224 lines
8.7 KiB
Ada
224 lines
8.7 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- A D A . S T R E A M S . S T R E A M _ I O --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1992-2012, Free Software Foundation, Inc. --
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-- --
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-- This specification is derived from the Ada Reference Manual for use with --
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-- GNAT. The copyright notice above, and the license provisions that follow --
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-- apply solely to the contents of the part following the private keyword. --
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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.IO_Exceptions;
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with System.File_Control_Block;
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package Ada.Streams.Stream_IO is
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pragma Preelaborate;
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type Stream_Access is access all Root_Stream_Type'Class;
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type File_Type is limited private;
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type File_Mode is (In_File, Out_File, Append_File);
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-- The following representation clause allows the use of unchecked
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-- conversion for rapid translation between the File_Mode type
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-- used in this package and System.File_IO.
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for File_Mode use
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(In_File => 0, -- System.File_IO.File_Mode'Pos (In_File)
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Out_File => 2, -- System.File_IO.File_Mode'Pos (Out_File)
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Append_File => 3); -- System.File_IO.File_Mode'Pos (Append_File)
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type Count is new Stream_Element_Offset
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range 0 .. Stream_Element_Offset'Last;
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subtype Positive_Count is Count range 1 .. Count'Last;
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-- Index into file, in stream elements
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---------------------
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-- File Management --
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---------------------
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procedure Create
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(File : in out File_Type;
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Mode : File_Mode := Out_File;
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Name : String := "";
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Form : String := "");
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procedure Open
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(File : in out File_Type;
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Mode : File_Mode;
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Name : String;
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Form : String := "");
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procedure Close (File : in out File_Type);
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procedure Delete (File : in out File_Type);
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procedure Reset (File : in out File_Type; Mode : File_Mode);
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procedure Reset (File : in out File_Type);
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function Mode (File : File_Type) return File_Mode;
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function Name (File : File_Type) return String;
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function Form (File : File_Type) return String;
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function Is_Open (File : File_Type) return Boolean;
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function End_Of_File (File : File_Type) return Boolean;
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function Stream (File : File_Type) return Stream_Access;
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-----------------------------
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-- Input-Output Operations --
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-----------------------------
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procedure Read
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(File : File_Type;
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Item : out Stream_Element_Array;
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Last : out Stream_Element_Offset;
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From : Positive_Count);
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procedure Read
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(File : File_Type;
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Item : out Stream_Element_Array;
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Last : out Stream_Element_Offset);
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procedure Write
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(File : File_Type;
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Item : Stream_Element_Array;
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To : Positive_Count);
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procedure Write
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(File : File_Type;
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Item : Stream_Element_Array);
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----------------------------------------
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-- Operations on Position within File --
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----------------------------------------
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procedure Set_Index (File : File_Type; To : Positive_Count);
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function Index (File : File_Type) return Positive_Count;
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function Size (File : File_Type) return Count;
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procedure Set_Mode (File : in out File_Type; Mode : File_Mode);
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-- Note: The parameter file is IN OUT in the RM, but this is clearly
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-- an oversight, and was intended to be IN, see AI95-00057.
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procedure Flush (File : File_Type);
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----------------
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-- Exceptions --
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----------------
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Status_Error : exception renames IO_Exceptions.Status_Error;
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Mode_Error : exception renames IO_Exceptions.Mode_Error;
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Name_Error : exception renames IO_Exceptions.Name_Error;
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Use_Error : exception renames IO_Exceptions.Use_Error;
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Device_Error : exception renames IO_Exceptions.Device_Error;
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End_Error : exception renames IO_Exceptions.End_Error;
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Data_Error : exception renames IO_Exceptions.Data_Error;
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private
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-- The following procedures have a File_Type formal of mode IN OUT because
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-- they may close the original file. The Close operation may raise an
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-- exception, but in that case we want any assignment to the formal to
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-- be effective anyway, so it must be passed by reference (or the caller
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-- will be left with a dangling pointer).
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pragma Export_Procedure
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(Internal => Close,
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External => "",
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Mechanism => Reference);
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pragma Export_Procedure
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(Internal => Delete,
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External => "",
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Mechanism => Reference);
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pragma Export_Procedure
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(Internal => Reset,
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External => "",
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Parameter_Types => (File_Type),
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Mechanism => Reference);
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pragma Export_Procedure
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(Internal => Reset,
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External => "",
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Parameter_Types => (File_Type, File_Mode),
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Mechanism => (File => Reference));
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pragma Export_Procedure
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(Internal => Set_Mode,
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External => "",
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Mechanism => (File => Reference));
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package FCB renames System.File_Control_Block;
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-----------------------------
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-- Stream_IO Control Block --
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-----------------------------
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type Operation is (Op_Read, Op_Write, Op_Other);
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-- Type used to record last operation (to optimize sequential operations)
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type Stream_AFCB is new FCB.AFCB with record
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Index : Count := 1;
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-- Current Index value
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File_Size : Stream_Element_Offset := -1;
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-- Cached value of File_Size, so that we do not keep recomputing it
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-- when not necessary (otherwise End_Of_File becomes gruesomely slow).
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-- A value of minus one means that there is no cached value.
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Last_Op : Operation := Op_Other;
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-- Last operation performed on file, used to avoid unnecessary
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-- repositioning between successive read or write operations.
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Update_Mode : Boolean := False;
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-- Set if the mode is changed from write to read or vice versa.
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-- Indicates that the file has been reopened in update mode.
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end record;
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type File_Type is access all Stream_AFCB;
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overriding function AFCB_Allocate
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(Control_Block : Stream_AFCB) return FCB.AFCB_Ptr;
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overriding procedure AFCB_Close (File : not null access Stream_AFCB);
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overriding procedure AFCB_Free (File : not null access Stream_AFCB);
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overriding procedure Read
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(File : in out Stream_AFCB;
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Item : out Ada.Streams.Stream_Element_Array;
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Last : out Ada.Streams.Stream_Element_Offset);
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-- Read operation used when Stream_IO file is treated directly as Stream
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overriding procedure Write
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(File : in out Stream_AFCB;
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Item : Ada.Streams.Stream_Element_Array);
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-- Write operation used when Stream_IO file is treated directly as Stream
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end Ada.Streams.Stream_IO;
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