gcc/ada/g-io_aux.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUNTIME COMPONENTS                          --
   4 --                                                                          --
   5 --                          G N A T . I O _ A U X                           --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --           Copyright (C) 1995-2002 Ada Core Technologies, Inc.            --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 with Interfaces.C_Streams; use Interfaces.C_Streams;
  35
  36 package body GNAT.IO_Aux is
  37
  38    Buflen : constant := 2000;
  39    --  Buffer length. Works for any non-zero value, larger values take
  40    --  more stack space, smaller values require more recursion.
  41
  42    -----------------
  43    -- File_Exists --
  44    -----------------
  45
  46    function File_Exists (Name : String) return Boolean
  47    is
  48       Namestr : aliased String (1 .. Name'Length + 1);
  49       --  Name as given with ASCII.NUL appended
  50
  51    begin
  52       Namestr (1 .. Name'Length) := Name;
  53       Namestr (Name'Length + 1)  := ASCII.NUL;
  54       return file_exists (Namestr'Address) /= 0;
  55    end File_Exists;
  56
  57    --------------
  58    -- Get_Line --
  59    --------------
  60
  61    --  Current_Input case
  62
  63    function Get_Line return String is
  64       Buffer : String (1 .. Buflen);
  65       --  Buffer to read in chunks of remaining line. Will work with any
  66       --  size buffer. We choose a length so that most of the time no
  67       --  recursion will be required.
  68
  69       Last : Natural;
  70
  71    begin
  72       Ada.Text_IO.Get_Line (Buffer, Last);
  73
  74       --  If the buffer is not full, then we are all done
  75
  76       if Last < Buffer'Last then
  77          return Buffer (1 .. Last);
  78
  79       --  Otherwise, we still have characters left on the line. Note that
  80       --  as specified by (RM A.10.7(19)) the end of line is not skipped
  81       --  in this case, even if we are right at it now.
  82
  83       else
  84          return Buffer & GNAT.IO_Aux.Get_Line;
  85       end if;
  86    end Get_Line;
  87
  88    --  Case of reading from a specified file. Note that we could certainly
  89    --  share code between these two versions, but these are very short
  90    --  routines, and we may as well aim for maximum speed, cutting out an
  91    --  intermediate call (calls returning string may be somewhat slow)
  92
  93    function Get_Line (File : Ada.Text_IO.File_Type) return String is
  94       Buffer : String (1 .. Buflen);
  95       Last   : Natural;
  96
  97    begin
  98       Ada.Text_IO.Get_Line (File, Buffer, Last);
  99
 100       if Last < Buffer'Last then
 101          return Buffer (1 .. Last);
 102       else
 103          return Buffer & Get_Line (File);
 104       end if;
 105    end Get_Line;
 106
 107 end GNAT.IO_Aux;