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.            --
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  23 -- unit, or you link  this unit with other files  to produce an executable, --
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  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
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  27 -- covered by the  GNU Public License.                                      --
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  29 -- GNAT is maintained by Ada Core Technologies Inc (http://www.gnat.com).   --
  30 --                                                                          --
  31 ------------------------------------------------------------------------------
  32
  33 with Interfaces.C_Streams; use Interfaces.C_Streams;
  34
  35 package body GNAT.IO_Aux is
  36
  37    Buflen : constant := 2000;
  38    --  Buffer length. Works for any non-zero value, larger values take
  39    --  more stack space, smaller values require more recursion.
  40
  41    -----------------
  42    -- File_Exists --
  43    -----------------
  44
  45    function File_Exists (Name : String) return Boolean
  46    is
  47       Namestr : aliased String (1 .. Name'Length + 1);
  48       --  Name as given with ASCII.NUL appended
  49
  50    begin
  51       Namestr (1 .. Name'Length) := Name;
  52       Namestr (Name'Length + 1)  := ASCII.NUL;
  53       return file_exists (Namestr'Address) /= 0;
  54    end File_Exists;
  55
  56    --------------
  57    -- Get_Line --
  58    --------------
  59
  60    --  Current_Input case
  61
  62    function Get_Line return String is
  63       Buffer : String (1 .. Buflen);
  64       --  Buffer to read in chunks of remaining line. Will work with any
  65       --  size buffer. We choose a length so that most of the time no
  66       --  recursion will be required.
  67
  68       Last : Natural;
  69
  70    begin
  71       Ada.Text_IO.Get_Line (Buffer, Last);
  72
  73       --  If the buffer is not full, then we are all done
  74
  75       if Last < Buffer'Last then
  76          return Buffer (1 .. Last);
  77
  78       --  Otherwise, we still have characters left on the line. Note that
  79       --  as specified by (RM A.10.7(19)) the end of line is not skipped
  80       --  in this case, even if we are right at it now.
  81
  82       else
  83          return Buffer & GNAT.IO_Aux.Get_Line;
  84       end if;
  85    end Get_Line;
  86
  87    --  Case of reading from a specified file. Note that we could certainly
  88    --  share code between these two versions, but these are very short
  89    --  routines, and we may as well aim for maximum speed, cutting out an
  90    --  intermediate call (calls returning string may be somewhat slow)
  91
  92    function Get_Line (File : Ada.Text_IO.File_Type) return String is
  93       Buffer : String (1 .. Buflen);
  94       Last   : Natural;
  95
  96    begin
  97       Ada.Text_IO.Get_Line (File, Buffer, Last);
  98
  99       if Last < Buffer'Last then
 100          return Buffer (1 .. Last);
 101       else
 102          return Buffer & Get_Line (File);
 103       end if;
 104    end Get_Line;
 105
 106 end GNAT.IO_Aux;