1# Copyright (c) 2002-2010 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 24 for Unicode 6.0 9# http://www.unicode.org/reports/tr14/ 10# 11# TODO: Rule LB 8 remains as it was in Unicode 5.2 12# This is only because of a limitation of ICU break engine implementation, 13# not because the older behavior is desirable. 14 15# 16# Character Classes defined by TR 14. 17# 18 19!!chain; 20!!LBCMNoChain; 21 22 23!!lookAheadHardBreak; 24# 25# !!lookAheadHardBreak Described here because it is (as yet) undocumented elsewhere 26# and only used for the line break rules. 27# 28# It is used in the implementation of rule LB 10 29# which says to treat any combining mark that is not attached to a base 30# character as if it were of class AL (alphabetic). 31# 32# The problem occurs in the reverse rules. 33# 34# Consider a sequence like, with correct breaks as shown 35# LF ID CM AL AL 36# ^ ^ ^ 37# Then consider the sequence without the initial ID (ideographic) 38# LF CM AL AL 39# ^ ^ 40# Our CM, which in the first example was attached to the ideograph, 41# is now unattached, becomes an alpha, and joins in with the other 42# alphas. 43# 44# When iterating forwards, these sequences do not present any problems 45# When iterating backwards, we need to look ahead when encountering 46# a CM to see whether it attaches to something further on or not. 47# (Look-ahead in a reverse rule is looking towards the start) 48# 49# If the CM is unattached, we need to force a break. 50# 51# !!lookAheadHardBreak forces the run time state machine to 52# stop immediately when a look ahead rule ( '/' operator) matches, 53# and set the match position to that of the look-ahead operator, 54# no matter what other rules may be in play at the time. 55# 56# See rule LB 19 for an example. 57# 58 59$AI = [:LineBreak = Ambiguous:]; 60$AL = [:LineBreak = Alphabetic:]; 61$BA = [:LineBreak = Break_After:]; 62$BB = [:LineBreak = Break_Before:]; 63$BK = [:LineBreak = Mandatory_Break:]; 64$B2 = [:LineBreak = Break_Both:]; 65$CB = [:LineBreak = Contingent_Break:]; 66$CL = [:LineBreak = Close_Punctuation:]; 67$CM = [:LineBreak = Combining_Mark:]; 68$CP = [:LineBreak = Close_Parenthesis:]; 69$CR = [:LineBreak = Carriage_Return:]; 70$EX = [:LineBreak = Exclamation:]; 71$GL = [:LineBreak = Glue:]; 72$HY = [:LineBreak = Hyphen:]; 73$H2 = [:LineBreak = H2:]; 74$H3 = [:LineBreak = H3:]; 75$ID = [:LineBreak = Ideographic:]; 76$IN = [:LineBreak = Inseperable:]; 77$IS = [:LineBreak = Infix_Numeric:]; 78$JL = [:LineBreak = JL:]; 79$JV = [:LineBreak = JV:]; 80$JT = [:LineBreak = JT:]; 81$LF = [:LineBreak = Line_Feed:]; 82$NL = [:LineBreak = Next_Line:]; 83$NS = [:LineBreak = Nonstarter:]; 84$NU = [:LineBreak = Numeric:]; 85$OP = [:LineBreak = Open_Punctuation:]; 86$PO = [:LineBreak = Postfix_Numeric:]; 87$PR = [:LineBreak = Prefix_Numeric:]; 88$QU = [:LineBreak = Quotation:]; 89$SA = [:LineBreak = Complex_Context:]; 90$SG = [:LineBreak = Surrogate:]; 91$SP = [:LineBreak = Space:]; 92$SY = [:LineBreak = Break_Symbols:]; 93$WJ = [:LineBreak = Word_Joiner:]; 94$XX = [:LineBreak = Unknown:]; 95$ZW = [:LineBreak = ZWSpace:]; 96 97# Dictionary character set, for triggering language-based break engines. Currently 98# limited to LineBreak=Complex_Context. Note that this set only works in Unicode 99# 5.0 or later as the definition of Complex_Context was corrected to include all 100# characters requiring dictionary break. 101 102$dictionary = [:LineBreak = Complex_Context:]; 103 104# 105# Rule LB1. By default, treat AI (characters with ambiguous east Asian width), 106# SA (South East Asian: Thai, Lao, Khmer) 107# SG (Unpaired Surrogates) 108# XX (Unknown, unassigned) 109# as $AL (Alphabetic) 110# 111$ALPlus = [$AL $AI $SA $SG $XX]; 112 113# 114# Combining Marks. X $CM* behaves as if it were X. Rule LB6. 115# 116$ALcm = $ALPlus $CM*; 117$BAcm = $BA $CM*; 118$BBcm = $BB $CM*; 119$B2cm = $B2 $CM*; 120$CLcm = $CL $CM*; 121$CPcm = $CP $CM*; 122$EXcm = $EX $CM*; 123$GLcm = $GL $CM*; 124$HYcm = $HY $CM*; 125$H2cm = $H2 $CM*; 126$H3cm = $H3 $CM*; 127$IDcm = $ID $CM*; 128$INcm = $IN $CM*; 129$IScm = $IS $CM*; 130$JLcm = $JL $CM*; 131$JVcm = $JV $CM*; 132$JTcm = $JT $CM*; 133$NScm = $NS $CM*; 134$NUcm = $NU $CM*; 135$OPcm = $OP $CM*; 136$POcm = $PO $CM*; 137$PRcm = $PR $CM*; 138$QUcm = $QU $CM*; 139$SYcm = $SY $CM*; 140$WJcm = $WJ $CM*; 141 142## ------------------------------------------------- 143 144!!forward; 145 146# 147# Each class of character can stand by itself as an unbroken token, with trailing combining stuff 148# 149$ALPlus $CM+; 150$BA $CM+; 151$BB $CM+; 152$B2 $CM+; 153$CL $CM+; 154$CP $CM+; 155$EX $CM+; 156$GL $CM+; 157$HY $CM+; 158$H2 $CM+; 159$H3 $CM+; 160$ID $CM+; 161$IN $CM+; 162$IS $CM+; 163$JL $CM+; 164$JV $CM+; 165$JT $CM+; 166$NS $CM+; 167$NU $CM+; 168$OP $CM+; 169$PO $CM+; 170$PR $CM+; 171$QU $CM+; 172$SY $CM+; 173$WJ $CM+; 174 175# 176# CAN_CM is the set of characters that may combine with CM combining chars. 177# Note that Linebreak UAX 14's concept of a combining char and the rules 178# for what they can combine with are _very_ different from the rest of Unicode. 179# 180# Note that $CM itself is left out of this set. If CM is needed as a base 181# it must be listed separately in the rule. 182# 183$CAN_CM = [^$SP $BK $CR $LF $NL $ZW $CM]; # Bases that can take CMs 184$CANT_CM = [ $SP $BK $CR $LF $NL $ZW $CM]; # Bases that can't take CMs 185 186# 187# AL_FOLLOW set of chars that can unconditionally follow an AL 188# Needed in rules where stand-alone $CM s are treated as AL. 189# Chaining is disabled with CM because it causes other failures, 190# so for this one case we need to manually list out longer sequences. 191# 192$AL_FOLLOW_NOCM = [$BK $CR $LF $NL $ZW $SP]; 193$AL_FOLLOW_CM = [$CL $CP $EX $IS $SY $WJ $GL $OP $QU $BA $HY $NS $IN $NU $ALPlus]; 194$AL_FOLLOW = [$AL_FOLLOW_NOCM $AL_FOLLOW_CM]; 195 196 197# 198# Rule LB 4, 5 Mandatory (Hard) breaks. 199# 200$LB4Breaks = [$BK $CR $LF $NL]; 201$LB4NonBreaks = [^$BK $CR $LF $NL]; 202$CR $LF {100}; 203 204# 205# LB 6 Do not break before hard line breaks. 206# 207$LB4NonBreaks? $LB4Breaks {100}; # LB 5 do not break before hard breaks. 208$CAN_CM $CM* $LB4Breaks {100}; 209$CM+ $LB4Breaks {100}; 210 211# LB 7 x SP 212# x ZW 213$LB4NonBreaks [$SP $ZW]; 214$CAN_CM $CM* [$SP $ZW]; 215$CM+ [$SP $ZW]; 216 217# 218# LB 8 Break after zero width space 219# TODO: ZW SP* <break> 220# An engine change is required to write the reverse rule for this. 221# For now, leave the Unicode 5.2 rule, ZW <break> 222# 223$LB8Breaks = [$LB4Breaks $ZW]; 224$LB8NonBreaks = [[$LB4NonBreaks] - [$ZW]]; 225 226 227# LB 9 Combining marks. X $CM needs to behave like X, where X is not $SP, $BK $CR $LF $NL 228# $CM not covered by the above needs to behave like $AL 229# See definition of $CAN_CM. 230 231$CAN_CM $CM+; # Stick together any combining sequences that don't match other rules. 232$CM+; 233 234# 235# LB 11 Do not break before or after WORD JOINER & related characters. 236# 237$CAN_CM $CM* $WJcm; 238$LB8NonBreaks $WJcm; 239$CM+ $WJcm; 240 241$WJcm $CANT_CM; 242$WJcm $CAN_CM $CM*; 243 244# 245# LB 12 Do not break after NBSP and related characters. 246# GL x 247# 248$GLcm $CAN_CM $CM*; 249$GLcm $CANT_CM; 250 251# 252# LB 12a Do not break before NBSP and related characters ... 253# [^SP BA HY] x GL 254# 255[[$LB8NonBreaks] - [$SP $BA $HY]] $CM* $GLcm; 256$CM+ GLcm; 257 258 259 260# 261# LB 13 Don't break before ']' or '!' or ';' or '/', even after spaces. 262# 263$LB8NonBreaks $CL; 264$CAN_CM $CM* $CL; 265$CM+ $CL; # by rule 10, stand-alone CM behaves as AL 266 267$LB8NonBreaks $CP; 268$CAN_CM $CM* $CP; 269$CM+ $CP; # by rule 10, stand-alone CM behaves as AL 270 271$LB8NonBreaks $EX; 272$CAN_CM $CM* $EX; 273$CM+ $EX; # by rule 10, stand-alone CM behaves as AL 274 275$LB8NonBreaks $IS; 276$CAN_CM $CM* $IS; 277$CM+ $IS; # by rule 10, stand-alone CM behaves as AL 278 279$LB8NonBreaks $SY; 280$CAN_CM $CM* $SY; 281$CM+ $SY; # by rule 10, stand-alone CM behaves as AL 282 283 284# 285# LB 14 Do not break after OP, even after spaces 286# 287$OPcm $SP* $CAN_CM $CM*; 288$OPcm $SP* $CANT_CM; 289 290$OPcm $SP+ $CM+ $AL_FOLLOW?; # by rule 10, stand-alone CM behaves as AL 291 292# LB 15 293$QUcm $SP* $OPcm; 294 295# LB 16 296($CLcm | $CPcm) $SP* $NScm; 297 298# LB 17 299$B2cm $SP* $B2cm; 300 301# 302# LB 18 Break after spaces. 303# 304$LB18NonBreaks = [$LB8NonBreaks - [$SP]]; 305$LB18Breaks = [$LB8Breaks $SP]; 306 307 308# LB 19 309# x QU 310$LB18NonBreaks $CM* $QUcm; 311$CM+ $QUcm; 312 313# QU x 314$QUcm .?; 315$QUcm $LB18NonBreaks $CM*; # Don't let a combining mark go onto $CR, $BK, etc. 316 # TODO: I don't think this rule is needed. 317 318 319# LB 20 320# <break> $CB 321# $CB <break> 322 323$LB20NonBreaks = [$LB18NonBreaks - $CB]; 324 325# LB 21 x (BA | HY | NS) 326# BB x 327# 328$LB20NonBreaks $CM* ($BAcm | $HYcm | $NScm); 329 330$BBcm [^$CB]; # $BB x 331$BBcm $LB20NonBreaks $CM*; 332 333# LB 22 334$ALcm $INcm; 335$CM+ $INcm; # by rule 10, any otherwise unattached CM behaves as AL 336$IDcm $INcm; 337$INcm $INcm; 338$NUcm $INcm; 339 340 341# $LB 23 342$IDcm $POcm; 343$ALcm $NUcm; # includes $LB19 344$CM+ $NUcm; # Rule 10, any otherwise unattached CM behaves as AL 345$NUcm $ALcm; 346 347# 348# LB 24 349# 350$PRcm $IDcm; 351$PRcm $ALcm; 352$POcm $ALcm; 353 354# 355# LB 25 Numbers. 356# 357($PRcm | $POcm)? ($OPcm | $HYcm)? $NUcm ($NUcm | $SYcm | $IScm)* ($CLcm | $CPcm)? ($PRcm | $POcm)?; 358 359# LB 26 Do not break a Korean syllable 360# 361$JLcm ($JLcm | $JVcm | $H2cm | $H3cm); 362($JVcm | $H2cm) ($JVcm | $JTcm); 363($JTcm | $H3cm) $JTcm; 364 365# LB 27 Treat korean Syllable Block the same as ID (don't break it) 366($JLcm | $JVcm | $JTcm | $H2cm | $H3cm) $INcm; 367($JLcm | $JVcm | $JTcm | $H2cm | $H3cm) $POcm; 368$PRcm ($JLcm | $JVcm | $JTcm | $H2cm | $H3cm); 369 370 371# LB 28 Do not break between alphabetics 372# 373$ALcm $ALcm; 374$CM+ $ALcm; # The $CM+ is from rule 10, an unattached CM is treated as AL 375 376# LB 29 377$IScm $ALcm; 378 379# LB 30 380($ALcm | $NUcm) $OPcm; 381$CM+ $OPcm; # The $CM+ is from rule 10, an unattached CM is treated as AL. 382$CPcm ($ALcm | $NUcm); 383 384 385# 386# Reverse Rules. 387# 388## ------------------------------------------------- 389 390!!reverse; 391 392$CM+ $ALPlus; 393$CM+ $BA; 394$CM+ $BB; 395$CM+ $B2; 396$CM+ $CL; 397$CM+ $CP; 398$CM+ $EX; 399$CM+ $GL; 400$CM+ $HY; 401$CM+ $H2; 402$CM+ $H3; 403$CM+ $ID; 404$CM+ $IN; 405$CM+ $IS; 406$CM+ $JL; 407$CM+ $JV; 408$CM+ $JT; 409$CM+ $NS; 410$CM+ $NU; 411$CM+ $OP; 412$CM+ $PO; 413$CM+ $PR; 414$CM+ $QU; 415$CM+ $SY; 416$CM+ $WJ; 417$CM+; 418 419 420# 421# Sequences of the form (shown forwards) 422# [CANT_CM] <break> [CM] [whatever] 423# The CM needs to behave as an AL 424# 425$AL_FOLLOW $CM+ / ( 426 [$BK $CR $LF $NL $ZW {eof}] | 427 $SP+ $CM+ $SP | 428 $SP+ $CM* ([^$OP $CM $SP] | [$AL {eof}])); # if LB 14 will match, need to surpress this break. 429 # LB14 says OP SP* x . 430 # becomes OP SP* x AL 431 # becomes OP SP* x CM+ AL_FOLLOW 432 # 433 # Further note: the $AL in [$AL {eof}] is only to work around 434 # a rule compiler bug which complains about 435 # empty sets otherwise. 436 437# 438# Sequences of the form (shown forwards) 439# [CANT_CM] <break> [CM] <break> [PR] 440# The CM needs to behave as an AL 441# This rule is concerned about getting the second of the two <breaks> in place. 442# 443 444[$PR ] / $CM+ [$BK $CR $LF $NL $ZW $SP {eof}]; 445 446 447 448# LB 4, 5, 5 449 450$LB4Breaks [$LB4NonBreaks-$CM]; 451$LB4Breaks $CM+ $CAN_CM; 452$LF $CR; 453 454 455# LB 7 x SP 456# x ZW 457[$SP $ZW] [$LB4NonBreaks-$CM]; 458[$SP $ZW] $CM+ $CAN_CM; 459 460# LB 8 ZW SP* <break> 461# TODO: to implement this, we need more than one look-ahead hard break in play at a time. 462# Requires an engine enhancement. 463# / $SP* $ZW 464 465# LB 9,10 Combining marks. 466# X $CM needs to behave like X, where X is not $SP or controls. 467# $CM not covered by the above needs to behave like $AL 468# Stick together any combining sequences that don't match other rules. 469$CM+ $CAN_CM; 470 471 472# LB 11 473$CM* $WJ $CM* $CAN_CM; 474$CM* $WJ [$LB8NonBreaks-$CM]; 475 476 $CANT_CM $CM* $WJ; 477$CM* $CAN_CM $CM* $WJ; 478 479# LB 12a 480# [^SP BA HY] x GL 481# 482$CM* $GL $CM* [$LB8NonBreaks-[$CM $SP $BA $HY]]; 483 484# LB 12 485# GL x 486# 487$CANT_CM $CM* $GL; 488$CM* $CAN_CM $CM* $GL; 489 490 491# LB 13 492$CL $CM+ $CAN_CM; 493$CP $CM+ $CAN_CM; 494$EX $CM+ $CAN_CM; 495$IS $CM+ $CAN_CM; 496$SY $CM+ $CAN_CM; 497 498$CL [$LB8NonBreaks-$CM]; 499$CP [$LB8NonBreaks-$CM]; 500$EX [$LB8NonBreaks-$CM]; 501$IS [$LB8NonBreaks-$CM]; 502$SY [$LB8NonBreaks-$CM]; 503 504# Rule 13 & 14 taken together for an edge case. 505# Match this, shown forward 506# OP SP+ ($CM+ behaving as $AL) (CL | CP | EX | IS | IY) 507# This really wants to chain at the $CM+ (which is acting as an $AL) 508# except for $CM chaining being disabled. 509[$CL $CP $EX $IS $SY] $CM+ $SP+ $CM* $OP; 510 511# LB 14 OP SP* x 512# 513$CM* $CAN_CM $SP* $CM* $OP; 514 $CANT_CM $SP* $CM* $OP; 515$AL_FOLLOW? $CM+ $SP $SP* $CM* $OP; # by LB 10, behaves like $AL_FOLLOW? $AL $SP* $CM* $OP 516 517 $AL_FOLLOW_NOCM $CM+ $SP+ $CM* $OP; 518$CM* $AL_FOLLOW_CM $CM+ $SP+ $CM* $OP; 519$SY $CM $SP+ $OP; # TODO: Experiment. Remove. 520 521 522 523# LB 15 524$CM* $OP $SP* $CM* $QU; 525 526# LB 16 527$CM* $NS $SP* $CM* ($CL | $CP); 528 529# LB 17 530$CM* $B2 $SP* $CM* $B2; 531 532# LB 18 break after spaces 533# Nothing explicit needed here. 534 535 536# 537# LB 19 538# 539$CM* $QU $CM* $CAN_CM; # . x QU 540$CM* $QU $LB18NonBreaks; 541 542 543$CM* $CAN_CM $CM* $QU; # QU x . 544 $CANT_CM $CM* $QU; 545 546# 547# LB 20 Break before and after CB. 548# nothing needed here. 549# 550 551# LB 21 552$CM* ($BA | $HY | $NS) $CM* [$LB20NonBreaks-$CM]; # . x (BA | HY | NS) 553 554$CM* [$LB20NonBreaks-$CM] $CM* $BB; # BB x . 555[^$CB] $CM* $BB; # 556 557 558 559# LB 22 560$CM* $IN $CM* $ALPlus; 561$CM* $IN $CM* $ID; 562$CM* $IN $CM* $IN; 563$CM* $IN $CM* $NU; 564 565# LB 23 566$CM* $PO $CM* $ID; 567$CM* $NU $CM* $ALPlus; 568$CM* $ALPlus $CM* $NU; 569 570# LB 24 571$CM* $ID $CM* $PR; 572$CM* $ALPlus $CM* $PR; 573$CM* $ALPlus $CM* $PO; 574 575 576# LB 25 577($CM* ($PR | $PO))? ($CM* ($CL | $CP))? ($CM* ($NU | $IS | $SY))* $CM* $NU ($CM* ($OP | $HY))? ($CM* ($PR | $PO))?; 578 579# LB 26 580$CM* ($H3 | $H2 | $JV | $JL) $CM* $JL; 581$CM* ($JT | $JV) $CM* ($H2 | $JV); 582$CM* $JT $CM* ($H3 | $JT); 583 584# LB 27 585$CM* $IN $CM* ($H3 | $H2 | $JT | $JV | $JL); 586$CM* $PO $CM* ($H3 | $H2 | $JT | $JV | $JL); 587$CM* ($H3 | $H2 | $JT | $JV | $JL) $CM* $PR; 588 589# LB 28 590$CM* $ALPlus $CM* $ALPlus; 591 592 593# LB 29 594$CM* $ALPlus $CM* $IS; 595 596# LB 30 597$CM* $OP $CM* ($ALPlus | $NU); 598$CM* ($ALPlus | $NU) $CM* $CP; 599 600 601## ------------------------------------------------- 602 603!!safe_reverse; 604 605# LB 9 606$CM+ [^$CM $BK $CR $LF $NL $ZW $SP]; 607$CM+ $SP / .; 608 609# LB 14 610$SP+ $CM* $OP; 611 612# LB 15 613$SP+ $CM* $QU; 614 615# LB 16 616$SP+ $CM* ($CL | $CP); 617 618# LB 17 619$SP+ $CM* $B2; 620 621# LB 25 622($CM* ($IS | $SY))+ $CM* $NU; 623($CL | $CP) $CM* ($NU | $IS | $SY); 624 625# For dictionary-based break 626$dictionary $dictionary; 627 628## ------------------------------------------------- 629 630!!safe_forward; 631 632# Skip forward over all character classes that are involved in 633# rules containing patterns with possibly more than one char 634# of context. 635# 636# It might be slightly more efficient to have specific rules 637# instead of one generic one, but only if we could 638# turn off rule chaining. We don't want to move more 639# than necessary. 640# 641[$CM $OP $QU $CL $CP $B2 $PR $HY $SP $dictionary]+ [^$CM $OP $QU $CL $CP $B2 $PR $HY $dictionary]; 642$dictionary $dictionary; 643 644