1 # Copyright (c) 2002-2009 International Business Machines Corporation and 2 # others. All Rights Reserved. 3 # 4 # file: line.txt 5 # 6 # Line Breaking Rules 7 # Implement default line breaking as defined by 8 # Unicode Standard Annex #14 Revision 22 for Unicode 5.1 9 # http://www.unicode.org/reports/tr14/ 10 11 12 13 # 14 # Character Classes defined by TR 14. 15 # 16 17 !!chain; 18 !!LBCMNoChain; 19 20 21 !!lookAheadHardBreak; 22 # 23 # !!lookAheadHardBreak Described here because it is (as yet) undocumented elsewhere 24 # and only used for the line break rules. 25 # 26 # It is used in the implementation of rule LB 10 27 # which says to treat any combining mark that is not attached to a base 28 # character as if it were of class AL (alphabetic). 29 # 30 # The problem occurs in the reverse rules. 31 # 32 # Consider a sequence like, with correct breaks as shown 33 # LF ID CM AL AL 34 # ^ ^ ^ 35 # Then consider the sequence without the initial ID (ideographic) 36 # LF CM AL AL 37 # ^ ^ 38 # Our CM, which in the first example was attached to the ideograph, 39 # is now unattached, becomes an alpha, and joins in with the other 40 # alphas. 41 # 42 # When iterating forwards, these sequences do not present any problems 43 # When iterating backwards, we need to look ahead when encountering 44 # a CM to see whether it attaches to something further on or not. 45 # (Look-ahead in a reverse rule is looking towards the start) 46 # 47 # If the CM is unattached, we need to force a break. 48 # 49 # !!lookAheadHardBreak forces the run time state machine to 50 # stop immediately when a look ahead rule ( '/' operator) matches, 51 # and set the match position to that of the look-ahead operator, 52 # no matter what other rules may be in play at the time. 53 # 54 # See rule LB 19 for an example. 55 # 56 57 $AI = [:LineBreak = Ambiguous:]; 58 $AL = [:LineBreak = Alphabetic:]; 59 $BA = [:LineBreak = Break_After:]; 60 $BB = [:LineBreak = Break_Before:]; 61 $BK = [:LineBreak = Mandatory_Break:]; 62 $B2 = [:LineBreak = Break_Both:]; 63 $CB = [:LineBreak = Contingent_Break:]; 64 $CL = [:LineBreak = Close_Punctuation:]; 65 $CM = [:LineBreak = Combining_Mark:]; 66 $CR = [:LineBreak = Carriage_Return:]; 67 $EX = [:LineBreak = Exclamation:]; 68 $GL = [:LineBreak = Glue:]; 69 $HY = [:LineBreak = Hyphen:]; 70 $H2 = [:LineBreak = H2:]; 71 $H3 = [:LineBreak = H3:]; 72 $IDDelta = [\ufe45\ufe46\ufe51]; 73 $ID = [[:LineBreak = Ideographic:] - $IDDelta]; 74 $IN = [:LineBreak = Inseperable:]; 75 $IS = [:LineBreak = Infix_Numeric:]; 76 $JL = [:LineBreak = JL:]; 77 $JV = [:LineBreak = JV:]; 78 $JT = [:LineBreak = JT:]; 79 $LF = [:LineBreak = Line_Feed:]; 80 $NL = [:LineBreak = Next_Line:]; 81 $NS = [[:LineBreak = Nonstarter:] $IDDelta \u23b5]; 82 $NU = [:LineBreak = Numeric:]; 83 $OP = [:LineBreak = Open_Punctuation:]; 84 $PO = [:LineBreak = Postfix_Numeric:]; 85 $PR = [:LineBreak = Prefix_Numeric:]; 86 $QU = [:LineBreak = Quotation:]; 87 $SA = [:LineBreak = Complex_Context:]; 88 $SG = [:LineBreak = Surrogate:]; 89 $SP = [:LineBreak = Space:]; 90 $SY = [:LineBreak = Break_Symbols:]; 91 $WJ = [:LineBreak = Word_Joiner:]; 92 $XX = [:LineBreak = Unknown:]; 93 $ZW = [:LineBreak = ZWSpace:]; 94 95 # Dictionary character set, for triggering language-based break engines. Currently 96 # limited to LineBreak=Complex_Context. Note that this set only works in Unicode 97 # 5.0 or later as the definition of Complex_Context was corrected to include all 98 # characters requiring dictionary break. 99 100 $dictionary = [:LineBreak = Complex_Context:]; 101 102 # 103 # Rule LB1. By default, treat AI (characters with ambiguous east Asian width), 104 # SA (South East Asian: Thai, Lao, Khmer) 105 # SG (Unpaired Surrogates) 106 # XX (Unknown, unassigned) 107 # as $AL (Alphabetic) 108 # 109 $ALPlus = [$AL $AI $SA $SG $XX]; 110 111 # 112 # Combining Marks. X $CM* behaves as if it were X. Rule LB6. 113 # 114 $ALcm = $ALPlus $CM*; 115 $BAcm = $BA $CM*; 116 $BBcm = $BB $CM*; 117 $B2cm = $B2 $CM*; 118 $CLcm = $CL $CM*; 119 $EXcm = $EX $CM*; 120 $GLcm = $GL $CM*; 121 $HYcm = $HY $CM*; 122 $H2cm = $H2 $CM*; 123 $H3cm = $H3 $CM*; 124 $IDcm = $ID $CM*; 125 $INcm = $IN $CM*; 126 $IScm = $IS $CM*; 127 $JLcm = $JL $CM*; 128 $JVcm = $JV $CM*; 129 $JTcm = $JT $CM*; 130 $NScm = $NS $CM*; 131 $NUcm = $NU $CM*; 132 $OPcm = $OP $CM*; 133 $POcm = $PO $CM*; 134 $PRcm = $PR $CM*; 135 $QUcm = $QU $CM*; 136 $SYcm = $SY $CM*; 137 $WJcm = $WJ $CM*; 138 139 ## ------------------------------------------------- 140 141 !!forward; 142 143 # 144 # Each class of character can stand by itself as an unbroken token, with trailing combining stuff 145 # 146 $ALPlus $CM+; 147 $BA $CM+; 148 $BB $CM+; 149 $B2 $CM+; 150 $CL $CM+; 151 $EX $CM+; 152 $GL $CM+; 153 $HY $CM+; 154 $H2 $CM+; 155 $H3 $CM+; 156 $ID $CM+; 157 $IN $CM+; 158 $IS $CM+; 159 $JL $CM+; 160 $JV $CM+; 161 $JT $CM+; 162 $NS $CM+; 163 $NU $CM+; 164 $OP $CM+; 165 $PO $CM+; 166 $PR $CM+; 167 $QU $CM+; 168 $SY $CM+; 169 $WJ $CM+; 170 171 # 172 # CAN_CM is the set of characters that may combine with CM combining chars. 173 # Note that Linebreak UAX 14's concept of a combining char and the rules 174 # for what they can combine with are _very_ different from the rest of Unicode. 175 # 176 # Note that $CM itself is left out of this set. If CM is needed as a base 177 # it must be listed separately in the rule. 178 # 179 $CAN_CM = [^$SP $BK $CR $LF $NL $ZW $CM]; # Bases that can take CMs 180 $CANT_CM = [ $SP $BK $CR $LF $NL $ZW $CM]; # Bases that can't take CMs 181 182 # 183 # AL_FOLLOW set of chars that can unconditionally follow an AL 184 # Needed in rules where stand-alone $CM s are treated as AL. 185 # Chaining is disabled with CM because it causes other failures, 186 # so for this one case we need to manually list out longer sequences. 187 # 188 $AL_FOLLOW_NOCM = [$BK $CR $LF $NL $ZW $SP]; 189 $AL_FOLLOW_CM = [$CL $EX $IS $SY $WJ $GL $QU $BA $HY $NS $IN $NU $ALPlus]; 190 $AL_FOLLOW = [$AL_FOLLOW_NOCM $AL_FOLLOW_CM]; 191 192 193 # 194 # Rule LB 4, 5 Mandatory (Hard) breaks. 195 # 196 $LB4Breaks = [$BK $CR $LF $NL]; 197 $LB4NonBreaks = [^$BK $CR $LF $NL]; 198 $CR $LF {100}; 199 200 # 201 # LB 6 Do not break before hard line breaks. 202 # 203 $LB4NonBreaks? $LB4Breaks {100}; # LB 5 do not break before hard breaks. 204 $CAN_CM $CM* $LB4Breaks {100}; 205 $CM+ $LB4Breaks {100}; 206 207 # LB 7 x SP 208 # x ZW 209 $LB4NonBreaks [$SP $ZW]; 210 $CAN_CM $CM* [$SP $ZW]; 211 $CM+ [$SP $ZW]; 212 213 # 214 # LB 8 Break after zero width space 215 # 216 $LB8Breaks = [$LB4Breaks $ZW]; 217 $LB8NonBreaks = [[$LB4NonBreaks] - [$ZW]]; 218 219 220 # LB 9 Combining marks. X $CM needs to behave like X, where X is not $SP, $BK $CR $LF $NL 221 # $CM not covered by the above needs to behave like $AL 222 # See definition of $CAN_CM. 223 224 $CAN_CM $CM+; # Stick together any combining sequences that don't match other rules. 225 $CM+; 226 227 # 228 # LB 11 Do not break before or after WORD JOINER & related characters. 229 # 230 $CAN_CM $CM* $WJcm; 231 $LB8NonBreaks $WJcm; 232 $CM+ $WJcm; 233 234 $WJcm $CANT_CM; 235 $WJcm $CAN_CM $CM*; 236 237 # 238 # LB 12 Do not break after NBSP and related characters. 239 # GL x 240 # 241 $GLcm $CAN_CM $CM*; 242 $GLcm $CANT_CM; 243 244 # 245 # LB 12a Do not break before NBSP and related characters ... 246 # [^SP BA HY] x GL 247 # 248 [[$LB8NonBreaks] - [$SP $BA $HY]] $CM* $GLcm; 249 $CM+ GLcm; 250 251 252 253 # 254 # LB 13 Don't break before ']' or '!' or ';' or '/', even after spaces. 255 # 256 $LB8NonBreaks $CL; 257 $CAN_CM $CM* $CL; 258 $CM+ $CL; # by rule 10, stand-alone CM behaves as AL 259 260 $LB8NonBreaks $EX; 261 $CAN_CM $CM* $EX; 262 $CM+ $EX; # by rule 10, stand-alone CM behaves as AL 263 264 $LB8NonBreaks $IS; 265 $CAN_CM $CM* $IS; 266 $CM+ $IS; # by rule 10, stand-alone CM behaves as AL 267 268 $LB8NonBreaks $SY; 269 $CAN_CM $CM* $SY; 270 $CM+ $SY; # by rule 10, stand-alone CM behaves as AL 271 272 273 # 274 # LB 14 Do not break after OP, even after spaces 275 # 276 $OPcm $SP* $CAN_CM $CM*; 277 $OPcm $SP* $CANT_CM; 278 279 $OPcm $SP+ $CM+ $AL_FOLLOW?; # by rule 10, stand-alone CM behaves as AL 280 281 # LB 15 282 $QUcm $SP* $OPcm; 283 284 # LB 16 285 $CLcm $SP* $NScm; 286 287 # LB 17 288 $B2cm $SP* $B2cm; 289 290 # 291 # LB 18 Break after spaces. 292 # 293 $LB18NonBreaks = [$LB8NonBreaks - [$SP]]; 294 $LB18Breaks = [$LB8Breaks $SP]; 295 296 297 # LB 19 298 # x QU 299 $LB18NonBreaks $CM* $QUcm; 300 $CM+ $QUcm; 301 302 # QU x 303 $QUcm .?; 304 $QUcm $LB18NonBreaks $CM*; # Don't let a combining mark go onto $CR, $BK, etc. 305 # TODO: I don't think this rule is needed. 306 307 308 # LB 20 309 # <break> $CB 310 # $CB <break> 311 312 $LB20NonBreaks = [$LB18NonBreaks - $CB]; 313 314 # LB 21 x (BA | HY | NS) 315 # BB x 316 # 317 $LB20NonBreaks $CM* ($BAcm | $HYcm | $NScm); 318 319 $BBcm [^$CB]; # $BB x 320 $BBcm $LB20NonBreaks $CM*; 321 322 # LB 22 323 $ALcm $INcm; 324 $CM+ $INcm; # by rule 10, any otherwise unattached CM behaves as AL 325 $IDcm $INcm; 326 $INcm $INcm; 327 $NUcm $INcm; 328 329 330 # $LB 23 331 $IDcm $POcm; 332 $ALcm $NUcm; # includes $LB19 333 $CM+ $NUcm; # Rule 10, any otherwise unattached CM behaves as AL 334 $NUcm $ALcm; 335 336 # 337 # LB 24 338 # 339 $PRcm $IDcm; 340 $PRcm $ALcm; 341 $POcm $ALcm; 342 343 # 344 # LB 25 Numbers. 345 # 346 ($PRcm | $POcm)? ($OPcm | $HYcm)? $NUcm ($NUcm | $SYcm | $IScm)* $CLcm? ($PRcm | $POcm)?; 347 348 # LB 26 Do not break a Korean syllable 349 # 350 $JLcm ($JLcm | $JVcm | $H2cm | $H3cm); 351 ($JVcm | $H2cm) ($JVcm | $JTcm); 352 ($JTcm | $H3cm) $JTcm; 353 354 # LB 27 Treat korean Syllable Block the same as ID (don't break it) 355 ($JLcm | $JVcm | $JTcm | $H2cm | $H3cm) $INcm; 356 ($JLcm | $JVcm | $JTcm | $H2cm | $H3cm) $POcm; 357 $PRcm ($JLcm | $JVcm | $JTcm | $H2cm | $H3cm); 358 359 360 # LB 28 Do not break between alphabetics 361 # 362 $ALcm $ALcm; 363 $CM+ $ALcm; # The $CM+ is from rule 10, an unattached CM is treated as AL 364 365 # LB 29 366 $IScm $ALcm; 367 368 369 # 370 # Reverse Rules. 371 # 372 ## ------------------------------------------------- 373 374 !!reverse; 375 376 $CM+ $ALPlus; 377 $CM+ $BA; 378 $CM+ $BB; 379 $CM+ $B2; 380 $CM+ $CL; 381 $CM+ $EX; 382 $CM+ $GL; 383 $CM+ $HY; 384 $CM+ $H2; 385 $CM+ $H3; 386 $CM+ $ID; 387 $CM+ $IN; 388 $CM+ $IS; 389 $CM+ $JL; 390 $CM+ $JV; 391 $CM+ $JT; 392 $CM+ $NS; 393 $CM+ $NU; 394 $CM+ $OP; 395 $CM+ $PO; 396 $CM+ $PR; 397 $CM+ $QU; 398 $CM+ $SY; 399 $CM+ $WJ; 400 $CM+; 401 402 403 # 404 # Sequences of the form (shown forwards) 405 # [CANT_CM] <break> [CM] [whatever] 406 # The CM needs to behave as an AL 407 # 408 $AL_FOLLOW $CM+ / ( 409 [$BK $CR $LF $NL $ZW {eof}] | 410 $SP+ $CM+ $SP | 411 $SP+ $CM* ([^$OP $CM $SP] | [$AL {eof}])); # if LB 14 will match, need to surpress this break. 412 # LB14 says OP SP* x . 413 # becomes OP SP* x AL 414 # becomes OP SP* x CM+ AL_FOLLOW 415 # 416 # Further note: the $AL in [$AL {eof}] is only to work around 417 # a rule compiler bug which complains about 418 # empty sets otherwise. 419 420 # 421 # Sequences of the form (shown forwards) 422 # [CANT_CM] <break> [CM] <break> [PR] 423 # The CM needs to behave as an AL 424 # This rule is concerned about getting the second of the two <breaks> in place. 425 # 426 427 [$PR ] / $CM+ [$BK $CR $LF $NL $ZW $SP {eof}]; 428 429 430 431 # LB 4, 5, 5 432 433 $LB4Breaks [$LB4NonBreaks-$CM]; 434 $LB4Breaks $CM+ $CAN_CM; 435 $LF $CR; 436 437 438 # LB 7 x SP 439 # x ZW 440 [$SP $ZW] [$LB4NonBreaks-$CM]; 441 [$SP $ZW] $CM+ $CAN_CM; 442 443 # LB 8 Break after zero width space 444 445 446 # LB 9,10 Combining marks. 447 # X $CM needs to behave like X, where X is not $SP or controls. 448 # $CM not covered by the above needs to behave like $AL 449 # Stick together any combining sequences that don't match other rules. 450 $CM+ $CAN_CM; 451 452 453 # LB 11 454 $CM* $WJ $CM* $CAN_CM; 455 $CM* $WJ [$LB8NonBreaks-$CM]; 456 457 $CANT_CM $CM* $WJ; 458 $CM* $CAN_CM $CM* $WJ; 459 460 # LB 12a 461 # [^SP BA HY] x GL 462 # 463 $CM* $GL $CM* [$LB8NonBreaks-[$CM $SP $BA $HY]]; 464 465 # LB 12 466 # GL x 467 # 468 $CANT_CM $CM* $GL; 469 $CM* $CAN_CM $CM* $GL; 470 471 472 # LB 13 473 $CL $CM+ $CAN_CM; 474 $EX $CM+ $CAN_CM; 475 $IS $CM+ $CAN_CM; 476 $SY $CM+ $CAN_CM; 477 478 $CL [$LB8NonBreaks-$CM]; 479 $EX [$LB8NonBreaks-$CM]; 480 $IS [$LB8NonBreaks-$CM]; 481 $SY [$LB8NonBreaks-$CM]; 482 483 # Rule 13 & 14 taken together for an edge case. 484 # Match this, shown forward 485 # OP SP+ ($CM+ behaving as $AL) (CL | EX | IS | IY) 486 # This really wants to chain at the $CM+ (which is acting as an $AL) 487 # except for $CM chaining being disabled. 488 [$CL $EX $IS $SY] $CM+ $SP+ $CM* $OP; 489 490 # LB 14 OP SP* x 491 # 492 $CM* $CAN_CM $SP* $CM* $OP; 493 $CANT_CM $SP* $CM* $OP; 494 $AL_FOLLOW? $CM+ $SP $SP* $CM* $OP; # by LB 10, behaves like $AL_FOLLOW? $AL $SP* $CM* $OP 495 496 $AL_FOLLOW_NOCM $CM+ $SP+ $CM* $OP; 497 $CM* $AL_FOLLOW_CM $CM+ $SP+ $CM* $OP; 498 $SY $CM $SP+ $OP; # TODO: Experiment. Remove. 499 500 501 502 # LB 15 503 $CM* $OP $SP* $CM* $QU; 504 505 # LB 16 506 $CM* $NS $SP* $CM* $CL; 507 508 # LB 17 509 $CM* $B2 $SP* $CM* $B2; 510 511 # LB 18 break after spaces 512 # Nothing explicit needed here. 513 514 515 # 516 # LB 19 517 # 518 $CM* $QU $CM* $CAN_CM; # . x QU 519 $CM* $QU $LB18NonBreaks; 520 521 522 $CM* $CAN_CM $CM* $QU; # QU x . 523 $CANT_CM $CM* $QU; 524 525 # 526 # LB 20 Break before and after CB. 527 # nothing needed here. 528 # 529 530 # LB 21 531 $CM* ($BA | $HY | $NS) $CM* [$LB20NonBreaks-$CM]; # . x (BA | HY | NS) 532 533 $CM* [$LB20NonBreaks-$CM] $CM* $BB; # BB x . 534 [^$CB] $CM* $BB; # 535 536 537 538 # LB 22 539 $CM* $IN $CM* $ALPlus; 540 $CM* $IN $CM* $ID; 541 $CM* $IN $CM* $IN; 542 $CM* $IN $CM* $NU; 543 544 # LB 23 545 $CM* $PO $CM* $ID; 546 $CM* $NU $CM* $ALPlus; 547 $CM* $ALPlus $CM* $NU; 548 549 # LB 24 550 $CM* $ID $CM* $PR; 551 $CM* $ALPlus $CM* $PR; 552 $CM* $ALPlus $CM* $PO; 553 554 555 # LB 25 556 ($CM* ($PR | $PO))? ($CM* $CL)? ($CM* ($NU | $IS | $SY))* $CM* $NU ($CM* ($OP | $HY))? ($CM* ($PR | $PO))?; 557 558 # LB 26 559 $CM* ($H3 | $H2 | $JV | $JL) $CM* $JL; 560 $CM* ($JT | $JV) $CM* ($H2 | $JV); 561 $CM* $JT $CM* ($H3 | $JT); 562 563 # LB 27 564 $CM* $IN $CM* ($H3 | $H2 | $JT | $JV | $JL); 565 $CM* $PO $CM* ($H3 | $H2 | $JT | $JV | $JL); 566 $CM* ($H3 | $H2 | $JT | $JV | $JL) $CM* $PR; 567 568 # LB 28 569 $CM* $ALPlus $CM* $ALPlus; 570 571 572 # LB 29 573 $CM* $ALPlus $CM* $IS; 574 575 576 ## ------------------------------------------------- 577 578 !!safe_reverse; 579 580 # LB 9 581 $CM+ [^$CM $BK $CR $LF $NL $ZW $SP]; 582 $CM+ $SP / .; 583 584 # LB 14 585 $SP+ $CM* $OP; 586 587 # LB 15 588 $SP+ $CM* $QU; 589 590 # LB 16 591 $SP+ $CM* $CL; 592 593 # LB 17 594 $SP+ $CM* $B2; 595 596 # LB 25 597 ($CM* ($IS | $SY))+ $CM* $NU; 598 $CL $CM* ($NU | $IS | $SY); 599 600 # For dictionary-based break 601 $dictionary $dictionary; 602 603 ## ------------------------------------------------- 604 605 !!safe_forward; 606 607 # Skip forward over all character classes that are involved in 608 # rules containing patterns with possibly more than one char 609 # of context. 610 # 611 # It might be slightly more efficient to have specific rules 612 # instead of one generic one, but only if we could 613 # turn off rule chaining. We don't want to move more 614 # than necessary. 615 # 616 [$CM $OP $QU $CL $B2 $PR $HY $SP $dictionary]+ [^$CM $OP $QU $CL $B2 $PR $HY $dictionary]; 617 $dictionary $dictionary; 618 619
