while ($tag =~ m{
    \G
    (?:
      ( \w+ )
      (?:
        \s* = \s*
        (?: ( \w+ ) | ' ([^']*) ' | " ([^"]*) " )
      )?
    |
      ' ([^']*) '
    | 
      " ([^"]*) "
    |
      ( : )
    ) 
    (?= \s | \z) \s* )
  }gcxs) {
    push @args, defined($5) ? $5  # 'quoted string'
      : defined($6) ? $6          # "quoted string"
      : defined($7) ? $7          # :
      : defined($2) ? [ $1, $2 ]  # bareword=bareword
      : defined($3) ? [ $1, $3 ]  # bareword='quoted string'
      : defined($4) ? [ $1, $4 ]  # bareword="quoted string"
      : $1                        # bareword
    ;
  }