#!/usr/bin/perl
#
# eyapp -- Front end to the Parse::Eyapp module
#
#

=head1 NAME

eyapp - A Perl front-end to the Parse::Eyapp module


=head1 SYNOPSYS

  eyapp [options] grammar[.eyp]

  eyapp [options] grammar[.yp]

  eyapp -V               # Produce .output file

  eyapp -h               # help

  eyapp -c grammar.eyp   # Strip semantic actions

  eyapp -vc grammar.eyp  # Strip comments also


=head1 DESCRIPTION

The eyapp compiler is a front-end to the L<Parse::Eyapp> module, which lets you compile
Parse::Eyapp grammar input files into Perl LALR(1) Object Oriented parser modules.


=head1 OPTIONS

=over 4

=item I<-v>

Creates a file F<grammar>.output describing your parser. It will
show you a summary of conflicts, rules, the DFA (Deterministic
Finite Automaton) states and overall usage of the parser.

This file F<grammar>.output will be also automatically generated 
if warnings are issued.

=item I<-s>

Create a standalone module in which the parsing driver is included.
The modules including the LALR driver (L<Parse::Eyapp::Driver>),
those for AST manipulations (L<Parse::Eyapp::Node> and
L<Parse::Eyapp::YATW>)) and L<Parse::Eyapp::Base> 
are included - almost verbatim - inside the generated module. 

Note that if you have more than one parser module called from a program, 
to have it standalone, you need this option only for one of your grammars;

=item I<-n>

Disable source file line numbering embedded in your parser module.
I don't know why one should need it, but it's there.

=item I<-m module>

Gives your parser module the package name (or name space or module name or
class name or whatever-you-call-it) of F<module>.  It defaults to F<grammar>

=item I<-o outfile>

The compiled output file will be named F<outfile> for your parser module.
It defaults to F<grammar>.pm or, if you specified the option
I<-m A::Module::Name> (see below), to F<Name.pm>.

=item I<-c grammar>[.eyp]

Produces as output (STDOUT) the grammar without the actions. Only the syntactic
parts are displayed. Comments will be also stripped 
if the C<-v> option is added.


=item I<-t filename>

The I<-t filename> option allows you to specify a file which should be 
used as template for generating the parser output.  The default is to 
use the internal template defined in F<Parse::Eyapp::Output.pm>.
For how to write your own template and which substitutions are available,
have a look to the module F<Parse::Eyapp::Output.pm> : it should be obvious. 

=item I<-b shebang>

If you work on systems that understand so called I<shebangs>, and your
generated parser is directly an executable script, you can specify one
with the I<-b> option, ie:

    eyapp -b '/usr/local/bin/perl -w' -o myscript.pl myscript.yp

This will output a file called F<myscript.pl> whose very first line is:

    #!/usr/local/bin/perl -w

The argument is mandatory, but if you specify an empty string, the value
of I<$Config{perlpath}> will be used instead.

=item I<grammar>

The input grammar file. If no suffix is given, and the file does not exists,
an attempt to open the file with a suffix of  F<.yp> is tried before exiting.

=item I<-V>

Display current version of Parse::Eyapp and gracefully exits.

=item I<-h>

Display the usage screen.

=back

=head1 AUTHOR

Casiano Rodriguez-Leon 

=head1 COPYRIGHT

(c) Copyright 2006 Casiano Rodriguez-Leon

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself, either Perl version 5.8.8 or,
at your option, any later version of Perl 5 you may have available.

=head1 SEE ALSO

=over

=item * L<Parse::Eyapp>,

=item *
perldoc L<vgg>,

=item * The tutorial I<Parsing Strings and Trees with> C<Parse::Eyapp>
(An Introduction to Compiler Construction in seven pages)> in

=item * The pdf file in L<http://nereida.deioc.ull.es/~pl/perlexamples/Eyapp.pdf> 

=item * L<http://nereida.deioc.ull.es/~pl/perlexamples/section_eyappts.html> (Spanish),

=item * L<eyapp>,

=item * L<treereg>,

=item * L<Parse::yapp>,

=item * yacc(1),

=item * bison(1),

=item * the classic book "Compilers: Principles, Techniques, and Tools" by Alfred V. Aho, Ravi Sethi and

=item * Jeffrey D. Ullman (Addison-Wesley 1986)

=item * L<Parse::RecDescent>.

=back



=cut

require 5.004;

use File::Basename;
use Getopt::Std;
use Config;
use Parse::Eyapp::Base qw(compute_lines);
use Parse::Eyapp;

use strict;

our ( $opt_n, $opt_m, $opt_V, $opt_v, $opt_o, $opt_h, $opt_s, $opt_t, $opt_b, $opt_c,);

sub Usage {
	my($prog)=(fileparse($0,'\..*'))[0];
	die <<EOF;

Usage:	$prog [options] grammar[.yp]
  or	$prog -V
  or	$prog -h

    -m module   Give your parser module the name <module>
                default is <grammar>
    -v          Create a file <grammar>.output describing your parser
    -s          Create a standalone module in which the driver is included
    -n          Disable source file line numbering embedded in your parser
    -o outfile  Create the file <outfile> for your parser module
                Default is <grammar>.pm or, if -m A::Module::Name is
                specified, Name.pm
    -t filename Uses the file <filename> as a template for creating the parser
                module file.  Default is to use internal template defined
                in Parse::Eyapp::Output
    -b shebang  Adds '#!<shebang>' as the very first line of the output file

    grammar     The grammar file. If no suffix is given, and the file
                does not exists, .yp is added

    -c grammar  Displays the "clean" grammar without actions     

    -V          Display current version of Parse::Eyapp and gracefully exits
    -h          Display this help screen

EOF
}

my($nbargs)=@ARGV;

	getopts('Vhvsnc:b:m:t:o:')
or	Usage;

   (  ($opt_V and $nbargs > 1)
    or $opt_h)
and Usage;

	$opt_V
and do {

    @ARGV == 0 or  Usage;

    print "This is Parse::Eyapp version $Parse::Eyapp::Driver::VERSION.\n";
    exit(0);

};

	$opt_c and do {
     my $file;

     local $/ = undef;
     open($file, $opt_c) or die "Cannot open grammar file $opt_c: $!\n";
     $opt_c = <$file>;
     close($file);

     require Parse::Eyapp::Cleaner;
     my @args = $opt_v ? (skipcomments => 1) : ();
     print Parse::Eyapp::Cleaner::ppcontroller(\$opt_c, @args);
     exit(0);
  };



# -t <filename> ($opt_t) option allows a file to be specified which 
# contains a 'template' to be used when generating the parser; 
# if defined, we open and read the file.   

	$opt_t
and do {
    local $/ = undef;
    local *TFILE;
    open(TFILE, $opt_t)
	or die "Cannot open template file $opt_t: $!\n";
    $opt_t = <TFILE>;
    close(TFILE);
};

    @ARGV == 1
or  Usage;

my($filename)=$ARGV[0];
my($base,$path,$sfx)=fileparse($filename,'\..*');

	-r "$filename"
or	do {
		($sfx eq '.yp' or $sfx eq '.eyp')
	or (-r "$filename.yp" and $filename.='.yp')
	or (-r "$filename.eyp" and $filename.='.eyp');

		-r "$filename"
	or	die "Cannot open $filename for reading.\n";
};

my($parser)=new Parse::Eyapp(inputfile => $filename);

my($warnings)=$parser->Warnings();

	$warnings !~ m{^\s*$} 
and	print STDERR "$warnings\n";

$parser->outputtables($path, $base) if $opt_v or $warnings;

my($outfile)="$path$base.pm";
my($package)="$base";

	$opt_m
and	do {
    $package=$opt_m;
    $package=~/^(?:(?:[^:]|:(?!:))*::)*(.*)$/;
    $outfile="$1.pm";
};

	$opt_o
and	$outfile=$opt_o;

$opt_s = $opt_s ? 1 : 0;

$opt_n = $opt_n ? 0 : 1;

	open(OUT,">$outfile")
or	die "Cannot open $outfile for writing.\n";

    defined($opt_b)
and do {
        $opt_b
    or  $opt_b = $Config{perlpath};
    print OUT "#!$opt_b\n";
};

my $text = $parser->Output(
                          classname  => $package,
                          standalone => $opt_s,
                          linenumbers => $opt_n,
                          template    => $opt_t,
                          #prefixname => 'R::',
                         );
compute_lines(\$text, $outfile, $Parse::Eyapp::Output::pattern) if $opt_n;

print OUT $text;

close(OUT);

chmod(0755, $outfile) if $opt_b;
