如何使用缩进属性来保存HTML?

I have this result (with $dom->saveHTML()):

<!DOCTYPE html>
<html>
    <head>
        <title>Complete!</title>
    </head>
    <body>
        <div id="foo" class="bar baz" data-foo="a" data-bar="b" data-baz="c"></div>
    </body>
</html>

But I want save result with indentation of attributes:

<!DOCTYPE html>
<html>
    <head>
        <title>Complete!</title>
    </head>
    <body>
        <div id="foo"
                class="bar baz"
                data-foo="a"
                data-bar="b"
                data-baz="c"></div>
    </body>
</html>

How make it with native(?) php DOMDocument/DOMNode/DOMElement/somethingelse?

UPD: Yes! I really need that specific formatting for human readable.

Himself answered. Maybe this will be a good solution:

$html = $dom->saveHTML();
$html = html_entity_decode($html, ENT_QUOTES, 'UTF-8');
$html = explode("
", $html);
foreach ($html as $num => $line) {
    if (preg_match('/^(\s*<[a-z]+\s+)([^>]+)(>)(.*)$/s', $line, $m)) {
        $offset = ceil(mb_strlen($m[1]) / 4);
        $attrs  = preg_split('/"\s+/', $m[2]);
        $attrs  = join("\"
" . str_repeat('    ', $offset), $attrs);
        $html[$num] = $m[1] . $attrs . $m[3] . $m[4];
    }
}
$html = join("
", $html);