includes/normal/UtfNormal.php

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