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<?php
/**
* Class Minify_CSS_Compressor
* @package Minify
*/
/**
* Compress CSS
*
* This is a heavy regex-based removal of whitespace, unnecessary
* comments and tokens, and some CSS value minimization, where practical.
* Many steps have been taken to avoid breaking comment-based hacks,
* including the ie5/mac filter (and its inversion), but expect tricky
* hacks involving comment tokens in 'content' value strings to break
* minimization badly. A test suite is available.
*
* @package Minify
* @author Stephen Clay <steve@mrclay.org>
* @author http://code.google.com/u/1stvamp/ (Issue 64 patch)
*/
class Minify_CSS_Compressor {
/**
* Minify a CSS string
*
* @param string $css
*
* @param array $options (currently ignored)
*
* @return string
*/
public static function process($css, $options = array()) {
$obj = new Minify_CSS_Compressor($options);
return $obj->_process($css);
}
/**
* @var array options
*/
protected $_options = null;
/**
* @var bool Are we "in" a hack?
*
* I.e. are some browsers targetted until the next comment?
*/
protected $_inHack = false;
/**
* Constructor
*
* @param array $options (currently ignored)
*
* @return null
*/
private function __construct($options) {
$this->_options = $options;
}
/**
* Minify a CSS string
*
* @param string $css
*
* @return string
*/
protected function _process($css) {
$this->_replacementHash = 'MINIFYCSS' . md5($_SERVER['REQUEST_TIME']);
$this->_placeholders = array();
$css = preg_replace_callback('~(".*"|\'.*\')~U', array($this, '_removeQuotesCB'), $css);
$css = str_replace("\r\n", "\n", $css);
// 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
$css = preg_replace_callback('@\\s*/\\*([\\s\\S]*?)\\*/\\s*@'
, array($this, '_commentCB'), $css);
// remove ws around { } and last semicolon in declaration block
$css = preg_replace('/\\s*{\\s*/', '{', $css);
$css = preg_replace('/;?\\s*}\\s*/', '}', $css);
// remove ws surrounding semicolons
$css = preg_replace('/\\s*;\\s*/', ';', $css);
// remove ws around urls
$css = preg_replace('/
url\\( # url(
\\s*
([^\\)]+?) # 1 = the URL (really just a bunch of non right parenthesis)
\\s*
\\) # )
/x', 'url($1)', $css);
// remove ws between rules and colons
$css = preg_replace('/
\\s*
([{;]) # 1 = beginning of block or rule separator
\\s*
([\\*_]?[\\w\\-]+) # 2 = property (and maybe IE filter)
\\s*
:
\\s*
(\\b|[#\'"-]) # 3 = first character of a value
/x', '$1$2:$3', $css);
// remove ws in selectors
$css = preg_replace_callback('/
(?: # non-capture
\\s*
[^~>+,\\s]+ # selector part
\\s*
[,>+~] # combinators
)+
\\s*
[^~>+,\\s]+ # selector part
{ # open declaration block
/x'
, array($this, '_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);
// remove spaces between font families
$css = preg_replace_callback('/font-family:([^;}]+)([;}])/'
, array($this, '_fontFamilyCB'), $css);
$css = preg_replace('/@import\\s+url/', '@import url', $css);
// replace any ws involving newlines with a single newline
$css = preg_replace('/[ \\t]*\\n+\\s*/', "\n", $css);
// separate common descendent selectors w/ newlines (to limit line lengths)
$css = preg_replace('/([\\w#\\.\\*]+)\\s+([\\w#\\.\\*]+){/', "$1\n$2{", $css);
// Use newline after 1st numeric value (to limit line lengths).
$css = preg_replace('/
((?:padding|margin|border|outline):\\d+(?:px|em)?) # 1 = prop : 1st numeric value
\\s+
/x'
, "$1\n", $css);
// prevent triggering IE6 bug: http://www.crankygeek.com/ie6pebug/
$css = preg_replace('/:first-l(etter|ine)\\{/', ':first-l$1 {', $css);
// fill placeholders
$css = str_replace(
array_keys($this->_placeholders)
, array_values($this->_placeholders)
, $css
);
if (isset($this->_options['stripCrlf']) && $this->_options['stripCrlf']) {
$css = preg_replace("~[\r\n]+~", ' ', $css);
} else {
$css = preg_replace("~[\r\n]+~", "\n", $css);
}
return trim($css);
}
/**
* Replace what looks like a set of selectors
*
* @param array $m regex matches
*
* @return string
*/
protected function _selectorsCB($m) {
// remove ws around the combinators
return preg_replace('/\\s*([,>+~])\\s*/', '$1', $m[0]);
}
/**
* Process a comment and return a replacement
*
* @param array $m regex matches
*
* @return string
*/
protected function _commentCB($m) {
$hasSurroundingWs = (trim($m[0]) !== $m[1]);
$m = $m[1];
// $m is the comment content w/o the surrounding tokens,
// but the return value will replace the entire comment.
if ($m === 'keep') {
return '/**/';
}
if ($m === '" "') {
// component of http://tantek.com/CSS/Examples/midpass.html
return '/*" "*/';
}
if (preg_match('@";\\}\\s*\\}/\\*\\s+@', $m)) {
// component of http://tantek.com/CSS/Examples/midpass.html
return '/*";}}/* */';
}
if ($this->_inHack) {
// inversion: feeding only to one browser
if (preg_match('@
^/ # comment started like /*/
\\s*
(\\S[\\s\\S]+?) # has at least some non-ws content
\\s*
/\\* # ends like /*/ or /**/
@x', $m, $n)) {
// end hack mode after this comment, but preserve the hack and comment content
$this->_inHack = false;
return "/*/{$n[1]}/**/";
}
}
if (substr($m, -1) === '\\') { // comment ends like \*/
// begin hack mode and preserve hack
$this->_inHack = true;
return '/*\\*/';
}
if ($m !== '' && $m[0] === '/') { // comment looks like /*/ foo */
// begin hack mode and preserve hack
$this->_inHack = true;
return '/*/*/';
}
if ($this->_inHack) {
// a regular comment ends hack mode but should be preserved
$this->_inHack = false;
return '/**/';
}
// Issue 107: if there's any surrounding whitespace, it may be important, so
// replace the comment with a single space
return $hasSurroundingWs // remove all other comments
? ' '
: '';
}
/**
* Process a font-family listing and return a replacement
*
* @param array $m regex matches
*
* @return string
*/
protected function _fontFamilyCB($m) {
// Issue 210: must not eliminate WS between words in unquoted families
$pieces = preg_split('/(\'[^\']+\'|"[^"]+")/', $m[1], null, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);
$out = 'font-family:';
while (null !== ($piece = array_shift($pieces))) {
if ($piece[0] !== '"' && $piece[0] !== "'") {
$piece = preg_replace('/\\s+/', ' ', $piece);
$piece = preg_replace('/\\s?,\\s?/', ',', $piece);
}
$out .= $piece;
}
return $out . $m[2];
}
protected function _reservePlace($content) {
$placeholder = '"' . $this->_replacementHash . count($this->_placeholders) . '"';
$this->_placeholders[$placeholder] = $content;
return $placeholder;
}
protected function _removeQuotesCB($m) {
return $this->_reservePlace($m[1]);
}
}
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