includes/normal/UtfNormal.php

   1 <?php
   2 /**
   3  * Unicode normalization routines
   4  *
   5  * Copyright © 2004 Brion Vibber <brion@pobox.com>
   6  * http://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 deterimine 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                 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                                                                 $replace[] = array( UTF8_REPLACEMENT,
 395                                                                                     $base + $i + 1 - strlen( $sequence ),
 396                                                                                     strlen( $sequence ) );
 397                                                                 $head = '';
 398                                                                 continue;
 399                                                         }
 400                                                 }
 401                                         }
 402
 403                                         if( isset( $utfCheckOrCombining[$sequence] ) ) {
 404                                                 # If it's NO or MAYBE, we'll have to rip
 405                                                 # the string apart and put it back together.
 406                                                 # That's going to be mighty slow.
 407                                                 $looksNormal = false;
 408                                         }
 409
 410                                         # The sequence is legal!
 411                                         $head = '';
 412                                 } elseif( $c < "\x80" ) {
 413                                         # ASCII byte.
 414                                         $head = '';
 415                                 } elseif( $c < "\xc0" ) {
 416                                         # Illegal tail bytes
 417                                         if( $head == '' ) {
 418                                                 # Out of the blue!
 419                                                 $replace[] = array( UTF8_REPLACEMENT, $base + $i, 1 );
 420                                         } else {
 421                                                 # Don't add if we're continuing a broken sequence;
 422                                                 # we already put a replacement character when we looked
 423                                                 # at the broken sequence.
 424                                                 $replace[] = array( '', $base + $i, 1 );
 425                                         }
 426                                 } else {
 427                                         # Miscellaneous freaks.
 428                                         $replace[] = array( UTF8_REPLACEMENT, $base + $i, 1 );
 429                                         $head = '';
 430                                 }
 431                         }
 432                         $base += $chunk;
 433                 }
 434                 if( count( $replace ) ) {
 435                         # There were illegal UTF-8 sequences we need to fix up.
 436                         $out = '';
 437                         $last = 0;
 438                         foreach( $replace as $rep ) {
 439                                 list( $replacement, $start, $length ) = $rep;
 440                                 if( $last < $start ) {
 441                                         $out .= substr( $string, $last, $start - $last );
 442                                 }
 443                                 $out .= $replacement;
 444                                 $last = $start + $length;
 445                         }
 446                         if( $last < strlen( $string ) ) {
 447                                 $out .= substr( $string, $last );
 448                         }
 449                         $string = $out;
 450                 }
 451                 return $looksNormal;
 452         }
 453
 454         # These take a string and run the normalization on them, without
 455         # checking for validity or any optimization etc. Input must be
 456         # VALID UTF-8!
 457         /**
 458          * @param $string string
 459          * @return string
 460          * @private
 461          */
 462         static function NFC( $string ) {
 463                 return UtfNormal::fastCompose( UtfNormal::NFD( $string ) );
 464         }
 465
 466         /**
 467          * @param $string string
 468          * @return string
 469          * @private
 470          */
 471         static function NFD( $string ) {
 472                 UtfNormal::loadData();
 473
 474                 return UtfNormal::fastCombiningSort(
 475                         UtfNormal::fastDecompose( $string, self::$utfCanonicalDecomp ) );
 476         }
 477
 478         /**
 479          * @param $string string
 480          * @return string
 481          * @private
 482          */
 483         static function NFKC( $string ) {
 484                 return UtfNormal::fastCompose( UtfNormal::NFKD( $string ) );
 485         }
 486
 487         /**
 488          * @param $string string
 489          * @return string
 490          * @private
 491          */
 492         static function NFKD( $string ) {
 493                 if( !isset( self::$utfCompatibilityDecomp ) ) {
 494                         require_once( 'UtfNormalDataK.inc' );
 495                 }
 496                 return self::fastCombiningSort(
 497                         self::fastDecompose( $string, self::$utfCompatibilityDecomp ) );
 498         }
 499
 500
 501         /**
 502          * Perform decomposition of a UTF-8 string into either D or KD form
 503          * (depending on which decomposition map is passed to us).
 504          * Input is assumed to be *valid* UTF-8. Invalid code will break.
 505          * @private
 506          * @param $string String: valid UTF-8 string
 507          * @param $map Array: hash of expanded decomposition map
 508          * @return string a UTF-8 string decomposed, not yet normalized (needs sorting)
 509          */
 510         static function fastDecompose( $string, $map ) {
 511                 UtfNormal::loadData();
 512                 $len = strlen( $string );
 513                 $out = '';
 514                 for( $i = 0; $i < $len; $i++ ) {
 515                         $c = $string[$i];
 516                         $n = ord( $c );
 517                         if( $n < 0x80 ) {
 518                                 # ASCII chars never decompose
 519                                 # THEY ARE IMMORTAL
 520                                 $out .= $c;
 521                                 continue;
 522                         } elseif( $n >= 0xf0 ) {
 523                                 $c = substr( $string, $i, 4 );
 524                                 $i += 3;
 525                         } elseif( $n >= 0xe0 ) {
 526                                 $c = substr( $string, $i, 3 );
 527                                 $i += 2;
 528                         } elseif( $n >= 0xc0 ) {
 529                                 $c = substr( $string, $i, 2 );
 530                                 $i++;
 531                         }
 532                         if( isset( $map[$c] ) ) {
 533                                 $out .= $map[$c];
 534                                 continue;
 535                         } else {
 536                                 if( $c >= UTF8_HANGUL_FIRST && $c <= UTF8_HANGUL_LAST ) {
 537                                         # Decompose a hangul syllable into jamo;
 538                                         # hardcoded for three-byte UTF-8 sequence.
 539                                         # A lookup table would be slightly faster,
 540                                         # but adds a lot of memory & disk needs.
 541                                         #
 542                                         $index = ( (ord( $c[0] ) & 0x0f) << 12
 543                                                  | (ord( $c[1] ) & 0x3f) <<  6
 544                                                  | (ord( $c[2] ) & 0x3f) )
 545                                                - UNICODE_HANGUL_FIRST;
 546                                         $l = intval( $index / UNICODE_HANGUL_NCOUNT );
 547                                         $v = intval( ($index % UNICODE_HANGUL_NCOUNT) / UNICODE_HANGUL_TCOUNT);
 548                                         $t = $index % UNICODE_HANGUL_TCOUNT;
 549                                         $out .= "\xe1\x84" . chr( 0x80 + $l ) . "\xe1\x85" . chr( 0xa1 + $v );
 550                                         if( $t >= 25 ) {
 551                                                 $out .= "\xe1\x87" . chr( 0x80 + $t - 25 );
 552                                         } elseif( $t ) {
 553                                                 $out .= "\xe1\x86" . chr( 0xa7 + $t );
 554                                         }
 555                                         continue;
 556                                 }
 557                         }
 558                         $out .= $c;
 559                 }
 560                 return $out;
 561         }
 562
 563         /**
 564          * Sorts combining characters into canonical order. This is the
 565          * final step in creating decomposed normal forms D and KD.
 566          * @private
 567          * @param $string String: a valid, decomposed UTF-8 string. Input is not validated.
 568          * @return string a UTF-8 string with combining characters sorted in canonical order
 569          */
 570         static function fastCombiningSort( $string ) {
 571                 UtfNormal::loadData();
 572                 $len = strlen( $string );
 573                 $out = '';
 574                 $combiners = array();
 575                 $lastClass = -1;
 576                 for( $i = 0; $i < $len; $i++ ) {
 577                         $c = $string[$i];
 578                         $n = ord( $c );
 579                         if( $n >= 0x80 ) {
 580                                 if( $n >= 0xf0 ) {
 581                                         $c = substr( $string, $i, 4 );
 582                                         $i += 3;
 583                                 } elseif( $n >= 0xe0 ) {
 584                                         $c = substr( $string, $i, 3 );
 585                                         $i += 2;
 586                                 } elseif( $n >= 0xc0 ) {
 587                                         $c = substr( $string, $i, 2 );
 588                                         $i++;
 589                                 }
 590                                 if( isset( self::$utfCombiningClass[$c] ) ) {
 591                                         $lastClass = self::$utfCombiningClass[$c];
 592                                         if( isset( $combiners[$lastClass] ) ) {
 593                                                 $combiners[$lastClass] .= $c;
 594                                         } else {
 595                                                 $combiners[$lastClass] = $c;
 596                                         }
 597                                         continue;
 598                                 }
 599                         }
 600                         if( $lastClass ) {
 601                                 ksort( $combiners );
 602                                 $out .= implode( '', $combiners );
 603                                 $combiners = array();
 604                         }
 605                         $out .= $c;
 606                         $lastClass = 0;
 607                 }
 608                 if( $lastClass ) {
 609                         ksort( $combiners );
 610                         $out .= implode( '', $combiners );
 611                 }
 612                 return $out;
 613         }
 614
 615         /**
 616          * Produces canonically composed sequences, i.e. normal form C or KC.
 617          *
 618          * @private
 619          * @param $string String: a valid UTF-8 string in sorted normal form D or KD. Input is not validated.
 620          * @return string a UTF-8 string with canonical precomposed characters used where possible
 621          */
 622         static function fastCompose( $string ) {
 623                 UtfNormal::loadData();
 624                 $len = strlen( $string );
 625                 $out = '';
 626                 $lastClass = -1;
 627                 $lastHangul = 0;
 628                 $startChar = '';
 629                 $combining = '';
 630                 $x1 = ord(substr(UTF8_HANGUL_VBASE, 0, 1));
 631                 $x2 = ord(substr(UTF8_HANGUL_TEND, 0, 1));
 632                 for( $i = 0; $i < $len; $i++ ) {
 633                         $c = $string[$i];
 634                         $n = ord( $c );
 635                         if( $n < 0x80 ) {
 636                                 # No combining characters here...
 637                                 $out .= $startChar;
 638                                 $out .= $combining;
 639                                 $startChar = $c;
 640                                 $combining = '';
 641                                 $lastClass = 0;
 642                                 continue;
 643                         } elseif( $n >= 0xf0 ) {
 644                                 $c = substr( $string, $i, 4 );
 645                                 $i += 3;
 646                         } elseif( $n >= 0xe0 ) {
 647                                 $c = substr( $string, $i, 3 );
 648                                 $i += 2;
 649                         } elseif( $n >= 0xc0 ) {
 650                                 $c = substr( $string, $i, 2 );
 651                                 $i++;
 652                         }
 653                         $pair = $startChar . $c;
 654                         if( $n > 0x80 ) {
 655                                 if( isset( self::$utfCombiningClass[$c] ) ) {
 656                                         # A combining char; see what we can do with it
 657                                         $class = self::$utfCombiningClass[$c];
 658                                         if( !empty( $startChar ) &&
 659                                                 $lastClass < $class &&
 660                                                 $class > 0 &&
 661                                                 isset( self::$utfCanonicalComp[$pair] ) ) {
 662                                                 $startChar = self::$utfCanonicalComp[$pair];
 663                                                 $class = 0;
 664                                         } else {
 665                                                 $combining .= $c;
 666                                         }
 667                                         $lastClass = $class;
 668                                         $lastHangul = 0;
 669                                         continue;
 670                                 }
 671                         }
 672                         # New start char
 673                         if( $lastClass == 0 ) {
 674                                 if( isset( self::$utfCanonicalComp[$pair] ) ) {
 675                                         $startChar = self::$utfCanonicalComp[$pair];
 676                                         $lastHangul = 0;
 677                                         continue;
 678                                 }
 679                                 if( $n >= $x1 && $n <= $x2 ) {
 680                                         # WARNING: Hangul code is painfully slow.
 681                                         # I apologize for this ugly, ugly code; however
 682                                         # performance is even more teh suck if we call
 683                                         # out to nice clean functions. Lookup tables are
 684                                         # marginally faster, but require a lot of space.
 685                                         #
 686                                         if( $c >= UTF8_HANGUL_VBASE &&
 687                                                 $c <= UTF8_HANGUL_VEND &&
 688                                                 $startChar >= UTF8_HANGUL_LBASE &&
 689                                                 $startChar <= UTF8_HANGUL_LEND ) {
 690                                                 #
 691                                                 #$lIndex = utf8ToCodepoint( $startChar ) - UNICODE_HANGUL_LBASE;
 692                                                 #$vIndex = utf8ToCodepoint( $c ) - UNICODE_HANGUL_VBASE;
 693                                                 $lIndex = ord( $startChar[2] ) - 0x80;
 694                                                 $vIndex = ord( $c[2]         ) - 0xa1;
 695
 696                                                 $hangulPoint = UNICODE_HANGUL_FIRST +
 697                                                         UNICODE_HANGUL_TCOUNT *
 698                                                         (UNICODE_HANGUL_VCOUNT * $lIndex + $vIndex);
 699
 700                                                 # Hardcode the limited-range UTF-8 conversion:
 701                                                 $startChar = chr( $hangulPoint >> 12 & 0x0f | 0xe0 ) .
 702                                                                          chr( $hangulPoint >>  6 & 0x3f | 0x80 ) .
 703                                                                          chr( $hangulPoint       & 0x3f | 0x80 );
 704                                                 $lastHangul = 0;
 705                                                 continue;
 706                                         } elseif( $c >= UTF8_HANGUL_TBASE &&
 707                                                           $c <= UTF8_HANGUL_TEND &&
 708                                                           $startChar >= UTF8_HANGUL_FIRST &&
 709                                                           $startChar <= UTF8_HANGUL_LAST &&
 710                                                           !$lastHangul ) {
 711                                                 # $tIndex = utf8ToCodepoint( $c ) - UNICODE_HANGUL_TBASE;
 712                                                 $tIndex = ord( $c[2] ) - 0xa7;
 713                                                 if( $tIndex < 0 ) $tIndex = ord( $c[2] ) - 0x80 + (0x11c0 - 0x11a7);
 714
 715                                                 # Increment the code point by $tIndex, without
 716                                                 # the function overhead of decoding and recoding UTF-8
 717                                                 #
 718                                                 $tail = ord( $startChar[2] ) + $tIndex;
 719                                                 if( $tail > 0xbf ) {
 720                                                         $tail -= 0x40;
 721                                                         $mid = ord( $startChar[1] ) + 1;
 722                                                         if( $mid > 0xbf ) {
 723                                                                 $startChar[0] = chr( ord( $startChar[0] ) + 1 );
 724                                                                 $mid -= 0x40;
 725                                                         }
 726                                                         $startChar[1] = chr( $mid );
 727                                                 }
 728                                                 $startChar[2] = chr( $tail );
 729
 730                                                 # If there's another jamo char after this, *don't* try to merge it.
 731                                                 $lastHangul = 1;
 732                                                 continue;
 733                                         }
 734                                 }
 735                         }
 736                         $out .= $startChar;
 737                         $out .= $combining;
 738                         $startChar = $c;
 739                         $combining = '';
 740                         $lastClass = 0;
 741                         $lastHangul = 0;
 742                 }
 743                 $out .= $startChar . $combining;
 744                 return $out;
 745         }
 746
 747         /**
 748          * This is just used for the benchmark, comparing how long it takes to
 749          * interate through a string without really doing anything of substance.
 750          * @param $string string
 751          * @return string
 752          */
 753         static function placebo( $string ) {
 754                 $len = strlen( $string );
 755                 $out = '';
 756                 for( $i = 0; $i < $len; $i++ ) {
 757                         $out .= $string[$i];
 758                 }
 759                 return $out;
 760         }
 761         /**
 762          * Function to replace some characters that we don't want
 763          * but most of the native normalize functions keep.
 764          *
 765          * @param $string String The string
 766          * @return String String with the character codes replaced.
 767          */
 768         private static function replaceForNativeNormalize( $string ) {
 769                 $string = preg_replace(
 770                         '/[\x00-\x08\x0b\x0c\x0e-\x1f]/',
 771                         UTF8_REPLACEMENT,
 772                         $string );
 773                 $string = str_replace( UTF8_FFFE, UTF8_REPLACEMENT, $string );
 774                 $string = str_replace( UTF8_FFFF, UTF8_REPLACEMENT, $string );
 775                 return $string;
 776         }
 777 }