protected function compressCssFiles($inputFiles, $outputFile)
{
if (empty($inputFiles)) {
return;
}
$this->stdout(" Compressing CSS files...\n");
if (is_string($this->cssCompressor)) {
$tmpFile = $outputFile . '.tmp';
$this->combineCssFiles($inputFiles, $tmpFile);
$this->stdout(shell_exec(strtr($this->cssCompressor, ['{from}' => escapeshellarg($tmpFile), '{to}' => escapeshellarg($outputFile)])));
@unlink($tmpFile);
} else {
call_user_func($this->cssCompressor, $this, $inputFiles, $outputFile);
}
if (!file_exists($outputFile)) {
throw new Exception("Unable to compress CSS files into '{$outputFile}'.");
}
$this->stdout(" CSS files compressed into '{$outputFile}'.\n");
}