# extracts the attributes from an HTML tag
# and displays them, separately, with one regex

$text = q{<img src="foo.jpg" ismap border=0>};
@section = ('attributes');
   
$text =~ m{
  (?{ @s = map [], 1 .. @section })

  < \w+
  
  (?:
    \s+
    
    (?{ local $s[0] = [ @{ $s[0] }, [ length "$`$&" ] ] })
     \w+
    (?{ $s[0][-1][1] = length "$`$&" })
   
    (?:
      \s* = \s*
      (?:
        "
        (?{ local $s[1] = [ @{ $s[1] }, [ length "$`$&" ] ] })
         [^"]*
        (?{ $s[1][-1][1] = length "$`$&" })
        "
        |
        '
        (?{ local $s[1] = [ @{ $s[1] }, [ length "$`$&" ] ] })
         [^']*
        (?{ $s[1][-1][1] = length "$`$&" })
        '
        |
        (?{ local $s[1] = [ @{ $s[1] }, [ length "$`$&" ] ] })
         [^\s>]+
        (?{ $s[1][-1][1] = length "$`$&" })
      )
      |
      (?{ local $s[1] = [ @{ $s[1] }, [ -1 ] ] })
    )
  )*

  \s* >
  
  (?{ @watch = @s })
}x; 
    
    
print "The following attributes were found:\n";
for (@watch) {
  my $i = 0;
  while (my $find = shift @{ $watch[$i++] }) {
    my ($s, $e) = @$find;
    print("\n"), next if $s == -1;
    print "=" if $i == 2;
    print substr($text, $s, $e-$s);
    print "\n" if $i == 2;
  }
}

__END__
output:

The following attributes were found:
src=foo.jpg
ismap
border=0