includes/normal/UtfNormal.php

   1 <?php
   2 /**
   3  * Unicode normalization routines
   4  *
   5  * Copyright © 2004 Brion Vibber <brion@pobox.com>
   6  * https://www.mediawiki.org/
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup UtfNormal
  25  */
  26
  27 /**
  28  * @defgroup UtfNormal UtfNormal
  29  */
  30
  31 define( 'NORMALIZE_ICU', function_exists( 'utf8_normalize' ) );
  32 define( 'NORMALIZE_INTL', function_exists( 'normalizer_normalize' ) );
  33
  34 /**
  35  * Unicode normalization routines for working with UTF-8 strings.
  36  * Currently assumes that input strings are valid UTF-8!
  37  *
  38  * Not as fast as I'd like, but should be usable for most purposes.
  39  * UtfNormal::toNFC() will bail early if given ASCII text or text
  40  * it can quickly determine is already normalized.
  41  *
  42  * All functions can be called static.
  43  *
  44  * See description of forms at http://www.unicode.org/reports/tr15/
  45  *
  46  * @ingroup UtfNormal
  47  */
  48 class UtfNormal {
  49         /**
  50          * For using the ICU wrapper
  51          */
  52         const UNORM_NONE = 1;
  53         const UNORM_NFD = 2;
  54         const UNORM_NFKD = 3;
  55         const UNORM_NFC = 4;
  56         const UNORM_NFKC = 5;
  57         const UNORM_FCD = 6;
  58         const UNORM_DEFAULT = self::UNORM_NFC;
  59
  60         public static $utfCombiningClass = null;
  61         public static $utfCanonicalComp = null;
  62         public static $utfCanonicalDecomp = null;
  63
  64         # Load compatibility decompositions on demand if they are needed.
  65         public static $utfCompatibilityDecomp = null;
  66         public static $utfCheckNFC;
  67
  68         /**
  69          * The ultimate convenience function! Clean up invalid UTF-8 sequences,
  70          * and convert to normal form C, canonical composition.
  71          *
  72          * Fast return for pure ASCII strings; some lesser optimizations for
  73          * strings containing only known-good characters. Not as fast as toNFC().
  74          *
  75          * @param string $string a UTF-8 string
  76          * @return string a clean, shiny, normalized UTF-8 string
  77          */
  78         static function cleanUp( $string ) {
  79                 if ( NORMALIZE_ICU ) {
  80                         $string = self::replaceForNativeNormalize( $string );
  81
  82                         # UnicodeString constructor fails if the string ends with a
  83                         # head byte. Add a junk char at the end, we'll strip it off.
  84                         return rtrim( utf8_normalize( $string . "\x01", self::UNORM_NFC ), "\x01" );
  85                 } elseif ( NORMALIZE_INTL ) {
  86                         $string = self::replaceForNativeNormalize( $string );
  87                         $norm = normalizer_normalize( $string, Normalizer::FORM_C );
  88                         if ( $norm === null || $norm === false ) {
  89                                 # normalizer_normalize will either return false or null
  90                                 # (depending on which doc you read) if invalid utf8 string.
  91                                 # quickIsNFCVerify cleans up invalid sequences.
  92
  93                                 if ( UtfNormal::quickIsNFCVerify( $string ) ) {
  94                                         # if that's true, the string is actually already normal.
  95                                         return $string;
  96                                 } else {
  97                                         # Now we are valid but non-normal
  98                                         return normalizer_normalize( $string, Normalizer::FORM_C );
  99                                 }
 100                         } else {
 101                                 return $norm;
 102                         }
 103                 } elseif ( UtfNormal::quickIsNFCVerify( $string ) ) {
 104                         # Side effect -- $string has had UTF-8 errors cleaned up.
 105                         return $string;
 106                 } else {
 107                         return UtfNormal::NFC( $string );
 108                 }
 109         }
 110
 111         /**
 112          * Convert a UTF-8 string to normal form C, canonical composition.
 113          * Fast return for pure ASCII strings; some lesser optimizations for
 114          * strings containing only known-good characters.
 115          *
 116          * @param string $string a valid UTF-8 string. Input is not validated.
 117          * @return string a UTF-8 string in normal form C
 118          */
 119         static function toNFC( $string ) {
 120                 if ( NORMALIZE_INTL )
 121                         return normalizer_normalize( $string, Normalizer::FORM_C );
 122                 elseif ( NORMALIZE_ICU )
 123                         return utf8_normalize( $string, self::UNORM_NFC );
 124                 elseif ( UtfNormal::quickIsNFC( $string ) )
 125                         return $string;
 126                 else
 127                         return UtfNormal::NFC( $string );
 128         }
 129
 130         /**
 131          * Convert a UTF-8 string to normal form D, canonical decomposition.
 132          * Fast return for pure ASCII strings.
 133          *
 134          * @param string $string a valid UTF-8 string. Input is not validated.
 135          * @return string a UTF-8 string in normal form D
 136          */
 137         static function toNFD( $string ) {
 138                 if ( NORMALIZE_INTL )
 139                         return normalizer_normalize( $string, Normalizer::FORM_D );
 140                 elseif ( NORMALIZE_ICU )
 141                         return utf8_normalize( $string, self::UNORM_NFD );
 142                 elseif ( preg_match( '/[\x80-\xff]/', $string ) )
 143                         return UtfNormal::NFD( $string );
 144                 else
 145                         return $string;
 146         }
 147
 148         /**
 149          * Convert a UTF-8 string to normal form KC, compatibility composition.
 150          * This may cause irreversible information loss, use judiciously.
 151          * Fast return for pure ASCII strings.
 152          *
 153          * @param string $string a valid UTF-8 string. Input is not validated.
 154          * @return string a UTF-8 string in normal form KC
 155          */
 156         static function toNFKC( $string ) {
 157                 if ( NORMALIZE_INTL )
 158                         return normalizer_normalize( $string, Normalizer::FORM_KC );
 159                 elseif ( NORMALIZE_ICU )
 160                         return utf8_normalize( $string, self::UNORM_NFKC );
 161                 elseif ( preg_match( '/[\x80-\xff]/', $string ) )
 162                         return UtfNormal::NFKC( $string );
 163                 else
 164                         return $string;
 165         }
 166
 167         /**
 168          * Convert a UTF-8 string to normal form KD, compatibility decomposition.
 169          * This may cause irreversible information loss, use judiciously.
 170          * Fast return for pure ASCII strings.
 171          *
 172          * @param string $string a valid UTF-8 string. Input is not validated.
 173          * @return string a UTF-8 string in normal form KD
 174          */
 175         static function toNFKD( $string ) {
 176                 if ( NORMALIZE_INTL )
 177                         return normalizer_normalize( $string, Normalizer::FORM_KD );
 178                 elseif ( NORMALIZE_ICU )
 179                         return utf8_normalize( $string, self::UNORM_NFKD );
 180                 elseif ( preg_match( '/[\x80-\xff]/', $string ) )
 181                         return UtfNormal::NFKD( $string );
 182                 else
 183                         return $string;
 184         }
 185
 186         /**
 187          * Load the basic composition data if necessary
 188          * @private
 189          */
 190         static function loadData() {
 191                 if ( !isset( self::$utfCombiningClass ) ) {
 192                         require_once __DIR__ . '/UtfNormalData.inc';
 193                 }
 194         }
 195
 196         /**
 197          * Returns true if the string is _definitely_ in NFC.
 198          * Returns false if not or uncertain.
 199          * @param string $string a valid UTF-8 string. Input is not validated.
 200          * @return bool
 201          */
 202         static function quickIsNFC( $string ) {
 203                 # ASCII is always valid NFC!
 204                 # If it's pure ASCII, let it through.
 205                 if ( !preg_match( '/[\x80-\xff]/', $string ) ) return true;
 206
 207                 UtfNormal::loadData();
 208                 $len = strlen( $string );
 209                 for ( $i = 0; $i < $len; $i++ ) {
 210                         $c = $string[$i];
 211                         $n = ord( $c );
 212                         if ( $n < 0x80 ) {
 213                                 continue;
 214                         } elseif ( $n >= 0xf0 ) {
 215                                 $c = substr( $string, $i, 4 );
 216                                 $i += 3;
 217                         } elseif ( $n >= 0xe0 ) {
 218                                 $c = substr( $string, $i, 3 );
 219                                 $i += 2;
 220                         } elseif ( $n >= 0xc0 ) {
 221                                 $c = substr( $string, $i, 2 );
 222                                 $i++;
 223                         }
 224                         if ( isset( self::$utfCheckNFC[$c] ) ) {
 225                                 # If it's NO or MAYBE, bail and do the slow check.
 226                                 return false;
 227                         }
 228                         if ( isset( self::$utfCombiningClass[$c] ) ) {
 229                                 # Combining character? We might have to do sorting, at least.
 230                                 return false;
 231                         }
 232                 }
 233
 234                 return true;
 235         }
 236
 237         /**
 238          * Returns true if the string is _definitely_ in NFC.
 239          * Returns false if not or uncertain.
 240          * @param string $string a UTF-8 string, altered on output to be valid UTF-8 safe for XML.
 241          * @return bool
 242          */
 243         static function quickIsNFCVerify( &$string ) {
 244                 # Screen out some characters that eg won't be allowed in XML
 245                 $string = preg_replace( '/[\x00-\x08\x0b\x0c\x0e-\x1f]/', UTF8_REPLACEMENT, $string );
 246
 247                 # ASCII is always valid NFC!
 248                 # If we're only ever given plain ASCII, we can avoid the overhead
 249                 # of initializing the decomposition tables by skipping out early.
 250                 if ( !preg_match( '/[\x80-\xff]/', $string ) ) return true;
 251
 252                 static $checkit = null, $tailBytes = null, $utfCheckOrCombining = null;
 253                 if ( !isset( $checkit ) ) {
 254                         # Load/build some scary lookup tables...
 255                         UtfNormal::loadData();
 256
 257                         $utfCheckOrCombining = array_merge( self::$utfCheckNFC, self::$utfCombiningClass );
 258
 259                         # Head bytes for sequences which we should do further validity checks
 260                         $checkit = array_flip( array_map( 'chr',
 261                                 array( 0xc0, 0xc1, 0xe0, 0xed, 0xef,
 262                                         0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
 263                                         0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff ) ) );
 264
 265                         # Each UTF-8 head byte is followed by a certain
 266                         # number of tail bytes.
 267                         $tailBytes = array();
 268                         for ( $n = 0; $n < 256; $n++ ) {
 269                                 if ( $n < 0xc0 ) {
 270                                         $remaining = 0;
 271                                 } elseif ( $n < 0xe0 ) {
 272                                         $remaining = 1;
 273                                 } elseif ( $n < 0xf0 ) {
 274                                         $remaining = 2;
 275                                 } elseif ( $n < 0xf8 ) {
 276                                         $remaining = 3;
 277                                 } elseif ( $n < 0xfc ) {
 278                                         $remaining = 4;
 279                                 } elseif ( $n < 0xfe ) {
 280                                         $remaining = 5;
 281                                 } else {
 282                                         $remaining = 0;
 283                                 }
 284                                 $tailBytes[chr( $n )] = $remaining;
 285                         }
 286                 }
 287
 288                 # Chop the text into pure-ASCII and non-ASCII areas;
 289                 # large ASCII parts can be handled much more quickly.
 290                 # Don't chop up Unicode areas for punctuation, though,
 291                 # that wastes energy.
 292                 $matches = array();
 293                 preg_match_all(
 294                         '/([\x00-\x7f]+|[\x80-\xff][\x00-\x40\x5b-\x5f\x7b-\xff]*)/',
 295                         $string, $matches );
 296
 297                 $looksNormal = true;
 298                 $base = 0;
 299                 $replace = array();
 300                 foreach ( $matches[1] as $str ) {
 301                         $chunk = strlen( $str );
 302
 303                         if ( $str[0] < "\x80" ) {
 304                                 # ASCII chunk: guaranteed to be valid UTF-8
 305                                 # and in normal form C, so skip over it.
 306                                 $base += $chunk;
 307                                 continue;
 308                         }
 309
 310                         # We'll have to examine the chunk byte by byte to ensure
 311                         # that it consists of valid UTF-8 sequences, and to see
 312                         # if any of them might not be normalized.
 313                         #
 314                         # Since PHP is not the fastest language on earth, some of
 315                         # this code is a little ugly with inner loop optimizations.
 316
 317                         $head = '';
 318                         $len = $chunk + 1; # Counting down is faster. I'm *so* sorry.
 319
 320                         for ( $i = -1; --$len; ) {
 321                                 $remaining = $tailBytes[$c = $str[++$i]];
 322                                 if ( $remaining ) {
 323                                         # UTF-8 head byte!
 324                                         $sequence = $head = $c;
 325                                         do {
 326                                                 # Look for the defined number of tail bytes...
 327                                                 if ( --$len && ( $c = $str[++$i] ) >= "\x80" && $c < "\xc0" ) {
 328                                                         # Legal tail bytes are nice.
 329                                                         $sequence .= $c;
 330                                                 } else {
 331                                                         if ( 0 == $len ) {
 332                                                                 # Premature end of string!
 333                                                                 # Drop a replacement character into output to
 334                                                                 # represent the invalid UTF-8 sequence.
 335                                                                 $replace[] = array( UTF8_REPLACEMENT,
 336                                                                         $base + $i + 1 - strlen( $sequence ),
 337                                                                         strlen( $sequence ) );
 338                                                                 break 2;
 339                                                         } else {
 340                                                                 # Illegal tail byte; abandon the sequence.
 341                                                                 $replace[] = array( UTF8_REPLACEMENT,
 342                                                                         $base + $i - strlen( $sequence ),
 343                                                                         strlen( $sequence ) );
 344                                                                 # Back up and reprocess this byte; it may itself
 345                                                                 # be a legal ASCII or UTF-8 sequence head.
 346                                                                 --$i;
 347                                                                 ++$len;
 348                                                                 continue 2;
 349                                                         }
 350                                                 }
 351                                         } while ( --$remaining );
 352
 353                                         if ( isset( $checkit[$head] ) ) {
 354                                                 # Do some more detailed validity checks, for
 355                                                 # invalid characters and illegal sequences.
 356                                                 if ( $head == "\xed" ) {
 357                                                         # 0xed is relatively frequent in Korean, which
 358                                                         # abuts the surrogate area, so we're doing
 359                                                         # this check separately to speed things up.
 360
 361                                                         if ( $sequence >= UTF8_SURROGATE_FIRST ) {
 362                                                                 # Surrogates are legal only in UTF-16 code.
 363                                                                 # They are totally forbidden here in UTF-8
 364                                                                 # utopia.
 365                                                                 $replace[] = array( UTF8_REPLACEMENT,
 366                                                                         $base + $i + 1 - strlen( $sequence ),
 367                                                                         strlen( $sequence ) );
 368                                                                 $head = '';
 369                                                                 continue;
 370                                                         }
 371                                                 } else {
 372                                                         # Slower, but rarer checks...
 373                                                         $n = ord( $head );
 374                                                         if (
 375                                                                 # "Overlong sequences" are those that are syntactically
 376                                                                 # correct but use more UTF-8 bytes than are necessary to
 377                                                                 # encode a character. Naïve string comparisons can be
 378                                                                 # tricked into failing to see a match for an ASCII
 379                                                                 # character, for instance, which can be a security hole
 380                                                                 # if blacklist checks are being used.
 381                                                                 ( $n < 0xc2 && $sequence <= UTF8_OVERLONG_A )
 382                                                                 || ( $n == 0xe0 && $sequence <= UTF8_OVERLONG_B )
 383                                                                 || ( $n == 0xf0 && $sequence <= UTF8_OVERLONG_C )
 384
 385                                                                 # U+FFFE and U+FFFF are explicitly forbidden in Unicode.
 386                                                                 || ( $n == 0xef &&
 387                                                                         ( $sequence == UTF8_FFFE )
 388                                                                         || ( $sequence == UTF8_FFFF ) )
 389
 390                                                                 # Unicode has been limited to 21 bits; longer
 391                                                                 # sequences are not allowed.
 392                                                                 || ( $n >= 0xf0 && $sequence > UTF8_MAX )
 393                                                         ) {
 394
 395                                                                 $replace[] = array( UTF8_REPLACEMENT,
 396                                                                         $base + $i + 1 - strlen( $sequence ),
 397                                                                         strlen( $sequence ) );
 398                                                                 $head = '';
 399                                                                 continue;
 400                                                         }
 401                                                 }
 402                                         }
 403
 404                                         if ( isset( $utfCheckOrCombining[$sequence] ) ) {
 405                                                 # If it's NO or MAYBE, we'll have to rip
 406                                                 # the string apart and put it back together.
 407                                                 # That's going to be mighty slow.
 408                                                 $looksNormal = false;
 409                                         }
 410
 411                                         # The sequence is legal!
 412                                         $head = '';
 413                                 } elseif ( $c < "\x80" ) {
 414                                         # ASCII byte.
 415                                         $head = '';
 416                                 } elseif ( $c < "\xc0" ) {
 417                                         # Illegal tail bytes
 418                                         if ( $head == '' ) {
 419                                                 # Out of the blue!
 420                                                 $replace[] = array( UTF8_REPLACEMENT, $base + $i, 1 );
 421                                         } else {
 422                                                 # Don't add if we're continuing a broken sequence;
 423                                                 # we already put a replacement character when we looked
 424                                                 # at the broken sequence.
 425                                                 $replace[] = array( '', $base + $i, 1 );
 426                                         }
 427                                 } else {
 428                                         # Miscellaneous freaks.
 429                                         $replace[] = array( UTF8_REPLACEMENT, $base + $i, 1 );
 430                                         $head = '';
 431                                 }
 432                         }
 433                         $base += $chunk;
 434                 }
 435                 if ( count( $replace ) ) {
 436                         # There were illegal UTF-8 sequences we need to fix up.
 437                         $out = '';
 438                         $last = 0;
 439                         foreach ( $replace as $rep ) {
 440                                 list( $replacement, $start, $length ) = $rep;
 441                                 if ( $last < $start ) {
 442                                         $out .= substr( $string, $last, $start - $last );
 443                                 }
 444                                 $out .= $replacement;
 445                                 $last = $start + $length;
 446                         }
 447                         if ( $last < strlen( $string ) ) {
 448                                 $out .= substr( $string, $last );
 449                         }
 450                         $string = $out;
 451                 }
 452
 453                 return $looksNormal;
 454         }
 455
 456         # These take a string and run the normalization on them, without
 457         # checking for validity or any optimization etc. Input must be
 458         # VALID UTF-8!
 459         /**
 460          * @param $string string
 461          * @return string
 462          * @private
 463          */
 464         static function NFC( $string ) {
 465                 return UtfNormal::fastCompose( UtfNormal::NFD( $string ) );
 466         }
 467
 468         /**
 469          * @param $string string
 470          * @return string
 471          * @private
 472          */
 473         static function NFD( $string ) {
 474                 UtfNormal::loadData();
 475
 476                 return UtfNormal::fastCombiningSort(
 477                         UtfNormal::fastDecompose( $string, self::$utfCanonicalDecomp ) );
 478         }
 479
 480         /**
 481          * @param $string string
 482          * @return string
 483          * @private
 484          */
 485         static function NFKC( $string ) {
 486                 return UtfNormal::fastCompose( UtfNormal::NFKD( $string ) );
 487         }
 488
 489         /**
 490          * @param $string string
 491          * @return string
 492          * @private
 493          */
 494         static function NFKD( $string ) {
 495                 if ( !isset( self::$utfCompatibilityDecomp ) ) {
 496                         require_once 'UtfNormalDataK.inc';
 497                 }
 498
 499                 return self::fastCombiningSort(
 500                         self::fastDecompose( $string, self::$utfCompatibilityDecomp ) );
 501         }
 502
 503         /**
 504          * Perform decomposition of a UTF-8 string into either D or KD form
 505          * (depending on which decomposition map is passed to us).
 506          * Input is assumed to be *valid* UTF-8. Invalid code will break.
 507          * @private
 508          * @param string $string valid UTF-8 string
 509          * @param array $map hash of expanded decomposition map
 510          * @return string a UTF-8 string decomposed, not yet normalized (needs sorting)
 511          */
 512         static function fastDecompose( $string, $map ) {
 513                 UtfNormal::loadData();
 514                 $len = strlen( $string );
 515                 $out = '';
 516                 for ( $i = 0; $i < $len; $i++ ) {
 517                         $c = $string[$i];
 518                         $n = ord( $c );
 519                         if ( $n < 0x80 ) {
 520                                 # ASCII chars never decompose
 521                                 # THEY ARE IMMORTAL
 522                                 $out .= $c;
 523                                 continue;
 524                         } elseif ( $n >= 0xf0 ) {
 525                                 $c = substr( $string, $i, 4 );
 526                                 $i += 3;
 527                         } elseif ( $n >= 0xe0 ) {
 528                                 $c = substr( $string, $i, 3 );
 529                                 $i += 2;
 530                         } elseif ( $n >= 0xc0 ) {
 531                                 $c = substr( $string, $i, 2 );
 532                                 $i++;
 533                         }
 534                         if ( isset( $map[$c] ) ) {
 535                                 $out .= $map[$c];
 536                                 continue;
 537                         } else {
 538                                 if ( $c >= UTF8_HANGUL_FIRST && $c <= UTF8_HANGUL_LAST ) {
 539                                         # Decompose a hangul syllable into jamo;
 540                                         # hardcoded for three-byte UTF-8 sequence.
 541                                         # A lookup table would be slightly faster,
 542                                         # but adds a lot of memory & disk needs.
 543                                         #
 544                                         $index = ( ( ord( $c[0] ) & 0x0f ) << 12
 545                                                         | ( ord( $c[1] ) & 0x3f ) << 6
 546                                                         | ( ord( $c[2] ) & 0x3f ) )
 547                                                 - UNICODE_HANGUL_FIRST;
 548                                         $l = intval( $index / UNICODE_HANGUL_NCOUNT );
 549                                         $v = intval( ( $index % UNICODE_HANGUL_NCOUNT ) / UNICODE_HANGUL_TCOUNT );
 550                                         $t = $index % UNICODE_HANGUL_TCOUNT;
 551                                         $out .= "\xe1\x84" . chr( 0x80 + $l ) . "\xe1\x85" . chr( 0xa1 + $v );
 552                                         if ( $t >= 25 ) {
 553                                                 $out .= "\xe1\x87" . chr( 0x80 + $t - 25 );
 554                                         } elseif ( $t ) {
 555                                                 $out .= "\xe1\x86" . chr( 0xa7 + $t );
 556                                         }
 557                                         continue;
 558                                 }
 559                         }
 560                         $out .= $c;
 561                 }
 562
 563                 return $out;
 564         }
 565
 566         /**
 567          * Sorts combining characters into canonical order. This is the
 568          * final step in creating decomposed normal forms D and KD.
 569          * @private
 570          * @param string $string a valid, decomposed UTF-8 string. Input is not validated.
 571          * @return string a UTF-8 string with combining characters sorted in canonical order
 572          */
 573         static function fastCombiningSort( $string ) {
 574                 UtfNormal::loadData();
 575                 $len = strlen( $string );
 576                 $out = '';
 577                 $combiners = array();
 578                 $lastClass = -1;
 579                 for ( $i = 0; $i < $len; $i++ ) {
 580                         $c = $string[$i];
 581                         $n = ord( $c );
 582                         if ( $n >= 0x80 ) {
 583                                 if ( $n >= 0xf0 ) {
 584                                         $c = substr( $string, $i, 4 );
 585                                         $i += 3;
 586                                 } elseif ( $n >= 0xe0 ) {
 587                                         $c = substr( $string, $i, 3 );
 588                                         $i += 2;
 589                                 } elseif ( $n >= 0xc0 ) {
 590                                         $c = substr( $string, $i, 2 );
 591                                         $i++;
 592                                 }
 593                                 if ( isset( self::$utfCombiningClass[$c] ) ) {
 594                                         $lastClass = self::$utfCombiningClass[$c];
 595                                         if ( isset( $combiners[$lastClass] ) ) {
 596                                                 $combiners[$lastClass] .= $c;
 597                                         } else {
 598                                                 $combiners[$lastClass] = $c;
 599                                         }
 600                                         continue;
 601                                 }
 602                         }
 603                         if ( $lastClass ) {
 604                                 ksort( $combiners );
 605                                 $out .= implode( '', $combiners );
 606                                 $combiners = array();
 607                         }
 608                         $out .= $c;
 609                         $lastClass = 0;
 610                 }
 611                 if ( $lastClass ) {
 612                         ksort( $combiners );
 613                         $out .= implode( '', $combiners );
 614                 }
 615
 616                 return $out;
 617         }
 618
 619         /**
 620          * Produces canonically composed sequences, i.e. normal form C or KC.
 621          *
 622          * @private
 623          * @param string $string a valid UTF-8 string in sorted normal form D or KD.
 624          *   Input is not validated.
 625          * @return string a UTF-8 string with canonical precomposed characters used
 626          *   where possible.
 627          */
 628         static function fastCompose( $string ) {
 629                 UtfNormal::loadData();
 630                 $len = strlen( $string );
 631                 $out = '';
 632                 $lastClass = -1;
 633                 $lastHangul = 0;
 634                 $startChar = '';
 635                 $combining = '';
 636                 $x1 = ord( substr( UTF8_HANGUL_VBASE, 0, 1 ) );
 637                 $x2 = ord( substr( UTF8_HANGUL_TEND, 0, 1 ) );
 638                 for ( $i = 0; $i < $len; $i++ ) {
 639                         $c = $string[$i];
 640                         $n = ord( $c );
 641                         if ( $n < 0x80 ) {
 642                                 # No combining characters here...
 643                                 $out .= $startChar;
 644                                 $out .= $combining;
 645                                 $startChar = $c;
 646                                 $combining = '';
 647                                 $lastClass = 0;
 648                                 continue;
 649                         } elseif ( $n >= 0xf0 ) {
 650                                 $c = substr( $string, $i, 4 );
 651                                 $i += 3;
 652                         } elseif ( $n >= 0xe0 ) {
 653                                 $c = substr( $string, $i, 3 );
 654                                 $i += 2;
 655                         } elseif ( $n >= 0xc0 ) {
 656                                 $c = substr( $string, $i, 2 );
 657                                 $i++;
 658                         }
 659                         $pair = $startChar . $c;
 660                         if ( $n > 0x80 ) {
 661                                 if ( isset( self::$utfCombiningClass[$c] ) ) {
 662                                         # A combining char; see what we can do with it
 663                                         $class = self::$utfCombiningClass[$c];
 664                                         if ( !empty( $startChar ) &&
 665                                                 $lastClass < $class &&
 666                                                 $class > 0 &&
 667                                                 isset( self::$utfCanonicalComp[$pair] )
 668                                         ) {
 669                                                 $startChar = self::$utfCanonicalComp[$pair];
 670                                                 $class = 0;
 671                                         } else {
 672                                                 $combining .= $c;
 673                                         }
 674                                         $lastClass = $class;
 675                                         $lastHangul = 0;
 676                                         continue;
 677                                 }
 678                         }
 679                         # New start char
 680                         if ( $lastClass == 0 ) {
 681                                 if ( isset( self::$utfCanonicalComp[$pair] ) ) {
 682                                         $startChar = self::$utfCanonicalComp[$pair];
 683                                         $lastHangul = 0;
 684                                         continue;
 685                                 }
 686                                 if ( $n >= $x1 && $n <= $x2 ) {
 687                                         # WARNING: Hangul code is painfully slow.
 688                                         # I apologize for this ugly, ugly code; however
 689                                         # performance is even more teh suck if we call
 690                                         # out to nice clean functions. Lookup tables are
 691                                         # marginally faster, but require a lot of space.
 692                                         #
 693                                         if ( $c >= UTF8_HANGUL_VBASE &&
 694                                                 $c <= UTF8_HANGUL_VEND &&
 695                                                 $startChar >= UTF8_HANGUL_LBASE &&
 696                                                 $startChar <= UTF8_HANGUL_LEND
 697                                         ) {
 698                                                 #
 699                                                 #$lIndex = utf8ToCodepoint( $startChar ) - UNICODE_HANGUL_LBASE;
 700                                                 #$vIndex = utf8ToCodepoint( $c ) - UNICODE_HANGUL_VBASE;
 701                                                 $lIndex = ord( $startChar[2] ) - 0x80;
 702                                                 $vIndex = ord( $c[2] ) - 0xa1;
 703
 704                                                 $hangulPoint = UNICODE_HANGUL_FIRST +
 705                                                         UNICODE_HANGUL_TCOUNT *
 706                                                         ( UNICODE_HANGUL_VCOUNT * $lIndex + $vIndex );
 707
 708                                                 # Hardcode the limited-range UTF-8 conversion:
 709                                                 $startChar = chr( $hangulPoint >> 12 & 0x0f | 0xe0 ) .
 710                                                         chr( $hangulPoint >> 6 & 0x3f | 0x80 ) .
 711                                                         chr( $hangulPoint & 0x3f | 0x80 );
 712                                                 $lastHangul = 0;
 713                                                 continue;
 714                                         } elseif ( $c >= UTF8_HANGUL_TBASE &&
 715                                                 $c <= UTF8_HANGUL_TEND &&
 716                                                 $startChar >= UTF8_HANGUL_FIRST &&
 717                                                 $startChar <= UTF8_HANGUL_LAST &&
 718                                                 !$lastHangul
 719                                         ) {
 720                                                 # $tIndex = utf8ToCodepoint( $c ) - UNICODE_HANGUL_TBASE;
 721                                                 $tIndex = ord( $c[2] ) - 0xa7;
 722                                                 if ( $tIndex < 0 ) $tIndex = ord( $c[2] ) - 0x80 + ( 0x11c0 - 0x11a7 );
 723
 724                                                 # Increment the code point by $tIndex, without
 725                                                 # the function overhead of decoding and recoding UTF-8
 726                                                 #
 727                                                 $tail = ord( $startChar[2] ) + $tIndex;
 728                                                 if ( $tail > 0xbf ) {
 729                                                         $tail -= 0x40;
 730                                                         $mid = ord( $startChar[1] ) + 1;
 731                                                         if ( $mid > 0xbf ) {
 732                                                                 $startChar[0] = chr( ord( $startChar[0] ) + 1 );
 733                                                                 $mid -= 0x40;
 734                                                         }
 735                                                         $startChar[1] = chr( $mid );
 736                                                 }
 737                                                 $startChar[2] = chr( $tail );
 738
 739                                                 # If there's another jamo char after this, *don't* try to merge it.
 740                                                 $lastHangul = 1;
 741                                                 continue;
 742                                         }
 743                                 }
 744                         }
 745                         $out .= $startChar;
 746                         $out .= $combining;
 747                         $startChar = $c;
 748                         $combining = '';
 749                         $lastClass = 0;
 750                         $lastHangul = 0;
 751                 }
 752                 $out .= $startChar . $combining;
 753
 754                 return $out;
 755         }
 756
 757         /**
 758          * This is just used for the benchmark, comparing how long it takes to
 759          * interate through a string without really doing anything of substance.
 760          * @param $string string
 761          * @return string
 762          */
 763         static function placebo( $string ) {
 764                 $len = strlen( $string );
 765                 $out = '';
 766                 for ( $i = 0; $i < $len; $i++ ) {
 767                         $out .= $string[$i];
 768                 }
 769
 770                 return $out;
 771         }
 772
 773         /**
 774          * Function to replace some characters that we don't want
 775          * but most of the native normalize functions keep.
 776          *
 777          * @param string $string The string
 778          * @return String String with the character codes replaced.
 779          */
 780         private static function replaceForNativeNormalize( $string ) {
 781                 $string = preg_replace(
 782                         '/[\x00-\x08\x0b\x0c\x0e-\x1f]/',
 783                         UTF8_REPLACEMENT,
 784                         $string );
 785                 $string = str_replace( UTF8_FFFE, UTF8_REPLACEMENT, $string );
 786                 $string = str_replace( UTF8_FFFF, UTF8_REPLACEMENT, $string );
 787
 788                 return $string;
 789         }
 790 }