Unicode::Collate(3) Perl Programmers Reference Guide Unicode::Collate(3)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 Standard #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 omitted, the return
value of "UCA_Version()" is used. "UCA_Version()" should return
the latest tracking version 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 ordering) 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 ele‐
ments 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
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 consistent 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 ordering 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 positive), it will
be added as a terminator primary weight to the end of every stan‐
dard Hangul syllable. Secondary and any higher weights for termina‐
tor 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 conjoin‐
ing Jamo behavior in the Unicode Standard and HangulSyllable‐
Type.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 bound‐
ary 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 automatically terminated with a
terminator primary weight. These characters may need terminator
included in a collation element table beforehand.
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 parameter is made
true, this is reversed.
NOTE: This parameter simplemindedly assumes that any hira‐
gana/katakana distinctions must occur in level 3, and their weights
at level 3 must be same as those mentioned 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 specified 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 include 'NFD',
'NFC', 'NFKD', and 'NFKC'. See "Unicode::Normalize::normalize()"
for detail. If omitted, 'NFD' is used.
"normalization" is performed after "preprocess" (if defined).
Furthermore, special values, "undef" and "prenormalized", can be
used, though they are not concerned with "Unicode::Normalize::nor‐
malize()".
If "undef" (not a string "undef") is passed explicitly as the value
for this key, any normalization is not carried out (this may make
tailoring easier if any normalization is not desired). Under "(nor‐
malization => 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 normaliza‐
tion is not performed, but non-contiguous contractions with combin‐
ing 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 Exten‐
sion" (its range is "U+3400..U+4DB5" and "U+20000..U+2A6D6").
Through "overrideCJK", ordering of CJK Unified Ideographs can be
overrided.
ex. CJK Unified Ideographs in the JIS code point order.
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 assign‐
ment of weight for CJK Unified Ideographs 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 mapping 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 Syl‐
lables 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 forma‐
tion of sort keys.
ex. dropping English articles, such as "a" or "the". Then, "the
pen" is before "a pencil".
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 rear‐
ranged. 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 re‐
arrangement).
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 elements via "entry").
A typical way to define a collation element table without any file
of table:
$onlyABC = Unicode::Collate->new(
table => undef,
entry => << 'ENTRIES',
0061 ; [.0101.0020.0002.0061] # LATIN SMALL LETTER A
0041 ; [.0101.0020.0008.0041] # LATIN CAPITAL LETTER A
0062 ; [.0102.0020.0002.0062] # LATIN SMALL LETTER B
0042 ; [.0102.0020.0008.0042] # LATIN CAPITAL LETTER B
0063 ; [.0103.0020.0002.0063] # LATIN SMALL LETTER C
0043 ; [.0103.0020.0008.0043] # LATIN CAPITAL LETTER C
ENTRIES
);
If "ignoreName" or "undefName" is used, character names should be
specified as a comment (following "#") on each line.
undefChar
undefName
-- see 6.3.4 Reducing the Repertoire, UTS #10.
Undefines the collation element as if it were unassigned in the ta‐
ble. This reduces the size of the table. If an unassigned charac‐
ter appears in the string to be collated, the sort key is made from
its codepoint as a single-character collation element, as it is
greater than any other assigned collation elements (in the code‐
point order among the unassigned characters). But, it'd be better
to ignore characters unfamiliar to you and maybe never used.
Through "undefChar", any character matching "qr/$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 parameter is
made true, this is reversed.
NOTE: This parameter simplemindedly assumes that any lower‐
case/uppercase distinctions must occur in level 3, and their
weights at level 3 must be same as those mentioned in 7.3.1, UTS
#10. If you define your collation elements which differs from this
requirement, this parameter doesn't work validly.
variable
-- see 3.2.2 Variable Weighting, UTS #10.
This key allows to variable weighting for variable collation ele‐
ments, 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 specification 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
"@sorted = $Collator->sort(@not_sorted)"
Sorts a list of strings.
"$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.
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_Ver‐
sion" 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
$Collator, calling these methods ("index", "match", "gmatch", "subst",
"gsubst") is croaked, as the position and the length might differ from
those on the specified string. (And "rearrange" and "hangul_termina‐
tor" parameters are neglected.)
The "match", "gmatch", "subst", "gsubst" methods work like "m//",
"m//g", "s///", "s///g", respectively, but they are not aware of any
pattern, but only a literal substring.
"$position = $Collator->index($string, $substring[, $position])"
"($position, $length) = $Collator->index($string, $substring[, $posi‐
tion])"
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
my $Collator = Unicode::Collate->new( normalization => undef, level => 1 );
# (normalization => undef) is REQUIRED.
my $str = "Ich mu� studieren Perl.";
my $sub = "M�SS";
my $match;
if (my($pos,$len) = $Collator->index($str, $sub)) {
$match = substr($str, $pos, $len);
}
and get "mu�" in $match since "mu�" is primary equal to "M�SS".
"$match_ref = $Collator->match($string, $substring)"
"($match) = $Collator->match($string, $substring)"
If $substring matches a part of $string, in scalar context, returns
a reference to the first occurrence of the matching part
($match_ref is always true if matches, since every reference is
true); in list context, returns the first occurrence of the match‐
ing 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";
}
"@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 $replacement ($string is modified)
and return $count (always 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 @Uni‐
code::Collate::ChangeOK and @Unicode::Collate::ChangeNG.
In the scalar context, returns the modified collator (but it is not
a clone from the original).
$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 version line (starting with @version),
returns "unknown".
"UCA_Version()"
Returns the tracking version number of UTS #10 this module con‐
sults.
"Base_Unicode_Version()"
Returns the version number of UTS #10 this module consults.
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>/Uni‐
code/Collate.
The most preferable one is "The Default Unicode Collation Element Ta‐
ble" (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::Normal‐
ize 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.
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::Col‐
late->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/>
perl v5.8.8 2008-09-19 Unicode::Collate(3)
