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 --                            $Revision: 1.7 $
  10 --                                                                          --
  11 --           Copyright (C) 1995-2000 Ada Core Technologies, Inc.            --
  12 --                                                                          --
  13 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  14 -- terms of the  GNU General Public License as published  by the Free Soft- --
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  17 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  18 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  19 -- for  more details.  You should have  received  a copy of the GNU General --
  20 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  21 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  22 -- MA 02111-1307, USA.                                                      --
  23 --                                                                          --
  24 -- As a special exception,  if other files  instantiate  generics from this --
  25 -- unit, or you link  this unit with other files  to produce an executable, --
  26 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  27 -- covered  by the  GNU  General  Public  License.  This exception does not --
  28 -- however invalidate  any other reasons why  the executable file  might be --
  29 -- covered by the  GNU Public License.                                      --
  30 --                                                                          --
  31 -- GNAT is maintained by Ada Core Technologies Inc (http://www.gnat.com).   --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 with Interfaces.C_Streams; use Interfaces.C_Streams;
  36
  37 package body GNAT.IO_Aux is
  38
  39    Buflen : constant := 2000;
  40    --  Buffer length. Works for any non-zero value, larger values take
  41    --  more stack space, smaller values require more recursion.
  42
  43    -----------------
  44    -- File_Exists --
  45    -----------------
  46
  47    function File_Exists (Name : String) return Boolean
  48    is
  49       Namestr : aliased String (1 .. Name'Length + 1);
  50       --  Name as given with ASCII.NUL appended
  51
  52    begin
  53       Namestr (1 .. Name'Length) := Name;
  54       Namestr (Name'Length + 1)  := ASCII.NUL;
  55       return file_exists (Namestr'Address) /= 0;
  56    end File_Exists;
  57
  58    --------------
  59    -- Get_Line --
  60    --------------
  61
  62    --  Current_Input case
  63
  64    function Get_Line return String is
  65       Buffer : String (1 .. Buflen);
  66       --  Buffer to read in chunks of remaining line. Will work with any
  67       --  size buffer. We choose a length so that most of the time no
  68       --  recursion will be required.
  69
  70       Last : Natural;
  71
  72    begin
  73       Ada.Text_IO.Get_Line (Buffer, Last);
  74
  75       --  If the buffer is not full, then we are all done
  76
  77       if Last < Buffer'Last then
  78          return Buffer (1 .. Last);
  79
  80       --  Otherwise, we still have characters left on the line. Note that
  81       --  as specified by (RM A.10.7(19)) the end of line is not skipped
  82       --  in this case, even if we are right at it now.
  83
  84       else
  85          return Buffer & GNAT.IO_Aux.Get_Line;
  86       end if;
  87    end Get_Line;
  88
  89    --  Case of reading from a specified file. Note that we could certainly
  90    --  share code between these two versions, but these are very short
  91    --  routines, and we may as well aim for maximum speed, cutting out an
  92    --  intermediate call (calls returning string may be somewhat slow)
  93
  94    function Get_Line (File : Ada.Text_IO.File_Type) return String is
  95       Buffer : String (1 .. Buflen);
  96       Last   : Natural;
  97
  98    begin
  99       Ada.Text_IO.Get_Line (File, Buffer, Last);
 100
 101       if Last < Buffer'Last then
 102          return Buffer (1 .. Last);
 103       else
 104          return Buffer & Get_Line (File);
 105       end if;
 106    end Get_Line;
 107
 108 end GNAT.IO_Aux;