------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                               O U T P U T                                --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--          Copyright (C) 1992-2001, Free Software Foundation, Inc.         --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 2,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
-- for  more details.  You should have  received  a copy of the GNU General --
-- Public License  distributed with GNAT;  see file COPYING.  If not, write --
-- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
-- MA 02111-1307, USA.                                                      --
--                                                                          --
-- As a special exception,  if other files  instantiate  generics from this --
-- unit, or you link  this unit with other files  to produce an executable, --
-- this  unit  does not  by itself cause  the resulting  executable  to  be --
-- covered  by the  GNU  General  Public  License.  This exception does not --
-- however invalidate  any other reasons why  the executable file  might be --
-- covered by the  GNU Public License.                                      --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

with GNAT.OS_Lib; use GNAT.OS_Lib;

package body Output is

   Current_FD : File_Descriptor := Standout;
   --  File descriptor for current output

   Special_Output_Proc : Output_Proc := null;
   --  Record argument to last call to Set_Special_Output. If this is
   --  non-null, then we are in special output mode.

   -------------------------
   -- Line Buffer Control --
   -------------------------

   --  Note: the following buffer and column position are maintained by
   --  the subprograms defined in this package, and are not normally
   --  directly modified or accessed by a client. However, a client is
   --  permitted to modify these values, using the knowledge that only
   --  Write_Eol actually generates any output.

   Buffer_Max : constant := 8192;
   Buffer     : String (1 .. Buffer_Max + 1);
   --  Buffer used to build output line. We do line buffering because it
   --  is needed for the support of the debug-generated-code option (-gnatD).
   --  Historically it was first added because on VMS, line buffering is
   --  needed with certain file formats. So in any case line buffering must
   --  be retained for this purpose, even if other reasons disappear. Note
   --  any attempt to write more output to a line than can fit in the buffer
   --  will be silently ignored.

   Next_Column : Pos range 1 .. Buffer'Length + 1 := 1;
   --  Column about to be written.

   -----------------------
   -- Local_Subprograms --
   -----------------------

   procedure Flush_Buffer;
   --  Flush buffer if non-empty and reset column counter

   ---------------------------
   -- Cancel_Special_Output --
   ---------------------------

   procedure Cancel_Special_Output is
   begin
      Special_Output_Proc := null;
   end Cancel_Special_Output;

   ------------------
   -- Flush_Buffer --
   ------------------

   procedure Flush_Buffer is
      Len : constant Natural := Natural (Next_Column - 1);

   begin
      if Len /= 0 then

         --  If Special_Output_Proc has been set, then use it

         if Special_Output_Proc /= null then
            Special_Output_Proc.all (Buffer (1 .. Len));

         --  If output is not set, then output to either standard output
         --  or standard error.

         elsif Len /= Write (Current_FD, Buffer'Address, Len) then

            --  If there are errors with standard error, just quit

            if Current_FD = Standerr then
               OS_Exit (2);

            --  Otherwise, set the output to standard error before
            --  reporting a failure and quitting.

            else
               Current_FD := Standerr;
               Next_Column := 1;
               Write_Line ("fatal error: disk full");
               OS_Exit (2);
            end if;
         end if;

         --  Buffer is now empty

         Next_Column := 1;
      end if;
   end Flush_Buffer;

   ------------
   -- Column --
   ------------

   function Column return Nat is
   begin
      return Next_Column;
   end Column;

   ------------------------
   -- Set_Special_Output --
   ------------------------

   procedure Set_Special_Output (P : Output_Proc) is
   begin
      Special_Output_Proc := P;
   end Set_Special_Output;

   ------------------------
   -- Set_Standard_Error --
   ------------------------

   procedure Set_Standard_Error is
   begin
      if Special_Output_Proc = null then
         Flush_Buffer;
         Next_Column := 1;
      end if;

      Current_FD := Standerr;
   end Set_Standard_Error;

   -------------------------
   -- Set_Standard_Output --
   -------------------------

   procedure Set_Standard_Output is
   begin
      if Special_Output_Proc = null then
         Flush_Buffer;
         Next_Column := 1;
      end if;

      Current_FD := Standout;
   end Set_Standard_Output;

   -------
   -- w --
   -------

   procedure w (C : Character) is
   begin
      Write_Char (''');
      Write_Char (C);
      Write_Char (''');
      Write_Eol;
   end w;

   procedure w (S : String) is
   begin
      Write_Str (S);
      Write_Eol;
   end w;

   procedure w (V : Int) is
   begin
      Write_Int (V);
      Write_Eol;
   end w;

   procedure w (B : Boolean) is
   begin
      if B then
         w ("True");
      else
         w ("False");
      end if;
   end w;

   procedure w (L : String; C : Character) is
   begin
      Write_Str (L);
      Write_Char (' ');
      w (C);
   end w;

   procedure w (L : String; S : String) is
   begin
      Write_Str (L);
      Write_Char (' ');
      w (S);
   end w;

   procedure w (L : String; V : Int) is
   begin
      Write_Str (L);
      Write_Char (' ');
      w (V);
   end w;

   procedure w (L : String; B : Boolean) is
   begin
      Write_Str (L);
      Write_Char (' ');
      w (B);
   end w;

   ----------------
   -- Write_Char --
   ----------------

   procedure Write_Char (C : Character) is
   begin
      if Next_Column < Buffer'Length then
         Buffer (Natural (Next_Column)) := C;
         Next_Column := Next_Column + 1;
      end if;
   end Write_Char;

   ---------------
   -- Write_Eol --
   ---------------

   procedure Write_Eol is
   begin
      Buffer (Natural (Next_Column)) := ASCII.LF;
      Next_Column := Next_Column + 1;
      Flush_Buffer;
   end Write_Eol;

   ---------------
   -- Write_Int --
   ---------------

   procedure Write_Int (Val : Int) is
   begin
      if Val < 0 then
         Write_Char ('-');
         Write_Int (-Val);

      else
         if Val > 9 then
            Write_Int (Val / 10);
         end if;

         Write_Char (Character'Val ((Val mod 10) + Character'Pos ('0')));
      end if;
   end Write_Int;

   ----------------
   -- Write_Line --
   ----------------

   procedure Write_Line (S : String) is
   begin
      Write_Str (S);
      Write_Eol;
   end Write_Line;

   ---------------
   -- Write_Str --
   ---------------

   procedure Write_Str (S : String) is
   begin
      for J in S'Range loop
         Write_Char (S (J));
      end loop;
   end Write_Str;

end Output;
