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1# Copyright (c) 2002-2010  International Business Machines Corporation and
2# others. All Rights Reserved.
3#
4#  file:  line_he.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:] - [[:Hebrew:] & [:Letter:]]];
61$HL = [[:Hebrew:] & [:Letter:]];
62$BA = [[:LineBreak =  Break_After:] - [\u2010]];
63$HH = [\u2010];
64$BB = [:LineBreak =  Break_Before:];
65$BK = [:LineBreak =  Mandatory_Break:];
66$B2 = [:LineBreak =  Break_Both:];
67$CB = [:LineBreak =  Contingent_Break:];
68$CL = [:LineBreak =  Close_Punctuation:];
69$CM = [:LineBreak =  Combining_Mark:];
70$CP = [:LineBreak =  Close_Parenthesis:];
71$CR = [:LineBreak =  Carriage_Return:];
72$EX = [:LineBreak =  Exclamation:];
73$GL = [:LineBreak =  Glue:];
74$HY = [:LineBreak =  Hyphen:];
75$H2 = [:LineBreak =  H2:];
76$H3 = [:LineBreak =  H3:];
77$ID = [:LineBreak =  Ideographic:];
78$IN = [:LineBreak =  Inseperable:];
79$IS = [:LineBreak =  Infix_Numeric:];
80$JL = [:LineBreak =  JL:];
81$JV = [:LineBreak =  JV:];
82$JT = [:LineBreak =  JT:];
83$LF = [:LineBreak =  Line_Feed:];
84$NL = [:LineBreak =  Next_Line:];
85$NS = [:LineBreak =  Nonstarter:];
86$NU = [:LineBreak =  Numeric:];
87$OP = [:LineBreak =  Open_Punctuation:];
88$PO = [:LineBreak =  Postfix_Numeric:];
89$PR = [:LineBreak =  Prefix_Numeric:];
90$QU = [:LineBreak =  Quotation:];
91$SA = [:LineBreak =  Complex_Context:];
92$SG = [:LineBreak =  Surrogate:];
93$SP = [:LineBreak =  Space:];
94$SY = [:LineBreak =  Break_Symbols:];
95$WJ = [:LineBreak =  Word_Joiner:];
96$XX = [:LineBreak =  Unknown:];
97$ZW = [:LineBreak =  ZWSpace:];
98
99#   Dictionary character set, for triggering language-based break engines. Currently
100#   limited to LineBreak=Complex_Context. Note that this set only works in Unicode
101#   5.0 or later as the definition of Complex_Context was corrected to include all
102#   characters requiring dictionary break.
103
104$dictionary = [:LineBreak = Complex_Context:];
105
106#
107#  Rule LB1.  By default, treat AI  (characters with ambiguous east Asian width),
108#                               SA  (South East Asian: Thai, Lao, Khmer)
109#                               SG  (Unpaired Surrogates)
110#                               XX  (Unknown, unassigned)
111#                         as $AL  (Alphabetic)
112#
113$ALPlus = [$AL $HL $AI $SA $SG $XX];
114
115#
116#  Combining Marks.   X $CM*  behaves as if it were X.  Rule LB6.
117#
118$ALcm = $ALPlus $CM*;
119$HLcm = $HL $CM*;
120$BAcm = $BA $CM*;
121$HHcm = $HH $CM*;
122$BBcm = $BB $CM*;
123$B2cm = $B2 $CM*;
124$CLcm = $CL $CM*;
125$CPcm = $CP $CM*;
126$EXcm = $EX $CM*;
127$GLcm = $GL $CM*;
128$HYcm = $HY $CM*;
129$H2cm = $H2 $CM*;
130$H3cm = $H3 $CM*;
131$IDcm = $ID $CM*;
132$INcm = $IN $CM*;
133$IScm = $IS $CM*;
134$JLcm = $JL $CM*;
135$JVcm = $JV $CM*;
136$JTcm = $JT $CM*;
137$NScm = $NS $CM*;
138$NUcm = $NU $CM*;
139$OPcm = $OP $CM*;
140$POcm = $PO $CM*;
141$PRcm = $PR $CM*;
142$QUcm = $QU $CM*;
143$SYcm = $SY $CM*;
144$WJcm = $WJ $CM*;
145
146## -------------------------------------------------
147
148!!forward;
149
150#
151#  Each class of character can stand by itself as an unbroken token, with trailing combining stuff
152#
153$ALPlus $CM+;
154$BA $CM+;
155$HH $CM+;
156$BB $CM+;
157$B2 $CM+;
158$CL $CM+;
159$CP $CM+;
160$EX $CM+;
161$GL $CM+;
162$HY $CM+;
163$H2 $CM+;
164$H3 $CM+;
165$ID $CM+;
166$IN $CM+;
167$IS $CM+;
168$JL $CM+;
169$JV $CM+;
170$JT $CM+;
171$NS $CM+;
172$NU $CM+;
173$OP $CM+;
174$PO $CM+;
175$PR $CM+;
176$QU $CM+;
177$SY $CM+;
178$WJ $CM+;
179
180#
181# CAN_CM  is the set of characters that may combine with CM combining chars.
182#         Note that Linebreak UAX 14's concept of a combining char and the rules
183#         for what they can combine with are _very_ different from the rest of Unicode.
184#
185#         Note that $CM itself is left out of this set.  If CM is needed as a base
186#         it must be listed separately in the rule.
187#
188$CAN_CM  = [^$SP $BK $CR $LF $NL $ZW $CM];       # Bases that can   take CMs
189$CANT_CM = [ $SP $BK $CR $LF $NL $ZW $CM];       # Bases that can't take CMs
190
191#
192# AL_FOLLOW  set of chars that can unconditionally follow an AL
193#            Needed in rules where stand-alone $CM s are treated as AL.
194#            Chaining is disabled with CM because it causes other failures,
195#            so for this one case we need to manually list out longer sequences.
196#
197$AL_FOLLOW_NOCM = [$BK $CR $LF $NL $ZW $SP];
198$AL_FOLLOW_CM   = [$CL $CP $EX $IS $SY $WJ $GL $OP $QU $BA $HH $HY $NS $IN $NU $ALPlus];
199$AL_FOLLOW      = [$AL_FOLLOW_NOCM $AL_FOLLOW_CM];
200
201
202#
203#  Rule LB 4, 5    Mandatory (Hard) breaks.
204#
205$LB4Breaks    = [$BK $CR $LF $NL];
206$LB4NonBreaks = [^$BK $CR $LF $NL];
207$CR $LF {100};
208
209#
210#  LB 6    Do not break before hard line breaks.
211#
212$LB4NonBreaks?  $LB4Breaks {100};    # LB 5  do not break before hard breaks.
213$CAN_CM $CM*    $LB4Breaks {100};
214$CM+            $LB4Breaks {100};
215
216# LB 7         x SP
217#              x ZW
218$LB4NonBreaks [$SP $ZW];
219$CAN_CM $CM*  [$SP $ZW];
220$CM+          [$SP $ZW];
221
222#
223# LB 8         Break after zero width space
224#              TODO:  ZW SP* <break>
225#              An engine change is required to write the reverse rule for this.
226#              For now, leave the Unicode 5.2 rule, ZW <break>
227#
228$LB8Breaks    = [$LB4Breaks $ZW];
229$LB8NonBreaks = [[$LB4NonBreaks] - [$ZW]];
230
231
232# LB 9     Combining marks.      X   $CM needs to behave like X, where X is not $SP, $BK $CR $LF $NL
233#                                $CM not covered by the above needs to behave like $AL
234#                                See definition of $CAN_CM.
235
236$CAN_CM $CM+;                   #  Stick together any combining sequences that don't match other rules.
237$CM+;
238
239#
240# LB 11  Do not break before or after WORD JOINER & related characters.
241#
242$CAN_CM $CM*  $WJcm;
243$LB8NonBreaks $WJcm;
244$CM+          $WJcm;
245
246$WJcm $CANT_CM;
247$WJcm $CAN_CM $CM*;
248
249#
250# LB 12  Do not break after NBSP and related characters.
251#         GL  x
252#
253$GLcm $CAN_CM $CM*;
254$GLcm $CANT_CM;
255
256#
257# LB 12a  Do not break before NBSP and related characters ...
258#            [^SP BA HY] x GL
259#
260[[$LB8NonBreaks] - [$SP $BA $HH $HY]] $CM* $GLcm;
261$CM+ GLcm;
262
263
264
265#
266# LB 13   Don't break before ']' or '!' or ';' or '/', even after spaces.
267#
268$LB8NonBreaks $CL;
269$CAN_CM $CM*  $CL;
270$CM+          $CL;              # by rule 10, stand-alone CM behaves as AL
271
272$LB8NonBreaks $CP;
273$CAN_CM $CM*  $CP;
274$CM+          $CP;              # by rule 10, stand-alone CM behaves as AL
275
276$LB8NonBreaks $EX;
277$CAN_CM $CM*  $EX;
278$CM+          $EX;              # by rule 10, stand-alone CM behaves as AL
279
280$LB8NonBreaks $IS;
281$CAN_CM $CM*  $IS;
282$CM+          $IS;              # by rule 10, stand-alone CM behaves as AL
283
284$LB8NonBreaks $SY;
285$CAN_CM $CM*  $SY;
286$CM+          $SY;              # by rule 10, stand-alone CM behaves as AL
287
288
289#
290# LB 14  Do not break after OP, even after spaces
291#
292$OPcm $SP* $CAN_CM $CM*;
293$OPcm $SP* $CANT_CM;
294
295$OPcm $SP+ $CM+ $AL_FOLLOW?;    # by rule 10, stand-alone CM behaves as AL
296
297# LB 15
298$QUcm $SP* $OPcm;
299
300# LB 16
301($CLcm | $CPcm) $SP* $NScm;
302
303# LB 17
304$B2cm $SP* $B2cm;
305
306#
307# LB 18  Break after spaces.
308#
309$LB18NonBreaks = [$LB8NonBreaks - [$SP]];
310$LB18Breaks    = [$LB8Breaks $SP];
311
312
313# LB 19
314#         x QU
315$LB18NonBreaks $CM* $QUcm;
316$CM+                $QUcm;
317
318#         QU  x
319$QUcm .?;
320$QUcm $LB18NonBreaks $CM*;    # Don't let a combining mark go onto $CR, $BK, etc.
321                              #  TODO:  I don't think this rule is needed.
322
323
324# LB 20
325#        <break>  $CB
326#        $CB   <break>
327
328$LB20NonBreaks = [$LB18NonBreaks - $CB];
329
330# LB 21        x   (BA | HY | NS)
331#           BB x
332#
333$LB20NonBreaks $CM* ($BAcm | $HHcm | $HYcm | $NScm);
334
335$BBcm [^$CB];                                  #  $BB  x
336$BBcm $LB20NonBreaks $CM*;
337
338# LB 22
339$ALcm    $INcm;
340$CM+     $INcm;     #  by rule 10, any otherwise unattached CM behaves as AL
341$IDcm    $INcm;
342$INcm    $INcm;
343$NUcm    $INcm;
344
345
346# $LB 23
347$IDcm  $POcm;
348$ALcm  $NUcm;       # includes $LB19
349$CM+   $NUcm;       # Rule 10, any otherwise unattached CM behaves as AL
350$NUcm  $ALcm;
351
352#
353# LB 24
354#
355$PRcm $IDcm;
356$PRcm $ALcm;
357$POcm $ALcm;
358
359#
360# LB 25   Numbers.
361#
362($PRcm | $POcm)? ($OPcm | $HYcm)? $NUcm ($NUcm | $SYcm | $IScm)* ($CLcm | $CPcm)? ($PRcm | $POcm)?;
363
364# LB 26  Do not break a Korean syllable
365#
366$JLcm ($JLcm | $JVcm | $H2cm | $H3cm);
367($JVcm | $H2cm) ($JVcm | $JTcm);
368($JTcm | $H3cm) $JTcm;
369
370# LB 27  Treat korean Syllable Block the same as ID  (don't break it)
371($JLcm | $JVcm | $JTcm | $H2cm | $H3cm) $INcm;
372($JLcm | $JVcm | $JTcm | $H2cm | $H3cm) $POcm;
373$PRcm ($JLcm | $JVcm | $JTcm | $H2cm | $H3cm);
374
375
376# LB 28   Do not break between alphabetics
377#
378$ALcm $ALcm;
379$CM+ $ALcm;      # The $CM+ is from rule 10, an unattached CM is treated as AL
380
381# LB 29
382$IScm $ALcm;
383
384# LB 30
385($ALcm | $NUcm) $OPcm;
386$CM+ $OPcm;         # The $CM+ is from rule 10, an unattached CM is treated as AL.
387$CPcm ($ALcm | $NUcm);
388
389# (LB 31) Add new rule to prevent the break we do not want, this is the behavior change
390$HLcm ($HY | $HH) $ALcm;
391
392#
393#  Reverse Rules.
394#
395## -------------------------------------------------
396
397!!reverse;
398
399$CM+ $ALPlus;
400$CM+ $BA;
401$CM+ $HH;
402$CM+ $BB;
403$CM+ $B2;
404$CM+ $CL;
405$CM+ $CP;
406$CM+ $EX;
407$CM+ $GL;
408$CM+ $HY;
409$CM+ $H2;
410$CM+ $H3;
411$CM+ $ID;
412$CM+ $IN;
413$CM+ $IS;
414$CM+ $JL;
415$CM+ $JV;
416$CM+ $JT;
417$CM+ $NS;
418$CM+ $NU;
419$CM+ $OP;
420$CM+ $PO;
421$CM+ $PR;
422$CM+ $QU;
423$CM+ $SY;
424$CM+ $WJ;
425$CM+;
426
427
428#
429#  Sequences of the form  (shown forwards)
430#      [CANT_CM]  <break>  [CM]  [whatever]
431#  The CM needs to behave as an AL
432#
433$AL_FOLLOW $CM+ / (
434          [$BK $CR $LF $NL $ZW {eof}] |
435          $SP+ $CM+ $SP |
436          $SP+ $CM* ([^$OP $CM $SP] | [$AL {eof}]));   # if LB 14 will match, need to surpress this break.
437                                               #  LB14 says    OP SP* x .
438                                               #    becomes    OP SP* x AL
439                                               #    becomes    OP SP* x CM+ AL_FOLLOW
440                                               #
441                                               # Further note:  the $AL in [$AL {eof}] is only to work around
442                                               #                a rule compiler bug which complains about
443                                               #                empty sets otherwise.
444
445#
446#  Sequences of the form  (shown forwards)
447#      [CANT_CM]  <break> [CM]  <break>  [PR]
448#  The CM needs to behave as an AL
449#  This rule is concerned about getting the second of the two <breaks> in place.
450#
451
452[$PR   ] / $CM+ [$BK $CR $LF $NL $ZW $SP {eof}];
453
454
455
456# LB 4, 5, 5
457
458$LB4Breaks [$LB4NonBreaks-$CM];
459$LB4Breaks $CM+ $CAN_CM;
460$LF $CR;
461
462
463# LB 7         x SP
464#              x ZW
465[$SP $ZW] [$LB4NonBreaks-$CM];
466[$SP $ZW] $CM+ $CAN_CM;
467
468# LB 8 ZW SP* <break>
469#     TODO: to implement this, we need more than one look-ahead hard break in play at a time.
470#           Requires an engine enhancement.
471#   / $SP* $ZW
472
473# LB 9,10  Combining marks.
474#    X   $CM needs to behave like X, where X is not $SP or controls.
475#    $CM not covered by the above needs to behave like $AL
476# Stick together any combining sequences that don't match other rules.
477$CM+ $CAN_CM;
478
479
480# LB 11
481$CM* $WJ $CM* $CAN_CM;
482$CM* $WJ      [$LB8NonBreaks-$CM];
483
484     $CANT_CM $CM* $WJ;
485$CM* $CAN_CM  $CM* $WJ;
486
487# LB 12a
488#      [^SP BA HY] x GL
489#
490$CM* $GL $CM* [$LB8NonBreaks-[$CM $SP $BA $HH $HY]];
491
492# LB 12
493#     GL  x
494#
495$CANT_CM $CM* $GL;
496$CM* $CAN_CM $CM* $GL;
497
498
499# LB 13
500$CL $CM+ $CAN_CM;
501$CP $CM+ $CAN_CM;
502$EX $CM+ $CAN_CM;
503$IS $CM+ $CAN_CM;
504$SY $CM+ $CAN_CM;
505
506$CL [$LB8NonBreaks-$CM];
507$CP [$LB8NonBreaks-$CM];
508$EX [$LB8NonBreaks-$CM];
509$IS [$LB8NonBreaks-$CM];
510$SY [$LB8NonBreaks-$CM];
511
512# Rule 13 & 14 taken together for an edge case.
513#   Match this, shown forward
514#     OP SP+  ($CM+ behaving as $AL) (CL | CP | EX | IS | IY)
515#   This really wants to chain at the $CM+ (which is acting as an $AL)
516#   except for $CM chaining being disabled.
517[$CL $CP $EX $IS $SY] $CM+ $SP+ $CM* $OP;
518
519# LB 14    OP SP* x
520#
521$CM* $CAN_CM    $SP* $CM* $OP;
522     $CANT_CM   $SP* $CM* $OP;
523$AL_FOLLOW? $CM+  $SP $SP* $CM* $OP;     #  by LB 10, behaves like $AL_FOLLOW? $AL $SP* $CM* $OP
524
525     $AL_FOLLOW_NOCM $CM+ $SP+ $CM* $OP;
526$CM* $AL_FOLLOW_CM   $CM+ $SP+ $CM* $OP;
527$SY $CM $SP+ $OP;   # TODO:  Experiment.  Remove.
528
529
530
531# LB 15
532$CM* $OP $SP* $CM* $QU;
533
534# LB 16
535$CM* $NS $SP* $CM* ($CL | $CP);
536
537# LB 17
538$CM* $B2 $SP* $CM* $B2;
539
540# LB 18  break after spaces
541#        Nothing explicit needed here.
542
543
544#
545# LB 19
546#
547$CM* $QU $CM* $CAN_CM;                                #   . x QU
548$CM* $QU      $LB18NonBreaks;
549
550
551$CM* $CAN_CM  $CM* $QU;                               #   QU x .
552     $CANT_CM $CM* $QU;
553
554#
555#  LB 20  Break before and after CB.
556#         nothing needed here.
557#
558
559# LB 21
560$CM* ($BA | $HH | $HY | $NS) $CM* [$LB20NonBreaks-$CM];     #  . x (BA | HY | NS)
561
562$CM* [$LB20NonBreaks-$CM] $CM* $BB;                   #  BB x .
563[^$CB] $CM* $BB;                                      #
564
565
566
567# LB 22
568$CM* $IN $CM* $ALPlus;
569$CM* $IN $CM* $ID;
570$CM* $IN $CM* $IN;
571$CM* $IN $CM* $NU;
572
573# LB 23
574$CM* $PO $CM* $ID;
575$CM* $NU $CM* $ALPlus;
576$CM* $ALPlus $CM* $NU;
577
578# LB 24
579$CM* $ID $CM* $PR;
580$CM* $ALPlus $CM* $PR;
581$CM* $ALPlus $CM* $PO;
582
583
584# LB 25
585($CM* ($PR | $PO))? ($CM* ($CL | $CP))? ($CM* ($NU | $IS | $SY))* $CM* $NU ($CM* ($OP | $HY))? ($CM* ($PR | $PO))?;
586
587# LB 26
588$CM* ($H3 | $H2 | $JV | $JL) $CM* $JL;
589$CM* ($JT | $JV) $CM* ($H2 | $JV);
590$CM* $JT $CM* ($H3 | $JT);
591
592# LB 27
593$CM* $IN $CM* ($H3 | $H2 | $JT | $JV | $JL);
594$CM* $PO $CM* ($H3 | $H2 | $JT | $JV | $JL);
595$CM* ($H3 | $H2 | $JT | $JV | $JL) $CM* $PR;
596
597# LB 28
598$CM* $ALPlus $CM* $ALPlus;
599
600
601# LB 29
602$CM* $ALPlus $CM* $IS;
603
604# LB 30
605$CM* $OP $CM* ($ALPlus | $NU);
606$CM* ($ALPlus | $NU) $CM* $CP;
607
608# (LB 31) Add new rule to prevent the break we do not want, this is the behavior change
609$CM* $ALPlus ($HY | $HH) $CM* $HL;
610
611## -------------------------------------------------
612
613!!safe_reverse;
614
615# LB 9
616$CM+ [^$CM $BK $CR $LF $NL $ZW $SP];
617$CM+ $SP / .;
618
619# LB 14
620$SP+ $CM* $OP;
621
622# LB 15
623$SP+ $CM* $QU;
624
625# LB 16
626$SP+ $CM* ($CL | $CP);
627
628# LB 17
629$SP+ $CM* $B2;
630
631# LB 25
632($CM* ($IS | $SY))+ $CM* $NU;
633($CL | $CP) $CM* ($NU | $IS | $SY);
634
635# For dictionary-based break
636$dictionary $dictionary;
637
638## -------------------------------------------------
639
640!!safe_forward;
641
642# Skip forward over all character classes that are involved in
643#   rules containing patterns with possibly more than one char
644#   of context.
645#
646#  It might be slightly more efficient to have specific rules
647#  instead of one generic one, but only if we could
648#  turn off rule chaining.  We don't want to move more
649#  than necessary.
650#
651[$CM $OP $QU $CL $CP $B2 $PR $HY $SP $dictionary]+ [^$CM $OP $QU $CL $CP $B2 $PR $HY $dictionary];
652$dictionary $dictionary;
653
654