my $line = q{one <two>};
$line =~ /
	([^<]+)
	(?:
		<
		(two|three)
		>
	)?
/x;

print $1, $2;

##</code><code>##

one two

##</code><code>##

my $line = q{one <four>};

##</code><code>##

while ($line =~ /pattern/g){
  # do something with $1 and $2
}

##</code><code>##

one [link|file.html] two [email|me@home.com] three [not a link]

##</code><code>##

  while (
    $line =~ 
      /
        (
          [^\[]*
        )
        (?:
          \[
          (
            (?:link|email|pdf)
            [^\]]*
          )
          \]
        )?
      /xg
  )
  {
    my $txt = $1;
    my $link = $2;
    if ($link){
      my ($type, $address, $txt) = split(/\|/, $link);
      # more stuff
    }
  }