X-Git-Url: https://git.saurik.com/apple/icu.git/blobdiff_plain/2ca993e82fb37b597a3c73ecd1586a139a6579c5..340931cb2e044a2141d11567dd0f782524e32994:/icuSources/data/brkitr/rules/line_loose.txt

diff --git a/icuSources/data/brkitr/rules/line_loose.txt b/icuSources/data/brkitr/rules/line_loose.txt
index d33ad061..2794554e 100644
--- a/icuSources/data/brkitr/rules/line_loose.txt
+++ b/icuSources/data/brkitr/rules/line_loose.txt
@@ -1,3 +1,6 @@
+# Copyright (C) 2016 and later: Unicode, Inc. and others.
+# License & terms of use: http://www.unicode.org/copyright.html
+#
 # Copyright (c) 2002-2016  International Business Machines Corporation and
 # others. All Rights Reserved.
 #
@@ -5,20 +8,14 @@
 #
 #         Line Breaking Rules
 #         Implement default line breaking as defined by
-#         Unicode Standard Annex #14 Revision 35 for Unicode 8.0
-#         http://www.unicode.org/reports/tr14/
-#
-#         Includes the Emoji breaking proposals from Unicode L2/16-011R3.
-#         http://www.unicode.org/L2/L2016/16011r3-break-prop-emoji.pdf
-#
-#         tailored as noted in 2nd paragraph below.
+#         Unicode Standard Annex #14 Revision 44 for Unicode 13.0
+#         http://www.unicode.org/reports/tr14/, with the following modification:
 #
-#         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.
+#         Boundaries between hyphens and following letters are suppressed when
+#         there is a boundary preceding the hyphen. See rule 20.9
 #
 #         This tailors the line break behavior to correspond to CSS
-#         line-break=loose (BCP47 -u-lb-loose) as defined for languages other than 
+#         line-break=loose (BCP47 -u-lb-loose) as defined for languages other than
 #         Chinese & Japanese.
 #         It sets characters of class CJ to behave like ID.
 #         In addition, it allows breaks:
@@ -30,67 +27,31 @@
 #
 
 !!chain;
+!!quoted_literals_only;
 
-!!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.
-#
-
-# Temporary definitions of Emoji Base and Emoji Modifiers, until properties are available.
-
-$EB = [\u261D\u26F9\u270A-\u270D\U0001F385\U0001F3C3-\U0001F3C4\U0001F3CA-\U0001F3CB\U0001F442-\U0001F443\U0001F446-\U0001F450\U0001F466-\U0001F469\U0001F46E\U0001F470-\U0001F478\U0001F47C\U0001F481-\U0001F483\U0001F485-\U0001F487\U0001F4AA\U0001F575\U0001F590\U0001F595-\U0001F596\U0001F645-\U0001F647\U0001F64B-\U0001F64F\U0001F6A3\U0001F6B4-\U0001F6B6\U0001F6C0\U0001F918];
-$EM = [\U0001F3FB-\U0001F3FF];
-
-$AI = [[:LineBreak =  Ambiguous:] - [\u2640\u2642]];
-$AL = [[:LineBreak =  Alphabetic:] - [$EM\u2764]];
+$AI = [:LineBreak =  Ambiguous:];
+$AL = [:LineBreak =  Alphabetic:];
 $BA = [:LineBreak =  Break_After:];
+$HH = [\u2010];     # \u2010 is HYPHEN, default line break is BA.
 $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:] \u200d];
+# $CM = [:LineBreak =  Combining_Mark:];
 $CP = [:LineBreak =  Close_Parenthesis:];
 $CR = [:LineBreak =  Carriage_Return:];
+$EB = [:LineBreak =  EB:];
+$EM = [:LineBreak =  EM:];
 $EX = [:LineBreak =  Exclamation:];
 $GL = [:LineBreak =  Glue:];
 $HL = [:LineBreak =  Hebrew_Letter:];
 $HY = [:LineBreak =  Hyphen:];
 $H2 = [:LineBreak =  H2:];
 $H3 = [:LineBreak =  H3:];
-$ID = [[:LineBreak =  Ideographic:]$CJ[\u2640\u2642\u2764] - $EB];
+# CSS Loose tailoring: CJ resolves to ID
+$ID = [[:LineBreak =  Ideographic:] $CJ];
 $IN = [:LineBreak =  Inseperable:];
 $IS = [:LineBreak =  Infix_Numeric:];
 $JL = [:LineBreak =  JL:];
@@ -113,92 +74,38 @@ $SY = [:LineBreak =  Break_Symbols:];
 $WJ = [:LineBreak =  Word_Joiner:];
 $XX = [:LineBreak =  Unknown:];
 $ZW = [:LineBreak =  ZWSpace:];
-$ZWJ = [\u200d];
+$ZWJ = [:LineBreak = ZWJ:];
+
+# OP30 and CP30 are variants of OP and CP that appear in-line in rule LB30 from UAX 14,
+# without a formal name. Because ICU rules require multiple uses of the expressions,
+# give them a single definition with a name
+
+$OP30 = [$OP - [\p{ea=F}\p{ea=W}\p{ea=H}]];
+$CP30 = [$CP - [\p{ea=F}\p{ea=W}\p{ea=H}]];
+
+# By LB9, a ZWJ also behaves as a CM. Including it in the definition of CM avoids having to explicitly
+#         list it in the numerous rules that use CM.
+# By LB1, SA characters with general categor of Mn or Mc also resolve to CM.
+
+$CM = [[:LineBreak = Combining_Mark:] $ZWJ [$SA & [[:Mn:][:Mc:]]]];
+$CMX = [[$CM] - [$ZWJ]];
 
 #   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.
+#   limited to LineBreak=Complex_Context (SA).
 
-$dictionary = [:LineBreak = Complex_Context:];
+$dictionary = [$SA];
 
 #
 #  Rule LB1.  By default, treat AI  (characters with ambiguous east Asian width),
-#                               SA  (South East Asian: Thai, Lao, Khmer)
+#                               SA  (Dictionary chars, excluding Mn and Mc)
 #                               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 $CM*;
-$INcm = $IN $CM*;
-$IScm = $IS $CM*;
-$JLcm = $JL $CM*;
-$JVcm = $JV $CM*;
-$JTcm = $JT $CM*;
-$NScm = $NS $CM*;
-$NSXcm = $NSX $CM*;
-$NUcm = $NU $CM*;
-$OPcm = $OP $CM*;
-$POcm = $PO $CM*;
-$PRcm = $PR $CM*;
-$QUcm = $QU $CM*;
-$RIcm = $RI $CM*;
-$SYcm = $SY $CM*;
-$WJcm = $WJ $CM*;
+$ALPlus = [$AL $AI $SG $XX [$SA-[[:Mn:][:Mc:]]]];
 
-## -------------------------------------------------
 
-!!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 $CM+;
-$EB $CM+;
-$EM $CM+;
-$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 $CM+;
-$NSX $CM+;
-$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.
@@ -214,12 +121,8 @@ $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 $AL_FOLLOW_CM];
+$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];
 
 
 #
@@ -244,16 +147,15 @@ $CAN_CM $CM*  [$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>
+#              ZW SP* ÷
 #
 $LB8Breaks    = [$LB4Breaks $ZW];
 $LB8NonBreaks = [[$LB4NonBreaks] - [$ZW]];
+$ZW $SP* / [^$SP $ZW $LB4Breaks];
 
-# LB 8a        ZWJ x ID    Emoji proposal.
+# LB 8a        ZWJ x            Do not break Emoji ZWJ sequences.
 #
-$ZWJ ($ID | $EB | $EM);
+$ZWJ [^$CM];
 
 # 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
@@ -265,31 +167,29 @@ $CAN_CM $CM+;                   #  Stick together any combining sequences that d
 #
 # LB 11  Do not break before or after WORD JOINER & related characters.
 #
-$CAN_CM $CM*  $WJcm;
-$LB8NonBreaks $WJcm;
-^$CM+         $WJcm;
+$CAN_CM $CM*  $WJ;
+$LB8NonBreaks $WJ;
+^$CM+         $WJ;
 
-$WJcm $CANT_CM;
-$WJcm $CAN_CM $CM*;
+$WJ $CM* .;
 
 #
 # LB 12  Do not break after NBSP and related characters.
 #         GL  x
 #
-$GLcm $CAN_CM $CM*;
-$GLcm $CANT_CM;
+$GL $CM* .;
 
 #
 # LB 12a  Do not break before NBSP and related characters ...
 #            [^SP BA HY] x GL
 #
-[[$LB8NonBreaks] - [$SP $BA $HY]] $CM* $GLcm;
-^$CM+ $GLcm;
+[[$LB8NonBreaks] - [$SP $BA $HY]] $CM* $GL;
+^$CM+ $GL;
 
 
 
-#
-# LB 13   Don't break before ']' or '!' or ';' or '/', even after spaces.
+
+# LB 13   Don't break before ']' or '!' or or '/', even after spaces.
 #
 $LB8NonBreaks $CL;
 $CAN_CM $CM*  $CL;
@@ -303,10 +203,6 @@ $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
@@ -314,22 +210,46 @@ $CAN_CM $CM*  $SY;
 
 #
 # LB 14  Do not break after OP, even after spaces
+#        Note subtle interaction with "SP IS /" rules in LB14a.
+#        This rule consumes the SP, chaining happens on the IS, effectivley overriding the  SP IS rules,
+#        which is the desired behavior.
+#
+$OP $CM* $SP* .;
+
+$OP $CM* $SP+ $CM+ $AL_FOLLOW?;    # by rule 10, stand-alone CM behaves as AL
+                                   # by rule 8, CM following a SP is stand-alone.
+
+
+# LB 14a Force a break before start of a number with a leading decimal pt, e.g. " .23"
+#        Note: would be simpler to express as "$SP / $IS $CM* $NU;", but ICU rules have limitations.
+#        See issue ICU-20303
+
+
+$CanFollowIS = [$BK $CR $LF $NL $SP $ZW $WJ $GL $CL $CP $EX $IS $SY $QU $BA $HY $NS $ALPlus $HL $IN];
+$SP $IS           / [^ $CanFollowIS $NU $CM];
+$SP $IS $CM* $CMX / [^ $CanFollowIS $NU $CM];
+
 #
-$OPcm $SP* $CAN_CM $CM*;
-$OPcm $SP* $CANT_CM;
+# LB 14b Do not break before numeric separators (IS), even after spaces.
+
+[$LB8NonBreaks - $SP] $IS;
+$SP $IS $CM* [$CanFollowIS {eof}];
+$SP $IS $CM* $ZWJ [^$CM $NU];
+
+$CAN_CM $CM*  $IS;
+^$CM+         $IS;              # by rule 10, stand-alone CM behaves as AL
 
-$OPcm $SP+ $CM+ $AL_FOLLOW?;    # by rule 10, stand-alone CM behaves as AL
 
 # LB 15
-$QUcm $SP* $OPcm;
+$QU $CM* $SP* $OP;
 
 # LB 16
 # Do not break between closing punctuation and $NS, even with intervening spaces
 # But DO allow a break between closing punctuation and $NSX, don't include it here
-($CLcm | $CPcm) $SP* $NScm;
+($CL | $CP) $CM* $SP* $NS;
 
 # LB 17
-$B2cm $SP* $B2cm;
+$B2 $CM* $SP* $B2;
 
 #
 # LB 18  Break after spaces.
@@ -340,408 +260,114 @@ $LB18Breaks    = [$LB8Breaks $SP];
 
 # LB 19
 #         x QU
-$LB18NonBreaks $CM* $QUcm;
-^$CM+               $QUcm;
+$LB18NonBreaks $CM* $QU;
+^$CM+               $QU;
 
 #         QU  x
-$QUcm .?;
-
+$QU $CM* .;
 
 # LB 20
 #        <break>  $CB
 #        $CB   <break>
-
+#
 $LB20NonBreaks = [$LB18NonBreaks - $CB];
 
+# LB 20.09    Don't break between Hyphens and Letters when there is a break preceding the hyphen.
+#             Originally added as a Finnish tailoring, now promoted to default ICU behavior.
+#             Note: this is not default UAX-14 behaviour. See issue ICU-8151.
+#
+^($HY | $HH) $CM* $ALPlus;
+
 # LB 21        x   (BA | HY | NS)
 #           BB x
 #
-# DO allow breaks here before NSXcm, so don't include it
-$LB20NonBreaks $CM* ($BAcm | $HYcm | $NScm);
-^$CM+ ($BAcm | $HYcm | $NScm);
+# DO allow breaks here before NSX, so don't include it
+$LB20NonBreaks $CM* ($BA | $HY | $NS);
+
 
-$BBcm [^$CB];                                  #  $BB  x
-$BBcm $LB20NonBreaks $CM*;
+^$CM+ ($BA | $HY | $NS);
+
+$BB $CM* [^$CB];                                  #  $BB  x
+$BB $CM* $LB20NonBreaks;
 
 # LB 21a Don't break after Hebrew + Hyphen
 #   HL (HY | BA) x
 #
-$HLcm ($HYcm | $BAcm) [^$CB]?;
+$HL $CM* ($HY | $BA) $CM* [^$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    $INcm;
-($ID | $EB | $EM) $CM*  $INcm;
-# $INcm  $INcm; # delete this rule for CSS loose
-$NUcm    $INcm;
-
+$SY $CM* $HL;
 
-# $LB 23
-($ID | $EB | $EM) $CM*  $POcm;
-$ALcm  $NUcm;       # includes $LB19
-$HLcm  $NUcm;
-^$CM+  $NUcm;       # Rule 10, any otherwise unattached CM behaves as AL
-$NUcm  $ALcm;
-$NUcm  $HLcm;
 
+# LB 22  Do not break before ellipses
 #
-# LB 24
-#
-$PRcm ($ID | $EB | $EM);
-$PRcm ($ALcm | $HLcm);
-$POcm ($ALcm | $HLcm);
-($ALcm | $HLcm) ($PRcm | $POcm);
-^$CM+ ($PRcm | $POcm);       # Rule 10, any otherwise unattached CM behaves as AL
-
-#
-# LB 25   Numbers.
-#
-($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 | $NUcm);
-
-# LB 30a  Do not break between regional indicators. Break after pairs of them.
-#         Tricky interaction with LB8a: ZWJ x ID
-$RIcm $RI                / [[^$BK $CR $LF $NL $SP $ZW $WJ $CL $CP $EX $IS $SY $GL $QU $BA $HY $NS $CM] {eof}];
-$RIcm $RI $CM*  $ZWJ     / [[^$BK $CR $LF $NL $SP $ZW $WJ $CL $CP $EX $IS $SY $GL $QU $BA $HY $NS $CM $ID $EB $EM] {eof}];
-$RIcm $RI $CM* [$CM-$ZWJ] / [[^$BK $CR $LF $NL $SP $ZW $WJ $CL $CP $EX $IS $SY $GL $QU $BA $HY $NS $CM] {eof}];
-
-$RIcm $RIcm [$BK $CR $LF $NL $SP $ZW $WJ $CL $CP $EX $IS $SY $GL $QU $BA $HY $NS {eof}];
-$RIcm $RIcm $ZWJ ($ID | $EB | $EM);
-
-# LB 30b Do not break between an Emoji Base and an Emoji Modifier
-$EB $CM* $EM;
-
-#
-#  Reverse Rules.
-#
-## -------------------------------------------------
-
-!!reverse;
-
-^$CM+ $ALPlus;
-^$CM+ $BA;
-^$CM+ $BB;
-^$CM+ $B2;
-^$CM+ $CL;
-^$CM+ $CP;
-^$CM+ $EB;
-^$CM+ $EM;
-^$CM+ $EX;
-^$CM+ $GL;
-^$CM+ $HL;
-^$CM+ $HY;
-^$CM+ $H2;
-^$CM+ $H3;
-^$CM+ $ID;
+[$LB20NonBreaks - $IN] $CM*    $IN;    # line_loose tailoring
 ^$CM+ $IN;
-^$CM+ $IS;
-^$CM+ $JL;
-^$CM+ $JV;
-^$CM+ $JT;
-^$CM+ $NS;
-^$CM+ $NSX;
-^$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.
 
+# LB 23
 #
-#  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.
-#
-
-# Apple early addition, remove this, superseded by LB24
-# [$PR   ] / $CM+ [$BK $CR $LF $NL $ZW $SP {eof}];
-
-
-
-# LB 4, 5, 6
-
-$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* $ZW
+($ALPlus | $HL) $CM* $NU;
+^$CM+  $NU;       # Rule 10, any otherwise unattached CM behaves as AL
+$NU $CM* ($ALPlus | $HL);
 
-# LB 8a        ZWJ x ID    Unicode Emoji proposal L2/16-011R3
-#                          The ZWJ will look like a CM to whatever precedes it.
+# LB 23a
 #
-($ID | $EB | $EM) $ZWJ $CM* $CAN_CM?;
-
-
-# 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+ $CAN_CM;
+$PR $CM* ($ID | $EB | $EM);
+($ID | $EB | $EM) $CM*  $PO;
 
 
-# LB 11
 #
-$WJ $CM* $CAN_CM;
-$WJ      [$LB8NonBreaks-$CM];
-
-     $CANT_CM $CM* $WJ;
-$CAN_CM  $CM* $WJ;
-
-# LB 12a
-#      [^SP BA HY] x GL
+# LB 24
 #
-$GL $CM* [$LB8NonBreaks-[$CM $SP $BA $HY]];
+($PR | $PO) $CM* ($ALPlus | $HL);
+($ALPlus | $HL) $CM* ($PR | $PO);
+^$CM+ ($PR | $PO);       # Rule 10, any otherwise unattached CM behaves as AL
 
-# LB 12
-#     GL  x
 #
-$CANT_CM $CM* $GL;
-$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* $OP;
-
-# LB 14    OP SP* x
+# LB 25   Numbers.
 #
-$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* $OP;
-$AL_FOLLOW_CM   $CM+ $SP+ $CM* $OP;
-
-
-# LB 15
-$OP $SP* $CM* $QU;
-
-# LB 16
-# Don't include $NSX here
-$NS $SP* $CM* ($CL | $CP);
+(($PR | $PO) $CM*)? (($OP | $HY) $CM*)? ($IS $CM*)? $NU ($CM* ($NU | $SY | $IS))*
+    ($CM* ($CL | $CP))? ($CM* ($PR | $PO))?;
 
-# LB 17
-$B2 $SP* $CM* $B2;
-
-# LB 18  break after spaces
-#        Nothing explicit needed here.
-
-
-#
-# LB 19
+# LB 26  Do not break a Korean syllable
 #
-$QU $CM* $CAN_CM;                                #   . x QU
-$QU      $LB18NonBreaks;
+$JL $CM* ($JL | $JV | $H2 | $H3);
+($JV | $H2) $CM* ($JV | $JT);
+($JT | $H3) $CM* $JT;
 
+# LB 27  Treat korean Syllable Block the same as ID  (don't break it)
+($JL | $JV | $JT | $H2 | $H3) $CM* $IN;
+($JL | $JV | $JT | $H2 | $H3) $CM* $PO;
+$PR $CM* ($JL | $JV | $JT | $H2 | $H3);
 
-$CAN_CM  $CM* $QU;                               #   QU x .
-     $CANT_CM $CM* $QU;
 
+# LB 28   Do not break between alphabetics
 #
-#  LB 20  Break before and after CB.
-#         nothing needed here.
-#
-
-# LB 21
-# Don't include $NSX here
-($BA | $HY | $NS) $CM* [$LB20NonBreaks-$CM];     #  . x (BA | HY | NS)
-
-[$LB20NonBreaks-$CM] $CM* $BB;                   #  BB x .
-[^$CB] $CM* $BB;                                      #
-
-# LB21a
-[^$CB] $CM* ($HY | $BA) $CM* $HL;
-
-# LB21b (reverse)
-$HL $CM* $SY;
-
-# LB 22
-$IN $CM* ($ALPlus | $HL);
-$IN $CM* $EX;
-$IN $CM* ($ID | $EB | $EM);
-# $IN $CM* $IN; # delete this rule for CSS loose
-$IN $CM* $NU;
-
-# LB 23
-$PO $CM* ($ID | $EB | $EM);
-$NU $CM* ($ALPlus | $HL);
-($ALPlus | $HL) $CM* $NU;
-
-# LB 24
-($ID | $EB | $EM) $CM* $PR;
-($ALPlus | $HL) $CM* $PR;
-($ALPlus | $HL) $CM* $PO;
-$CM* ($PR | $PO) $CM* ($ALPlus | $HL);
-$CM* ($PR | $PO) $CM+ / [$BK $CR $LF $NL $ZW $SP {eof}];
-
-# LB 25
-($CM* ($PR | $PO))? ($CM* ($CL | $CP))? ($CM* ($NU | $IS | $SY))* $CM* $NU ($CM* ($OP | $HY))? ($CM* ($PR | $PO))?;
-
-# LB 26
-($H3 | $H2 | $JV | $JL) $CM* $JL;
-($JT | $JV) $CM* ($H2 | $JV);
-$JT $CM* ($H3 | $JT);
-
-# LB 27
-$IN $CM* ($H3 | $H2 | $JT | $JV | $JL);
-$PO $CM* ($H3 | $H2 | $JT | $JV | $JL);
- ($H3 | $H2 | $JT | $JV | $JL) $CM* $PR;
-
-# LB 28
 ($ALPlus | $HL) $CM* ($ALPlus | $HL);
-
+^$CM+ ($ALPlus | $HL);      # The $CM+ is from rule 10, an unattached CM is treated as AL
 
 # LB 29
-($ALPlus | $HL) $CM* $IS;
+$IS $CM* ($ALPlus | $HL);
 
 # LB 30
-$OP $CM* ($ALPlus | $HL | $NU);
-($ALPlus | $HL | $NU) $CM* $CP;
-
-# LB 30a
-#    Pairs of Regional Indicators.
-#    The following two rules are nearly identical. The first matches only sequences with an odd number of adjacent RIs,
-#    the second with an even number. Stripping away the cruft they look like
-#         [^RI] RI / (RI RI)+ ^RI;
-#         [^RI] RI RI / (RI RI)+ ^RI;
-#
-# Line Loose tailoring: Don't include NSX here.
-[{bof} $NS $HY $BA $QU $CL $CP $EX $IS $SY $WJ $GL $ZW $SP $BK $CR $LF $NL $ZWJ] $CM* $RI / ($CM* $RI $CM* $RI)+ $CM* [{eof}[^$RI $CM]];
-[{bof} $NS $HY $BA $QU $CL $CP $EX $IS $SY $WJ $GL $ZW $SP $BK $CR $LF $NL $ZWJ] $CM* $RI $CM* $RI / ($CM* $RI $CM* $RI)+ $CM* [{eof}[^$RI $CM]];
-
-# In general, adjacent RIs stay together. The hard-break rules, above, overide this, forcing in the boundaries between pairs.
-$RI $CM* $RI;
-
-#    WJ, GL, QU, etc. are classes with rules like "WJ x "   which includes "WJ x RI".
-$RI $CM* ([$WJ $GL $QU $BB] |  (($HY | $BA)$CM* $HL));
+($ALPlus | $HL | $NU) $CM* $OP30;
+^$CM+ $OP30;         # The $CM+ is from rule 10, an unattached CM is treated as AL.
+$CP30 $CM* ($ALPlus | $HL | $NU);
 
+# LB 30a  Do not break between regional indicators. Break after pairs of them.
+#         Tricky interaction with LB8a: ZWJ x .   together with ZWJ acting like a CM.
+$RI $CM* $RI                 / [[^$BK $CR $LF $NL $SP $ZW $WJ $CL $CP $EX $IS $SY $GL $QU $BA $HY $NS $IN $CM]];
+$RI $CM* $RI $CM* [$CM-$ZWJ] / [[^$BK $CR $LF $NL $SP $ZW $WJ $CL $CP $EX $IS $SY $GL $QU $BA $HY $NS $IN $CM]];
+$RI $CM* $RI $CM* [$BK $CR $LF $NL $SP $ZW $WJ $CL $CP $EX $IS $SY $GL $QU $BA $HY $NS $IN $ZWJ {eof}];
+# note: the preceding rule includes {eof} rather than having the last [set] term qualified with '?'
+#       because of the chain-out behavior difference. The rule must chain out only from the [set characters],
+#       not from the preceding $RI or $CM, which it would be able to do if the set were optional.
 
 # LB 30b Do not break between an Emoji Base and an Emoji Modifier
-$EM $CM* $EB;
-
-
-## -------------------------------------------------
-
-!!safe_reverse;
-
-# LB 9
-^$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 | $SY);
-
-#  LB 30
-($CM* $RI)+;
-
-# For dictionary-based break
-$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 $RI $ZWJ $dictionary]+ [^$CM $OP $QU $CL $CP $B2 $PR $HY $BA $RI $ZWJ $dictionary];
-$dictionary $dictionary;
+$EB $CM* $EM;
 
+# LB 31 Break everywhere else.
+#       Match a single code point if no other rule applies.
+.;