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