/**
* Minify a CSS string
*
* @param string $css
*
* @param array $options To enable URL rewriting, set the value
* for key 'prependRelativePath'.
*
* @return string
*/
protected static function _minify($css, $options)
{
// preserve empty comment after '>'
// http://www.webdevout.net/css-hacks#in_css-selectors
$css = preg_replace('/>\\/\\*\\s*\\*\\//', '>/*keep*/', $css);
// preserve empty comment between property and value
// http://css-discuss.incutio.com/?page=BoxModelHack
$css = preg_replace('/\\/\\*\\s*\\*\\/\\s*:/', '/*keep*/:', $css);
$css = preg_replace('/:\\s*\\/\\*\\s*\\*\\//', ':/*keep*/', $css);
// apply callback to all valid comments (and strip out surrounding ws
self::$_inHack = false;
$css = preg_replace_callback('/\\s*\\/\\*([\\s\\S]*?)\\*\\/\\s*/', array('Minify_CSS', '_commentCB'), $css);
// compress whitespace.
$css = preg_replace('/\\s+/', ' ', $css);
// leave needed comments
$css = str_replace('/*keep*/', '/**/', $css);
// remove ws around { }
$css = preg_replace('/\\s*{\\s*/', '{', $css);
$css = preg_replace('/;?\\s*}\\s*/', '}', $css);
// remove ws between rules
$css = preg_replace('/\\s*;\\s*/', ';', $css);
// remove ws around urls
$css = preg_replace('/url\\([\\s]*([^\\)]+?)[\\s]*\\)/', 'url($1)', $css);
// remove ws between rules and colons
$css = preg_replace('/\\s*([{;])\\s*([\\w\\-]+)\\s*:\\s*\\b/', '$1$2:', $css);
// remove ws in selectors
$css = preg_replace_callback('/(?:\\s*[^~>+,\\s]+\\s*[,>+~])+\\s*[^~>+,\\s]+{/', array('Minify_CSS', '_selectorsCB'), $css);
// minimize hex colors
$css = preg_replace('/([^=])#([a-f\\d])\\2([a-f\\d])\\3([a-f\\d])\\4([\\s;\\}])/i', '$1#$2$3$4$5', $css);
$rewrite = false;
if (isset($options['prependRelativePath'])) {
self::$_tempPrepend = $options['prependRelativePath'];
$rewrite = true;
} elseif (isset($options['currentPath'])) {
self::$_tempCurrentPath = $options['currentPath'];
$rewrite = true;
}
if ($rewrite) {
$css = preg_replace_callback('/@import ([\'"])(.*?)[\'"]\\s*;/', array('Minify_CSS', '_urlCB'), $css);
$css = preg_replace_callback('/url\\(([^\\)]+)\\)/', array('Minify_CSS', '_urlCB'), $css);
}
self::$_tempPrepend = self::$_tempCurrentPath = '';
return trim($css);
}
