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                 $patterns['four_notation_quantity'] = "/(:\s*){$patterns['possibly_negative_quantity']}(\s+){$patterns['possibly_negative_quantity']}(\s+){$patterns['possibly_negative_quantity']}(\s+){$patterns['possibly_negative_quantity']}(\s*[;}])/i";
 117                 $patterns['four_notation_color'] = "/(-color\s*:\s*){$patterns['color']}(\s+){$patterns['color']}(\s+){$patterns['color']}(\s+){$patterns['color']}(\s*[;}])/i";
 118                 $patterns['border_radius'] = "/(border-radius\s*:\s*){$patterns['possibly_negative_quantity']}(\s+){$patterns['possibly_negative_quantity']}(\s+){$patterns['possibly_negative_quantity']}(\s+){$patterns['possibly_negative_quantity']}(\s*[;}])/i";
 119                 $patterns['box_shadow'] = "/(box-shadow\s*:\s*(?:inset\s*)?){$patterns['possibly_negative_quantity']}/i";
 120                 $patterns['text_shadow1'] = "/(text-shadow\s*:\s*){$patterns['color']}(\s*){$patterns['possibly_negative_quantity']}/i";
 121                 $patterns['text_shadow2'] = "/(text-shadow\s*:\s*){$patterns['possibly_negative_quantity']}/i";
 122                 // The two regexes below are parenthesized differently then in the original implementation to make the
 123                 // callback's job more straightforward
 124                 $patterns['bg_horizontal_percentage'] = "/(background(?:-position)?\s*:\s*[^%]*?)(-?{$patterns['num']})(%\s*(?:{$patterns['quantity']}|{$patterns['ident']}))/";
 125                 $patterns['bg_horizontal_percentage_x'] = "/(background-position-x\s*:\s*)(-?{$patterns['num']})(%)/";
 126                 // @codingStandardsIgnoreEnd
 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 http://code.google.com/p/cssjanus/issues/detail?id=15 and
 188          * TODO: URL
 189          * @param $css string
 190          * @return string
 191          */
 192         private static function fixDirection( $css ) {
 193                 $css = preg_replace( self::$patterns['direction_ltr'],
 194                         '$1' . self::$patterns['tmpToken'], $css );
 195                 $css = preg_replace( self::$patterns['direction_rtl'], '$1ltr', $css );
 196                 $css = str_replace( self::$patterns['tmpToken'], 'rtl', $css );
 197
 198                 return $css;
 199         }
 200
 201         /**
 202          * Replace 'ltr' with 'rtl' and vice versa in background URLs
 203          * @param $css string
 204          * @return string
 205          */
 206         private static function fixLtrRtlInURL( $css ) {
 207                 $css = preg_replace( self::$patterns['ltr_in_url'], self::$patterns['tmpToken'], $css );
 208                 $css = preg_replace( self::$patterns['rtl_in_url'], 'ltr', $css );
 209                 $css = str_replace( self::$patterns['tmpToken'], 'rtl', $css );
 210
 211                 return $css;
 212         }
 213
 214         /**
 215          * Replace 'left' with 'right' and vice versa in background URLs
 216          * @param $css string
 217          * @return string
 218          */
 219         private static function fixLeftRightInURL( $css ) {
 220                 $css = preg_replace( self::$patterns['left_in_url'], self::$patterns['tmpToken'], $css );
 221                 $css = preg_replace( self::$patterns['right_in_url'], 'left', $css );
 222                 $css = str_replace( self::$patterns['tmpToken'], 'right', $css );
 223
 224                 return $css;
 225         }
 226
 227         /**
 228          * Flip rules like left: , padding-right: , etc.
 229          * @param $css string
 230          * @return string
 231          */
 232         private static function fixLeftAndRight( $css ) {
 233                 $css = preg_replace( self::$patterns['left'], self::$patterns['tmpToken'], $css );
 234                 $css = preg_replace( self::$patterns['right'], 'left', $css );
 235                 $css = str_replace( self::$patterns['tmpToken'], 'right', $css );
 236
 237                 return $css;
 238         }
 239
 240         /**
 241          * Flip East and West in rules like cursor: nw-resize;
 242          * @param $css string
 243          * @return string
 244          */
 245         private static function fixCursorProperties( $css ) {
 246                 $css = preg_replace( self::$patterns['cursor_east'],
 247                         '$1' . self::$patterns['tmpToken'], $css );
 248                 $css = preg_replace( self::$patterns['cursor_west'], '$1e-resize', $css );
 249                 $css = str_replace( self::$patterns['tmpToken'], 'w-resize', $css );
 250
 251                 return $css;
 252         }
 253
 254         /**
 255          * Swap the second and fourth parts in four-part notation rules like
 256          * padding: 1px 2px 3px 4px;
 257          *
 258          * Unlike the original implementation, this function doesn't suffer from
 259          * the bug where whitespace is not preserved when flipping four-part rules
 260          * and four-part color rules with multiple whitespace characters between
 261          * colors are not recognized.
 262          * See http://code.google.com/p/cssjanus/issues/detail?id=16
 263          * @param $css string
 264          * @return string
 265          */
 266         private static function fixFourPartNotation( $css ) {
 267                 $css = preg_replace( self::$patterns['four_notation_quantity'], '$1$2$3$8$5$6$7$4$9', $css );
 268                 $css = preg_replace( self::$patterns['four_notation_color'], '$1$2$3$8$5$6$7$4$9', $css );
 269                 return $css;
 270         }
 271
 272         /**
 273          * Swaps appropriate corners in four-part border-radius rules.
 274          * Needs to undo the effect of fixFourPartNotation() on those rules, too.
 275          *
 276          * @param $css string
 277          * @return string
 278          */
 279         private static function fixBorderRadius( $css ) {
 280                 // Undo four_notation_quantity
 281                 $css = preg_replace( self::$patterns['border_radius'], '$1$2$3$8$5$6$7$4$9', $css );
 282                 // Do the real thing
 283                 $css = preg_replace( self::$patterns['border_radius'], '$1$4$3$2$5$8$7$6$9', $css );
 284
 285                 return $css;
 286         }
 287
 288         /**
 289          * Negates horizontal offset in box-shadow and text-shadow rules.
 290          *
 291          * @param $css string
 292          * @return string
 293          */
 294         private static function fixShadows( $css ) {
 295                 // Flips the sign of a CSS value, possibly with a unit.
 296                 // (We can't just negate the value with unary minus due to the units.)
 297                 $flipSign = function ( $cssValue ) {
 298                         // Don't mangle zeroes
 299                         if ( floatval( $cssValue ) === 0.0 ) {
 300                                 return $cssValue;
 301                         } elseif ( $cssValue[0] === '-' ) {
 302                                 return substr( $cssValue, 1 );
 303                         } else {
 304                                 return "-" . $cssValue;
 305                         }
 306                 };
 307
 308                 $css = preg_replace_callback(
 309                         self::$patterns['box_shadow'], function ( $matches ) use ( $flipSign ) {
 310                                 return $matches[1] . $flipSign( $matches[2] );
 311                         },
 312                         $css
 313                 );
 314
 315                 $css = preg_replace_callback(
 316                         self::$patterns['text_shadow1'],
 317                         function ( $matches ) use ( $flipSign ) {
 318                                 return $matches[1] . $matches[2] . $matches[3] . $flipSign( $matches[4] );
 319                         },
 320                         $css
 321                 );
 322
 323                 $css = preg_replace_callback(
 324                         self::$patterns['text_shadow2'],
 325                         function ( $matches ) use ( $flipSign ) {
 326                                 return $matches[1] . $flipSign( $matches[2] );
 327                         },
 328                         $css
 329                 );
 330
 331                 return $css;
 332         }
 333
 334         /**
 335          * Flip horizontal background percentages.
 336          * @param $css string
 337          * @return string
 338          */
 339         private static function fixBackgroundPosition( $css ) {
 340                 $replaced = preg_replace_callback( self::$patterns['bg_horizontal_percentage'],
 341                         array( 'self', 'calculateNewBackgroundPosition' ), $css );
 342                 if ( $replaced !== null ) {
 343                         // Check for null; sometimes preg_replace_callback() returns null here for some weird reason
 344                         $css = $replaced;
 345                 }
 346                 $replaced = preg_replace_callback( self::$patterns['bg_horizontal_percentage_x'],
 347                         array( 'self', 'calculateNewBackgroundPosition' ), $css );
 348                 if ( $replaced !== null ) {
 349                         $css = $replaced;
 350                 }
 351
 352                 return $css;
 353         }
 354
 355         /**
 356          * Callback for calculateNewBackgroundPosition()
 357          * @param $matches array
 358          * @return string
 359          */
 360         private static function calculateNewBackgroundPosition( $matches ) {
 361                 return $matches[1] . ( 100 - $matches[2] ) . $matches[3];
 362         }
 363 }
 364
 365 /**
 366  * Utility class used by CSSJanus that tokenizes and untokenizes things we want
 367  * to protect from being janused.
 368  * @author Roan Kattouw
 369  */
 370 class CSSJanusTokenizer {
 371         private $regex, $token;
 372         private $originals;
 373
 374         /**
 375          * Constructor
 376          * @param string $regex Regular expression whose matches to replace by a token.
 377          * @param string $token Token
 378          */
 379         public function __construct( $regex, $token ) {
 380                 $this->regex = $regex;
 381                 $this->token = $token;
 382                 $this->originals = array();
 383         }
 384
 385         /**
 386          * Replace all occurrences of $regex in $str with a token and remember
 387          * the original strings.
 388          * @param string $str to tokenize
 389          * @return string Tokenized string
 390          */
 391         public function tokenize( $str ) {
 392                 return preg_replace_callback( $this->regex, array( $this, 'tokenizeCallback' ), $str );
 393         }
 394
 395         /**
 396          * @param $matches array
 397          * @return string
 398          */
 399         private function tokenizeCallback( $matches ) {
 400                 $this->originals[] = $matches[0];
 401                 return $this->token;
 402         }
 403
 404         /**
 405          * Replace tokens with their originals. If multiple strings were tokenized, it's important they be
 406          * detokenized in exactly the SAME ORDER.
 407          * @param string $str previously run through tokenize()
 408          * @return string Original string
 409          */
 410         public function detokenize( $str ) {
 411                 // PHP has no function to replace only the first occurrence or to
 412                 // replace occurrences of the same string with different values,
 413                 // so we use preg_replace_callback() even though we don't really need a regex
 414                 return preg_replace_callback( '/' . preg_quote( $this->token, '/' ) . '/',
 415                         array( $this, 'detokenizeCallback' ), $str );
 416         }
 417
 418         /**
 419          * @param $matches
 420          * @return mixed
 421          */
 422         private function detokenizeCallback( $matches ) {
 423                 $retval = current( $this->originals );
 424                 next( $this->originals );
 425
 426                 return $retval;
 427         }
 428 }