gcc/ada/a-ststio.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                A D A . S T R E A M S . S T R E A M _ I O                 --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2012, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- This specification is derived from the Ada Reference Manual for use with --
  12 -- GNAT. The copyright notice above, and the license provisions that follow --
  13 -- apply solely to the  contents of the part following the private keyword. --
  14 --                                                                          --
  15 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  16 -- terms of the  GNU General Public License as published  by the Free Soft- --
  17 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  18 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  19 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  20 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  21 --                                                                          --
  22 -- As a special exception under Section 7 of GPL version 3, you are granted --
  23 -- additional permissions described in the GCC Runtime Library Exception,   --
  24 -- version 3.1, as published by the Free Software Foundation.               --
  25 --                                                                          --
  26 -- You should have received a copy of the GNU General Public License and    --
  27 -- a copy of the GCC Runtime Library Exception along with this program;     --
  28 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  29 -- <http://www.gnu.org/licenses/>.                                          --
  30 --                                                                          --
  31 -- GNAT was originally developed  by the GNAT team at  New York University. --
  32 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  33 --                                                                          --
  34 ------------------------------------------------------------------------------
  35
  36 with Ada.IO_Exceptions;
  37 with System.File_Control_Block;
  38
  39 package Ada.Streams.Stream_IO is
  40    pragma Preelaborate;
  41
  42    type Stream_Access is access all Root_Stream_Type'Class;
  43
  44    type File_Type is limited private;
  45
  46    type File_Mode is (In_File, Out_File, Append_File);
  47
  48    --  The following representation clause allows the use of unchecked
  49    --  conversion for rapid translation between the File_Mode type
  50    --  used in this package and System.File_IO.
  51
  52    for File_Mode use
  53      (In_File     => 0,  -- System.File_IO.File_Mode'Pos (In_File)
  54       Out_File    => 2,  -- System.File_IO.File_Mode'Pos (Out_File)
  55       Append_File => 3); -- System.File_IO.File_Mode'Pos (Append_File)
  56
  57    type Count is new Stream_Element_Offset
  58      range 0 .. Stream_Element_Offset'Last;
  59
  60    subtype Positive_Count is Count range 1 .. Count'Last;
  61    --  Index into file, in stream elements
  62
  63    ---------------------
  64    -- File Management --
  65    ---------------------
  66
  67    procedure Create
  68      (File : in out File_Type;
  69       Mode : File_Mode := Out_File;
  70       Name : String := "";
  71       Form : String := "");
  72
  73    procedure Open
  74      (File : in out File_Type;
  75       Mode : File_Mode;
  76       Name : String;
  77       Form : String := "");
  78
  79    procedure Close  (File : in out File_Type);
  80    procedure Delete (File : in out File_Type);
  81    procedure Reset  (File : in out File_Type; Mode : File_Mode);
  82    procedure Reset  (File : in out File_Type);
  83
  84    function Mode (File : File_Type) return File_Mode;
  85    function Name (File : File_Type) return String;
  86    function Form (File : File_Type) return String;
  87
  88    function Is_Open     (File : File_Type) return Boolean;
  89    function End_Of_File (File : File_Type) return Boolean;
  90
  91    function Stream (File : File_Type) return Stream_Access;
  92
  93    -----------------------------
  94    -- Input-Output Operations --
  95    -----------------------------
  96
  97    procedure Read
  98      (File : File_Type;
  99       Item : out Stream_Element_Array;
 100       Last : out Stream_Element_Offset;
 101       From : Positive_Count);
 102
 103    procedure Read
 104      (File : File_Type;
 105       Item : out Stream_Element_Array;
 106       Last : out Stream_Element_Offset);
 107
 108    procedure Write
 109      (File : File_Type;
 110       Item : Stream_Element_Array;
 111       To   : Positive_Count);
 112
 113    procedure Write
 114      (File : File_Type;
 115       Item : Stream_Element_Array);
 116
 117    ----------------------------------------
 118    -- Operations on Position within File --
 119    ----------------------------------------
 120
 121    procedure Set_Index (File : File_Type; To : Positive_Count);
 122
 123    function Index (File : File_Type) return Positive_Count;
 124    function Size  (File : File_Type) return Count;
 125
 126    procedure Set_Mode (File : in out File_Type; Mode : File_Mode);
 127
 128    --  Note: The parameter file is IN OUT in the RM, but this is clearly
 129    --  an oversight, and was intended to be IN, see AI95-00057.
 130
 131    procedure Flush (File : File_Type);
 132
 133    ----------------
 134    -- Exceptions --
 135    ----------------
 136
 137    Status_Error : exception renames IO_Exceptions.Status_Error;
 138    Mode_Error   : exception renames IO_Exceptions.Mode_Error;
 139    Name_Error   : exception renames IO_Exceptions.Name_Error;
 140    Use_Error    : exception renames IO_Exceptions.Use_Error;
 141    Device_Error : exception renames IO_Exceptions.Device_Error;
 142    End_Error    : exception renames IO_Exceptions.End_Error;
 143    Data_Error   : exception renames IO_Exceptions.Data_Error;
 144
 145 private
 146
 147    --  The following procedures have a File_Type formal of mode IN OUT because
 148    --  they may close the original file. The Close operation may raise an
 149    --  exception, but in that case we want any assignment to the formal to
 150    --  be effective anyway, so it must be passed by reference (or the caller
 151    --  will be left with a dangling pointer).
 152
 153    pragma Export_Procedure
 154      (Internal  => Close,
 155       External  => "",
 156       Mechanism => Reference);
 157    pragma Export_Procedure
 158      (Internal  => Delete,
 159       External  => "",
 160       Mechanism => Reference);
 161    pragma Export_Procedure
 162      (Internal        => Reset,
 163       External        => "",
 164       Parameter_Types => (File_Type),
 165       Mechanism       => Reference);
 166    pragma Export_Procedure
 167      (Internal        => Reset,
 168       External        => "",
 169       Parameter_Types => (File_Type, File_Mode),
 170       Mechanism       => (File => Reference));
 171    pragma Export_Procedure
 172      (Internal  => Set_Mode,
 173       External  => "",
 174       Mechanism => (File => Reference));
 175
 176    package FCB renames System.File_Control_Block;
 177
 178    -----------------------------
 179    -- Stream_IO Control Block --
 180    -----------------------------
 181
 182    type Operation is (Op_Read, Op_Write, Op_Other);
 183    --  Type used to record last operation (to optimize sequential operations)
 184
 185    type Stream_AFCB is new FCB.AFCB with record
 186       Index : Count := 1;
 187       --  Current Index value
 188
 189       File_Size : Stream_Element_Offset := -1;
 190       --  Cached value of File_Size, so that we do not keep recomputing it
 191       --  when not necessary (otherwise End_Of_File becomes gruesomely slow).
 192       --  A value of minus one means that there is no cached value.
 193
 194       Last_Op : Operation := Op_Other;
 195       --  Last operation performed on file, used to avoid unnecessary
 196       --  repositioning between successive read or write operations.
 197
 198       Update_Mode : Boolean := False;
 199       --  Set if the mode is changed from write to read or vice versa.
 200       --  Indicates that the file has been reopened in update mode.
 201
 202    end record;
 203
 204    type File_Type is access all Stream_AFCB;
 205
 206    overriding function AFCB_Allocate
 207      (Control_Block : Stream_AFCB) return FCB.AFCB_Ptr;
 208
 209    overriding procedure AFCB_Close (File : not null access Stream_AFCB);
 210    overriding procedure AFCB_Free  (File : not null access Stream_AFCB);
 211
 212    overriding procedure Read
 213      (File : in out Stream_AFCB;
 214       Item : out Ada.Streams.Stream_Element_Array;
 215       Last : out Ada.Streams.Stream_Element_Offset);
 216    --  Read operation used when Stream_IO file is treated directly as Stream
 217
 218    overriding procedure Write
 219      (File : in out Stream_AFCB;
 220       Item : Ada.Streams.Stream_Element_Array);
 221    --  Write operation used when Stream_IO file is treated directly as Stream
 222
 223 end Ada.Streams.Stream_IO;