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--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                             G N A T P R E P                              --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 1992-2005, 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,  51  Franklin  Street,  Fifth  Floor, --

-- Boston, MA 02110-1301, USA.                                              --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

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--  This program provides a simple preprocessing capability for Ada programs.

--  It is designed for use with GNAT, but is not dependent on any special

--  features of GNAT.

--    To call gnatprep use

--      gnatprep infile outfile [deffile] [-v] [-c] [-b] [-r] [-s] [-u]

--            [-Dsymbol=value]

--    where

--      infile is the full name of the input file, which is an Ada source

--      file containing preprocessor directives.

--      outfile is the full name of the output file, which is an Ada source

--      in standard Ada form. When used with GNAT, this file name will

--      normally have an ads or adb suffix.

--      deffile is the full name of a text file containing definitions of

--      symbols to be referenced by the preprocessor. This argument is

--      optional.

--      The -c switch, causes both preprocessor lines and the lines deleted

--      by preprocessing to be retained in the output source as comments marked

--      with the special string "--! ". This option will result in line numbers

--      being preserved in the output file.

--      The -b switch causes both preprocessor lines and the lines deleted by

--      preprocessing to be replaced by blank lines in the output source file,

--      thus preserving line numbers in the output file.

--      The -r switch causes a Source_Reference pragma to be generated that

--      references the original input file, so that error messages will use

--      the file name of this original file.

--      The -u switch causes gnatprep to treat any undefined symbol that it

--      encounters as having the value False. Otherwise an undefined symbol

--      is a fatal error.

--      The -s switch causes a sorted list of symbol names and values to be

--      listed on the standard output file.

--      The -v switch causes a Copyright notice to be displayed, and

--      lines containing errors in the input file or the definition file

--      to be displayed before the errors.

--      The -D switch causes symbol 'symbol' to be associated with 'value'.

--      This symbols can then be referenced by the preprocessor. Several

--      -D switches may be specified.

--      Note: if neither -b nor -c is present, then preprocessor lines and

--      deleted lines are completely removed from the output, unless -r is

--      specified, in which case -b is assumed.

--   The definitions file contains lines of the form

--      symbol := value

--   where symbol is an identifier, following normal Ada (case-insensitive)

--   rules for its syntax, and value is one of the following:

--      Empty, corresponding to a null substitution

--      A string literal using normal Ada syntax

--      Any sequence of characters from the set

--        (letters, digits, period, underline)

--   Comment lines may also appear in the definitions file, starting with

--   the usual --, and comments may be added to the definitions lines.

--   The input text may contain preprocessor conditional inclusion lines,

--   and also general symbol substitution sequences.

--   The preprocessor conditional inclusion commands have the form

--      #if <expression> [then]

--         lines

--      #elsif <expression> [then]

--         lines

--      #elsif <expression> [then]

--         lines

--      ...

--      #else

--         lines

--      #end if;

--

--     Where expression is defined by the following grammar :

--        expression ::=  <symbol>

--        expression ::=  <symbol> = "<value>"

--        expression ::=  <symbol> = <symbol>

--        expression ::=  <symbol> 'Defined

--        expression ::=  not <expression>

--        expression ::=  <expression> and <expression>

--        expression ::=  <expression> or <expression>

--        expression ::=  <expression> and then <expression>

--        expression ::=  <expression> or else <expression>

--        expression ::=  ( <expression> )

--        "or" and "and" may not be used in the same expression without

--        using parentheses.

--     For these Boolean tests, the symbol must have either the value True or

--     False. If the value is True, then the corresponding lines are included,

--     and if the value is False, they are excluded. It is an error to

--     reference a symbol not defined in the symbol definitions file, or

--     to reference a symbol that has a value other than True or False.

--     The use of the not operator inverts the sense of this logical test, so

--     that the lines are included only if the symbol is not defined.

--     The THEN keyword is optional as shown

--     Spaces or tabs may appear between the # and the keyword. The keywords

--     and the symbols are case insensitive as in normal Ada code. Comments

--     may be used on a preprocessor line, but other than that, no other

--     tokens may appear on a preprocessor line.

--     Any number of #elsif clauses can be present, including none at all

--     The #else is optional, as in Ada

--     The # marking the start of a preprocessor line must be the first

--     non-blank character on the line, i.e. it must be preceded only by

--     spaces or horizontal tabs.

--   Symbol substitution is obtained by using the sequence

--     $symbol

--   anywhere within a source line, except in a comment. The identifier

--   following the $ must match one of the symbols defined in the symbol

--   definition file, and the result is to substitute the value of the

--   symbol in place of $symbol in the output file.

procedure GNATprep;