includes/normal/UtfNormal.php

   1 <?php
   2 # Copyright (C) 2004 Brion Vibber <brion@pobox.com>
   3 # http://www.mediawiki.org/
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License as published by
   7 # the Free Software Foundation; either version 2 of the License, or
   8 # (at your option) any later version.
   9 #
  10 # This program is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13 # GNU General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU General Public License along
  16 # with this program; if not, write to the Free Software Foundation, Inc.,
  17 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18 # http://www.gnu.org/copyleft/gpl.html
  19
  20 /**
  21  * @defgroup UtfNormal UtfNormal
  22  */
  23
  24 /** */
  25 require_once dirname(__FILE__).'/UtfNormalUtil.php';
  26
  27 global $utfCombiningClass, $utfCanonicalComp, $utfCanonicalDecomp;
  28 $utfCombiningClass = null;
  29 $utfCanonicalComp = null;
  30 $utfCanonicalDecomp = null;
  31
  32 # Load compatibility decompositions on demand if they are needed.
  33 global $utfCompatibilityDecomp;
  34 $utfCompatibilityDecomp = null;
  35
  36 /**
  37  * For using the ICU wrapper
  38  */
  39 define( 'UNORM_NONE', 1 );
  40 define( 'UNORM_NFD',  2 );
  41 define( 'UNORM_NFKD', 3 );
  42 define( 'UNORM_NFC',  4 );
  43 define( 'UNORM_DEFAULT', UNORM_NFC );
  44 define( 'UNORM_NFKC', 5 );
  45 define( 'UNORM_FCD',  6 );
  46
  47 define( 'NORMALIZE_ICU', function_exists( 'utf8_normalize' ) );
  48 define( 'NORMALIZE_INTL', function_exists( 'normalizer_normalize' ) );
  49
  50 /**
  51  * Unicode normalization routines for working with UTF-8 strings.
  52  * Currently assumes that input strings are valid UTF-8!
  53  *
  54  * Not as fast as I'd like, but should be usable for most purposes.
  55  * UtfNormal::toNFC() will bail early if given ASCII text or text
  56  * it can quickly deterimine is already normalized.
  57  *
  58  * All functions can be called static.
  59  *
  60  * See description of forms at http://www.unicode.org/reports/tr15/
  61  *
  62  * @ingroup UtfNormal
  63  */
  64 class UtfNormal {
  65         /**
  66          * The ultimate convenience function! Clean up invalid UTF-8 sequences,
  67          * and convert to normal form C, canonical composition.
  68          *
  69          * Fast return for pure ASCII strings; some lesser optimizations for
  70          * strings containing only known-good characters. Not as fast as toNFC().
  71          *
  72          * @param $string String: a UTF-8 string
  73          * @return string a clean, shiny, normalized UTF-8 string
  74          */
  75         static function cleanUp( $string ) {
  76                 if( extension_loaded( 'iconv' ) ) {
  77                         wfSuppressWarnings();
  78                         $ret = iconv( "UTF-8","UTF-8//IGNORE", $string );
  79                         wfRestoreWarnings();
  80                         return $ret;
  81                 }
  82
  83                 if( NORMALIZE_ICU || NORMALIZE_INTL ) {
  84                         # We exclude a few chars that ICU would not.
  85                         $string = preg_replace(
  86                                 '/[\x00-\x08\x0b\x0c\x0e-\x1f]/',
  87                                 UTF8_REPLACEMENT,
  88                                 $string );
  89                         $string = str_replace( UTF8_FFFE, UTF8_REPLACEMENT, $string );
  90                         $string = str_replace( UTF8_FFFF, UTF8_REPLACEMENT, $string );
  91
  92                         # UnicodeString constructor fails if the string ends with a
  93                         # head byte. Add a junk char at the end, we'll strip it off.
  94                         if ( NORMALIZE_ICU ) return rtrim( utf8_normalize( $string . "\x01", UNORM_NFC ), "\x01" );
  95                         if ( NORMALIZE_INTL ) return normalizer_normalize( $string, Normalizer::FORM_C );
  96                 } elseif( UtfNormal::quickIsNFCVerify( $string ) ) {
  97                         # Side effect -- $string has had UTF-8 errors cleaned up.
  98                         return $string;
  99                 } else {
 100                         return UtfNormal::NFC( $string );
 101                 }
 102         }
 103
 104         /**
 105          * Convert a UTF-8 string to normal form C, canonical composition.
 106          * Fast return for pure ASCII strings; some lesser optimizations for
 107          * strings containing only known-good characters.
 108          *
 109          * @param $string String: a valid UTF-8 string. Input is not validated.
 110          * @return string a UTF-8 string in normal form C
 111          */
 112         static function toNFC( $string ) {
 113                 if( NORMALIZE_INTL )
 114                         return normalizer_normalize( $string, Normalizer::FORM_C );
 115                 elseif( NORMALIZE_ICU )
 116                         return utf8_normalize( $string, UNORM_NFC );
 117                 elseif( UtfNormal::quickIsNFC( $string ) )
 118                         return $string;
 119                 else
 120                         return UtfNormal::NFC( $string );
 121         }
 122
 123         /**
 124          * Convert a UTF-8 string to normal form D, canonical decomposition.
 125          * Fast return for pure ASCII strings.
 126          *
 127          * @param $string String: a valid UTF-8 string. Input is not validated.
 128          * @return string a UTF-8 string in normal form D
 129          */
 130         static function toNFD( $string ) {
 131                 if( NORMALIZE_INTL )
 132                         return normalizer_normalize( $string, Normalizer::FORM_D );
 133                 elseif( NORMALIZE_ICU )
 134                         return utf8_normalize( $string, UNORM_NFD );
 135                 elseif( preg_match( '/[\x80-\xff]/', $string ) )
 136                         return UtfNormal::NFD( $string );
 137                 else
 138                         return $string;
 139         }
 140
 141         /**
 142          * Convert a UTF-8 string to normal form KC, compatibility composition.
 143          * This may cause irreversible information loss, use judiciously.
 144          * Fast return for pure ASCII strings.
 145          *
 146          * @param $string String: a valid UTF-8 string. Input is not validated.
 147          * @return string a UTF-8 string in normal form KC
 148          */
 149         static function toNFKC( $string ) {
 150                 if( NORMALIZE_INTL )
 151                         return normalizer_normalize( $string, Normalizer::FORM_KC );
 152                 elseif( NORMALIZE_ICU )
 153                         return utf8_normalize( $string, UNORM_NFKC );
 154                 elseif( preg_match( '/[\x80-\xff]/', $string ) )
 155                         return UtfNormal::NFKC( $string );
 156                 else
 157                         return $string;
 158         }
 159
 160         /**
 161          * Convert a UTF-8 string to normal form KD, compatibility decomposition.
 162          * This may cause irreversible information loss, use judiciously.
 163          * Fast return for pure ASCII strings.
 164          *
 165          * @param $string String: a valid UTF-8 string. Input is not validated.
 166          * @return string a UTF-8 string in normal form KD
 167          */
 168         static function toNFKD( $string ) {
 169                 if( NORMALIZE_INTL )
 170                         return normalizer_normalize( $string, Normalizer::FORM_KD );
 171                 elseif( NORMALIZE_ICU )
 172                         return utf8_normalize( $string, UNORM_NFKD );
 173                 elseif( preg_match( '/[\x80-\xff]/', $string ) )
 174                         return UtfNormal::NFKD( $string );
 175                 else
 176                         return $string;
 177         }
 178
 179         /**
 180          * Load the basic composition data if necessary
 181          * @private
 182          */
 183         static function loadData() {
 184                 global $utfCombiningClass;
 185                 if( !isset( $utfCombiningClass ) ) {
 186                         require_once( dirname(__FILE__) . '/UtfNormalData.inc' );
 187                 }
 188         }
 189
 190         /**
 191          * Returns true if the string is _definitely_ in NFC.
 192          * Returns false if not or uncertain.
 193          * @param $string String: a valid UTF-8 string. Input is not validated.
 194          * @return bool
 195          */
 196         static function quickIsNFC( $string ) {
 197                 # ASCII is always valid NFC!
 198                 # If it's pure ASCII, let it through.
 199                 if( !preg_match( '/[\x80-\xff]/', $string ) ) return true;
 200
 201                 UtfNormal::loadData();
 202                 global $utfCheckNFC, $utfCombiningClass;
 203                 $len = strlen( $string );
 204                 for( $i = 0; $i < $len; $i++ ) {
 205                         $c = $string{$i};
 206                         $n = ord( $c );
 207                         if( $n < 0x80 ) {
 208                                 continue;
 209                         } elseif( $n >= 0xf0 ) {
 210                                 $c = substr( $string, $i, 4 );
 211                                 $i += 3;
 212                         } elseif( $n >= 0xe0 ) {
 213                                 $c = substr( $string, $i, 3 );
 214                                 $i += 2;
 215                         } elseif( $n >= 0xc0 ) {
 216                                 $c = substr( $string, $i, 2 );
 217                                 $i++;
 218                         }
 219                         if( isset( $utfCheckNFC[$c] ) ) {
 220                                 # If it's NO or MAYBE, bail and do the slow check.
 221                                 return false;
 222                         }
 223                         if( isset( $utfCombiningClass[$c] ) ) {
 224                                 # Combining character? We might have to do sorting, at least.
 225                                 return false;
 226                         }
 227                 }
 228                 return true;
 229         }
 230
 231         /**
 232          * Returns true if the string is _definitely_ in NFC.
 233          * Returns false if not or uncertain.
 234          * @param $string String: a UTF-8 string, altered on output to be valid UTF-8 safe for XML.
 235          */
 236         static function quickIsNFCVerify( &$string ) {
 237                 # Screen out some characters that eg won't be allowed in XML
 238                 $string = preg_replace( '/[\x00-\x08\x0b\x0c\x0e-\x1f]/', UTF8_REPLACEMENT, $string );
 239
 240                 # ASCII is always valid NFC!
 241                 # If we're only ever given plain ASCII, we can avoid the overhead
 242                 # of initializing the decomposition tables by skipping out early.
 243                 if( !preg_match( '/[\x80-\xff]/', $string ) ) return true;
 244
 245                 static $checkit = null, $tailBytes = null, $utfCheckOrCombining = null;
 246                 if( !isset( $checkit ) ) {
 247                         # Load/build some scary lookup tables...
 248                         UtfNormal::loadData();
 249                         global $utfCheckNFC, $utfCombiningClass;
 250
 251                         $utfCheckOrCombining = array_merge( $utfCheckNFC, $utfCombiningClass );
 252
 253                         # Head bytes for sequences which we should do further validity checks
 254                         $checkit = array_flip( array_map( 'chr',
 255                                         array( 0xc0, 0xc1, 0xe0, 0xed, 0xef,
 256                                                    0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
 257                                                    0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff ) ) );
 258
 259                         # Each UTF-8 head byte is followed by a certain
 260                         # number of tail bytes.
 261                         $tailBytes = array();
 262                         for( $n = 0; $n < 256; $n++ ) {
 263                                 if( $n < 0xc0 ) {
 264                                         $remaining = 0;
 265                                 } elseif( $n < 0xe0 ) {
 266                                         $remaining = 1;
 267                                 } elseif( $n < 0xf0 ) {
 268                                         $remaining = 2;
 269                                 } elseif( $n < 0xf8 ) {
 270                                         $remaining = 3;
 271                                 } elseif( $n < 0xfc ) {
 272                                         $remaining = 4;
 273                                 } elseif( $n < 0xfe ) {
 274                                         $remaining = 5;
 275                                 } else {
 276                                         $remaining = 0;
 277                                 }
 278                                 $tailBytes[chr($n)] = $remaining;
 279                         }
 280                 }
 281
 282                 # Chop the text into pure-ASCII and non-ASCII areas;
 283                 # large ASCII parts can be handled much more quickly.
 284                 # Don't chop up Unicode areas for punctuation, though,
 285                 # that wastes energy.
 286                 $matches = array();
 287                 preg_match_all(
 288                         '/([\x00-\x7f]+|[\x80-\xff][\x00-\x40\x5b-\x5f\x7b-\xff]*)/',
 289                         $string, $matches );
 290
 291                 $looksNormal = true;
 292                 $base = 0;
 293                 $replace = array();
 294                 foreach( $matches[1] as $str ) {
 295                         $chunk = strlen( $str );
 296
 297                         if( $str{0} < "\x80" ) {
 298                                 # ASCII chunk: guaranteed to be valid UTF-8
 299                                 # and in normal form C, so skip over it.
 300                                 $base += $chunk;
 301                                 continue;
 302                         }
 303
 304                         # We'll have to examine the chunk byte by byte to ensure
 305                         # that it consists of valid UTF-8 sequences, and to see
 306                         # if any of them might not be normalized.
 307                         #
 308                         # Since PHP is not the fastest language on earth, some of
 309                         # this code is a little ugly with inner loop optimizations.
 310
 311                         $head = '';
 312                         $len = $chunk + 1; # Counting down is faster. I'm *so* sorry.
 313
 314                         for( $i = -1; --$len; ) {
 315                                 if( $remaining = $tailBytes[$c = $str{++$i}] ) {
 316                                         # UTF-8 head byte!
 317                                         $sequence = $head = $c;
 318                                         do {
 319                                                 # Look for the defined number of tail bytes...
 320                                                 if( --$len && ( $c = $str{++$i} ) >= "\x80" && $c < "\xc0" ) {
 321                                                         # Legal tail bytes are nice.
 322                                                         $sequence .= $c;
 323                                                 } else {
 324                                                         if( 0 == $len ) {
 325                                                                 # Premature end of string!
 326                                                                 # Drop a replacement character into output to
 327                                                                 # represent the invalid UTF-8 sequence.
 328                                                                 $replace[] = array( UTF8_REPLACEMENT,
 329                                                                                                         $base + $i + 1 - strlen( $sequence ),
 330                                                                                                         strlen( $sequence ) );
 331                                                                 break 2;
 332                                                         } else {
 333                                                                 # Illegal tail byte; abandon the sequence.
 334                                                                 $replace[] = array( UTF8_REPLACEMENT,
 335                                                                                                         $base + $i - strlen( $sequence ),
 336                                                                                                         strlen( $sequence ) );
 337                                                                 # Back up and reprocess this byte; it may itself
 338                                                                 # be a legal ASCII or UTF-8 sequence head.
 339                                                                 --$i;
 340                                                                 ++$len;
 341                                                                 continue 2;
 342                                                         }
 343                                                 }
 344                                         } while( --$remaining );
 345
 346                                         if( isset( $checkit[$head] ) ) {
 347                                                 # Do some more detailed validity checks, for
 348                                                 # invalid characters and illegal sequences.
 349                                                 if( $head == "\xed" ) {
 350                                                         # 0xed is relatively frequent in Korean, which
 351                                                         # abuts the surrogate area, so we're doing
 352                                                         # this check separately to speed things up.
 353
 354                                                         if( $sequence >= UTF8_SURROGATE_FIRST ) {
 355                                                                 # Surrogates are legal only in UTF-16 code.
 356                                                                 # They are totally forbidden here in UTF-8
 357                                                                 # utopia.
 358                                                                 $replace[] = array( UTF8_REPLACEMENT,
 359                                                                              $base + $i + 1 - strlen( $sequence ),
 360                                                                              strlen( $sequence ) );
 361                                                                 $head = '';
 362                                                                 continue;
 363                                                         }
 364                                                 } else {
 365                                                         # Slower, but rarer checks...
 366                                                         $n = ord( $head );
 367                                                         if(
 368                                                                 # "Overlong sequences" are those that are syntactically
 369                                                                 # correct but use more UTF-8 bytes than are necessary to
 370                                                                 # encode a character. Naïve string comparisons can be
 371                                                                 # tricked into failing to see a match for an ASCII
 372                                                                 # character, for instance, which can be a security hole
 373                                                                 # if blacklist checks are being used.
 374                                                                ($n  < 0xc2 && $sequence <= UTF8_OVERLONG_A)
 375                                                                 || ($n == 0xe0 && $sequence <= UTF8_OVERLONG_B)
 376                                                                 || ($n == 0xf0 && $sequence <= UTF8_OVERLONG_C)
 377
 378                                                                 # U+FFFE and U+FFFF are explicitly forbidden in Unicode.
 379                                                                 || ($n == 0xef &&
 380                                                                            ($sequence == UTF8_FFFE)
 381                                                                         || ($sequence == UTF8_FFFF) )
 382
 383                                                                 # Unicode has been limited to 21 bits; longer
 384                                                                 # sequences are not allowed.
 385                                                                 || ($n >= 0xf0 && $sequence > UTF8_MAX) ) {
 386
 387                                                                 $replace[] = array( UTF8_REPLACEMENT,
 388                                                                                     $base + $i + 1 - strlen( $sequence ),
 389                                                                                     strlen( $sequence ) );
 390                                                                 $head = '';
 391                                                                 continue;
 392                                                         }
 393                                                 }
 394                                         }
 395
 396                                         if( isset( $utfCheckOrCombining[$sequence] ) ) {
 397                                                 # If it's NO or MAYBE, we'll have to rip
 398                                                 # the string apart and put it back together.
 399                                                 # That's going to be mighty slow.
 400                                                 $looksNormal = false;
 401                                         }
 402
 403                                         # The sequence is legal!
 404                                         $head = '';
 405                                 } elseif( $c < "\x80" ) {
 406                                         # ASCII byte.
 407                                         $head = '';
 408                                 } elseif( $c < "\xc0" ) {
 409                                         # Illegal tail bytes
 410                                         if( $head == '' ) {
 411                                                 # Out of the blue!
 412                                                 $replace[] = array( UTF8_REPLACEMENT, $base + $i, 1 );
 413                                         } else {
 414                                                 # Don't add if we're continuing a broken sequence;
 415                                                 # we already put a replacement character when we looked
 416                                                 # at the broken sequence.
 417                                                 $replace[] = array( '', $base + $i, 1 );
 418                                         }
 419                                 } else {
 420                                         # Miscellaneous freaks.
 421                                         $replace[] = array( UTF8_REPLACEMENT, $base + $i, 1 );
 422                                         $head = '';
 423                                 }
 424                         }
 425                         $base += $chunk;
 426                 }
 427                 if( count( $replace ) ) {
 428                         # There were illegal UTF-8 sequences we need to fix up.
 429                         $out = '';
 430                         $last = 0;
 431                         foreach( $replace as $rep ) {
 432                                 list( $replacement, $start, $length ) = $rep;
 433                                 if( $last < $start ) {
 434                                         $out .= substr( $string, $last, $start - $last );
 435                                 }
 436                                 $out .= $replacement;
 437                                 $last = $start + $length;
 438                         }
 439                         if( $last < strlen( $string ) ) {
 440                                 $out .= substr( $string, $last );
 441                         }
 442                         $string = $out;
 443                 }
 444                 return $looksNormal;
 445         }
 446
 447         # These take a string and run the normalization on them, without
 448         # checking for validity or any optimization etc. Input must be
 449         # VALID UTF-8!
 450         /**
 451          * @param $string string
 452          * @return string
 453          * @private
 454          */
 455         static function NFC( $string ) {
 456                 return UtfNormal::fastCompose( UtfNormal::NFD( $string ) );
 457         }
 458
 459         /**
 460          * @param $string string
 461          * @return string
 462          * @private
 463          */
 464         static function NFD( $string ) {
 465                 UtfNormal::loadData();
 466                 global $utfCanonicalDecomp;
 467                 return UtfNormal::fastCombiningSort(
 468                         UtfNormal::fastDecompose( $string, $utfCanonicalDecomp ) );
 469         }
 470
 471         /**
 472          * @param $string string
 473          * @return string
 474          * @private
 475          */
 476         static function NFKC( $string ) {
 477                 return UtfNormal::fastCompose( UtfNormal::NFKD( $string ) );
 478         }
 479
 480         /**
 481          * @param $string string
 482          * @return string
 483          * @private
 484          */
 485         static function NFKD( $string ) {
 486                 global $utfCompatibilityDecomp;
 487                 if( !isset( $utfCompatibilityDecomp ) ) {
 488                         require_once( 'UtfNormalDataK.inc' );
 489                 }
 490                 return UtfNormal::fastCombiningSort(
 491                         UtfNormal::fastDecompose( $string, $utfCompatibilityDecomp ) );
 492         }
 493
 494
 495         /**
 496          * Perform decomposition of a UTF-8 string into either D or KD form
 497          * (depending on which decomposition map is passed to us).
 498          * Input is assumed to be *valid* UTF-8. Invalid code will break.
 499          * @private
 500          * @param $string String: valid UTF-8 string
 501          * @param $map Array: hash of expanded decomposition map
 502          * @return string a UTF-8 string decomposed, not yet normalized (needs sorting)
 503          */
 504         static function fastDecompose( $string, $map ) {
 505                 UtfNormal::loadData();
 506                 $len = strlen( $string );
 507                 $out = '';
 508                 for( $i = 0; $i < $len; $i++ ) {
 509                         $c = $string{$i};
 510                         $n = ord( $c );
 511                         if( $n < 0x80 ) {
 512                                 # ASCII chars never decompose
 513                                 # THEY ARE IMMORTAL
 514                                 $out .= $c;
 515                                 continue;
 516                         } elseif( $n >= 0xf0 ) {
 517                                 $c = substr( $string, $i, 4 );
 518                                 $i += 3;
 519                         } elseif( $n >= 0xe0 ) {
 520                                 $c = substr( $string, $i, 3 );
 521                                 $i += 2;
 522                         } elseif( $n >= 0xc0 ) {
 523                                 $c = substr( $string, $i, 2 );
 524                                 $i++;
 525                         }
 526                         if( isset( $map[$c] ) ) {
 527                                 $out .= $map[$c];
 528                                 continue;
 529                         } else {
 530                                 if( $c >= UTF8_HANGUL_FIRST && $c <= UTF8_HANGUL_LAST ) {
 531                                         # Decompose a hangul syllable into jamo;
 532                                         # hardcoded for three-byte UTF-8 sequence.
 533                                         # A lookup table would be slightly faster,
 534                                         # but adds a lot of memory & disk needs.
 535                                         #
 536                                         $index = ( (ord( $c{0} ) & 0x0f) << 12
 537                                                  | (ord( $c{1} ) & 0x3f) <<  6
 538                                                  | (ord( $c{2} ) & 0x3f) )
 539                                                - UNICODE_HANGUL_FIRST;
 540                                         $l = intval( $index / UNICODE_HANGUL_NCOUNT );
 541                                         $v = intval( ($index % UNICODE_HANGUL_NCOUNT) / UNICODE_HANGUL_TCOUNT);
 542                                         $t = $index % UNICODE_HANGUL_TCOUNT;
 543                                         $out .= "\xe1\x84" . chr( 0x80 + $l ) . "\xe1\x85" . chr( 0xa1 + $v );
 544                                         if( $t >= 25 ) {
 545                                                 $out .= "\xe1\x87" . chr( 0x80 + $t - 25 );
 546                                         } elseif( $t ) {
 547                                                 $out .= "\xe1\x86" . chr( 0xa7 + $t );
 548                                         }
 549                                         continue;
 550                                 }
 551                         }
 552                         $out .= $c;
 553                 }
 554                 return $out;
 555         }
 556
 557         /**
 558          * Sorts combining characters into canonical order. This is the
 559          * final step in creating decomposed normal forms D and KD.
 560          * @private
 561          * @param $string String: a valid, decomposed UTF-8 string. Input is not validated.
 562          * @return string a UTF-8 string with combining characters sorted in canonical order
 563          */
 564         static function fastCombiningSort( $string ) {
 565                 UtfNormal::loadData();
 566                 global $utfCombiningClass;
 567                 $len = strlen( $string );
 568                 $out = '';
 569                 $combiners = array();
 570                 $lastClass = -1;
 571                 for( $i = 0; $i < $len; $i++ ) {
 572                         $c = $string{$i};
 573                         $n = ord( $c );
 574                         if( $n >= 0x80 ) {
 575                                 if( $n >= 0xf0 ) {
 576                                         $c = substr( $string, $i, 4 );
 577                                         $i += 3;
 578                                 } elseif( $n >= 0xe0 ) {
 579                                         $c = substr( $string, $i, 3 );
 580                                         $i += 2;
 581                                 } elseif( $n >= 0xc0 ) {
 582                                         $c = substr( $string, $i, 2 );
 583                                         $i++;
 584                                 }
 585                                 if( isset( $utfCombiningClass[$c] ) ) {
 586                                         $lastClass = $utfCombiningClass[$c];
 587                                         if( isset( $combiners[$lastClass] ) ) {
 588                                                 $combiners[$lastClass] .= $c;
 589                                         } else {
 590                                                 $combiners[$lastClass] = $c;
 591                                         }
 592                                         continue;
 593                                 }
 594                         }
 595                         if( $lastClass ) {
 596                                 ksort( $combiners );
 597                                 $out .= implode( '', $combiners );
 598                                 $combiners = array();
 599                         }
 600                         $out .= $c;
 601                         $lastClass = 0;
 602                 }
 603                 if( $lastClass ) {
 604                         ksort( $combiners );
 605                         $out .= implode( '', $combiners );
 606                 }
 607                 return $out;
 608         }
 609
 610         /**
 611          * Produces canonically composed sequences, i.e. normal form C or KC.
 612          *
 613          * @private
 614          * @param $string String: a valid UTF-8 string in sorted normal form D or KD. Input is not validated.
 615          * @return string a UTF-8 string with canonical precomposed characters used where possible
 616          */
 617         static function fastCompose( $string ) {
 618                 UtfNormal::loadData();
 619                 global $utfCanonicalComp, $utfCombiningClass;
 620                 $len = strlen( $string );
 621                 $out = '';
 622                 $lastClass = -1;
 623                 $lastHangul = 0;
 624                 $startChar = '';
 625                 $combining = '';
 626                 $x1 = ord(substr(UTF8_HANGUL_VBASE,0,1));
 627                 $x2 = ord(substr(UTF8_HANGUL_TEND,0,1));
 628                 for( $i = 0; $i < $len; $i++ ) {
 629                         $c = $string{$i};
 630                         $n = ord( $c );
 631                         if( $n < 0x80 ) {
 632                                 # No combining characters here...
 633                                 $out .= $startChar;
 634                                 $out .= $combining;
 635                                 $startChar = $c;
 636                                 $combining = '';
 637                                 $lastClass = 0;
 638                                 continue;
 639                         } elseif( $n >= 0xf0 ) {
 640                                 $c = substr( $string, $i, 4 );
 641                                 $i += 3;
 642                         } elseif( $n >= 0xe0 ) {
 643                                 $c = substr( $string, $i, 3 );
 644                                 $i += 2;
 645                         } elseif( $n >= 0xc0 ) {
 646                                 $c = substr( $string, $i, 2 );
 647                                 $i++;
 648                         }
 649                         $pair = $startChar . $c;
 650                         if( $n > 0x80 ) {
 651                                 if( isset( $utfCombiningClass[$c] ) ) {
 652                                         # A combining char; see what we can do with it
 653                                         $class = $utfCombiningClass[$c];
 654                                         if( !empty( $startChar ) &&
 655                                                 $lastClass < $class &&
 656                                                 $class > 0 &&
 657                                                 isset( $utfCanonicalComp[$pair] ) ) {
 658                                                 $startChar = $utfCanonicalComp[$pair];
 659                                                 $class = 0;
 660                                         } else {
 661                                                 $combining .= $c;
 662                                         }
 663                                         $lastClass = $class;
 664                                         $lastHangul = 0;
 665                                         continue;
 666                                 }
 667                         }
 668                         # New start char
 669                         if( $lastClass == 0 ) {
 670                                 if( isset( $utfCanonicalComp[$pair] ) ) {
 671                                         $startChar = $utfCanonicalComp[$pair];
 672                                         $lastHangul = 0;
 673                                         continue;
 674                                 }
 675                                 if( $n >= $x1 && $n <= $x2 ) {
 676                                         # WARNING: Hangul code is painfully slow.
 677                                         # I apologize for this ugly, ugly code; however
 678                                         # performance is even more teh suck if we call
 679                                         # out to nice clean functions. Lookup tables are
 680                                         # marginally faster, but require a lot of space.
 681                                         #
 682                                         if( $c >= UTF8_HANGUL_VBASE &&
 683                                                 $c <= UTF8_HANGUL_VEND &&
 684                                                 $startChar >= UTF8_HANGUL_LBASE &&
 685                                                 $startChar <= UTF8_HANGUL_LEND ) {
 686                                                 #
 687                                                 #$lIndex = utf8ToCodepoint( $startChar ) - UNICODE_HANGUL_LBASE;
 688                                                 #$vIndex = utf8ToCodepoint( $c ) - UNICODE_HANGUL_VBASE;
 689                                                 $lIndex = ord( $startChar{2} ) - 0x80;
 690                                                 $vIndex = ord( $c{2}         ) - 0xa1;
 691
 692                                                 $hangulPoint = UNICODE_HANGUL_FIRST +
 693                                                         UNICODE_HANGUL_TCOUNT *
 694                                                         (UNICODE_HANGUL_VCOUNT * $lIndex + $vIndex);
 695
 696                                                 # Hardcode the limited-range UTF-8 conversion:
 697                                                 $startChar = chr( $hangulPoint >> 12 & 0x0f | 0xe0 ) .
 698                                                                          chr( $hangulPoint >>  6 & 0x3f | 0x80 ) .
 699                                                                          chr( $hangulPoint       & 0x3f | 0x80 );
 700                                                 $lastHangul = 0;
 701                                                 continue;
 702                                         } elseif( $c >= UTF8_HANGUL_TBASE &&
 703                                                           $c <= UTF8_HANGUL_TEND &&
 704                                                           $startChar >= UTF8_HANGUL_FIRST &&
 705                                                           $startChar <= UTF8_HANGUL_LAST &&
 706                                                           !$lastHangul ) {
 707                                                 # $tIndex = utf8ToCodepoint( $c ) - UNICODE_HANGUL_TBASE;
 708                                                 $tIndex = ord( $c{2} ) - 0xa7;
 709                                                 if( $tIndex < 0 ) $tIndex = ord( $c{2} ) - 0x80 + (0x11c0 - 0x11a7);
 710
 711                                                 # Increment the code point by $tIndex, without
 712                                                 # the function overhead of decoding and recoding UTF-8
 713                                                 #
 714                                                 $tail = ord( $startChar{2} ) + $tIndex;
 715                                                 if( $tail > 0xbf ) {
 716                                                         $tail -= 0x40;
 717                                                         $mid = ord( $startChar{1} ) + 1;
 718                                                         if( $mid > 0xbf ) {
 719                                                                 $startChar{0} = chr( ord( $startChar{0} ) + 1 );
 720                                                                 $mid -= 0x40;
 721                                                         }
 722                                                         $startChar{1} = chr( $mid );
 723                                                 }
 724                                                 $startChar{2} = chr( $tail );
 725
 726                                                 # If there's another jamo char after this, *don't* try to merge it.
 727                                                 $lastHangul = 1;
 728                                                 continue;
 729                                         }
 730                                 }
 731                         }
 732                         $out .= $startChar;
 733                         $out .= $combining;
 734                         $startChar = $c;
 735                         $combining = '';
 736                         $lastClass = 0;
 737                         $lastHangul = 0;
 738                 }
 739                 $out .= $startChar . $combining;
 740                 return $out;
 741         }
 742
 743         /**
 744          * This is just used for the benchmark, comparing how long it takes to
 745          * interate through a string without really doing anything of substance.
 746          * @param $string string
 747          * @return string
 748          */
 749         static function placebo( $string ) {
 750                 $len = strlen( $string );
 751                 $out = '';
 752                 for( $i = 0; $i < $len; $i++ ) {
 753                         $out .= $string{$i};
 754                 }
 755                 return $out;
 756         }
 757 }