# skip initial whitespace, if any
$tag =~ /^\s*/gcxs;

# look for optional key, and a bareword or the start of a quoted string
while ($tag =~ / \G (?: (\w+) \s* = \s*)? ( ['"](?=.) | \w+ ) /gcxs) {
	my ($k, $v) = ($1, $2);

	# extract quoted string
	if ($v eq "'" || $v eq '"') {
		$tag =~ / \G ( (?: \\. | [^$v] )* ) $v /gcxs or last;
		$v = $1;
		$v =~ s/\\(.)/$1/g;	# unescape characters
	}

	# skip optional separator
	$tag =~ / \G \s* :? \s* /gcxs;

	# save value
	push @args, $k ? [$k, $v] : $v;
}

# check if parsing was successful
die if pos $tag != length $tag;