# Copyright (c) 2002-2015 International Business Machines Corporation and
# others. All Rights Reserved.
#
# file: line.txt
#
# Line Breaking Rules
# Implement default line breaking as defined by
# Unicode Standard Annex #14 Revision 34 for Unicode 8.0
# http://www.unicode.org/reports/tr14/
#
# TODO: Rule LB 8 remains as it was in Unicode 5.2
# This is only because of a limitation of ICU break engine implementation,
# not because the older behavior is desirable.
#
# This corresponds to CSS line-break=strict (BCP47 -u-lb-strict).
# It sets characters of class CJ to behave like NS.
#
# Character Classes defined by TR 14.
#
!!chain;
!!LBCMNoChain;
!!lookAheadHardBreak;
#
# !!lookAheadHardBreak Described here because it is (as yet) undocumented elsewhere
# and only used for the line break rules.
#
# It is used in the implementation of rule LB 10
# which says to treat any combining mark that is not attached to a base
# character as if it were of class AL (alphabetic).
#
# The problem occurs in the reverse rules.
#
# Consider a sequence like, with correct breaks as shown
# LF ID CM AL AL
# ^ ^ ^
# Then consider the sequence without the initial ID (ideographic)
# LF CM AL AL
# ^ ^
# Our CM, which in the first example was attached to the ideograph,
# is now unattached, becomes an alpha, and joins in with the other
# alphas.
#
# When iterating forwards, these sequences do not present any problems
# When iterating backwards, we need to look ahead when encountering
# a CM to see whether it attaches to something further on or not.
# (Look-ahead in a reverse rule is looking towards the start)
#
# If the CM is unattached, we need to force a break.
#
# !!lookAheadHardBreak forces the run time state machine to
# stop immediately when a look ahead rule ( '/' operator) matches,
# and set the match position to that of the look-ahead operator,
# no matter what other rules may be in play at the time.
#
# See rule LB 19 for an example.
#
$AI = [:LineBreak = Ambiguous:];
$AL = [:LineBreak = Alphabetic:];
$BA = [:LineBreak = Break_After:];
$BB = [:LineBreak = Break_Before:];
$BK = [:LineBreak = Mandatory_Break:];
$B2 = [:LineBreak = Break_Both:];
$CB = [:LineBreak = Contingent_Break:];
$CJ = [:LineBreak = Conditional_Japanese_Starter:];
$CL = [:LineBreak = Close_Punctuation:];
$CM = [:LineBreak = Combining_Mark:];
$CP = [:LineBreak = Close_Parenthesis:];
$CR = [:LineBreak = Carriage_Return:];
$EX = [:LineBreak = Exclamation:];
$GL = [:LineBreak = Glue:];
$HL = [:LineBreak = Hebrew_Letter:];
$HY = [:LineBreak = Hyphen:];
$H2 = [:LineBreak = H2:];
$H3 = [:LineBreak = H3:];
$ID = [:LineBreak = Ideographic:];
$IN = [:LineBreak = Inseperable:];
$IS = [:LineBreak = Infix_Numeric:];
$JL = [:LineBreak = JL:];
$JV = [:LineBreak = JV:];
$JT = [:LineBreak = JT:];
$LF = [:LineBreak = Line_Feed:];
$NL = [:LineBreak = Next_Line:];
$NS = [[:LineBreak = Nonstarter:] $CJ];
$NU = [:LineBreak = Numeric:];
$OP = [:LineBreak = Open_Punctuation:];
$PO = [:LineBreak = Postfix_Numeric:];
$PR = [:LineBreak = Prefix_Numeric:];
$QU = [:LineBreak = Quotation:];
$RI = [:LineBreak = Regional_Indicator:];
$SA = [:LineBreak = Complex_Context:];
$SG = [:LineBreak = Surrogate:];
$SP = [:LineBreak = Space:];
$SY = [:LineBreak = Break_Symbols:];
$WJ = [:LineBreak = Word_Joiner:];
$XX = [:LineBreak = Unknown:];
$ZW = [:LineBreak = ZWSpace:];
# Dictionary character set, for triggering language-based break engines. Currently
# limited to LineBreak=Complex_Context. Note that this set only works in Unicode
# 5.0 or later as the definition of Complex_Context was corrected to include all
# characters requiring dictionary break.
$dictionary = [:LineBreak = Complex_Context:];
#
# Rule LB1. By default, treat AI (characters with ambiguous east Asian width),
# SA (South East Asian: Thai, Lao, Khmer)
# SG (Unpaired Surrogates)
# XX (Unknown, unassigned)
# as $AL (Alphabetic)
#
$ALPlus = [$AL $AI $SA $SG $XX];
#
# Combining Marks. X $CM* behaves as if it were X. Rule LB6.
#
$ALcm = $ALPlus $CM*;
$BAcm = $BA $CM*;
$BBcm = $BB $CM*;
$B2cm = $B2 $CM*;
$CLcm = $CL $CM*;
$CPcm = $CP $CM*;
$EXcm = $EX $CM*;
$GLcm = $GL $CM*;
$HLcm = $HL $CM*;
$HYcm = $HY $CM*;
$H2cm = $H2 $CM*;
$H3cm = $H3 $CM*;
$IDcm = $ID $CM*;
$INcm = $IN $CM*;
$IScm = $IS $CM*;
$JLcm = $JL $CM*;
$JVcm = $JV $CM*;
$JTcm = $JT $CM*;
$NScm = $NS $CM*;
$NUcm = $NU $CM*;
$OPcm = $OP $CM*;
$POcm = $PO $CM*;
$PRcm = $PR $CM*;
$QUcm = $QU $CM*;
$RIcm = $RI $CM*;
$SYcm = $SY $CM*;
$WJcm = $WJ $CM*;
## -------------------------------------------------
!!forward;
#
# Each class of character can stand by itself as an unbroken token, with trailing combining stuff
#
$ALPlus $CM+;
$BA $CM+;
$BB $CM+;
$B2 $CM+;
$CL $CM+;
$CP $CM+;
$EX $CM+;
$GL $CM+;
$HL $CM+;
$HY $CM+;
$H2 $CM+;
$H3 $CM+;
$ID $CM+;
$IN $CM+;
$IS $CM+;
$JL $CM+;
$JV $CM+;
$JT $CM+;
$NS $CM+;
$NU $CM+;
$OP $CM+;
$PO $CM+;
$PR $CM+;
$QU $CM+;
$RI $CM+;
$SY $CM+;
$WJ $CM+;
#
# CAN_CM is the set of characters that may combine with CM combining chars.
# Note that Linebreak UAX 14's concept of a combining char and the rules
# for what they can combine with are _very_ different from the rest of Unicode.
#
# Note that $CM itself is left out of this set. If CM is needed as a base
# it must be listed separately in the rule.
#
$CAN_CM = [^$SP $BK $CR $LF $NL $ZW $CM]; # Bases that can take CMs
$CANT_CM = [ $SP $BK $CR $LF $NL $ZW $CM]; # Bases that can't take CMs
#
# AL_FOLLOW set of chars that can unconditionally follow an AL
# Needed in rules where stand-alone $CM s are treated as AL.
# Chaining is disabled with CM because it causes other failures,
# so for this one case we need to manually list out longer sequences.
#
$AL_FOLLOW_NOCM = [$BK $CR $LF $NL $ZW $SP];
$AL_FOLLOW_CM = [$CL $CP $EX $HL $IS $SY $WJ $GL $OP $QU $BA $HY $NS $IN $NU $ALPlus];
$AL_FOLLOW = [$AL_FOLLOW_NOCM $AL_FOLLOW_CM];
#
# Rule LB 4, 5 Mandatory (Hard) breaks.
#
$LB4Breaks = [$BK $CR $LF $NL];
$LB4NonBreaks = [^$BK $CR $LF $NL];
$CR $LF {100};
#
# LB 6 Do not break before hard line breaks.
#
$LB4NonBreaks? $LB4Breaks {100}; # LB 5 do not break before hard breaks.
$CAN_CM $CM* $LB4Breaks {100};
$CM+ $LB4Breaks {100};
# LB 7 x SP
# x ZW
$LB4NonBreaks [$SP $ZW];
$CAN_CM $CM* [$SP $ZW];
$CM+ [$SP $ZW];
#
# LB 8 Break after zero width space
# TODO: ZW SP* <break>
# An engine change is required to write the reverse rule for this.
# For now, leave the Unicode 5.2 rule, ZW <break>
#
$LB8Breaks = [$LB4Breaks $ZW];
$LB8NonBreaks = [[$LB4NonBreaks] - [$ZW]];
# LB 9 Combining marks. X $CM needs to behave like X, where X is not $SP, $BK $CR $LF $NL
# $CM not covered by the above needs to behave like $AL
# See definition of $CAN_CM.
$CAN_CM $CM+; # Stick together any combining sequences that don't match other rules.
$CM+;
#
# LB 11 Do not break before or after WORD JOINER & related characters.
#
$CAN_CM $CM* $WJcm;
$LB8NonBreaks $WJcm;
$CM+ $WJcm;
$WJcm $CANT_CM;
$WJcm $CAN_CM $CM*;
#
# LB 12 Do not break after NBSP and related characters.
# GL x
#
$GLcm $CAN_CM $CM*;
$GLcm $CANT_CM;
#
# LB 12a Do not break before NBSP and related characters ...
# [^SP BA HY] x GL
#
[[$LB8NonBreaks] - [$SP $BA $HY]] $CM* $GLcm;
$CM+ GLcm;
#
# LB 13 Don't break before ']' or '!' or ';' or '/', even after spaces.
#
$LB8NonBreaks $CL;
$CAN_CM $CM* $CL;
$CM+ $CL; # by rule 10, stand-alone CM behaves as AL
$LB8NonBreaks $CP;
$CAN_CM $CM* $CP;
$CM+ $CP; # by rule 10, stand-alone CM behaves as AL
$LB8NonBreaks $EX;
$CAN_CM $CM* $EX;
$CM+ $EX; # by rule 10, stand-alone CM behaves as AL
$LB8NonBreaks $IS;
$CAN_CM $CM* $IS;
$CM+ $IS; # by rule 10, stand-alone CM behaves as AL
$LB8NonBreaks $SY;
$CAN_CM $CM* $SY;
$CM+ $SY; # by rule 10, stand-alone CM behaves as AL
#
# LB 14 Do not break after OP, even after spaces
#
$OPcm $SP* $CAN_CM $CM*;
$OPcm $SP* $CANT_CM;
$OPcm $SP+ $CM+ $AL_FOLLOW?; # by rule 10, stand-alone CM behaves as AL
# LB 15
$QUcm $SP* $OPcm;
# LB 16
($CLcm | $CPcm) $SP* $NScm;
# LB 17
$B2cm $SP* $B2cm;
#
# LB 18 Break after spaces.
#
$LB18NonBreaks = [$LB8NonBreaks - [$SP]];
$LB18Breaks = [$LB8Breaks $SP];
# LB 19
# x QU
$LB18NonBreaks $CM* $QUcm;
$CM+ $QUcm;
# QU x
$QUcm .?;
$QUcm $LB18NonBreaks $CM*; # Don't let a combining mark go onto $CR, $BK, etc.
# TODO: I don't think this rule is needed.
# LB 20
# <break> $CB
# $CB <break>
$LB20NonBreaks = [$LB18NonBreaks - $CB];
# LB 21 x (BA | HY | NS)
# BB x
#
$LB20NonBreaks $CM* ($BAcm | $HYcm | $NScm);
$BBcm [^$CB]; # $BB x
$BBcm $LB20NonBreaks $CM*;
# LB 21a Don't break after Hebrew + Hyphen
# HL (HY | BA) x
#
$HLcm ($HYcm | $BAcm) [^$CB]?;
# LB 21b (forward) Don't break between SY and HL
# (break between HL and SY already disallowed by LB 13 above)
$SYcm $HLcm;
# LB 22
($ALcm | $HLcm) $INcm;
$CM+ $INcm; # by rule 10, any otherwise unattached CM behaves as AL
$EXcm $INcm;
$IDcm $INcm;
$INcm $INcm;
$NUcm $INcm;
# $LB 23
$IDcm $POcm;
$ALcm $NUcm; # includes $LB19
$HLcm $NUcm;
$CM+ $NUcm; # Rule 10, any otherwise unattached CM behaves as AL
$NUcm $ALcm;
$NUcm $HLcm;
#
# LB 24
#
$PRcm $IDcm;
$PRcm ($ALcm | $HLcm);
$POcm ($ALcm | $HLcm);
#
# LB 25 Numbers.
#
($PRcm | $POcm)? ($OPcm | $HYcm)? $NUcm ($NUcm | $SYcm | $IScm)* ($CLcm | $CPcm)? ($PRcm | $POcm)?;
# LB 26 Do not break a Korean syllable
#
$JLcm ($JLcm | $JVcm | $H2cm | $H3cm);
($JVcm | $H2cm) ($JVcm | $JTcm);
($JTcm | $H3cm) $JTcm;
# LB 27 Treat korean Syllable Block the same as ID (don't break it)
($JLcm | $JVcm | $JTcm | $H2cm | $H3cm) $INcm;
($JLcm | $JVcm | $JTcm | $H2cm | $H3cm) $POcm;
$PRcm ($JLcm | $JVcm | $JTcm | $H2cm | $H3cm);
# LB 28 Do not break between alphabetics
#
($ALcm | $HLcm) ($ALcm | $HLcm);
$CM+ ($ALcm | $HLcm); # The $CM+ is from rule 10, an unattached CM is treated as AL
# LB 29
$IScm ($ALcm | $HLcm);
# LB 30
($ALcm | $HLcm | $NUcm) $OPcm;
$CM+ $OPcm; # The $CM+ is from rule 10, an unattached CM is treated as AL.
$CPcm ($ALcm | $HLcm | $NUcm);
# LB 30a Do not break between regional indicators.
$RIcm $RIcm;
#
# Reverse Rules.
#
## -------------------------------------------------
!!reverse;
$CM+ $ALPlus;
$CM+ $BA;
$CM+ $BB;
$CM+ $B2;
$CM+ $CL;
$CM+ $CP;
$CM+ $EX;
$CM+ $GL;
$CM+ $HL;
$CM+ $HY;
$CM+ $H2;
$CM+ $H3;
$CM+ $ID;
$CM+ $IN;
$CM+ $IS;
$CM+ $JL;
$CM+ $JV;
$CM+ $JT;
$CM+ $NS;
$CM+ $NU;
$CM+ $OP;
$CM+ $PO;
$CM+ $PR;
$CM+ $QU;
$CM+ $RI;
$CM+ $SY;
$CM+ $WJ;
$CM+;
#
# Sequences of the form (shown forwards)
# [CANT_CM] <break> [CM] [whatever]
# The CM needs to behave as an AL
#
$AL_FOLLOW $CM+ / (
[$BK $CR $LF $NL $ZW {eof}] |
$SP+ $CM+ $SP |
$SP+ $CM* ([^$OP $CM $SP] | [$AL {eof}])); # if LB 14 will match, need to surpress this break.
# LB14 says OP SP* x .
# becomes OP SP* x AL
# becomes OP SP* x CM+ AL_FOLLOW
#
# Further note: the $AL in [$AL {eof}] is only to work around
# a rule compiler bug which complains about
# empty sets otherwise.
#
# Sequences of the form (shown forwards)
# [CANT_CM] <break> [CM] <break> [PR]
# The CM needs to behave as an AL
# This rule is concerned about getting the second of the two <breaks> in place.
#
[$PR ] / $CM+ [$BK $CR $LF $NL $ZW $SP {eof}];
# LB 4, 5, 5
$LB4Breaks [$LB4NonBreaks-$CM];
$LB4Breaks $CM+ $CAN_CM;
$LF $CR;
# LB 7 x SP
# x ZW
[$SP $ZW] [$LB4NonBreaks-$CM];
[$SP $ZW] $CM+ $CAN_CM;
# LB 8 ZW SP* <break>
# TODO: to implement this, we need more than one look-ahead hard break in play at a time.
# Requires an engine enhancement.
# / $SP* $ZW
# LB 9,10 Combining marks.
# X $CM needs to behave like X, where X is not $SP or controls.
# $CM not covered by the above needs to behave like $AL
# Stick together any combining sequences that don't match other rules.
$CM+ $CAN_CM;
# LB 11
$CM* $WJ $CM* $CAN_CM;
$CM* $WJ [$LB8NonBreaks-$CM];
$CANT_CM $CM* $WJ;
$CM* $CAN_CM $CM* $WJ;
# LB 12a
# [^SP BA HY] x GL
#
$CM* $GL $CM* [$LB8NonBreaks-[$CM $SP $BA $HY]];
# LB 12
# GL x
#
$CANT_CM $CM* $GL;
$CM* $CAN_CM $CM* $GL;
# LB 13
$CL $CM+ $CAN_CM;
$CP $CM+ $CAN_CM;
$EX $CM+ $CAN_CM;
$IS $CM+ $CAN_CM;
$SY $CM+ $CAN_CM;
$CL [$LB8NonBreaks-$CM];
$CP [$LB8NonBreaks-$CM];
$EX [$LB8NonBreaks-$CM];
$IS [$LB8NonBreaks-$CM];
$SY [$LB8NonBreaks-$CM];
# Rule 13 & 14 taken together for an edge case.
# Match this, shown forward
# OP SP+ ($CM+ behaving as $AL) (CL | CP | EX | IS | IY)
# This really wants to chain at the $CM+ (which is acting as an $AL)
# except for $CM chaining being disabled.
[$CL $CP $EX $IS $SY] $CM+ $SP+ $CM* $OP;
# LB 14 OP SP* x
#
$CM* $CAN_CM $SP* $CM* $OP;
$CANT_CM $SP* $CM* $OP;
$AL_FOLLOW? $CM+ $SP $SP* $CM* $OP; # by LB 10, behaves like $AL_FOLLOW? $AL $SP* $CM* $OP
$AL_FOLLOW_NOCM $CM+ $SP+ $CM* $OP;
$CM* $AL_FOLLOW_CM $CM+ $SP+ $CM* $OP;
$SY $CM $SP+ $OP; # TODO: Experiment. Remove.
# LB 15
$CM* $OP $SP* $CM* $QU;
# LB 16
$CM* $NS $SP* $CM* ($CL | $CP);
# LB 17
$CM* $B2 $SP* $CM* $B2;
# LB 18 break after spaces
# Nothing explicit needed here.
#
# LB 19
#
$CM* $QU $CM* $CAN_CM; # . x QU
$CM* $QU $LB18NonBreaks;
$CM* $CAN_CM $CM* $QU; # QU x .
$CANT_CM $CM* $QU;
#
# LB 20 Break before and after CB.
# nothing needed here.
#
# LB 21
$CM* ($BA | $HY | $NS) $CM* [$LB20NonBreaks-$CM]; # . x (BA | HY | NS)
$CM* [$LB20NonBreaks-$CM] $CM* $BB; # BB x .
[^$CB] $CM* $BB; #
# LB21a
[^$CB] $CM* ($HY | $BA) $CM* $HL;
# LB21b (reverse)
$CM* $HL $CM* $SY;
# LB 22
$CM* $IN $CM* ($ALPlus | $HL);
$CM* $IN $CM* $EX;
$CM* $IN $CM* $ID;
$CM* $IN $CM* $IN;
$CM* $IN $CM* $NU;
# LB 23
$CM* $PO $CM* $ID;
$CM* $NU $CM* ($ALPlus | $HL);
$CM* ($ALPlus | $HL) $CM* $NU;
# LB 24
$CM* $ID $CM* $PR;
$CM* ($ALPlus | $HL) $CM* $PR;
$CM* ($ALPlus | $HL) $CM* $PO;
# LB 25
($CM* ($PR | $PO))? ($CM* ($CL | $CP))? ($CM* ($NU | $IS | $SY))* $CM* $NU ($CM* ($OP | $HY))? ($CM* ($PR | $PO))?;
# LB 26
$CM* ($H3 | $H2 | $JV | $JL) $CM* $JL;
$CM* ($JT | $JV) $CM* ($H2 | $JV);
$CM* $JT $CM* ($H3 | $JT);
# LB 27
$CM* $IN $CM* ($H3 | $H2 | $JT | $JV | $JL);
$CM* $PO $CM* ($H3 | $H2 | $JT | $JV | $JL);
$CM* ($H3 | $H2 | $JT | $JV | $JL) $CM* $PR;
# LB 28
$CM* ($ALPlus | $HL) $CM* ($ALPlus | $HL);
# LB 29
$CM* ($ALPlus | $HL) $CM* $IS;
# LB 30
$CM* $OP $CM* ($ALPlus | $HL | $NU);
$CM* ($ALPlus | $HL | $NU) $CM* $CP;
# LB 30a
$CM* $RI $CM* $RI;
## -------------------------------------------------
!!safe_reverse;
# LB 9
$CM+ [^$CM $BK $CR $LF $NL $ZW $SP];
$CM+ $SP / .;
# LB 14
$SP+ $CM* $OP;
# LB 15
$SP+ $CM* $QU;
# LB 16
$SP+ $CM* ($CL | $CP);
# LB 17
$SP+ $CM* $B2;
# LB 21
$CM* ($HY | $BA) $CM* $HL;
# LB 25
($CM* ($IS | $SY))+ $CM* $NU;
($CL | $CP) $CM* ($NU | $IS | $SY);
# For dictionary-based break
$dictionary $dictionary;
## -------------------------------------------------
!!safe_forward;
# Skip forward over all character classes that are involved in
# rules containing patterns with possibly more than one char
# of context.
#
# It might be slightly more efficient to have specific rules
# instead of one generic one, but only if we could
# turn off rule chaining. We don't want to move more
# than necessary.
#
[$CM $OP $QU $CL $CP $B2 $PR $HY $BA $SP $dictionary]+ [^$CM $OP $QU $CL $CP $B2 $PR $HY $BA $dictionary];
$dictionary $dictionary;