Unicode::Collate(Perl Programmers Reference GUnicode::Collate(3p)NAMEUnicode::Collate - Unicode Collation Algorithm
SYNOPSIS
use Unicode::Collate;
#construct
$Collator = Unicode::Collate->new(%tailoring);
#sort
@sorted = $Collator->sort(@not_sorted);
#compare
$result = $Collator->cmp($a, $b); # returns 1, 0, or -1.
# If %tailoring is false (i.e. empty),
# $Collator should do the default collation.
DESCRIPTION
This module is an implementation of Unicode Technical Stan-
dard #10 (a.k.a. UTS #10) - Unicode Collation Algorithm
(a.k.a. UCA).
Constructor and Tailoring
The "new" method returns a collator object.
$Collator = Unicode::Collate->new(
UCA_Version => $UCA_Version,
alternate => $alternate, # deprecated: use of 'variable' is recommended.
backwards => $levelNumber, # or \@levelNumbers
entry => $element,
hangul_terminator => $term_primary_weight,
ignoreName => qr/$ignoreName/,
ignoreChar => qr/$ignoreChar/,
katakana_before_hiragana => $bool,
level => $collationLevel,
normalization => $normalization_form,
overrideCJK => \&overrideCJK,
overrideHangul => \&overrideHangul,
preprocess => \&preprocess,
rearrange => \@charList,
table => $filename,
undefName => qr/$undefName/,
undefChar => qr/$undefChar/,
upper_before_lower => $bool,
variable => $variable,
);
UCA_Version
If the tracking version number of UCA is given, behavior
of that tracking version is emulated on collating. If
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omitted, the return value of "UCA_Version()" is used.
"UCA_Version()" should return the latest tracking ver-
sion supported.
The supported tracking version: 8, 9, 11, or 14.
UCA Unicode Standard DUCET (@version)
---------------------------------------------------
8 3.1 3.0.1 (3.0.1d9)
9 3.1 with Corrigendum 3 3.1.1 (3.1.1)
11 4.0 4.0.0 (4.0.0)
14 4.1.0 4.1.0 (4.1.0)
Note: Recent UTS #10 renames "Tracking Version" to
"Revision."
alternate
-- see 3.2.2 Alternate Weighting, version 8 of UTS #10
For backward compatibility, "alternate" (old name) can
be used as an alias for "variable".
backwards
-- see 3.1.2 French Accents, UTS #10.
backwards => $levelNumber or \@levelNumbers
Weights in reverse order; ex. level 2 (diacritic order-
ing) in French. If omitted, forwards at all the levels.
entry
-- see 3.1 Linguistic Features; 3.2.1 File Format, UTS
#10.
If the same character (or a sequence of characters)
exists in the collation element table through "table",
mapping to collation elements is overrided. If it does
not exist, the mapping is defined additionally.
entry => <<'ENTRY', # for DUCET v4.0.0 (allkeys-4.0.0.txt)
0063 0068 ; [.0E6A.0020.0002.0063] # ch
0043 0068 ; [.0E6A.0020.0007.0043] # Ch
0043 0048 ; [.0E6A.0020.0008.0043] # CH
006C 006C ; [.0F4C.0020.0002.006C] # ll
004C 006C ; [.0F4C.0020.0007.004C] # Ll
004C 004C ; [.0F4C.0020.0008.004C] # LL
00F1 ; [.0F7B.0020.0002.00F1] # n-tilde
006E 0303 ; [.0F7B.0020.0002.00F1] # n-tilde
00D1 ; [.0F7B.0020.0008.00D1] # N-tilde
004E 0303 ; [.0F7B.0020.0008.00D1] # N-tilde
ENTRY
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entry => <<'ENTRY', # for DUCET v4.0.0 (allkeys-4.0.0.txt)
00E6 ; [.0E33.0020.0002.00E6][.0E8B.0020.0002.00E6] # ae ligature as <a><e>
00C6 ; [.0E33.0020.0008.00C6][.0E8B.0020.0008.00C6] # AE ligature as <A><E>
ENTRY
NOTE: The code point in the UCA file format (before ';')
must be a Unicode code point (defined as hexadecimal),
but not a native code point. So 0063 must always denote
"U+0063", but not a character of "\x63".
Weighting may vary depending on collation element table.
So ensure the weights defined in "entry" will be con-
sistent with those in the collation element table loaded
via "table".
In DUCET v4.0.0, primary weight of "C" is 0E60 and that
of "D" is "0E6D". So setting primary weight of "CH" to
"0E6A" (as a value between 0E60 and "0E6D") makes order-
ing as "C < CH < D". Exactly speaking DUCET already has
some characters between "C" and "D": "small capital C"
("U+1D04") with primary weight 0E64, "c-hook/C-hook"
("U+0188/U+0187") with 0E65, and "c-curl" ("U+0255")
with 0E69. Then primary weight "0E6A" for "CH" makes
"CH" ordered between "c-curl" and "D".
hangul_terminator
-- see 7.1.4 Trailing Weights, UTS #10.
If a true value is given (non-zero but should be posi-
tive), it will be added as a terminator primary weight
to the end of every standard Hangul syllable. Secondary
and any higher weights for terminator are set to zero.
If the value is false or "hangul_terminator" key does
not exist, insertion of terminator weights will not be
performed.
Boundaries of Hangul syllables are determined according
to conjoining Jamo behavior in the Unicode Standard and
HangulSyllableType.txt.
Implementation Note: (1) For expansion mapping (Unicode
character mapped to a sequence of collation elements), a
terminator will not be added between collation elements,
even if Hangul syllable boundary exists there. Addition
of terminator is restricted to the next position to the
last collation element.
(2) Non-conjoining Hangul letters (Compatibility Jamo,
halfwidth Jamo, and enclosed letters) are not automati-
cally terminated with a terminator primary weight. These
characters may need terminator included in a collation
element table beforehand.
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ignoreChar
ignoreName
-- see 3.2.2 Variable Weighting, UTS #10.
Makes the entry in the table completely ignorable; i.e.
as if the weights were zero at all level.
Through "ignoreChar", any character matching
"qr/$ignoreChar/" will be ignored. Through "ignoreName",
any character whose name (given in the "table" file as a
comment) matches "qr/$ignoreName/" will be ignored.
E.g. when 'a' and 'e' are ignorable, 'element' is equal
to 'lament' (or 'lmnt').
katakana_before_hiragana
-- see 7.3.1 Tertiary Weight Table, UTS #10.
By default, hiragana is before katakana. If the parame-
ter is made true, this is reversed.
NOTE: This parameter simplemindedly assumes that any
hiragana/katakana distinctions must occur in level 3,
and their weights at level 3 must be same as those men-
tioned in 7.3.1, UTS #10. If you define your collation
elements which violate this requirement, this parameter
does not work validly.
level
-- see 4.3 Form Sort Key, UTS #10.
Set the maximum level. Any higher levels than the speci-
fied one are ignored.
Level 1: alphabetic ordering
Level 2: diacritic ordering
Level 3: case ordering
Level 4: tie-breaking (e.g. in the case when variable is 'shifted')
ex.level => 2,
If omitted, the maximum is the 4th.
normalization
-- see 4.1 Normalize, UTS #10.
If specified, strings are normalized before preparation
of sort keys (the normalization is executed after
preprocess).
A form name "Unicode::Normalize::normalize()" accepts
will be applied as $normalization_form. Acceptable names
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include 'NFD', 'NFC', 'NFKD', and 'NFKC'. See
"Unicode::Normalize::normalize()" for detail. If omit-
ted, 'NFD' is used.
"normalization" is performed after "preprocess" (if
defined).
Furthermore, special values, "undef" and "prenormal-
ized", can be used, though they are not concerned with
"Unicode::Normalize::normalize()".
If "undef" (not a string "undef") is passed explicitly
as the value for this key, any normalization is not car-
ried out (this may make tailoring easier if any normali-
zation is not desired). Under "(normalization =>
undef)", only contiguous contractions are resolved; e.g.
even if "A-ring" (and "A-ring-cedilla") is ordered after
"Z", "A-cedilla-ring" would be primary equal to "A". In
this point, "(normalization => undef, preprocess => sub
{ NFD(shift) })" is not equivalent to "(normalization =>
'NFD')".
In the case of "(normalization => "prenormalized")", any
normalization is not performed, but non-contiguous con-
tractions with combining characters are performed.
Therefore "(normalization => 'prenormalized', preprocess
=> sub { NFD(shift) })" is equivalent to "(normalization
=> 'NFD')". If source strings are finely prenormalized,
"(normalization => 'prenormalized')" may save time for
normalization.
Except "(normalization => undef)", Unicode::Normalize is
required (see also CAVEAT).
overrideCJK
-- see 7.1 Derived Collation Elements, UTS #10.
By default, CJK Unified Ideographs are ordered in
Unicode codepoint order but "CJK Unified Ideographs" (if
"UCA_Version" is 8 to 11, its range is "U+4E00..U+9FA5";
if "UCA_Version" is 14, its range is "U+4E00..U+9FBB")
are lesser than "CJK Unified Ideographs Extension" (its
range is "U+3400..U+4DB5" and "U+20000..U+2A6D6").
Through "overrideCJK", ordering of CJK Unified Ideo-
graphs can be overrided.
ex. CJK Unified Ideographs in the JIS code point order.
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overrideCJK => sub {
my $u = shift; # get a Unicode codepoint
my $b = pack('n', $u); # to UTF-16BE
my $s = your_unicode_to_sjis_converter($b); # convert
my $n = unpack('n', $s); # convert sjis to short
[ $n, 0x20, 0x2, $u ]; # return the collation element
},
ex. ignores all CJK Unified Ideographs.
overrideCJK => sub {()}, # CODEREF returning empty list
# where ->eq("Pe\x{4E00}rl", "Perl") is true
# as U+4E00 is a CJK Unified Ideograph and to be ignorable.
If "undef" is passed explicitly as the value for this
key, weights for CJK Unified Ideographs are treated as
undefined. But assignment of weight for CJK Unified Ide-
ographs in table or "entry" is still valid.
overrideHangul
-- see 7.1 Derived Collation Elements, UTS #10.
By default, Hangul Syllables are decomposed into Hangul
Jamo, even if "(normalization => undef)". But the map-
ping of Hangul Syllables may be overrided.
This parameter works like "overrideCJK", so see there
for examples.
If you want to override the mapping of Hangul Syllables,
NFD, NFKD, and FCD are not appropriate, since they will
decompose Hangul Syllables before overriding.
If "undef" is passed explicitly as the value for this
key, weight for Hangul Syllables is treated as undefined
without decomposition into Hangul Jamo. But definition
of weight for Hangul Syllables in table or "entry" is
still valid.
preprocess
-- see 5.1 Preprocessing, UTS #10.
If specified, the coderef is used to preprocess before
the formation of sort keys.
ex. dropping English articles, such as "a" or "the".
Then, "the pen" is before "a pencil".
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preprocess => sub {
my $str = shift;
$str =~ s/\b(?:an?|the)\s+//gi;
return $str;
},
"preprocess" is performed before "normalization" (if
defined).
rearrange
-- see 3.1.3 Rearrangement, UTS #10.
Characters that are not coded in logical order and to be
rearranged. If "UCA_Version" is equal to or lesser than
11, default is:
rearrange => [ 0x0E40..0x0E44, 0x0EC0..0x0EC4 ],
If you want to disallow any rearrangement, pass "undef"
or "[]" (a reference to empty list) as the value for
this key.
If "UCA_Version" is equal to 14, default is "[]" (i.e.
no rearrangement).
According to the version 9 of UCA, this parameter shall
not be used; but it is not warned at present.
table
-- see 3.2 Default Unicode Collation Element Table, UTS
#10.
You can use another collation element table if desired.
The table file should locate in the Unicode/Collate
directory on @INC. Say, if the filename is Foo.txt, the
table file is searched as Unicode/Collate/Foo.txt in
@INC.
By default, allkeys.txt (as the filename of DUCET) is
used. If you will prepare your own table file, any name
other than allkeys.txt may be better to avoid namespace
conflict.
If "undef" is passed explicitly as the value for this
key, no file is read (but you can define collation ele-
ments via "entry").
A typical way to define a collation element table
without any file of table:
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$onlyABC = Unicode::Collate->new(
table => undef,
entry => << 'ENTRIES',
0061 ; [.0101.0020.0002.0061] # LATIN SMALL LETTER A
0041 ; [.0101.0020.0008.0041] # LATIN CAPITAL LETTER A
0062 ; [.0102.0020.0002.0062] # LATIN SMALL LETTER B
0042 ; [.0102.0020.0008.0042] # LATIN CAPITAL LETTER B
0063 ; [.0103.0020.0002.0063] # LATIN SMALL LETTER C
0043 ; [.0103.0020.0008.0043] # LATIN CAPITAL LETTER C
ENTRIES
);
If "ignoreName" or "undefName" is used, character names
should be specified as a comment (following "#") on each
line.
undefChar
undefName
-- see 6.3.4 Reducing the Repertoire, UTS #10.
Undefines the collation element as if it were unassigned
in the table. This reduces the size of the table. If an
unassigned character appears in the string to be col-
lated, the sort key is made from its codepoint as a
single-character collation element, as it is greater
than any other assigned collation elements (in the
codepoint order among the unassigned characters). But,
it'd be better to ignore characters unfamiliar to you
and maybe never used.
Through "undefChar", any character matching
"qr/$undefChar/" will be undefined. Through "undefName",
any character whose name (given in the "table" file as a
comment) matches "qr/$undefName/" will be undefined.
ex. Collation weights for beyond-BMP characters are not
stored in object:
undefChar => qr/[^\0-\x{fffd}]/,
upper_before_lower
-- see 6.6 Case Comparisons, UTS #10.
By default, lowercase is before uppercase. If the param-
eter is made true, this is reversed.
NOTE: This parameter simplemindedly assumes that any
lowercase/uppercase distinctions must occur in level 3,
and their weights at level 3 must be same as those men-
tioned in 7.3.1, UTS #10. If you define your collation
elements which differs from this requirement, this
parameter doesn't work validly.
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variable
-- see 3.2.2 Variable Weighting, UTS #10.
This key allows to variable weighting for variable col-
lation elements, which are marked with an ASTERISK in
the table (NOTE: Many punction marks and symbols are
variable in allkeys.txt).
variable => 'blanked', 'non-ignorable', 'shifted', or 'shift-trimmed'.
These names are case-insensitive. By default (if specif-
ication is omitted), 'shifted' is adopted.
'Blanked' Variable elements are made ignorable at levels 1 through 3;
considered at the 4th level.
'Non-Ignorable' Variable elements are not reset to ignorable.
'Shifted' Variable elements are made ignorable at levels 1 through 3
their level 4 weight is replaced by the old level 1 weight.
Level 4 weight for Non-Variable elements is 0xFFFF.
'Shift-Trimmed' Same as 'shifted', but all FFFF's at the 4th level
are trimmed.
Methods for Collation
"@soSorts=a$listaofrstrings.not_sorted)"
"$result = $Collator->cmp($a, $b)"
Returns 1 (when $a is greater than $b) or 0 (when $a is
equal to $b) or -1 (when $a is lesser than $b).
"$result = $Collator->eq($a, $b)"
"$result = $Collator->ne($a, $b)"
"$result = $Collator->lt($a, $b)"
"$result = $Collator->le($a, $b)"
"$result = $Collator->gt($a, $b)"
"$result = $Collator->ge($a, $b)"
They works like the same name operators as theirs.
eq : whether $a is equal to $b.
ne : whether $a is not equal to $b.
lt : whether $a is lesser than $b.
le : whether $a is lesser than $b or equal to $b.
gt : whether $a is greater than $b.
ge : whether $a is greater than $b or equal to $b.
"$sortKey = $Collator->getSortKey($string)"
-- see 4.3 Form Sort Key, UTS #10.
Returns a sort key.
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You compare the sort keys using a binary comparison and
get the result of the comparison of the strings using
UCA.
$Collator->getSortKey($a) cmp $Collator->getSortKey($b)
is equivalent to
$Collator->cmp($a, $b)
"$sortKeyForm = $Collator->viewSortKey($string)"
Converts a sorting key into its representation form. If
"UCA_Version" is 8, the output is slightly different.
use Unicode::Collate;
my $c = Unicode::Collate->new();
print $c->viewSortKey("Perl"),"\n";
# output:
# [0B67 0A65 0B7F 0B03 | 0020 0020 0020 0020 | 0008 0002 0002 0002 | FFFF FFFF FFFF FFFF]
# Level 1 Level 2 Level 3 Level 4
Methods for Searching
DISCLAIMER: If "preprocess" or "normalization" parameter is
true for $Collator, calling these methods ("index", "match",
"gmatch", "subst", "gsubst") is croaked, as the position and
the length might differ from those on the specified string.
(And "rearrange" and "hangul_terminator" parameters are
neglected.)
The "match", "gmatch", "subst", "gsubst" methods work like
"m//", "m//g", "s///", "s///g", respectively, but they are
not aware of any pattern, but only a literal substring.
"$position = $Collator->index($string, $substring[, $position])"
$position])"
"($position, $length) = $Collator->index($string, $substring[,
If $substring matches a part of $string, returns the
position of the first occurrence of the matching part in
scalar context; in list context, returns a two-element
list of the position and the length of the matching
part.
If $substring does not match any part of $string,
returns "-1" in scalar context and an empty list in list
context.
e.g. you say
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my $Collator = Unicode::Collate->new( normalization => undef, level => 1 );
# (normalization => undef) is REQUIRED.
my $str = "Ich mu_ studieren Perl.";
my $sub = "MSS";
my $match;
if (my($pos,$len) = $Collator->index($str, $sub)) {
$match = substr($str, $pos, $len);
}
and get "mu_" in $match since "mu_" is primary equal to
"MSS".
"$match_ref = $Collator->match($string, $substring)"
"($match) = $Collator->match($string, $substring)"
If $substring matches a part of $string, in scalar con-
text, returns a reference to the first occurrence of the
matching part ($match_ref is always true if matches,
since every reference is true); in list context, returns
the first occurrence of the matching part.
If $substring does not match any part of $string,
returns "undef" in scalar context and an empty list in
list context.
e.g.
if ($match_ref = $Collator->match($str, $sub)) { # scalar context
print "matches [$$match_ref].\n";
} else {
print "doesn't match.\n";
}
or
if (($match) = $Collator->match($str, $sub)) { # list context
print "matches [$match].\n";
} else {
print "doesn't match.\n";
}
atch = $Collator->gmatch($string, $substring)"@u-3p
"@match = $Collator->gmatch($string, $substring)"
If $substring matches a part of $string, returns all the
matching parts (or matching count in scalar context).
If $substring does not match any part of $string,
returns an empty list.
"$count = $Collator->subst($string, $substring, $replacement)"
If $substring matches a part of $string, the first
occurrence of the matching part is replaced by $replace-
ment ($string is modified) and return $count (always
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equals to 1).
$replacement can be a "CODEREF", taking the matching
part as an argument, and returning a string to replace
the matching part (a bit similar to
"s/(..)/$coderef->($1)/e").
"$count = $Collator->gsubst($string, $substring, $replacement)"
If $substring matches a part of $string, all the
occurrences of the matching part is replaced by
$replacement ($string is modified) and return $count.
$replacement can be a "CODEREF", taking the matching
part as an argument, and returning a string to replace
the matching part (a bit similar to
"s/(..)/$coderef->($1)/eg").
e.g.
my $Collator = Unicode::Collate->new( normalization => undef, level => 1 );
# (normalization => undef) is REQUIRED.
my $str = "Camel donkey zebra came\x{301}l CAMEL horse cAm\0E\0L...";
$Collator->gsubst($str, "camel", sub { "<b>$_[0]</b>" });
# now $str is "<b>Camel</b> donkey zebra <b>came\x{301}l</b> <b>CAMEL</b> horse <b>cAm\0E\0L</b>...";
# i.e., all the camels are made bold-faced.
Other Methods
"%old_tailoring = $Collator->change(%new_tailoring)"
Change the value of specified keys and returns the
changed part.
$Collator = Unicode::Collate->new(level => 4);
$Collator->eq("perl", "PERL"); # false
%old = $Collator->change(level => 2); # returns (level => 4).
$Collator->eq("perl", "PERL"); # true
$Collator->change(%old); # returns (level => 2).
$Collator->eq("perl", "PERL"); # false
Not all "(key,value)"s are allowed to be changed. See
also @Unicode::Collate::ChangeOK and
@Unicode::Collate::ChangeNG.
In the scalar context, returns the modified collator
(but it is not a clone from the original).
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$Collator->change(level => 2)->eq("perl", "PERL"); # true
$Collator->eq("perl", "PERL"); # true; now max level is 2nd.
$Collator->change(level => 4)->eq("perl", "PERL"); # false
"$version = $Collator->version()"
Returns the version number (a string) of the Unicode
Standard which the "table" file used by the collator
object is based on. If the table does not include a ver-
sion line (starting with @version), returns "unknown".
"UCA_Version()"
Returns the tracking version number of UTS #10 this
module consults.
"Base_Unicode_Version()"
Returns the version number of UTS #10 this module con-
sults.
EXPORT
No method will be exported.
INSTALL
Though this module can be used without any "table" file, to
use this module easily, it is recommended to install a table
file in the UCA format, by copying it under the directory <a
place in @INC>/Unicode/Collate.
The most preferable one is "The Default Unicode Collation
Element Table" (aka DUCET), available from the Unicode
Consortium's website:
http://www.unicode.org/Public/UCA/
http://www.unicode.org/Public/UCA/latest/allkeys.txt (latest version)
If DUCET is not installed, it is recommended to copy the
file from
http://www.unicode.org/Public/UCA/latest/allkeys.txt to <a
place in @INC>/Unicode/Collate/allkeys.txt manually.
CAVEATS
Normalization
Use of the "normalization" parameter requires the
Unicode::Normalize module (see Unicode::Normalize).
If you need not it (say, in the case when you need not
handle any combining characters), assign "normalization
=> undef" explicitly.
-- see 6.5 Avoiding Normalization, UTS #10.
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Conformance Test
The Conformance Test for the UCA is available under
<http://www.unicode.org/Public/UCA/>.
For CollationTest_SHIFTED.txt, a collator via
"Unicode::Collate->new( )" should be used; for
CollationTest_NON_IGNORABLE.txt, a collator via
"Unicode::Collate->new(variable => "non-ignorable",
level => 3)".
Unicode::Normalize is required to try The Conformance
Test.
AUTHOR, COPYRIGHT AND LICENSE
The Unicode::Collate module for perl was written by SADAHIRO
Tomoyuki, <SADAHIRO@cpan.org>. This module is Copyright(C)
2001-2005, SADAHIRO Tomoyuki. Japan. All rights reserved.
This module is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
The file Unicode/Collate/allkeys.txt was copied directly
from <http://www.unicode.org/Public/UCA/4.1.0/allkeys.txt>.
This file is Copyright (c) 1991-2005 Unicode, Inc. All
rights reserved. Distributed under the Terms of Use in
<http://www.unicode.org/copyright.html>.
SEE ALSO
Unicode Collation Algorithm - UTS #10
<http://www.unicode.org/reports/tr10/>
The Default Unicode Collation Element Table (DUCET)
<http://www.unicode.org/Public/UCA/latest/allkeys.txt>
The conformance test for the UCA
<http://www.unicode.org/Public/UCA/latest/CollationTest.html>
<http://www.unicode.org/Public/UCA/latest/CollationTest.zip>
Hangul Syllable Type
<http://www.unicode.org/Public/UNIDATA/HangulSyllableType.txt>
Unicode Normalization Forms - UAX #15
<http://www.unicode.org/reports/tr15/>
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