summaryrefslogtreecommitdiff
path: root/includes/libs/CSSJanus.php
blob: 4ebbc4971872992049bb539d6a980cadea444e1d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
<?php
/**
 * PHP port of CSSJanus.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 */

/**
 * This is a PHP port of CSSJanus, a utility that transforms CSS style sheets
 * written for LTR to RTL.
 *
 * The original Python version of CSSJanus is Copyright 2008 by Google Inc. and
 * is distributed under the Apache license. This PHP port is Copyright 2010 by
 * Roan Kattouw and is dual-licensed under the GPL (as in the comment above) and
 * the Apache (as in the original code) licenses.
 *
 * Original code: http://code.google.com/p/cssjanus/source/browse/trunk/cssjanus.py
 * License of original code: http://code.google.com/p/cssjanus/source/browse/trunk/LICENSE
 * @author Roan Kattouw
 *
 */
class CSSJanus {
	// Patterns defined as null are built dynamically by buildPatterns()
	private static $patterns = array(
		'tmpToken' => '`TMP`',
		'nonAscii' => '[\200-\377]',
		'unicode' => '(?:(?:\\[0-9a-f]{1,6})(?:\r\n|\s)?)',
		'num' => '(?:[0-9]*\.[0-9]+|[0-9]+)',
		'unit' => '(?:em|ex|px|cm|mm|in|pt|pc|deg|rad|grad|ms|s|hz|khz|%)',
		'body_selector' => 'body\s*{\s*',
		'direction' => 'direction\s*:\s*',
		'escape' => null,
		'nmstart' => null,
		'nmchar' => null,
		'ident' => null,
		'quantity' => null,
		'possibly_negative_quantity' => null,
		'color' => null,
		'url_special_chars' => '[!#$%&*-~]',
		'valid_after_uri_chars' => '[\'\"]?\s*',
		'url_chars' => null,
		'lookahead_not_open_brace' => null,
		'lookahead_not_closing_paren' => null,
		'lookahead_for_closing_paren' => null,
		'lookbehind_not_letter' => '(?<![a-zA-Z])',
		'chars_within_selector' => '[^\}]*?',
		'noflip_annotation' => '\/\*\s*@noflip\s*\*\/',
		'noflip_single' => null,
		'noflip_class' => null,
		'comment' => '/\/\*[^*]*\*+([^\/*][^*]*\*+)*\//',
		'direction_ltr' => null,
		'direction_rtl' => null,
		'left' => null,
		'right' => null,
		'left_in_url' => null,
		'right_in_url' => null,
		'ltr_in_url' => null,
		'rtl_in_url' => null,
		'cursor_east' => null,
		'cursor_west' => null,
		'four_notation_quantity' => null,
		'four_notation_color' => null,
		'bg_horizontal_percentage' => null,
		'bg_horizontal_percentage_x' => null,
	);

	/**
	 * Build patterns we can't define above because they depend on other patterns.
	 */
	private static function buildPatterns() {
		if ( !is_null( self::$patterns['escape'] ) ) {
			// Patterns have already been built
			return;
		}

		$patterns =& self::$patterns;
		$patterns['escape'] = "(?:{$patterns['unicode']}|\\[^\r\n\f0-9a-f])";
		$patterns['nmstart'] = "(?:[_a-z]|{$patterns['nonAscii']}|{$patterns['escape']})";
		$patterns['nmchar'] = "(?:[_a-z0-9-]|{$patterns['nonAscii']}|{$patterns['escape']})";
		$patterns['ident'] = "-?{$patterns['nmstart']}{$patterns['nmchar']}*";
		$patterns['quantity'] = "{$patterns['num']}(?:\s*{$patterns['unit']}|{$patterns['ident']})?";
		$patterns['possibly_negative_quantity'] = "((?:-?{$patterns['quantity']})|(?:inherit|auto))";
		$patterns['color'] = "(#?{$patterns['nmchar']}+)";
		$patterns['url_chars'] = "(?:{$patterns['url_special_chars']}|{$patterns['nonAscii']}|{$patterns['escape']})*";
		$patterns['lookahead_not_open_brace'] = "(?!({$patterns['nmchar']}|\r?\n|\s|#|\:|\.|\,|\+|>)*?{)";
		$patterns['lookahead_not_closing_paren'] = "(?!{$patterns['url_chars']}?{$patterns['valid_after_uri_chars']}\))";
		$patterns['lookahead_for_closing_paren'] = "(?={$patterns['url_chars']}?{$patterns['valid_after_uri_chars']}\))";
		$patterns['noflip_single'] = "/({$patterns['noflip_annotation']}{$patterns['lookahead_not_open_brace']}[^;}]+;?)/i";
		$patterns['noflip_class'] = "/({$patterns['noflip_annotation']}{$patterns['chars_within_selector']}})/i";
		$patterns['direction_ltr'] = "/({$patterns['direction']})ltr/i";
		$patterns['direction_rtl'] = "/({$patterns['direction']})rtl/i";
		$patterns['left'] = "/{$patterns['lookbehind_not_letter']}(left){$patterns['lookahead_not_closing_paren']}{$patterns['lookahead_not_open_brace']}/i";
		$patterns['right'] = "/{$patterns['lookbehind_not_letter']}(right){$patterns['lookahead_not_closing_paren']}{$patterns['lookahead_not_open_brace']}/i";
		$patterns['left_in_url'] = "/{$patterns['lookbehind_not_letter']}(left){$patterns['lookahead_for_closing_paren']}/i";
		$patterns['right_in_url'] = "/{$patterns['lookbehind_not_letter']}(right){$patterns['lookahead_for_closing_paren']}/i";
		$patterns['ltr_in_url'] = "/{$patterns['lookbehind_not_letter']}(ltr){$patterns['lookahead_for_closing_paren']}/i";
		$patterns['rtl_in_url'] = "/{$patterns['lookbehind_not_letter']}(rtl){$patterns['lookahead_for_closing_paren']}/i";
		$patterns['cursor_east'] = "/{$patterns['lookbehind_not_letter']}([ns]?)e-resize/";
		$patterns['cursor_west'] = "/{$patterns['lookbehind_not_letter']}([ns]?)w-resize/";
		$patterns['four_notation_quantity'] = "/{$patterns['possibly_negative_quantity']}(\s+){$patterns['possibly_negative_quantity']}(\s+){$patterns['possibly_negative_quantity']}(\s+){$patterns['possibly_negative_quantity']}/i";
		$patterns['four_notation_color'] = "/(-color\s*:\s*){$patterns['color']}(\s+){$patterns['color']}(\s+){$patterns['color']}(\s+){$patterns['color']}/i";
		// The two regexes below are parenthesized differently then in the original implementation to make the
		// callback's job more straightforward
		$patterns['bg_horizontal_percentage'] = "/(background(?:-position)?\s*:\s*[^%]*?)(-?{$patterns['num']})(%\s*(?:{$patterns['quantity']}|{$patterns['ident']}))/";
		$patterns['bg_horizontal_percentage_x'] = "/(background-position-x\s*:\s*)(-?{$patterns['num']})(%)/";
	}

	/**
	 * Transform an LTR stylesheet to RTL
	 * @param $css String: stylesheet to transform
	 * @param $swapLtrRtlInURL Boolean: If true, swap 'ltr' and 'rtl' in URLs
	 * @param $swapLeftRightInURL Boolean: If true, swap 'left' and 'right' in URLs
	 * @return string Transformed stylesheet
	 */
	public static function transform( $css, $swapLtrRtlInURL = false, $swapLeftRightInURL = false ) {
		// We wrap tokens in ` , not ~ like the original implementation does.
		// This was done because ` is not a legal character in CSS and can only
		// occur in URLs, where we escape it to %60 before inserting our tokens.
		$css = str_replace( '`', '%60', $css );

		self::buildPatterns();

		// Tokenize single line rules with /* @noflip */
		$noFlipSingle = new CSSJanus_Tokenizer( self::$patterns['noflip_single'], '`NOFLIP_SINGLE`' );
		$css = $noFlipSingle->tokenize( $css );

		// Tokenize class rules with /* @noflip */
		$noFlipClass = new CSSJanus_Tokenizer( self::$patterns['noflip_class'], '`NOFLIP_CLASS`' );
		$css = $noFlipClass->tokenize( $css );

		// Tokenize comments
		$comments = new CSSJanus_Tokenizer( self::$patterns['comment'], '`C`' );
		$css = $comments->tokenize( $css );

		// LTR->RTL fixes start here
		$css = self::fixDirection( $css );
		if ( $swapLtrRtlInURL ) {
			$css = self::fixLtrRtlInURL( $css );
		}

		if ( $swapLeftRightInURL ) {
			$css = self::fixLeftRightInURL( $css );
		}
		$css = self::fixLeftAndRight( $css );
		$css = self::fixCursorProperties( $css );
		$css = self::fixFourPartNotation( $css );
		$css = self::fixBackgroundPosition( $css );

		// Detokenize stuff we tokenized before
		$css = $comments->detokenize( $css );
		$css = $noFlipClass->detokenize( $css );
		$css = $noFlipSingle->detokenize( $css );

		return $css;
	}

	/**
	 * Replace direction: ltr; with direction: rtl; and vice versa.
	 *
	 * The original implementation only does this inside body selectors
	 * and misses "body\n{\ndirection:ltr;\n}". This function does not have
	 * these problems.
	 *
	 * See http://code.google.com/p/cssjanus/issues/detail?id=15 and
	 * TODO: URL
	 * @param $css string
	 * @return string
	 */
	private static function fixDirection( $css ) {
		$css = preg_replace( self::$patterns['direction_ltr'],
			'$1' . self::$patterns['tmpToken'], $css );
		$css = preg_replace( self::$patterns['direction_rtl'], '$1ltr', $css );
		$css = str_replace( self::$patterns['tmpToken'], 'rtl', $css );

		return $css;
	}

	/**
	 * Replace 'ltr' with 'rtl' and vice versa in background URLs
	 * @param $css string
	 * @return string
	 */
	private static function fixLtrRtlInURL( $css ) {
		$css = preg_replace( self::$patterns['ltr_in_url'], self::$patterns['tmpToken'], $css );
		$css = preg_replace( self::$patterns['rtl_in_url'], 'ltr', $css );
		$css = str_replace( self::$patterns['tmpToken'], 'rtl', $css );

		return $css;
	}

	/**
	 * Replace 'left' with 'right' and vice versa in background URLs
	 * @param $css string
	 * @return string
	 */
	private static function fixLeftRightInURL( $css ) {
		$css = preg_replace( self::$patterns['left_in_url'], self::$patterns['tmpToken'], $css );
		$css = preg_replace( self::$patterns['right_in_url'], 'left', $css );
		$css = str_replace( self::$patterns['tmpToken'], 'right', $css );

		return $css;
	}

	/**
	 * Flip rules like left: , padding-right: , etc.
	 * @param $css string
	 * @return string
	 */
	private static function fixLeftAndRight( $css ) {
		$css = preg_replace( self::$patterns['left'], self::$patterns['tmpToken'], $css );
		$css = preg_replace( self::$patterns['right'], 'left', $css );
		$css = str_replace( self::$patterns['tmpToken'], 'right', $css );

		return $css;
	}

	/**
	 * Flip East and West in rules like cursor: nw-resize;
	 * @param $css string
	 * @return string
	 */
	private static function fixCursorProperties( $css ) {
		$css = preg_replace( self::$patterns['cursor_east'],
			'$1' . self::$patterns['tmpToken'], $css );
		$css = preg_replace( self::$patterns['cursor_west'], '$1e-resize', $css );
		$css = str_replace( self::$patterns['tmpToken'], 'w-resize', $css );

		return $css;
	}

	/**
	 * Swap the second and fourth parts in four-part notation rules like
	 * padding: 1px 2px 3px 4px;
	 *
	 * Unlike the original implementation, this function doesn't suffer from
	 * the bug where whitespace is not preserved when flipping four-part rules
	 * and four-part color rules with multiple whitespace characters between
	 * colors are not recognized.
	 * See http://code.google.com/p/cssjanus/issues/detail?id=16
	 * @param $css string
	 * @return string
	 */
	private static function fixFourPartNotation( $css ) {
		$css = preg_replace( self::$patterns['four_notation_quantity'], '$1$2$7$4$5$6$3', $css );
		$css = preg_replace( self::$patterns['four_notation_color'], '$1$2$3$8$5$6$7$4', $css );

		return $css;
	}

	/**
	 * Flip horizontal background percentages.
	 * @param $css string
	 * @return string
	 */
	private static function fixBackgroundPosition( $css ) {
		$replaced = preg_replace_callback( self::$patterns['bg_horizontal_percentage'],
			array( 'self', 'calculateNewBackgroundPosition' ), $css );
		if ( $replaced !== null ) {
			// Check for null; sometimes preg_replace_callback() returns null here for some weird reason
			$css = $replaced;
		}
		$replaced = preg_replace_callback( self::$patterns['bg_horizontal_percentage_x'],
			array( 'self', 'calculateNewBackgroundPosition' ), $css );
		if ( $replaced !== null ) {
			$css = $replaced;
		}

		return $css;
	}

	/**
	 * Callback for calculateNewBackgroundPosition()
	 * @param $matches array
	 * @return string
	 */
	private static function calculateNewBackgroundPosition( $matches ) {
		return $matches[1] . ( 100 - $matches[2] ) . $matches[3];
	}
}

/**
 * Utility class used by CSSJanus that tokenizes and untokenizes things we want
 * to protect from being janused.
 * @author Roan Kattouw
 */
class CSSJanus_Tokenizer {
	private $regex, $token;
	private $originals;

	/**
	 * Constructor
	 * @param $regex string Regular expression whose matches to replace by a token.
	 * @param $token string Token
	 */
	public function __construct( $regex, $token ) {
		$this->regex = $regex;
		$this->token = $token;
		$this->originals = array();
	}

	/**
	 * Replace all occurrences of $regex in $str with a token and remember
	 * the original strings.
	 * @param $str String to tokenize
	 * @return string Tokenized string
	 */
	public function tokenize( $str ) {
		return preg_replace_callback( $this->regex, array( $this, 'tokenizeCallback' ), $str );
	}

	/**
	 * @param $matches array
	 * @return string
	 */
	private function tokenizeCallback( $matches ) {
		$this->originals[] = $matches[0];
		return $this->token;
	}

	/**
	 * Replace tokens with their originals. If multiple strings were tokenized, it's important they be
	 * detokenized in exactly the SAME ORDER.
	 * @param $str String: previously run through tokenize()
	 * @return string Original string
	 */
	public function detokenize( $str ) {
		// PHP has no function to replace only the first occurrence or to
		// replace occurrences of the same string with different values,
		// so we use preg_replace_callback() even though we don't really need a regex
		return preg_replace_callback( '/' . preg_quote( $this->token, '/' ) . '/',
			array( $this, 'detokenizeCallback' ), $str );
	}

	/**
	 * @param $matches
	 * @return mixed
	 */
	private function detokenizeCallback( $matches ) {
		$retval = current( $this->originals );
		next( $this->originals );

		return $retval;
	}
}