/**
* Compile .scss file
*
* @param string $in Input path (.scss)
* @param string $out Output path (.css)
*
* @return array
*/
protected function compile($in, $out)
{
$start = microtime(true);
$css = $this->scss->compile(file_get_contents($in), $in);
$elapsed = round(microtime(true) - $start, 4);
$v = Version::VERSION;
$t = @date('r');
$css = "/* compiled by scssphp {$v} on {$t} ({$elapsed}s) */\n\n" . $css;
$etag = md5($css);
file_put_contents($out, $css);
file_put_contents($this->metadataName($out), serialize(array('etag' => $etag, 'imports' => $this->scss->getParsedFiles())));
return array($css, $etag);
}