includes/libs/CSSJanus.php

   1 <?php
   2 /**
   3  * PHP port of CSSJanus.
   4  *
   5  * Copyright 2008 Google Inc.
   6  * Copyright 2010 Roan Kattouw
   7  *
   8  * Licensed under the Apache License, Version 2.0 (the "License");
   9  * you may not use this file except in compliance with the License.
  10  * You may obtain a copy of the License at
  11  *
  12  * http://www.apache.org/licenses/LICENSE-2.0
  13  *
  14  * Unless required by applicable law or agreed to in writing, software
  15  * distributed under the License is distributed on an "AS IS" BASIS,
  16  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  17  * See the License for the specific language governing permissions and
  18  * limitations under the License.
  19  *
  20  * @file
  21  */
  22
  23 /**
  24  * This is a PHP port of CSSJanus, a utility that transforms CSS style sheets
  25  * written for LTR to RTL.
  26  *
  27  * Original code: http://code.google.com/p/cssjanus/source/browse/trunk/cssjanus.py
  28  *
  29  * @author Lindsey Simon <elsigh@google.com>
  30  * @author Roan Kattouw
  31  */
  32 class CSSJanus {
  33         // Patterns defined as null are built dynamically by buildPatterns()
  34         private static $patterns = array(
  35                 'tmpToken' => '`TMP`',
  36                 'nonAscii' => '[\200-\377]',
  37                 'unicode' => '(?:(?:\\[0-9a-f]{1,6})(?:\r\n|\s)?)',
  38                 'num' => '(?:[0-9]*\.[0-9]+|[0-9]+)',
  39                 'unit' => '(?:em|ex|px|cm|mm|in|pt|pc|deg|rad|grad|ms|s|hz|khz|%)',
  40                 'body_selector' => 'body\s*{\s*',
  41                 'direction' => 'direction\s*:\s*',
  42                 'escape' => null,
  43                 'nmstart' => null,
  44                 'nmchar' => null,
  45                 'ident' => null,
  46                 'quantity' => null,
  47                 'possibly_negative_quantity' => null,
  48                 'color' => null,
  49                 'url_special_chars' => '[!#$%&*-~]',
  50                 'valid_after_uri_chars' => '[\'\"]?\s*',
  51                 'url_chars' => null,
  52                 'lookahead_not_open_brace' => null,
  53                 'lookahead_not_closing_paren' => null,
  54                 'lookahead_for_closing_paren' => null,
  55                 'lookahead_not_letter' => '(?![a-zA-Z])',
  56                 'lookbehind_not_letter' => '(?<![a-zA-Z])',
  57                 'chars_within_selector' => '[^\}]*?',
  58                 'noflip_annotation' => '\/\*\!?\s*@noflip\s*\*\/',
  59                 'noflip_single' => null,
  60                 'noflip_class' => null,
  61                 'comment' => '/\/\*[^*]*\*+([^\/*][^*]*\*+)*\//',
  62                 'direction_ltr' => null,
  63                 'direction_rtl' => null,
  64                 'left' => null,
  65                 'right' => null,
  66                 'left_in_url' => null,
  67                 'right_in_url' => null,
  68                 'ltr_in_url' => null,
  69                 'rtl_in_url' => null,
  70                 'cursor_east' => null,
  71                 'cursor_west' => null,
  72                 'four_notation_quantity' => null,
  73                 'four_notation_color' => null,
  74                 'border_radius' => null,
  75                 'box_shadow' => null,
  76                 'text_shadow1' => null,
  77                 'text_shadow2' => null,
  78                 'bg_horizontal_percentage' => null,
  79                 'bg_horizontal_percentage_x' => null,
  80         );
  81
  82         /**
  83          * Build patterns we can't define above because they depend on other patterns.
  84          */
  85         private static function buildPatterns() {
  86                 if (!is_null(self::$patterns['escape'])) {
  87                         // Patterns have already been built
  88                         return;
  89                 }
  90
  91                 // @codingStandardsIgnoreStart Generic.Files.LineLength.TooLong
  92                 $patterns =& self::$patterns;
  93                 $patterns['escape'] = "(?:{$patterns['unicode']}|\\[^\r\n\f0-9a-f])";
  94                 $patterns['nmstart'] = "(?:[_a-z]|{$patterns['nonAscii']}|{$patterns['escape']})";
  95                 $patterns['nmchar'] = "(?:[_a-z0-9-]|{$patterns['nonAscii']}|{$patterns['escape']})";
  96                 $patterns['ident'] = "-?{$patterns['nmstart']}{$patterns['nmchar']}*";
  97                 $patterns['quantity'] = "{$patterns['num']}(?:\s*{$patterns['unit']}|{$patterns['ident']})?";
  98                 $patterns['possibly_negative_quantity'] = "((?:-?{$patterns['quantity']})|(?:inherit|auto))";
  99                 $patterns['color'] = "(#?{$patterns['nmchar']}+|(?:rgba?|hsla?)\([ \d.,%-]+\))";
 100                 $patterns['url_chars'] = "(?:{$patterns['url_special_chars']}|{$patterns['nonAscii']}|{$patterns['escape']})*";
 101                 $patterns['lookahead_not_open_brace'] = "(?!({$patterns['nmchar']}|\r?\n|\s|#|\:|\.|\,|\+|>|\(|\)|\[|\]|=|\*=|~=|\^=|'[^']*'])*?{)";
 102                 $patterns['lookahead_not_closing_paren'] = "(?!{$patterns['url_chars']}?{$patterns['valid_after_uri_chars']}\))";
 103                 $patterns['lookahead_for_closing_paren'] = "(?={$patterns['url_chars']}?{$patterns['valid_after_uri_chars']}\))";
 104                 $patterns['noflip_single'] = "/({$patterns['noflip_annotation']}{$patterns['lookahead_not_open_brace']}[^;}]+;?)/i";
 105                 $patterns['noflip_class'] = "/({$patterns['noflip_annotation']}{$patterns['chars_within_selector']}})/i";
 106                 $patterns['direction_ltr'] = "/({$patterns['direction']})ltr/i";
 107                 $patterns['direction_rtl'] = "/({$patterns['direction']})rtl/i";
 108                 $patterns['left'] = "/{$patterns['lookbehind_not_letter']}(left){$patterns['lookahead_not_letter']}{$patterns['lookahead_not_closing_paren']}{$patterns['lookahead_not_open_brace']}/i";
 109                 $patterns['right'] = "/{$patterns['lookbehind_not_letter']}(right){$patterns['lookahead_not_letter']}{$patterns['lookahead_not_closing_paren']}{$patterns['lookahead_not_open_brace']}/i";
 110                 $patterns['left_in_url'] = "/{$patterns['lookbehind_not_letter']}(left){$patterns['lookahead_for_closing_paren']}/i";
 111                 $patterns['right_in_url'] = "/{$patterns['lookbehind_not_letter']}(right){$patterns['lookahead_for_closing_paren']}/i";
 112                 $patterns['ltr_in_url'] = "/{$patterns['lookbehind_not_letter']}(ltr){$patterns['lookahead_for_closing_paren']}/i";
 113                 $patterns['rtl_in_url'] = "/{$patterns['lookbehind_not_letter']}(rtl){$patterns['lookahead_for_closing_paren']}/i";
 114                 $patterns['cursor_east'] = "/{$patterns['lookbehind_not_letter']}([ns]?)e-resize/";
 115                 $patterns['cursor_west'] = "/{$patterns['lookbehind_not_letter']}([ns]?)w-resize/";
 116                 $patterns['four_notation_quantity_props'] = "((?:margin|padding|border-width)\s*:\s*)";
 117                 $patterns['four_notation_quantity'] = "/{$patterns['four_notation_quantity_props']}{$patterns['possibly_negative_quantity']}(\s+){$patterns['possibly_negative_quantity']}(\s+){$patterns['possibly_negative_quantity']}(\s+){$patterns['possibly_negative_quantity']}(\s*[;}])/i";
 118                 $patterns['four_notation_color'] = "/((?:-color|border-style)\s*:\s*){$patterns['color']}(\s+){$patterns['color']}(\s+){$patterns['color']}(\s+){$patterns['color']}(\s*[;}])/i";
 119                 $patterns['border_radius'] = "/(border-radius\s*:\s*)([^;}]*)/";
 120                 $patterns['box_shadow'] = "/(box-shadow\s*:\s*(?:inset\s*)?){$patterns['possibly_negative_quantity']}/i";
 121                 $patterns['text_shadow1'] = "/(text-shadow\s*:\s*){$patterns['color']}(\s*){$patterns['possibly_negative_quantity']}/i";
 122                 $patterns['text_shadow2'] = "/(text-shadow\s*:\s*){$patterns['possibly_negative_quantity']}/i";
 123                 $patterns['bg_horizontal_percentage'] = "/(background(?:-position)?\s*:\s*(?:[^:;}\s]+\s+)*?)({$patterns['quantity']})/i";
 124                 $patterns['bg_horizontal_percentage_x'] = "/(background-position-x\s*:\s*)(-?{$patterns['num']}%)/i";
 125                 // @codingStandardsIgnoreEnd
 126
 127         }
 128
 129         /**
 130          * Transform an LTR stylesheet to RTL
 131          * @param string $css stylesheet to transform
 132          * @param $swapLtrRtlInURL Boolean: If true, swap 'ltr' and 'rtl' in URLs
 133          * @param $swapLeftRightInURL Boolean: If true, swap 'left' and 'right' in URLs
 134          * @return string Transformed stylesheet
 135          */
 136         public static function transform($css, $swapLtrRtlInURL = false, $swapLeftRightInURL = false) {
 137                 // We wrap tokens in ` , not ~ like the original implementation does.
 138                 // This was done because ` is not a legal character in CSS and can only
 139                 // occur in URLs, where we escape it to %60 before inserting our tokens.
 140                 $css = str_replace('`', '%60', $css);
 141
 142                 self::buildPatterns();
 143
 144                 // Tokenize single line rules with /* @noflip */
 145                 $noFlipSingle = new CSSJanusTokenizer(self::$patterns['noflip_single'], '`NOFLIP_SINGLE`');
 146                 $css = $noFlipSingle->tokenize($css);
 147
 148                 // Tokenize class rules with /* @noflip */
 149                 $noFlipClass = new CSSJanusTokenizer(self::$patterns['noflip_class'], '`NOFLIP_CLASS`');
 150                 $css = $noFlipClass->tokenize($css);
 151
 152                 // Tokenize comments
 153                 $comments = new CSSJanusTokenizer(self::$patterns['comment'], '`C`');
 154                 $css = $comments->tokenize($css);
 155
 156                 // LTR->RTL fixes start here
 157                 $css = self::fixDirection($css);
 158                 if ($swapLtrRtlInURL) {
 159                         $css = self::fixLtrRtlInURL($css);
 160                 }
 161
 162                 if ($swapLeftRightInURL) {
 163                         $css = self::fixLeftRightInURL($css);
 164                 }
 165                 $css = self::fixLeftAndRight($css);
 166                 $css = self::fixCursorProperties($css);
 167                 $css = self::fixFourPartNotation($css);
 168                 $css = self::fixBorderRadius($css);
 169                 $css = self::fixBackgroundPosition($css);
 170                 $css = self::fixShadows($css);
 171
 172                 // Detokenize stuff we tokenized before
 173                 $css = $comments->detokenize($css);
 174                 $css = $noFlipClass->detokenize($css);
 175                 $css = $noFlipSingle->detokenize($css);
 176
 177                 return $css;
 178         }
 179
 180         /**
 181          * Replace direction: ltr; with direction: rtl; and vice versa.
 182          *
 183          * The original implementation only does this inside body selectors
 184          * and misses "body\n{\ndirection:ltr;\n}". This function does not have
 185          * these problems.
 186          *
 187          * See https://code.google.com/p/cssjanus/issues/detail?id=15
 188          *
 189          * @param $css string
 190          * @return string
 191          */
 192         private static function fixDirection($css) {
 193                 $css = preg_replace(
 194                         self::$patterns['direction_ltr'],
 195                         '$1' . self::$patterns['tmpToken'],
 196                         $css
 197                 );
 198                 $css = preg_replace(self::$patterns['direction_rtl'], '$1ltr', $css);
 199                 $css = str_replace(self::$patterns['tmpToken'], 'rtl', $css);
 200
 201                 return $css;
 202         }
 203
 204         /**
 205          * Replace 'ltr' with 'rtl' and vice versa in background URLs
 206          * @param $css string
 207          * @return string
 208          */
 209         private static function fixLtrRtlInURL($css) {
 210                 $css = preg_replace(self::$patterns['ltr_in_url'], self::$patterns['tmpToken'], $css);
 211                 $css = preg_replace(self::$patterns['rtl_in_url'], 'ltr', $css);
 212                 $css = str_replace(self::$patterns['tmpToken'], 'rtl', $css);
 213
 214                 return $css;
 215         }
 216
 217         /**
 218          * Replace 'left' with 'right' and vice versa in background URLs
 219          * @param $css string
 220          * @return string
 221          */
 222         private static function fixLeftRightInURL($css) {
 223                 $css = preg_replace(self::$patterns['left_in_url'], self::$patterns['tmpToken'], $css);
 224                 $css = preg_replace(self::$patterns['right_in_url'], 'left', $css);
 225                 $css = str_replace(self::$patterns['tmpToken'], 'right', $css);
 226
 227                 return $css;
 228         }
 229
 230         /**
 231          * Flip rules like left: , padding-right: , etc.
 232          * @param $css string
 233          * @return string
 234          */
 235         private static function fixLeftAndRight($css) {
 236                 $css = preg_replace(self::$patterns['left'], self::$patterns['tmpToken'], $css);
 237                 $css = preg_replace(self::$patterns['right'], 'left', $css);
 238                 $css = str_replace(self::$patterns['tmpToken'], 'right', $css);
 239
 240                 return $css;
 241         }
 242
 243         /**
 244          * Flip East and West in rules like cursor: nw-resize;
 245          * @param $css string
 246          * @return string
 247          */
 248         private static function fixCursorProperties($css) {
 249                 $css = preg_replace(
 250                         self::$patterns['cursor_east'],
 251                         '$1' . self::$patterns['tmpToken'],
 252                         $css
 253                 );
 254                 $css = preg_replace(self::$patterns['cursor_west'], '$1e-resize', $css);
 255                 $css = str_replace(self::$patterns['tmpToken'], 'w-resize', $css);
 256
 257                 return $css;
 258         }
 259
 260         /**
 261          * Swap the second and fourth parts in four-part notation rules like
 262          * padding: 1px 2px 3px 4px;
 263          *
 264          * Unlike the original implementation, this function doesn't suffer from
 265          * the bug where whitespace is not preserved when flipping four-part rules
 266          * and four-part color rules with multiple whitespace characters between
 267          * colors are not recognized.
 268          * See https://code.google.com/p/cssjanus/issues/detail?id=16
 269          * @param $css string
 270          * @return string
 271          */
 272         private static function fixFourPartNotation($css) {
 273                 $css = preg_replace(self::$patterns['four_notation_quantity'], '$1$2$3$8$5$6$7$4$9', $css);
 274                 $css = preg_replace(self::$patterns['four_notation_color'], '$1$2$3$8$5$6$7$4$9', $css);
 275                 return $css;
 276         }
 277
 278         /**
 279          * Swaps appropriate corners in border-radius values.
 280          *
 281          * @param $css string
 282          * @return string
 283          */
 284         private static function fixBorderRadius($css) {
 285                 $css = preg_replace_callback(self::$patterns['border_radius'], function ($matches) {
 286                         $pre = $matches[1];
 287                         $values = $matches[2];
 288                         $numValues = count(preg_split('/\s+/', trim($values)));
 289                         switch ($numValues) {
 290                                 case 4:
 291                                         $values = preg_replace('/^(\S+)(\s*)(\S+)(\s*)(\S+)(\s*)(\S+)/', '$3$2$1$4$7$6$5', $values);
 292                                         break;
 293                                 case 3:
 294                                 case 2:
 295                                         $values = preg_replace('/^(\S+)(\s*)(\S+)/', '$3$2$1', $values);
 296                                         break;
 297                         }
 298                         return $pre . $values;
 299                 }, $css);
 300
 301                 return $css;
 302         }
 303
 304         /**
 305          * Negates horizontal offset in box-shadow and text-shadow rules.
 306          *
 307          * @param $css string
 308          * @return string
 309          */
 310         private static function fixShadows($css) {
 311                 // Flips the sign of a CSS value, possibly with a unit.
 312                 // (We can't just negate the value with unary minus due to the units.)
 313                 $flipSign = function ($cssValue) {
 314                         // Don't mangle zeroes
 315                         if (floatval($cssValue) === 0.0) {
 316                                 return $cssValue;
 317                         } elseif ($cssValue[0] === '-') {
 318                                 return substr($cssValue, 1);
 319                         } else {
 320                                 return "-" . $cssValue;
 321                         }
 322                 };
 323
 324                 $css = preg_replace_callback(self::$patterns['box_shadow'], function ($matches) use ($flipSign) {
 325                         return $matches[1] . $flipSign($matches[2]);
 326                 }, $css);
 327
 328                 $css = preg_replace_callback(self::$patterns['text_shadow1'], function ($matches) use ($flipSign) {
 329                         return $matches[1] . $matches[2] . $matches[3] . $flipSign($matches[4]);
 330                 }, $css);
 331
 332                 $css = preg_replace_callback(self::$patterns['text_shadow2'], function ($matches) use ($flipSign) {
 333                         return $matches[1] . $flipSign($matches[2]);
 334                 }, $css);
 335
 336                 return $css;
 337         }
 338
 339         /**
 340          * Flip horizontal background percentages.
 341          * @param $css string
 342          * @return string
 343          */
 344         private static function fixBackgroundPosition($css) {
 345                 $replaced = preg_replace_callback(
 346                         self::$patterns['bg_horizontal_percentage'],
 347                         array('self', 'calculateNewBackgroundPosition'),
 348                         $css
 349                 );
 350                 if ($replaced !== null) {
 351                         // preg_replace_callback() sometimes returns null
 352                         $css = $replaced;
 353                 }
 354                 $replaced = preg_replace_callback(
 355                         self::$patterns['bg_horizontal_percentage_x'],
 356                         array('self', 'calculateNewBackgroundPosition'),
 357                         $css
 358                 );
 359                 if ($replaced !== null) {
 360                         $css = $replaced;
 361                 }
 362
 363                 return $css;
 364         }
 365
 366         /**
 367          * Callback for fixBackgroundPosition()
 368          * @param $matches array
 369          * @return string
 370          */
 371         private static function calculateNewBackgroundPosition($matches) {
 372                 $value = $matches[2];
 373                 if (substr($value, -1) === '%') {
 374                         $idx = strpos($value, '.');
 375                         if ($idx !== false) {
 376                                 $len = strlen($value) - $idx - 2;
 377                                 $value = number_format(100 - $value, $len) . '%';
 378                         } else {
 379                                 $value = (100 - $value) . '%';
 380                         }
 381                 }
 382                 return $matches[1] . $value;
 383         }
 384 }
 385
 386 /**
 387  * Utility class used by CSSJanus that tokenizes and untokenizes things we want
 388  * to protect from being janused.
 389  * @author Roan Kattouw
 390  */
 391 class CSSJanusTokenizer {
 392         private $regex;
 393         private $token;
 394         private $originals;
 395
 396         /**
 397          * Constructor
 398          * @param string $regex Regular expression whose matches to replace by a token.
 399          * @param string $token Token
 400          */
 401         public function __construct($regex, $token) {
 402                 $this->regex = $regex;
 403                 $this->token = $token;
 404                 $this->originals = array();
 405         }
 406
 407         /**
 408          * Replace all occurrences of $regex in $str with a token and remember
 409          * the original strings.
 410          * @param string $str to tokenize
 411          * @return string Tokenized string
 412          */
 413         public function tokenize($str) {
 414                 return preg_replace_callback($this->regex, array($this, 'tokenizeCallback'), $str);
 415         }
 416
 417         /**
 418          * @param $matches array
 419          * @return string
 420          */
 421         private function tokenizeCallback($matches) {
 422                 $this->originals[] = $matches[0];
 423                 return $this->token;
 424         }
 425
 426         /**
 427          * Replace tokens with their originals. If multiple strings were tokenized, it's important they be
 428          * detokenized in exactly the SAME ORDER.
 429          * @param string $str previously run through tokenize()
 430          * @return string Original string
 431          */
 432         public function detokenize($str) {
 433                 // PHP has no function to replace only the first occurrence or to
 434                 // replace occurrences of the same string with different values,
 435                 // so we use preg_replace_callback() even though we don't really need a regex
 436                 return preg_replace_callback(
 437                         '/' . preg_quote($this->token, '/') . '/',
 438                         array($this, 'detokenizeCallback'),
 439                         $str
 440                 );
 441         }
 442
 443         /**
 444          * @param $matches
 445          * @return mixed
 446          */
 447         private function detokenizeCallback($matches) {
 448                 $retval = current($this->originals);
 449                 next($this->originals);
 450
 451                 return $retval;
 452         }
 453 }