1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                               O U T P U T                                --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 1992-2020, Free Software Foundation, 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 3,  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 COPYING3.  If not, go to --
19-- http://www.gnu.org/licenses for a complete copy of the license.          --
20--                                                                          --
21-- GNAT was originally developed  by the GNAT team at  New York University. --
22-- Extensive contributions were provided by Ada Core Technologies Inc.      --
23--                                                                          --
24------------------------------------------------------------------------------
25
26--  This package contains low level output routines used by the compiler for
27--  writing error messages and informational output. It is also used by the
28--  debug source file output routines (see Sprint.Print_Debug_Line).
29
30with Hostparm;
31with Types;    use Types;
32
33pragma Warnings (Off);
34--  This package is used also by gnatcoll
35with System.OS_Lib; use System.OS_Lib;
36pragma Warnings (On);
37
38package Output is
39   pragma Elaborate_Body;
40
41   type Output_Proc is access procedure (S : String);
42   --  This type is used for the Set_Special_Output procedure. If Output_Proc
43   --  is called, then instead of lines being written to standard error or
44   --  standard output, a call is made to the given procedure for each line,
45   --  passing the line with an end of line character (which is a single
46   --  ASCII.LF character, even in systems which normally use CR/LF or some
47   --  other sequence for line end).
48
49   -----------------
50   -- Subprograms --
51   -----------------
52
53   procedure Set_Special_Output (P : Output_Proc);
54   --  Sets subsequent output to call procedure P. If P is null, then the call
55   --  cancels the effect of a previous call, reverting the output to standard
56   --  error or standard output depending on the mode at the time of previous
57   --  call. Any exception generated by calls to P is simply propagated to
58   --  the caller of the routine causing the write operation.
59
60   procedure Cancel_Special_Output;
61   --  Cancels the effect of a call to Set_Special_Output, if any. The output
62   --  is then directed to standard error or standard output depending on the
63   --  last call to Set_Standard_Error or Set_Standard_Output. It is never an
64   --  error to call Cancel_Special_Output. It has the same effect as calling
65   --  Set_Special_Output (null).
66
67   procedure Ignore_Output (S : String);
68   --  Does nothing. To disable output, pass Ignore_Output'Access to
69   --  Set_Special_Output.
70
71   procedure Set_Standard_Error;
72   --  Sets subsequent output to appear on the standard error file (whatever
73   --  that might mean for the host operating system, if anything) when
74   --  no special output is in effect. When a special output is in effect,
75   --  the output will appear on standard error only after special output
76   --  has been cancelled.
77
78   procedure Set_Standard_Output;
79   --  Sets subsequent output to appear on the standard output file (whatever
80   --  that might mean for the host operating system, if anything) when no
81   --  special output is in effect. When a special output is in effect, the
82   --  output will appear on standard output only after special output has been
83   --  cancelled. Output to standard output is the default mode before any call
84   --  to either of the Set procedures.
85
86   procedure Set_Output (FD : File_Descriptor);
87   --  Sets subsequent output to appear on the given file descriptor when no
88   --  special output is in effect. When a special output is in effect, the
89   --  output will appear on the given file descriptor only after special
90   --  output has been cancelled.
91
92   procedure Push_Output;
93   --  Saves the current output destination on a stack, but leaves it
94   --  unchanged. This subprogram only supports a small stack and is normally
95   --  used with a depth of one.
96
97   procedure Pop_Output;
98   --  Changes the current output destination to be the last output destination
99   --  popped using Push_Output.
100
101   procedure Indent;
102   --  Increases the current indentation level. Whenever a line is written
103   --  (triggered by Eol), an appropriate amount of whitespace is added to the
104   --  beginning of the line, wrapping around if it gets too long.
105
106   procedure Outdent;
107   --  Decreases the current indentation level
108
109   procedure Write_Char (C : Character);
110   --  Write one character to the standard output file. If the character is LF,
111   --  this is equivalent to Write_Eol.
112
113   procedure Write_Erase_Char (C : Character);
114   --  If last character in buffer matches C, erase it, otherwise no effect
115
116   procedure Write_Eol;
117   --  Write an end of line (whatever is required by the system in use, e.g.
118   --  CR/LF for DOS, or LF for Unix) to the standard output file. This routine
119   --  also empties the line buffer, actually writing it to the file. Note that
120   --  Write_Eol is the only routine that causes any actual output to be
121   --  written. Trailing spaces are removed.
122
123   procedure Write_Eol_Keep_Blanks;
124   --  Similar as Write_Eol, except that trailing spaces are not removed
125
126   procedure Write_Int (Val : Int);
127   --  Write an integer value with no leading blanks or zeroes. Negative values
128   --  are preceded by a minus sign).
129
130   procedure Write_Spaces (N : Nat);
131   --  Write N spaces
132
133   procedure Write_Str (S : String);
134   --  Write a string of characters to the standard output file. Note that
135   --  end of line is normally handled separately using WRITE_EOL, but it is
136   --  allowable for the string to contain LF (but not CR) characters, which
137   --  are properly interpreted as end of line characters. The string may also
138   --  contain horizontal tab characters.
139
140   procedure Write_Line (S : String);
141   --  Equivalent to Write_Str (S) followed by Write_Eol;
142
143   function Last_Char return Character;
144   --  Returns last character written on the current line, or null if the
145   --  current line is (so far) empty.
146
147   procedure Delete_Last_Char;
148   --  Deletes last character written on the current line, no effect if the
149   --  current line is (so far) empty.
150
151   function Column return Pos;
152   pragma Inline (Column);
153   --  Returns the number of the column about to be written (e.g. a value of 1
154   --  means the current line is empty).
155
156   -------------------------
157   -- Buffer Save/Restore --
158   -------------------------
159
160   --  This facility allows the current line buffer to be saved and restored
161
162   type Saved_Output_Buffer is private;
163   --  Type used for Save/Restore_Buffer
164
165   Buffer_Max : constant := Hostparm.Max_Line_Length;
166   --  Maximal size of a buffered output line
167
168   function Save_Output_Buffer return Saved_Output_Buffer;
169   --  Save current line buffer and reset line buffer to empty
170
171   procedure Restore_Output_Buffer (S : Saved_Output_Buffer);
172   --  Restore previously saved output buffer. The value in S is not affected
173   --  so it is legitimate to restore a buffer more than once.
174
175   --------------------------
176   -- Debugging Procedures --
177   --------------------------
178
179   --  The following procedures are intended only for debugging purposes,
180   --  for temporary insertion into the text in environments where a debugger
181   --  is not available. They all have non-standard very short lower case
182   --  names, precisely to make sure that they are only used for debugging.
183
184   procedure w (C : Character);
185   --  Dump quote, character, quote, followed by line return
186
187   procedure w (S : String);
188   --  Dump string followed by line return
189
190   procedure w (V : Int);
191   --  Dump integer followed by line return
192
193   procedure w (B : Boolean);
194   --  Dump Boolean followed by line return
195
196   procedure w (L : String; C : Character);
197   --  Dump contents of string followed by blank, quote, character, quote
198
199   procedure w (L : String; S : String);
200   --  Dump two strings separated by blanks, followed by line return
201
202   procedure w (L : String; V : Int);
203   --  Dump contents of string followed by blank, integer, line return
204
205   procedure w (L : String; B : Boolean);
206   --  Dump contents of string followed by blank, Boolean, line return
207
208private
209
210   type Saved_Output_Buffer is record
211      Buffer          : String (1 .. Buffer_Max + 1);
212      Next_Col        : Positive;
213      Cur_Indentation : Natural;
214   end record;
215
216end Output;
217