source/data/brkitr/rules/char.txt

#
#   Copyright (C) 2002-2016, International Business Machines Corporation and others.
#       All Rights Reserved.
#
#   file:  char.txt
#
#   ICU Character Break Rules, also known as Grapheme Cluster Boundaries
#      See Unicode Standard Annex #29.
#      These rules are based on UAX #29 Revision 28 (Draft 7) for Unicode Version 9.0
#

#
#  Character Class Definitions.
#
$CR          = [\p{Grapheme_Cluster_Break = CR}];
$LF          = [\p{Grapheme_Cluster_Break = LF}];
$Control     = [[\p{Grapheme_Cluster_Break = Control}]];
$Extend      = [[\p{Grapheme_Cluster_Break = Extend}]];
$ZWJ         = [\p{Grapheme_Cluster_Break = ZWJ}];
$Regional_Indicator = [\p{Grapheme_Cluster_Break = Regional_Indicator}];
$Prepend     = [\p{Grapheme_Cluster_Break = Prepend}];
$SpacingMark = [\p{Grapheme_Cluster_Break = SpacingMark}];

#
# Korean Syllable Definitions
#
$L           = [\p{Grapheme_Cluster_Break = L}];
$V           = [\p{Grapheme_Cluster_Break = V}];
$T           = [\p{Grapheme_Cluster_Break = T}];

$LV          = [\p{Grapheme_Cluster_Break = LV}];
$LVT         = [\p{Grapheme_Cluster_Break = LVT}];

# Emoji defintions

$E_Base      = [\p{Grapheme_Cluster_Break = EB}];
$E_Modifier  = [\p{Grapheme_Cluster_Break = EM}];
$GAZ         = [\p{Grapheme_Cluster_Break = GAZ}];
$E_Base_GAZ  = [\p{Grapheme_Cluster_Break = EBG}];

## -------------------------------------------------
!!chain;
!!lookAheadHardBreak;
!!forward;

$CR $LF;

$L ($L | $V | $LV | $LVT);
($LV | $V) ($V | $T);
($LVT | $T) $T;

# GB 9
[^$Control $CR $LF] ($Extend | $ZWJ);

# GB 9a (only for extended grapheme clusters)
[^$Control $CR $LF] $SpacingMark;

# GB 9b
$Prepend [^$Control $CR $LF];

# GB 10 Do not break within emoji modifier sequences or emoji zwj sequences.
($E_Base | $E_Base_GAZ) $Extend* $E_Modifier;

# GB 11
$ZWJ ($GAZ | $E_Base_GAZ);

# GB 12-13. Keep pairs of regional indicators together
#           Note that hard break '/' rule triggers only if there are three or more initial RIs,

^$Prepend* $Regional_Indicator $Regional_Indicator / $Regional_Indicator;
^$Prepend* $Regional_Indicator $Regional_Indicator;

## -------------------------------------------------

!!reverse;
$LF $CR;
($L | $V | $LV | $LVT) $L;
($V | $T) ($LV | $V);
$T ($LVT | $T);

# GB 9
($Extend | $ZWJ)   [^$Control $CR $LF];    #note that this will chain into Regional_Indicator when needed.

# GB 9a
$SpacingMark [^$Control $CR $LF];

# GB 9b
[^$Control $CR $LF] $Prepend;

# GB 10
$E_Modifier $Extend* ($E_Base | $E_Base_GAZ);

# GB 11 Don't break between ZWJ and Glue_After_ZWJ
($GAZ | $E_Base_GAZ) $ZWJ;

# GB 12-13. Going backwards, we must scan through any number of regional indicators as pairs.
#
[{bof} $Extend $ZWJ $SpacingMark] $Regional_Indicator $Regional_Indicator / ($Regional_Indicator $Regional_Indicator)+ [{eof}[^$Regional_Indicator]];
[{bof} $Extend $ZWJ $SpacingMark]                     $Regional_Indicator / ($Regional_Indicator $Regional_Indicator)+ [{eof}[^$Regional_Indicator]];
$Regional_Indicator $Regional_Indicator;
$Regional_Indicator $Prepend;

## -------------------------------------------------

!!safe_reverse;
$Regional_Indicator $Regional_Indicator;
($Extend | $ZWJ)+ .;

## -------------------------------------------------

!!safe_forward;
$Regional_Indicator $Regional_Indicator;
($Extend | $ZWJ)+ .;