1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                             G N A T P R E P                              --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 1992-2021, 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 program provides a simple preprocessing capability for Ada programs.
27--  It is designed for use with GNAT, but is not dependent on any special
28--  features of GNAT.
29
30--    To call gnatprep use
31
32--      gnatprep infile outfile [deffile] [-v] [-c] [-b] [-r] [-s] [-u]
33--            [-Dsymbol=value]
34
35--    where
36
37--      infile is the full name of the input file, which is an Ada source
38--      file containing preprocessor directives.
39
40--      outfile is the full name of the output file, which is an Ada source
41--      in standard Ada form. When used with GNAT, this file name will
42--      normally have an ads or adb suffix.
43
44--      deffile is the full name of a text file containing definitions of
45--      symbols to be referenced by the preprocessor. This argument is
46--      optional.
47
48--      The -c switch, causes both preprocessor lines and the lines deleted
49--      by preprocessing to be retained in the output source as comments marked
50--      with the special string "--! ". This option will result in line numbers
51--      being preserved in the output file.
52
53--      The -b switch causes both preprocessor lines and the lines deleted by
54--      preprocessing to be replaced by blank lines in the output source file,
55--      thus preserving line numbers in the output file.
56
57--      The -r switch causes a Source_Reference pragma to be generated that
58--      references the original input file, so that error messages will use
59--      the file name of this original file.
60
61--      The -u switch causes gnatprep to treat any undefined symbol that it
62--      encounters as having the value False. Otherwise an undefined symbol
63--      is a fatal error.
64
65--      The -s switch causes a sorted list of symbol names and values to be
66--      listed on the standard output file.
67
68--      The -v switch causes a Copyright notice to be displayed, and
69--      lines containing errors in the input file or the definition file
70--      to be displayed before the errors.
71
72--      The -D switch causes symbol 'symbol' to be associated with 'value'.
73--      This symbols can then be referenced by the preprocessor. Several
74--      -D switches may be specified.
75
76--      Note: if neither -b nor -c is present, then preprocessor lines and
77--      deleted lines are completely removed from the output, unless -r is
78--      specified, in which case -b is assumed.
79
80--   The definitions file contains lines of the form
81
82--      symbol := value
83
84--   where symbol is an identifier, following normal Ada (case-insensitive)
85--   rules for its syntax, and value is one of the following:
86
87--      Empty, corresponding to a null substitution
88
89--      A string literal using normal Ada syntax
90
91--      Any sequence of characters from the set
92--        (letters, digits, period, underline)
93
94--   Comment lines may also appear in the definitions file, starting with
95--   the usual --, and comments may be added to the definitions lines.
96
97--   The input text may contain preprocessor conditional inclusion lines,
98--   and also general symbol substitution sequences.
99
100--   The preprocessor conditional inclusion commands have the form
101
102--      #if <expression> [then]
103--         lines
104--      #elsif <expression> [then]
105--         lines
106--      #elsif <expression> [then]
107--         lines
108--      ...
109--      #else
110--         lines
111--      #end if;
112--
113--     Where expression is defined by the following grammar :
114--        expression ::=  <symbol>
115--        expression ::=  <symbol> = "<value>"
116--        expression ::=  <symbol> = <symbol>
117--        expression ::=  <symbol> 'Defined
118--        expression ::=  not <expression>
119--        expression ::=  <expression> and <expression>
120--        expression ::=  <expression> or <expression>
121--        expression ::=  <expression> and then <expression>
122--        expression ::=  <expression> or else <expression>
123--        expression ::=  ( <expression> )
124
125--        "or" and "and" may not be used in the same expression without
126--        using parentheses.
127
128--     For these Boolean tests, the symbol must have either the value True or
129--     False. If the value is True, then the corresponding lines are included,
130--     and if the value is False, they are excluded. It is an error to
131--     reference a symbol not defined in the symbol definitions file, or
132--     to reference a symbol that has a value other than True or False.
133
134--     The use of the not operator inverts the sense of this logical test, so
135--     that the lines are included only if the symbol is not defined.
136
137--     The THEN keyword is optional as shown
138
139--     Spaces or tabs may appear between the # and the keyword. The keywords
140--     and the symbols are case insensitive as in normal Ada code. Comments
141--     may be used on a preprocessor line, but other than that, no other
142--     tokens may appear on a preprocessor line.
143
144--     Any number of #elsif clauses can be present, including none at all
145
146--     The #else is optional, as in Ada
147
148--     The # marking the start of a preprocessor line must be the first
149--     non-blank character on the line, i.e. it must be preceded only by
150--     spaces or horizontal tabs.
151
152--   Symbol substitution is obtained by using the sequence
153
154--     $symbol
155
156--   anywhere within a source line, except in a comment. The identifier
157--   following the $ must match one of the symbols defined in the symbol
158--   definition file, and the result is to substitute the value of the
159--   symbol in place of $symbol in the output file.
160
161procedure GNATprep;
162