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363 lines
11 KiB
363 lines
11 KiB
# Copyright (C) 2016 and later: Unicode, Inc. and others.
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# License & terms of use: http://www.unicode.org/copyright.html
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# Copyright (c) 2002-2016 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
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# Unicode Standard Annex #14 Revision 44 for Unicode 13.0
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# http://www.unicode.org/reports/tr14/, with the following modification:
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#
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# Boundaries between hyphens and following letters are suppressed when
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# there is a boundary preceding the hyphen. See rule 20.9
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#
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# This corresponds to CSS line-break=strict (BCP47 -u-lb-strict).
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# It sets characters of class CJ to behave like NS.
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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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!!quoted_literals_only;
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$AI = [:LineBreak = Ambiguous:];
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$AL = [:LineBreak = Alphabetic:];
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$BA = [:LineBreak = Break_After:];
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$HH = [\u2010]; # \u2010 is HYPHEN, default line break is BA.
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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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$CJ = [:LineBreak = Conditional_Japanese_Starter:];
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$CL = [:LineBreak = Close_Punctuation:];
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# $CM = [:LineBreak = Combining_Mark:];
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$CP = [:LineBreak = Close_Parenthesis:];
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$CR = [:LineBreak = Carriage_Return:];
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$EB = [:LineBreak = EB:];
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$EM = [:LineBreak = EM:];
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$EX = [:LineBreak = Exclamation:];
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$GL = [:LineBreak = Glue:];
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$HL = [:LineBreak = Hebrew_Letter:];
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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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$NL = [:LineBreak = Next_Line:];
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# NS includes CJ for CSS strict line breaking.
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$NS = [[:LineBreak = Nonstarter:] $CJ];
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$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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$RI = [:LineBreak = Regional_Indicator:];
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$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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$ZWJ = [:LineBreak = ZWJ:];
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# OP30 and CP30 are variants of OP and CP that appear in-line in rule LB30 from UAX 14,
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# without a formal name. Because ICU rules require multiple uses of the expressions,
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# give them a single definition with a name
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$OP30 = [$OP - [\p{ea=F}\p{ea=W}\p{ea=H}]];
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$CP30 = [$CP - [\p{ea=F}\p{ea=W}\p{ea=H}]];
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# By LB9, a ZWJ also behaves as a CM. Including it in the definition of CM avoids having to explicitly
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# list it in the numerous rules that use CM.
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# By LB1, SA characters with general categor of Mn or Mc also resolve to CM.
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$CM = [[:LineBreak = Combining_Mark:] $ZWJ [$SA & [[:Mn:][:Mc:]]]];
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$CMX = [[$CM] - [$ZWJ]];
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# Dictionary character set, for triggering language-based break engines. Currently
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# limited to LineBreak=Complex_Context (SA).
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$dictionary = [$SA];
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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 (Dictionary chars, excluding Mn and Mc)
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# SG (Unpaired Surrogates)
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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 $SG $XX [$SA-[[:Mn:][:Mc:]]]];
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## -------------------------------------------------
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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 = [^$SP $BK $CR $LF $NL $ZW $CM]; # Bases that can take CMs
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$CANT_CM = [ $SP $BK $CR $LF $NL $ZW $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 $CM s are treated as AL.
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#
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$AL_FOLLOW = [$BK $CR $LF $NL $ZW $SP $CL $CP $EX $HL $IS $SY $WJ $GL $OP30 $QU $BA $HY $NS $IN $NU $PR $PO $ALPlus];
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#
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# Rule LB 4, 5 Mandatory (Hard) breaks.
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#
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$LB4Breaks = [$BK $CR $LF $NL];
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$LB4NonBreaks = [^$BK $CR $LF $NL $CM];
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$CR $LF {100};
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#
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# LB 6 Do not break before hard line breaks.
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#
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$LB4NonBreaks? $LB4Breaks {100}; # LB 5 do not break before hard breaks.
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$CAN_CM $CM* $LB4Breaks {100};
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^$CM+ $LB4Breaks {100};
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# LB 7 x SP
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# x ZW
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$LB4NonBreaks [$SP $ZW];
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$CAN_CM $CM* [$SP $ZW];
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^$CM+ [$SP $ZW];
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#
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# LB 8 Break after zero width space
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# ZW SP* ÷
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#
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$LB8Breaks = [$LB4Breaks $ZW];
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$LB8NonBreaks = [[$LB4NonBreaks] - [$ZW]];
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$ZW $SP* / [^$SP $ZW $LB4Breaks];
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# LB 8a ZWJ x Do not break Emoji ZWJ sequences.
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#
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$ZWJ [^$CM];
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# LB 9 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 11 Do not break before or after WORD JOINER & related characters.
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#
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$CAN_CM $CM* $WJ;
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$LB8NonBreaks $WJ;
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^$CM+ $WJ;
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$WJ $CM* .;
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#
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# LB 12 Do not break after NBSP and related characters.
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# GL x
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#
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$GL $CM* .;
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#
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# LB 12a Do not break before NBSP and related characters ...
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# [^SP BA HY] x GL
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#
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[[$LB8NonBreaks] - [$SP $BA $HY]] $CM* $GL;
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^$CM+ $GL;
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# LB 13 Don't break before ']' or '!' or or '/', even after spaces.
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#
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$LB8NonBreaks $CL;
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$CAN_CM $CM* $CL;
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^$CM+ $CL; # by rule 10, stand-alone CM behaves as AL
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$LB8NonBreaks $CP;
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$CAN_CM $CM* $CP;
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^$CM+ $CP; # by rule 10, stand-alone CM behaves as AL
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$LB8NonBreaks $EX;
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$CAN_CM $CM* $EX;
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^$CM+ $EX; # by rule 10, stand-alone CM behaves as AL
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$LB8NonBreaks $SY;
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$CAN_CM $CM* $SY;
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^$CM+ $SY; # by rule 10, stand-alone CM behaves as AL
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#
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# LB 14 Do not break after OP, even after spaces
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# Note subtle interaction with "SP IS /" rules in LB14a.
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# This rule consumes the SP, chaining happens on the IS, effectivley overriding the SP IS rules,
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# which is the desired behavior.
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#
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$OP $CM* $SP* .;
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$OP $CM* $SP+ $CM+ $AL_FOLLOW?; # by rule 10, stand-alone CM behaves as AL
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# by rule 8, CM following a SP is stand-alone.
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# LB 14a Force a break before start of a number with a leading decimal pt, e.g. " .23"
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# Note: would be simpler to express as "$SP / $IS $CM* $NU;", but ICU rules have limitations.
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# See issue ICU-20303
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$CanFollowIS = [$BK $CR $LF $NL $SP $ZW $WJ $GL $CL $CP $EX $IS $SY $QU $BA $HY $NS $ALPlus $HL $IN];
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$SP $IS / [^ $CanFollowIS $NU $CM];
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$SP $IS $CM* $CMX / [^ $CanFollowIS $NU $CM];
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#
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# LB 14b Do not break before numeric separators (IS), even after spaces.
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[$LB8NonBreaks - $SP] $IS;
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$SP $IS $CM* [$CanFollowIS {eof}];
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$SP $IS $CM* $ZWJ [^$CM $NU];
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$CAN_CM $CM* $IS;
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^$CM+ $IS; # by rule 10, stand-alone CM behaves as AL
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# LB 15
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$QU $CM* $SP* $OP;
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# LB 16
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($CL | $CP) $CM* $SP* $NS;
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# LB 17
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$B2 $CM* $SP* $B2;
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#
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# LB 18 Break after spaces.
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#
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$LB18NonBreaks = [$LB8NonBreaks - [$SP]];
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$LB18Breaks = [$LB8Breaks $SP];
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# LB 19
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# x QU
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$LB18NonBreaks $CM* $QU;
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^$CM+ $QU;
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# QU x
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$QU $CM* .;
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# LB 20
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# <break> $CB
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# $CB <break>
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#
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$LB20NonBreaks = [$LB18NonBreaks - $CB];
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# LB 20.09 Don't break between Hyphens and Letters when there is a break preceding the hyphen.
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# Originally added as a Finnish tailoring, now promoted to default ICU behavior.
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# Note: this is not default UAX-14 behaviour. See issue ICU-8151.
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#
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^($HY | $HH) $CM* $ALPlus;
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# LB 21 x (BA | HY | NS)
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# BB x
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#
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$LB20NonBreaks $CM* ($BA | $HY | $NS);
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^$CM+ ($BA | $HY | $NS);
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$BB $CM* [^$CB]; # $BB x
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$BB $CM* $LB20NonBreaks;
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# LB 21a Don't break after Hebrew + Hyphen
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# HL (HY | BA) x
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#
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$HL $CM* ($HY | $BA) $CM* [^$CB]?;
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# LB 21b (forward) Don't break between SY and HL
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# (break between HL and SY already disallowed by LB 13 above)
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$SY $CM* $HL;
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# LB 22 Do not break before ellipses
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#
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$LB20NonBreaks $CM* $IN;
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^$CM+ $IN;
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# LB 23
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#
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($ALPlus | $HL) $CM* $NU;
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^$CM+ $NU; # Rule 10, any otherwise unattached CM behaves as AL
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$NU $CM* ($ALPlus | $HL);
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# LB 23a
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#
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$PR $CM* ($ID | $EB | $EM);
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($ID | $EB | $EM) $CM* $PO;
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#
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# LB 24
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#
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($PR | $PO) $CM* ($ALPlus | $HL);
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($ALPlus | $HL) $CM* ($PR | $PO);
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^$CM+ ($PR | $PO); # Rule 10, any otherwise unattached CM behaves as AL
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#
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# LB 25 Numbers.
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#
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(($PR | $PO) $CM*)? (($OP | $HY) $CM*)? ($IS $CM*)? $NU ($CM* ($NU | $SY | $IS))*
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($CM* ($CL | $CP))? ($CM* ($PR | $PO))?;
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# LB 26 Do not break a Korean syllable
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#
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$JL $CM* ($JL | $JV | $H2 | $H3);
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($JV | $H2) $CM* ($JV | $JT);
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($JT | $H3) $CM* $JT;
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# LB 27 Treat korean Syllable Block the same as ID (don't break it)
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($JL | $JV | $JT | $H2 | $H3) $CM* $IN;
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($JL | $JV | $JT | $H2 | $H3) $CM* $PO;
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$PR $CM* ($JL | $JV | $JT | $H2 | $H3);
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# LB 28 Do not break between alphabetics
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#
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($ALPlus | $HL) $CM* ($ALPlus | $HL);
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^$CM+ ($ALPlus | $HL); # The $CM+ is from rule 10, an unattached CM is treated as AL
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# LB 29
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$IS $CM* ($ALPlus | $HL);
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# LB 30
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($ALPlus | $HL | $NU) $CM* $OP30;
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^$CM+ $OP30; # The $CM+ is from rule 10, an unattached CM is treated as AL.
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$CP30 $CM* ($ALPlus | $HL | $NU);
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# LB 30a Do not break between regional indicators. Break after pairs of them.
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# Tricky interaction with LB8a: ZWJ x . together with ZWJ acting like a CM.
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$RI $CM* $RI / [[^$BK $CR $LF $NL $SP $ZW $WJ $CL $CP $EX $IS $SY $GL $QU $BA $HY $NS $IN $CM]];
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$RI $CM* $RI $CM* [$CM-$ZWJ] / [[^$BK $CR $LF $NL $SP $ZW $WJ $CL $CP $EX $IS $SY $GL $QU $BA $HY $NS $IN $CM]];
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$RI $CM* $RI $CM* [$BK $CR $LF $NL $SP $ZW $WJ $CL $CP $EX $IS $SY $GL $QU $BA $HY $NS $IN $ZWJ {eof}];
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# note: the preceding rule includes {eof} rather than having the last [set] term qualified with '?'
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# because of the chain-out behavior difference. The rule must chain out only from the [set characters],
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# not from the preceding $RI or $CM, which it would be able to do if the set were optional.
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# LB 30b Do not break between an Emoji Base and an Emoji Modifier
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$EB $CM* $EM;
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# LB 31 Break everywhere else.
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# Match a single code point if no other rule applies.
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.;
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