);

   pragma Export_Procedure

     (Internal        => Reset,

      External        => "",

      Parameter_Types => (File_Type),

      Mechanism       => Reference);

   pragma Export_Procedure

     (Internal        => Reset,

      External        => "",

      Parameter_Types => (File_Type, File_Mode),

      Mechanism       => (File => Reference));

   pragma Export_Procedure

     (Internal  => Set_Mode,

      External  => "",

      Mechanism => (File => Reference));

   package FCB renames System.File_Control_Block;

   -----------------------------

   -- Stream_IO Control Block --

   -----------------------------

   type Operation is (Op_Read, Op_Write, Op_Other);

   --  Type used to record last operation (to optimize sequential operations)

   type Stream_AFCB is new FCB.AFCB with record

      Index : Count := 1;

      --  Current Index value

      File_Size : Stream_Element_Offset := -1;

      --  Cached value of File_Size, so that we do not keep recomputing it

      --  when not necessary (otherwise End_Of_File becomes gruesomely slow).

      --  A value of minus one means that there is no cached value.

      Last_Op : Operation := Op_Other;

      --  Last operation performed on file, used to avoid unnecessary

      --  repositioning between successive read or write operations.

      Update_Mode : Boolean := False;

      --  Set if the mode is changed from write to read or vice versa.

      --  Indicates that the file has been reopened in update mode.

   end record;

   type File_Type is access all Stream_AFCB;

   overriding function AFCB_Allocate

     (Control_Block : Stream_AFCB) return FCB.AFCB_Ptr;

   overriding procedure AFCB_Close (File : not null access Stream_AFCB);

   overriding procedure AFCB_Free  (File : not null access Stream_AFCB);

   overriding procedure Read

     (File : in out Stream_AFCB;

      Item : out Ada.Streams.Stream_Element_Array;

      Last : out Ada.Streams.Stream_Element_Offset);

   --  Read operation used when Stream_IO file is treated directly as Stream

   overriding procedure Write

     (File : in out Stream_AFCB;

      Item : Ada.Streams.Stream_Element_Array);

   --  Write operation used when Stream_IO file is treated directly as Stream

end Ada.Streams.Stream_IO;