568 lines
14 KiB
Plaintext
568 lines
14 KiB
Plaintext
# Copyright (c) 2002-2005 International Business Machines Corporation and
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# others. All Rights Reserved.
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#
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# file: line.txt
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#
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# Line Breaking Rules
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# Implement default line breaking as defined by Unicode TR 14.
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#
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#
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# Character Classes defined by TR 14.
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#
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!!chain;
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!!LBCMNoChain;
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!!lookAheadHardBreak;
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#
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# !!lookAheadHardBreak Described here because it is (as yet) undocumented elsewhere
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# and only used for the line break rules.
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#
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# It is used in the implementation of the incredibly annoying rule LB 7c
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# which says to treat any combining mark that is not attached to a base
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# character as if it were of class AL (alphabetic).
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#
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# The problem occurs in the reverse rules.
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#
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# Consider a sequence like, with correct breaks as shown
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# LF ID CM AL AL
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# ^ ^ ^
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# Then consider the sequence without the initial ID (ideographic)
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# LF CM AL AL
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# ^ ^
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# Our CM, which in the first example was attached to the ideograph,
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# is now unattached, becomes an alpha, and joins in with the other
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# alphas.
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#
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# When interating forwards, these sequences do not present any problems
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# When interating backwards, we need to look ahead when encountering
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# a CM to see whether it attaches to something further on or not.
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# (Look-ahead in a reverse rule is looking towards the start)
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#
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# If the CM is unattached, we need to force a break.
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#
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# !!lookAheadHardBreak forces the run time state machine to
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# stop immediately when a look ahead rule ( '/' operator) matches,
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# and set the match position to that of the look-ahead operator,
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# no matter what other rules may be in play at the time.
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#
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# See rule LB 19 for an example.
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#
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$AI = [:LineBreak = Ambiguous:];
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$AL = [:LineBreak = Alphabetic:];
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$BA = [:LineBreak = Break_After:];
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$BB = [:LineBreak = Break_Before:];
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$BK = [:LineBreak = Mandatory_Break:];
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$B2 = [:LineBreak = Break_Both:];
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$CB = [:LineBreak = Contingent_Break:];
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$CL = [:LineBreak = Close_Punctuation:];
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$CM = [:LineBreak = Combining_Mark:];
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$CR = [:LineBreak = Carriage_Return:];
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$EX = [:LineBreak = Exclamation:];
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$GL = [:LineBreak = Glue:];
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$HY = [:LineBreak = Hyphen:];
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$H2 = [:LineBreak = H2:];
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$H3 = [:LineBreak = H3:];
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$ID = [:LineBreak = Ideographic:];
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$IN = [:LineBreak = Inseperable:];
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$IS = [:LineBreak = Infix_Numeric:];
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$JL = [:LineBreak = JL:];
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$JV = [:LineBreak = JV:];
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$JT = [:LineBreak = JT:];
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$LF = [:LineBreak = Line_Feed:];
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$NL = [:LineBreak = Next_Line:];
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$NS = [:LineBreak = Nonstarter:];
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$NU = [:LineBreak = Numeric:];
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$OP = [:LineBreak = Open_Punctuation:];
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$PO = [:LineBreak = Postfix_Numeric:];
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$PR = [:LineBreak = Prefix_Numeric:];
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$QU = [:LineBreak = Quotation:];
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$SA = [:LineBreak = Complex_Context:];
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$SG = [:LineBreak = Surrogate:];
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$SP = [:LineBreak = Space:];
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$SY = [:LineBreak = Break_Symbols:];
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$WJ = [:LineBreak = Word_Joiner:];
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$XX = [:LineBreak = Unknown:];
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$ZW = [:LineBreak = ZWSpace:];
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#
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# Rule LB1. By default, treat AI (characters with ambiguous east Asian width),
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# SA (South East Asian: Thai, Lao, Khmer)
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# XX (Unknown, unassigned)
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# as $AL (Alphabetic)
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#
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$ALPlus = [$AL $AI $SA $XX];
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#
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# Combining Marks. X $CM* behaves as if it were X. Rule LB6.
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#
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$ALcm = $ALPlus $CM*;
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$BAcm = $BA $CM*;
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$BBcm = $BB $CM*;
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$B2cm = $B2 $CM*;
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$CLcm = $CL $CM*;
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$EXcm = $EX $CM*;
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$GLcm = $GL $CM*;
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$HYcm = $HY $CM*;
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$H2cm = $H2 $CM*;
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$H3cm = $H3 $CM*;
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$IDcm = $ID $CM*;
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$INcm = $IN $CM*;
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$IScm = $IS $CM*;
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$JLcm = $JL $CM*;
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$JVcm = $JV $CM*;
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$JTcm = $JT $CM*;
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$NScm = $NS $CM*;
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$NUcm = $NU $CM*;
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$OPcm = $OP $CM*;
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$POcm = $PO $CM*;
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$PRcm = $PR $CM*;
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$QUcm = $QU $CM*;
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$SYcm = $SY $CM*;
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$WJcm = $WJ $CM*;
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## -------------------------------------------------
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!!forward;
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#
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# Each class of character can stand by itself as an unbroken token, with trailing combining stuff
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#
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$ALPlus $CM+;
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$BA $CM+;
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$BB $CM+;
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$B2 $CM+;
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$CL $CM+;
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$EX $CM+;
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$GL $CM+;
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$HY $CM+;
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$H2 $CM+;
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$H3 $CM+;
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$ID $CM+;
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$IN $CM+;
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$IS $CM+;
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$JL $CM+;
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$JV $CM+;
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$JT $CM+;
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$NS $CM+;
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$NU $CM+;
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$OP $CM+;
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$PO $CM+;
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$PR $CM+;
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$QU $CM+;
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$SY $CM+;
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$WJ $CM+;
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#
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# CAN_CM is the set of characters that may combine with CM combining chars.
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# Note that Linebreak UAX 14's concept of a combining char and the rules
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# for what they can combine with are _very_ different from the rest of Unicode.
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#
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# Note that $CM itself is left out of this set. If CM is needed as a base
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# it must be listed separately in the rule.
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#
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$CAN_CM = [^$BK $CR $LF $NL $ZW $SP $CM]; # Bases that can take CMs
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$CANT_CM = [ $BK $CR $LF $NL $ZW $SP $CM]; # Bases that can't take CMs
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#
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# AL_FOLLOW set of chars that can unconditionally follow an AL
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# Needed in rules where stand-alone $CM s are treated as AL.
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# Chaining is disabled with CM because it causes other failures,
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# so for this one case we need to manually list out longer sequences.
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#
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$AL_FOLLOW_NOCM = [$BK $CR $LF $NL $ZW $SP];
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$AL_FOLLOW_CM = [$CL $EX $IS $SY $WJ $GL $QU $BA $HY $NS $IN $NU $ALPlus];
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$AL_FOLLOW = [$AL_FOLLOW_NOCM $AL_FOLLOW_CM];
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#
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# Rule LB 3 Mandatory (Hard) breaks.
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#
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$LB3Breaks = [$BK $CR $LF $NL];
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$LB3NonBreaks = [^$BK $CR $LF $NL];
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$LB3NonBreaks? $LB3Breaks {100}; # LB 3c do not break before hard breaks.
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$CAN_CM $CM* $LB3Breaks {100};
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$CM+ $LB3Breaks {100};
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$CR $LF {100};
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# LB 4 x SP
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# x ZW
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$LB3NonBreaks [$SP $ZW];
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$CAN_CM $CM* [$SP $ZW];
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$CM+ [$SP $ZW];
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# LB 5 Break after zero width space
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$LB5Breaks = [$LB3Breaks $ZW];
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$LB5NonBreaks = [[$LB3NonBreaks] - [$ZW]];
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# LB 7 Combining marks. X $CM needs to behave like X, where X is not $SP, $BK $CR $LF $NL
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# $CM not covered by the above needs to behave like $AL
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# See definition of $CAN_CM.
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$CAN_CM $CM+; # Stick together any combining sequences that don't match other rules.
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$CM+;
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#
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# LB 8
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#
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$LB5NonBreaks $CL;
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$CAN_CM $CM* $CL;
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$CM+ $CL; # by rule 7c, stand-alone CM behaves as AL
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$LB5NonBreaks $EX;
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$CAN_CM $CM* $EX;
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$CM+ $EX; # by rule 7c, stand-alone CM behaves as AL
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$LB5NonBreaks $IS;
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$CAN_CM $CM* $IS;
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$CM+ $IS; # by rule 7c, stand-alone CM behaves as AL
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$LB5NonBreaks $SY;
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$CAN_CM $CM* $SY;
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$CM+ $SY; # by rule 7c, stand-alone CM behaves as AL
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#
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# LB 9
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#
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$OPcm $SP* $CAN_CM $CM*;
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$OPcm $SP* $CANT_CM;
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$OPcm $SP+ $CM+ $AL_FOLLOW?; # by rule 7c, stand-alone CM behaves as AL
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# LB 10
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$QUcm $SP* $OPcm;
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# LB 11
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$CLcm $SP* $NScm;
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# LB 11a
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$B2cm $SP* $B2cm;
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# LB 11b Word Joiner
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#
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$CAN_CM $CM* $WJcm;
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$LB5NonBreaks $WJcm;
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$CM+ $WJcm;
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$WJcm [^$CAN_CM];
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$WJcm $CAN_CM $CM*;
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# LB 12
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$LB12NonBreaks = [$LB5NonBreaks - [$SP]];
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$LB12Breaks = [$LB5Breaks $SP];
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# LB 13
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# x GL
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$LB12NonBreaks $CM* $GLcm;
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$CM+ $GLcm;
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# GL x
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#
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$GLcm $LB12Breaks;
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$GLcm $LB12NonBreaks $CM*; # Don't let a combining mark go onto $CR, $BK, etc.
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# TODO: I don't think we need this rule.
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# All but $CM will chain off of preceding rule.
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# $GLcm will pick up the CM case by itself.
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# LB 14
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# x QU
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$LB12NonBreaks $CM* $QUcm;
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$CM+ $QUcm;
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# QU x
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$QUcm .?;
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$QUcm $LB12NonBreaks $CM*; # Don't let a combining mark go onto $CR, $BK, etc.
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# TODO: I don't think this rule is needed.
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# LB 14a
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# <break> $CB
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# $CB <break>
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$LB14NonBreaks = [$LB12NonBreaks - $CB];
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# LB 15
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$LB14NonBreaks $CM* ($BAcm | $HYcm | $NScm);
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$BBcm [^$CB]; # $BB x
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$BBcm $LB14NonBreaks $CM*;
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# LB 16
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$ALcm $INcm;
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$CM+ $INcm; # by rule 7c, any otherwise unattached CM behaves as AL
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$IDcm $INcm;
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$INcm $INcm;
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$NUcm $INcm;
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# $LB 17
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$IDcm $POcm;
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$ALcm $NUcm; # includes $LB19
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$CM+ $NUcm; # Rule 7c, any otherwise unattached CM behaves as AL
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$NUcm $ALcm;
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# LB 18
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$PRcm? ($OPcm | $HYcm)? $NUcm ($NUcm | $SYcm | $IScm)* $CLcm? $POcm?;
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$PRcm $ALcm;
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$PRcm $IDcm;
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# LB 18b Do not break a Korean syllable
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$JLcm ($JLcm | $JVcm | $H2cm | $H3cm);
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($JVcm | $H2cm) ($JVcm | $JTcm);
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($JTcm | $H3cm) $JTcm;
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# LB 18c Treat korean Syllable Block the same as ID (don't break it)
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($JLcm | $JVcm | $JTcm | $H2cm | $H3cm) $INcm;
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($JLcm | $JVcm | $JTcm | $H2cm | $H3cm) $POcm;
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$PRcm ($JLcm | $JVcm | $JTcm | $H2cm | $H3cm);
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# LB 19
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$ALcm $ALcm;
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$CM+ $ALcm; # The $CM+ is from rule 7C, and unattached CM is treated as AL
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# LB 19b
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$IScm $ALcm;
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#
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# Reverse Rules.
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#
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## -------------------------------------------------
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!!reverse;
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$CM+ $ALPlus;
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$CM+ $BA;
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$CM+ $BB;
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$CM+ $B2;
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$CM+ $CL;
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$CM+ $EX;
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$CM+ $GL;
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$CM+ $HY;
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$CM+ $H2;
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$CM+ $H3;
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$CM+ $ID;
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$CM+ $IN;
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$CM+ $IS;
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$CM+ $JL;
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$CM+ $JV;
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$CM+ $JT;
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$CM+ $NS;
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$CM+ $NU;
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$CM+ $OP;
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$CM+ $PO;
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$CM+ $PR;
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$CM+ $QU;
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$CM+ $SY;
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$CM+ $WJ;
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$CM+;
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#
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# Sequences of the form (shown forwards)
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# [CANT_CM] <break> [CM] [whatever]
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# The CM needs to behave as an AL
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#
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$AL_FOLLOW $CM+ / (
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[$BK $CR $LF $NL $ZW {eof}] |
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$SP+ $CM+ $SP |
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$SP+ $CM* ([^$OP $CM $SP] | [$AL {eof}])); # if LB9 will match, need to surpress this break.
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# LB9 says OP SP* x .
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# becomes OP SP* x AL
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# becomes OP SP* x CM+ AL_FOLLOW
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#
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# Further note: the $AL in [$AL {eof}] is only to work around
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# a rule compiler bug which complains about
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# empty sets otherwise.
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#
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# Sequences of the form (shown forwards)
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# [CANT_CM] <break> [CM] <break> [PR]
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# The CM needs to behave as an AL
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# This rule is concerned about getting the second of the two <breaks> in place.
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#
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[$PR ] / $CM+ [$BK $CR $LF $NL $ZW $SP {eof}];
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# LB 3
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$LB3Breaks [$LB3NonBreaks-$CM];
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$LB3Breaks $CM+ $CAN_CM;
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$LF $CR;
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# LB 4 x SP
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# x ZW
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[$SP $ZW] [$LB3NonBreaks-$CM];
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[$SP $ZW] $CM+ $CAN_CM;
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# LB 5 Break after zero width space
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# LB 7 Combining marks.
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# X $CM needs to behave like X, where X is not $SP or controls.
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# $CM not covered by the above needs to behave like $AL
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# Stick together any combining sequences that don't match other rules.
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$CM+ $CAN_CM;
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# LB 8
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$CL $CM+ $CAN_CM;
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$EX $CM+ $CAN_CM;
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$IS $CM+ $CAN_CM;
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$SY $CM+ $CAN_CM;
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$CL [$LB5NonBreaks-$CM];
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$EX [$LB5NonBreaks-$CM];
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$IS [$LB5NonBreaks-$CM];
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$SY [$LB5NonBreaks-$CM];
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# Rule 9 & 8 together.
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# This really wants to chain at the $CM+ (which is acting as an $AL)
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# except for $CM chaining being disabled.
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[$CL $EX $IS $SY] $CM+ $SP+ $CM* $OP;
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# LB 9 OP SP* x
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#
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$CM* $CAN_CM $SP* $CM* $OP;
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$CANT_CM $SP* $CM* $OP;
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$AL_FOLLOW? $CM+ $SP $SP* $CM* $OP; # by LB 7, behaves like $AL_FOLLOW? $AL $SP* $CM* $OP
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$AL_FOLLOW_NOCM $CM+ $SP+ $CM* $OP;
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$CM* $AL_FOLLOW_CM $CM+ $SP+ $CM* $OP;
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$SY $CM $SP+ $OP; # Experiment. Remove.
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# LB 10
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$CM* $OP $SP* $CM* $QU;
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# LB 11
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$CM* $NS $SP* $CM* $CL;
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# LB 11a
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$CM* $B2 $SP* $CM* $B2;
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# LB 11b
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$CM* $WJ $CM* $CAN_CM;
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$CM* $WJ [$LB5NonBreaks-$CM];
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$CANT_CM $CM* $WJ;
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$CM* $CAN_CM $CM* $WJ;
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# LB 12
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# LB 13
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# x GL
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#
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$CM* $GL $CM* [$LB12NonBreaks-$CM];
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#
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# GL x
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#
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$CANT_CM $CM* $GL;
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$CM* $CAN_CM $CM* $GL;
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#
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# LB 14
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#
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$CM* $QU $CM* $CAN_CM; # . x QU
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$CM* $QU $LB12NonBreaks;
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$CM* $CAN_CM $CM* $QU; # QU x .
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$CANT_CM $CM* $QU;
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# LB 15
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$CM* ($BA | $HY | $NS) $CM* [$LB14NonBreaks-$CM]; # . x (BA | HY | NS)
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$CM* [$LB14NonBreaks-$CM] $CM* $BB; # BB x .
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[^$CB] $CM* $BB; #
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# LB 16
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$CM* $IN $CM* $ALPlus;
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$CM* $IN $CM* $ID;
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$CM* $IN $CM* $IN;
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$CM* $IN $CM* $NU;
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# $LB 17
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$CM* $PO $CM* $ID;
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$CM* $NU $CM* $ALPlus;
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$CM* $ALPlus $CM* $NU;
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# LB 18
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($CM* $PO)? ($CM* $CL)? ($CM* ($NU | $IS | $SY))* $CM* $NU ($CM* ($OP | $HY))? ($CM* $PR)?;
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$CM* $ALPlus $CM* $PR;
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$CM* $ID $CM* $PR;
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# LB 18b
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$CM* ($H3 | $H2 | $JV | $JL) $CM* $JL;
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$CM* ($JT | $JV) $CM* ($H2 | $JV);
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$CM* $JT $CM* ($H3 | $JT);
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# LB 18c
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$CM* $IN $CM* ($H3 | $H2 | $JT | $JV | $JL);
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$CM* $PO $CM* ($H3 | $H2 | $JT | $JV | $JL);
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$CM* ($H3 | $H2 | $JT | $JV | $JL) $CM* $PR;
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|
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# LB 19
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|
$CM* $ALPlus $CM* $ALPlus;
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|
|
|
|
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# LB 19b
|
|
$CM* $ALPlus $CM* $IS;
|
|
|
|
|
|
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## -------------------------------------------------
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|
|
|
!!safe_reverse;
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|
|
|
# LB 7
|
|
$CM+ [^$CM $BK $CR $LF $NL $ZW $SP];
|
|
$CM+ $SP / .;
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|
|
|
# LB 9
|
|
$SP+ $CM* $OP;
|
|
|
|
# LB 10
|
|
$SP+ $CM* $QU;
|
|
|
|
# LB 11
|
|
$SP+ $CM* $CL;
|
|
$SP+ $CM* $B2;
|
|
|
|
# LB 18
|
|
($CM* ($IS | $SY))+ $CM* $NU;
|
|
$CL $CM* ($NU | $IS | $SY);
|
|
|
|
## -------------------------------------------------
|
|
|
|
!!safe_forward;
|
|
|
|
# Skip forward over all character classes that are involved in
|
|
# rules containing patterns with possibly more than one char
|
|
# of context.
|
|
#
|
|
# It might be slightly more efficient to have specific rules
|
|
# instead of one generic one, but only if we could
|
|
# turn off rule chaining. We don't want to move more
|
|
# than necessary.
|
|
#
|
|
[$CM $OP $QU $CL $B2 $PR $HY $SP]+ [^$CM $OP $QU $CL $B2 $PR $HY];
|
|
|