------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                               O U T P U T                                --
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--                            $Revision$
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--          Copyright (C) 1992-2001 Free Software Foundation, Inc.          --
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-- GNAT is free software;  you can  redistribute it  and/or modify it under --
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-- As a special exception,  if other files  instantiate  generics from this --
-- unit, or you link  this unit with other files  to produce an executable, --
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-- covered by the  GNU Public License.                                      --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
--                                                                          --
------------------------------------------------------------------------------

--  This package contains low level output routines used by the compiler
--  for writing error messages and informational output. It is also used
--  by the debug source file output routines (see Sprintf.Print_Eol).

with Types; use Types;

package Output is
pragma Elaborate_Body (Output);

   type Output_Proc is access procedure (S : String);
   --  This type is used for the Set_Special_Output procedure. If this
   --  procedure is called, then instead of lines being written to
   --  standard error or standard output, a call is made to the given
   --  procedure for each line, passing the line with an end of line
   --  character (which is a single ASCII.LF character, even in systems
   --  which normally use CR/LF or some other sequence for line end).

   -----------------
   -- Subprograms --
   -----------------

   procedure Set_Special_Output (P : Output_Proc);
   --  Sets subsequent output to call procedure P. If P is null, then
   --  the call cancels the effect of a previous call, reverting the
   --  output to standard error or standard output depending on the
   --  mode at the time of previous call. Any exception generated by
   --  by calls to P is simply propagated to the caller of the routine
   --  causing the write operation.

   procedure Cancel_Special_Output;
   --  Cancels the effect of a call to Set_Special_Output, if any.
   --  The output is then directed to standard error or standard output
   --  depending on the last call to Set_Standard_Error or Set_Standard_Output.
   --  It is never an error to call Cancel_Special_Output. It has the same
   --  effect as calling Set_Special_Output (null).

   procedure Set_Standard_Error;
   --  Sets subsequent output to appear on the standard error file (whatever
   --  that might mean for the host operating system, if anything) when
   --  no special output is in effect. When a special output is in effect,
   --  the output will appear on standard error only after special output
   --  has been cancelled.

   procedure Set_Standard_Output;
   --  Sets subsequent output to appear on the standard output file (whatever
   --  that might mean for the host operating system, if anything) when
   --  no special output is in effect. When a special output is in effect,
   --  the output will appear on standard output only after special output
   --  has been cancelled. Output to standard output is the default mode
   --  before any call to either of the Set procedures.

   procedure Write_Char (C : Character);
   --  Write one character to the standard output file. Note that the
   --  character should not be LF or CR (use Write_Eol for end of line)

   procedure Write_Eol;
   --  Write an end of line (whatever is required by the system in use,
   --  e.g. CR/LF for DOS, or LF for Unix) to the standard output file.
   --  This routine also empties the line buffer, actually writing it
   --  to the file. Note that Write_Eol is the only routine that causes
   --  any actual output to be written.

   procedure Write_Int (Val : Int);
   --  Write an integer value with no leading blanks or zeroes. Negative
   --  values are preceded by a minus sign).

   procedure Write_Str (S : String);
   --  Write a string of characters to the standard output file. Note that
   --  end of line is handled separately using WRITE_EOL, so the string
   --  should not contain either of the characters LF or CR, but it may
   --  contain horizontal tab characters.

   procedure Write_Line (S : String);
   --  Equivalent to Write_Str (S) followed by Write_Eol;

   function Column return Nat;
   pragma Inline (Column);
   --  Returns the number of the column about to be written (e.g. a value
   --  of 1 means the current line is empty).

   --------------------------
   -- Debugging Procedures --
   --------------------------

   --  The following procedures are intended only for debugging purposes,
   --  for temporary insertion into the text in environments where a debugger
   --  is not available. They all have non-standard very short lower case
   --  names, precisely to make sure that they are only used for debugging!

   procedure w (C : Character);
   --  Dump quote, character quote, followed by line return

   procedure w (S : String);
   --  Dump string followed by line return

   procedure w (V : Int);
   --  Dump integer followed by line return

   procedure w (B : Boolean);
   --  Dump Boolean followed by line return

   procedure w (L : String; C : Character);
   --  Dump contents of string followed by blank, quote, character, quote

   procedure w (L : String; S : String);
   --  Dump two strings separated by blanks, followed by line return

   procedure w (L : String; V : Int);
   --  Dump contents of string followed by blank, integer, line return

   procedure w (L : String; B : Boolean);
   --  Dump contents of string followed by blank, Boolean, line return

end Output;
