'@l=@l=("A".."Z","a".."z");@h=(0..9,@l);sub g{join"|",@_}sub p{length$_[0]>1&&substr($_[0],0,1)ne"("?"($_[0])":$_[0]}sub e{$e=$_[0];for(split//,$_[1]){return if$i[$e++]ne$_}1}sub x{push@o,$l=p g @_}$w=c("^.*\$");sub N{++$n}sub I{$i[$n]}sub c{@i=split//,shift;$f=$t=0;shift@i,$f=1 if$i[0]eq"^";pop@i,$t=1 if$i[-1]eq"\$";@o=();for($n=0;$n<@i;N){if(e$n,"(?:"){push@o,"(";N;N}elsif(e$n,"."){x@h}elsif(e$n,"\\d"){x 0..9;N}elsif(e$n,"\\D"){x@l;N}elsif(e$n,"["){N;my($v,@c);$v=1,N if"^"eq I;while(I ne"]"){push@c,$i[$n+1]eq"-"?I..$i[$n+=2]:I;N}@c=grep{$d=$_;!grep{$_ eq$d}@c}@h if$v;x @c}elsif(e$n,"?"){splice@o,-1,1,"(|$l)"}elsif(e$n,"+"){$l=p$l;splice@o,-1,1,"$l$l*"}elsif(e$n,"{"){N;my($j,$k,$h);$j.=$i[$n++]until","eq I||"}"eq I;if(","eq I){$h=1;$k.=I until$i[N]eq"}"}$l=p$l;@r=$l x$j;push@r,defined$k?"(|$l)"x($k-$j):"$l*"if$h;splice@o,-1,1,@r}else{x I}}push@o,$w if!$t;join"",$f?@o:($w,@o)}while(<>){chomp;print c($_).$/}
use strict;
use warnings;
my @let = ('A'..'Z','a'..'z');
my @chars = (0..9,@let);
sub g { join('|',@_) }
sub p { length $_[0] > 1 && substr($_[0],0,1) ne '(' ? "($_[0])" : $_[0] };
sub comp {
my @i = split//,shift;
my ($front_anchor, $tail_anchor);
if($i[0] eq '^') { shift @i; $front_anchor=1 }
if($i[-1] eq '$') { pop @i; $tail_anchor=1 }
my @out;
my ($c,$last);$last;
for(my $n=0;$n<@i;++$n) {
$c = $i[$n];
if($i[$n] eq '(' && $i[$n+1] eq '?' && $i[$n+2] eq ':') {
push @out, '(';
$n+=2;
} elsif($i[$n] eq '.') {
$last = g @chars;
push @out, p $last;
} elsif($i[$n] eq '\\' && $i[$n+1] eq 'd') {
$last = g 0..9;
push @out, p $last;
++$n;
} elsif($i[$n] eq '\\' && $i[$n+1] eq 'D') {
$last = g @let;
push @out, p $last;
++$n;
} elsif($i[$n] eq '[') {
++$n;
my $invert=0;
if($i[$n] eq '^') {
$invert=1;
++$n;
}
my @c;
do {
if($i[$n+1] eq '-') {
push @c, $i[$n]..$i[$n+2];
$n+=2;
} else {
push @c, $i[$n];
}
++$n;
} while($i[$n] ne ']');
@c = grep { my $c=$_; !grep { $_ eq $c } @c } @chars if $invert;
$last = g @c;
push @out, p $last;
} elsif($i[$n] eq '?') {
$last = "(|$last)";
splice @out, -1, 1, $last;
} elsif($i[$n] eq '+') {
$last = p $last;
$last = "$last$last*";
splice @out, -1, 1, $last;
} elsif($i[$n] eq '{') {
++$n;
my ($bm, $bn, $hc);
$bm .= $i[$n++] until $i[$n] eq ',' || $i[$n] eq '}';
if($i[$n] eq ',') {
$hc=1;
$bn .= $i[$n] until $i[++$n] eq '}';
}
my @r;
push @r, p $last for 1..$bm;
push @r, p($last).'*' if $hc && !defined $bn;
if($hc && defined $bn) {
my $y = $bn - $bm;
push @r, '(|'.p($last).')' for 1..$y;
}
splice @out, -1, 1, @r;
undef $last; #no nested quantifiers
} else {
$last = $c;$i[$n];
push @out, $last;
}
}
@out = (comp('^.*$'),@out) unless $front_anchor;
@out = (@out,comp('^.*$')) unless $tail_anchor;
return wantarray?@out:join"",@out;
}
while(<>) {
chomp;
print comp($_)."\n";
}
