autoptimize / classes / minify-css-compressor.php

minify-css-compressor.php in Autoptimize 1.3, at classes/minify-css-compressor.php

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1	<?php
2	/**
3	* Class Minify_CSS_Compressor
4	* @package Minify
5	*/
6
7	/**
8	* Compress CSS
9	*
10	* This is a heavy regex-based removal of whitespace, unnecessary
11	* comments and tokens, and some CSS value minimization, where practical.
12	* Many steps have been taken to avoid breaking comment-based hacks,
13	* including the ie5/mac filter (and its inversion), but expect tricky
14	* hacks involving comment tokens in 'content' value strings to break
15	* minimization badly. A test suite is available.
16	*
17	* @package Minify
18	* @author Stephen Clay <steve@mrclay.org>
19	* @author http://code.google.com/u/1stvamp/ (Issue 64 patch)
20	*/
21	class Minify_CSS_Compressor {
22
23	/**
24	* Minify a CSS string
25	*
26	* @param string $css
27	*
28	* @param array $options (currently ignored)
29	*
30	* @return string
31	*/
32	public static function process($css, $options = array())
33	{
34	$obj = new Minify_CSS_Compressor($options);
35	return $obj->_process($css);
36	}
37
38	/**
39	* @var array options
40	*/
41	protected $_options = null;
42
43	/**
44	* @var bool Are we "in" a hack?
45	*
46	* I.e. are some browsers targetted until the next comment?
47	*/
48	protected $_inHack = false;
49
50
51	/**
52	* Constructor
53	*
54	* @param array $options (currently ignored)
55	*
56	* @return null
57	*/
58	private function __construct($options) {
59	$this->_options = $options;
60	}
61
62	/**
63	* Minify a CSS string
64	*
65	* @param string $css
66	*
67	* @return string
68	*/
69	protected function _process($css)
70	{
71	$css = str_replace("\r\n", "\n", $css);
72
73	// preserve empty comment after '>'
74	// http://www.webdevout.net/css-hacks#in_css-selectors
75	$css = preg_replace('@>/\\\\s\\/@', '>/keep*/', $css);
76
77	// preserve empty comment between property and value
78	// http://css-discuss.incutio.com/?page=BoxModelHack
79	$css = preg_replace('@/\\\\s\\/\\s:@', '/keep/:', $css);
80	$css = preg_replace('@:\\s/\\\\s\\/@', ':/keep/', $css);
81
82	// apply callback to all valid comments (and strip out surrounding ws
83	$css = preg_replace_callback('@\\s/\\([\\s\\S]?)\\/\\s*@'
84	,array($this, '_commentCB'), $css);
85
86	// remove ws around { } and last semicolon in declaration block
87	$css = preg_replace('/\\s{\\s/', '{', $css);
88	$css = preg_replace('/;?\\s}\\s/', '}', $css);
89
90	// remove ws surrounding semicolons
91	$css = preg_replace('/\\s;\\s/', ';', $css);
92
93	// remove ws around urls
94	$css = preg_replace('/
95	url\\( # url(
96	\\s*
97	([^\\)]+?) # 1 = the URL (really just a bunch of non right parenthesis)
98	\\s*
99	\\) # )
100	/x', 'url($1)', $css);
101
102	// remove ws between rules and colons
103	$css = preg_replace('/
104	\\s*
105	([{;]) # 1 = beginning of block or rule separator
106	\\s*
107	([\\*_]?[\\w\\-]+) # 2 = property (and maybe IE filter)
108	\\s*
109	:
110	\\s*
111	(\\b\|[#\'"]) # 3 = first character of a value
112	/x', '$1$2:$3', $css);
113
114	// remove ws in selectors
115	$css = preg_replace_callback('/
116	(?: # non-capture
117	\\s*
118	[^~>+,\\s]+ # selector part
119	\\s*
120	[,>+~] # combinators
121	)+
122	\\s*
123	[^~>+,\\s]+ # selector part
124	{ # open declaration block
125	/x'
126	,array($this, '_selectorsCB'), $css);
127
128	// minimize hex colors
129	$css = preg_replace('/([^=])#([a-f\\d])\\2([a-f\\d])\\3([a-f\\d])\\4([\\s;\\}])/i'
130	, '$1#$2$3$4$5', $css);
131
132	// remove spaces between font families
133	$css = preg_replace_callback('/font-family:([^;}]+)([;}])/'
134	,array($this, '_fontFamilyCB'), $css);
135
136	$css = preg_replace('/@import\\s+url/', '@import url', $css);
137
138	// replace any ws involving newlines with a single newline
139	$css = preg_replace('/[ \\t]\\n+\\s/', "\n", $css);
140
141	// separate common descendent selectors w/ newlines (to limit line lengths)
142	$css = preg_replace('/([\\w#\\.\\]+)\\s+([\\w#\\.\\]+){/', "$1\n$2{", $css);
143
144	// Use newline after 1st numeric value (to limit line lengths).
145	$css = preg_replace('/
146	((?:padding\|margin\|border\|outline):\\d+(?:px\|em)?) # 1 = prop : 1st numeric value
147	\\s+
148	/x'
149	,"$1\n", $css);
150
151	// prevent triggering IE6 bug: http://www.crankygeek.com/ie6pebug/
152	$css = preg_replace('/:first-l(etter\|ine)\\{/', ':first-l$1 {', $css);
153
154	return trim($css);
155	}
156
157	/**
158	* Replace what looks like a set of selectors
159	*
160	* @param array $m regex matches
161	*
162	* @return string
163	*/
164	protected function _selectorsCB($m)
165	{
166	// remove ws around the combinators
167	return preg_replace('/\\s([,>+~])\\s/', '$1', $m[0]);
168	}
169
170	/**
171	* Process a comment and return a replacement
172	*
173	* @param array $m regex matches
174	*
175	* @return string
176	*/
177	protected function _commentCB($m)
178	{
179	$hasSurroundingWs = (trim($m[0]) !== $m[1]);
180	$m = $m[1];
181	// $m is the comment content w/o the surrounding tokens,
182	// but the return value will replace the entire comment.
183	if ($m === 'keep') {
184	return '/**/';
185	}
186	if ($m === '" "') {
187	// component of http://tantek.com/CSS/Examples/midpass.html
188	return '/" "/';
189	}
190	if (preg_match('@";\\}\\s\\}/\\\\s+@', $m)) {
191	// component of http://tantek.com/CSS/Examples/midpass.html
192	return '/";}}/ */';
193	}
194	if ($this->_inHack) {
195	// inversion: feeding only to one browser
196	if (preg_match('@
197	^/ # comment started like /*/
198	\\s*
199	(\\S[\\s\\S]+?) # has at least some non-ws content
200	\\s*
201	/\\* # ends like // or /*/
202	@x', $m, $n)) {
203	// end hack mode after this comment, but preserve the hack and comment content
204	$this->_inHack = false;
205	return "//{$n[1]}/*/";
206	}
207	}
208	if (substr($m, -1) === '\\') { // comment ends like \*/
209	// begin hack mode and preserve hack
210	$this->_inHack = true;
211	return '/\\/';
212	}
213	if ($m !== '' && $m[0] === '/') { // comment looks like // foo /
214	// begin hack mode and preserve hack
215	$this->_inHack = true;
216	return '///';
217	}
218	if ($this->_inHack) {
219	// a regular comment ends hack mode but should be preserved
220	$this->_inHack = false;
221	return '/**/';
222	}
223	// Issue 107: if there's any surrounding whitespace, it may be important, so
224	// replace the comment with a single space
225	return $hasSurroundingWs // remove all other comments
226	? ' '
227	: '';
228	}
229
230	/**
231	* Process a font-family listing and return a replacement
232	*
233	* @param array $m regex matches
234	*
235	* @return string
236	*/
237	protected function _fontFamilyCB($m)
238	{
239	$m[1] = preg_replace('/
240	\\s*
241	(
242	"[^"]+" # 1 = family in double qutoes
243	\|\'[^\']+\' # or 1 = family in single quotes
244	\|[\\w\\-]+ # or 1 = unquoted family
245	)
246	\\s*
247	/x', '$1', $m[1]);
248	return 'font-family:' . $m[1] . $m[2];
249	}
250	}
251