use strict;

sub state {
    my $c=shift;
    my $next=shift;
    my $alt=shift;
    my $visited=0;
    return {c => $c, next => $next, alt => $alt, visited => $visited};
}

sub NFA {
    my $in=shift;
    my $out=shift;
    return {in => $in, out => $out};
}

sub sym {
    my $c=shift;
    my $s=state($c, 0, 0);
    return NFA($s, $s);
}

sub dot {
    my $nfa1=shift;
    my $nfa2=shift;
    $nfa1->{out}{next}=$nfa2->{in};
    return NFA($nfa1->{in}, $nfa2->{out});
}

sub bar {
    my $nfa1=shift;
    my $nfa2=shift;
    my $s=state(256, $nfa1->{in}, $nfa2->{in});
    my $t=state(256, 0, 0);
    $nfa1->{out}{next}=$nfa2->{out}{next}=$t;
    return NFA($s, $t);
}

sub que {
    my $nfa=shift;
    my $t=state(256, 0, 0);
    my $s=state(256, $nfa->{in}, $t);
    $nfa->{out}{next}=$t;
    return NFA($s, $t);
}

sub star {
    my $nfa=shift;
    my $s=state(256, 0, $nfa->{in});
    $nfa->{out}{next}=$s;
    return NFA($s, $s);
}

sub plus {
    my $nfa=shift;
    my $s=state(256, 0, $nfa->{in});
    $nfa->{out}{next}=$s;
    return NFA($nfa->{in}, $s);
}

sub acpt {
    my $nfa=shift;
    my $s=state(257, 0, 0);
    $nfa->{out}{next}=$s;
    return NFA($nfa->{in}, $s);
}

#example use
my $nfa=acpt(
	     dot(
		 sym('a'),
		 dot(
		     star(
			  dot(
			      sym('b'),
			      sym('b')
			      )
			  ),
		     sym('a')
		     )
		 )
	     );