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