# Copyright (c) 2002-2003  International Business Machines Corporation and
# others. All Rights Reserved.
#
#  file:  line.txt
#
#         Line Breaking Rules
#         Implement default line breaking as defined by Unicode TR 14.
#


#
#  Character Classes defined by TR 14.
#

$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:];
$CL = [:LineBreak =  Close_Punctuation:];
$CM = [:LineBreak =  Combining_Mark:];
$CR = [:LineBreak =  Carriage_Return:];
$EX = [:LineBreak =  Exclamation:];
$GL = [:LineBreak =  Glue:];
$HY = [:LineBreak =  Hyphen:];
$ID = [:LineBreak =  Ideographic:];
$IN = [:LineBreak =  Inseperable:];
$IS = [:LineBreak =  Infix_Numeric:];
$LF = [:LineBreak =  Line_Feed:];
$NS = [:LineBreak =  Nonstarter:];
$NU = [:LineBreak =  Numeric:];
$OP = [:LineBreak =  Open_Punctuation:];
$PO = [:LineBreak =  Postfix_Numeric:];
$PR = [:LineBreak =  Prefix_Numeric:];
$QU = [:LineBreak =  Quotation:];
$SA = [:LineBreak =  Complex_Context:];
$SG = [:LineBreak =  Surrogate:];
$SP = [:LineBreak =  Space:];
$SY = [:LineBreak =  Break_Symbols:];
$XX = [:LineBreak =  Unknown:];
$ZW = [:LineBreak =  ZWSpace:];


#
#  Character classes from TR 29.  Needed for finding characters.
#
#
$Extend  = [:Grapheme_Extend = TRUE:];


#
#  Rule LB1.  By default, treat AI  (characters with ambiguous east Asian width) and
#                               SA  (South East Asian: Thai, Lao, Khmer) as $AL  (Alphabetic)
#
$ALPlus = $AL | $AI | $SA;

#
#  Combining Marks.   X $CM*  behaves as if it were X.  Rule LB6.
#
$ALcm = $ALPlus $CM*;
$IDcm = ($ID $CM* | $SP $CM+);
$NUcm = $NU $Extend*;
$HYcm = $HY $Extend*;
$QUcm = $QU $Extend*;
$POcm = $PO $Extend*;
$OPcm = $OP $Extend*;
$BAcm = $BA $Extend*;
$BBcm = $BB $Extend*;
$NScm = $NS $Extend*;
$GLcm = $GL $Extend*;
$B2cm = $B2 $Extend*;
$INcm = $IN $Extend*;


#  New Lines.  Always break after, never break before.
#              Rule LB 3
#
#  Endings.    NewLine or Zero Width Space, or both.  Rules 4, 5
#              Because we never break before these things, $Endings
#              appears at the end of line break rule.
#
$NLF = $BK | $CR | $LF | $CR $LF;
$Endings = $SP* $ZW* $NLF?;


#
#  Openings  Sequences that can precede Words, and that should not be separated from them.
#            Rules LB 9, 10
#
$Openings = (($QUcm $SP*)? $OPcm $SP*)*;

#
#  Closings  Seqences that follow words, and that should not be separated from them,
#            Rule LB 8, 11, 15
$Closings =  ($SP*( ($CL ($SP* $NScm)?  |  $EX  | $IS  | $SY) $Extend*) | $BAcm | $HYcm  | $NScm)*;

#
#  Words.  Includes mixed Alpha-numerics.
#          Rules 11a, 16, 17, 19, more or less.
#
$NumberInterior = $IDcm | ($NUcm | $ALcm | $IS $NUcm)+;  
$Number         =  $PR? ($OPcm | $HYcm)? $NumberInterior $CL? $POcm?; # Fancy Number     18 
$Word   = (($IDcm | ($ALcm | $NUcm)+) ($POcm? | $INcm?))  ;           # Alpha-numeric.   16, 17 
$Dashes = (($B2cm $SP*)*);                                            # Dashes           11a   
        
        
$Word15 = ($BBcm* ($Word | $Number | $Dashes)? ($BAcm | $HYcm | $NScm)*) |  # Rule 15. Stuff sticks around words.
          [^[:Cc:] $BK $CR $LF $ZW $SP $GL] $Extend*  |                 # Allow characters that don't meet the
          [^$BK $CR $LF $ZW $SP $GL ];                                   #  more elaborate definitions for WORD
                                                                    #  to be glued.
        
$GluedWord  = ($GLcm | $QUcm)? $Word15 (($GLcm | $QUcm) $Word15)*;  # "Glue" will stick anything below it together.
                                                                    # Rules 13, 14

#
#  The actual rule, a combination of everything defined above.
#
$Openings $GluedWord  $Closings $Endings;
# $GluedWord;


#
#  Reverse Rules.
#
#     Back up to a hard break or a space that will cause a boundary.
#     Not all spaces cause line breaks.  $SpaceGlue represents a sequence
#     containing a space that may inhibit a break from occuring.
#

$SpaceGlue  = ([$ZW $CL $IS $NS $OP]  ($Extend* $SP)) | (($Extend* $SP)+ $OP);
$ClumpingChars = [^$SP $BK $CR $LF];

!. . $ClumpingChars*  ($SpaceGlue $ClumpingChars*)* (. | $LF $CR);