my $txt = "Some long html document";
  my $tag = "img"
  my $matches = ( 
    $txt =~ s%
       (<\Q$tag\E\s+        # begin with tag and space
         (?:
          \w+                   # key/bareword
            (?:
             =(["']?)           # begin with quote or not 
             (?:|.*?[^\\])      # some value that doesn't end with \
             \2         # close quote maybe
            )?          # possible bareword
          (?:\s+|>)     # something trailing (force match)
         )+             # multiple groups
        >?)             # trailing > (handles <$tag word=val >)
       %&tag_handler($1)%gexis );