File : gnatprep.ads
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) 1992-2007, 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
161 procedure GNATprep;