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#! /usr/bin/perl -w
#
# assemble - read lines from STDIN and assemble them into a pattern
#
# Copyright (C) David Landgren 2004-2008

use strict;
use Getopt::Std;
use Regexp::Assemble;

use Time::HiRes 'time';

use vars '$VERSION';
$VERSION = '0.92';

getopts( 'abcd:f:i:nprsSt:TuUvw', \my %opt );

print "$VERSION\n" and exit if $opt{v};

$opt{d} |= 8 if $opt{T};

my $ra = Regexp::Assemble->new(
    chomp            => 1,
    debug            => $opt{d} || 0,
    fold_meta_pairs  => exists $opt{f} ? 0 : 1,
    reduce           => exists $opt{r} ? 0 : 1,
    dup_warn         => exists $opt{u} ? 1 : 0,
    lookahead        => exists $opt{a} ? 1 : 0,
    unroll_plus      => exists $opt{U} ? 1 : 0,
);

if( $opt{b} or $opt{c} ) {
    if( !$opt{b} ) {
        # filter comments
        $ra->pre_filter( sub { $_[0] =~ s/\s*#.*$//; 1 } );
    }
    elsif( !$opt{c} ) {
        # filter blank lines
        $ra->pre_filter( sub { length(shift) } );
    }
    else {
        # filter comments and blank lines.
        # (removing a comment may can cause a line to become blank
        $ra->pre_filter( sub {
            $_[0] =~ s/\s*#.*$//;
            length($_[0])
        } );
    }
}

$ra->add( <> );

# need to tickle reduction explicitly in the event of -S and -d8
$ra->_reduce() if $opt{S} and $opt{d} and ($opt{d} & 8);

if( $opt{i} or $opt{p} or not ($opt{t} or $opt{S}) ) {
    print $ra->as_string( indent => $opt{i} || 0 );
    print "\n" unless $opt{n};
}

if( $opt{s} or $opt{S} ) {
    warn qq{# nr=@{[$ra->stats_add]} dup=@{[$ra->stats_dup]} raw=@{[$ra->stats_raw]} cooked=@{[$ra->stats_cooked]} len=@{[$ra->stats_length]}\n};
}

if( $opt{t} ) {
    my $error = 0;
    my $file = $opt{t};
    open IN, $file or die "Cannot open $file for input: $!\n";
    print $ra->as_string, "\n";
    while( <IN> ) {
        chomp;
        if( $opt{w} ) {
            next if $_ =~ /^$ra$/;
        }
        else {
            next if $_ =~ /$ra/;
        }
        print "FAIL <$_>\n";
        ++$error;
    }
    close IN;
    exit $error ? 1 : 0;
}

=head1 NAME

assemble - Assemble a list of regular expressions from a file

=head1 SYNOPSIS

  assemble -abcdfinprsStTuUvw file [...]

=head1 DESCRIPTION

Assemble a list of regular expression either from standard input or a
file, using the Regexp::Assemble module.

=head1 OPTIONS

=over 5

=item B<-a>

look Ahead. Insert C<(?=...)> zero-width lookahead assertions in the pattern,
where necessary.

=item B<-b>

Blank. Ignore blank lines.

=item B<-c>

Comment. Basic comment filtering. Strip off perl/shell comments (C<\s*#.*$/>).

=item B<-d>

Debug. Turns on debugging output. See L<Regexp::Assemble> for suitable values.

=item B<-i>

Indent. Print the regular expression using and indent of n to display
nesting. A.k.a pretty-printing. Implies -p.

=item B<-n>

No newline. Do not print a newline after the pattern. Useful when
interpolating the output into a templating system or similar.

=item B<-p>

Print. Print the pattern. This is the default, however, it is
required when the -t switch is enabled (because if you want to test
patterns ordinarily you don't care what the the assembled pattern
looks like).

=item B<-r>

Reduce. The default behaviour is to reduce the assembled pattern.
Enabling this switch causes the reduction algorithm to be switched
off. This can help you determine how much reduction is performed.

  assemble pattern.file | wc
  # versus
  assemble -r pattern.file | wc

=item B<-s>

Statistics. Print some statistics about the assembled pattern. The
output is sent to STDERR (in order to allow the generated pattern
to be redirected elsewhere).

=item B<-S>

Statistics only. Like B<-s>, except that the pattern itself is not
output. Useful with B<-d 8> to see the time taken.

=item B<-t>

Test. Test the assembled expression against the contents of a file.
Each line is read from the file and is matched against the pattern.
Lines that fail to match are printed. In other words, no output is
good output. In this mode of operation, error status is 1 in the
case of a failure, 0 if all lines matched.

=item B<-T>

Time. Print statistics on the time taken to reduce and assemble the
pattern. (This is merely a lazy person's synonym for C<-d 8>).

=item B<-u>

Unique. Carp if duplicate patterns are found.

=item B<-U>

Unroll. Transform C<a+> I<et al> into C<aa*> (which may
allow additional reductions).

=item B<-v>

Version. Print the version of the assemble script.

=item B<-w>

Word/Whole. When testing the contents of a file with C<-t>, bracket
the expression with C<^> and C<$> in order to match the whole word
or line from the file.

=back

=head1 DIAGNOSTICS

Will print out a summary of the problem if an added pattern causes
the assembly to fail.

=head1 SEE ALSO

L<Regexp::Assemble>

=head1 AUTHOR

Copyright (C) 2004-2008 David Landgren. All rights reserved.

=head1 LICENSE

This script is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.