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