Unicode::Collate(3pm) Perl Programmers Reference Guide Unicode::Collate(3pm)
NAME
Unicode::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.
DESCRIPTION
This module is an implementation of Unicode Technical Standard #10 (UTS #10) "Unicode Collation Algorithm."
Constructor and Tailoring
The "new" method returns a collator object.
$Collator = Unicode::Collate->new(
UCA_Version => $UCA_Version,
alternate => $alternate,
backwards => $levelNumber, # or @levelNumbers
entry => $element,
normalization => $normalization_form,
ignoreName => qr/$ignoreName/,
ignoreChar => qr/$ignoreChar/,
katakana_before_hiragana => $bool,
level => $collationLevel,
overrideCJK => &overrideCJK,
overrideHangul => &overrideHangul,
preprocess => &preprocess,
rearrange => @charList,
table => $filename,
undefName => qr/$undefName/,
undefChar => qr/$undefChar/,
upper_before_lower => $bool,
);
# if %tailoring is false (i.e. empty),
# $Collator should do the default collation.
UCA_Version
If the version number of the older UCA is given, the older behavior of that version is emulated on collating. If omitted, the return
value of "UCA_Version()" is used.
The supported version: 8 or 9.
This parameter may be removed in the future version, as switching the algorithm would affect the performance.
alternate
-- see 3.2.2 Variable Weighting, UTS #10.
(the title in UCA version 8: Alternate Weighting)
This key allows to alternate weighting for variable collation elements, which are marked with an ASTERISK in the table (NOTE: Many
punction marks and symbols are variable in allkeys.txt).
alternate => '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.
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.
Overrides a default order or defines additional collation elements
entry => <<'ENTRIES', # use the UCA file format
00E6 ; [.0861.0020.0002.00E6] [.08B1.0020.0002.00E6] # ligature <ae> as <a><e>
0063 0068 ; [.0893.0020.0002.0063] # "ch" in traditional Spanish
0043 0068 ; [.0893.0020.0008.0043] # "Ch" in traditional Spanish
ENTRIES
NOTE: The code point in the UCA file format (before ';') must be a Unicode code point, but not a native code point. So 0063 must
always denote "U+0063", but not a character of "x63".
ignoreName
ignoreChar
-- see Completely Ignorable, 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.
E.g. when 'a' and 'e' are ignorable, 'element' is equal to 'lament' (or 'lmnt').
level
-- see 4.3 Form a sort key for each string, 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 alternate is 'shifted')
ex.level => 2,
If omitted, the maximum is the 4th.
normalization
-- see 4.1 Normalize each input string, UTS #10.
If specified, strings are normalized before preparation of sort keys (the normalization is executed after preprocess).
As a form name, one of the following names must be used.
'C' or 'NFC' for Normalization Form C
'D' or 'NFD' for Normalization Form D
'KC' or 'NFKC' for Normalization Form KC
'KD' or 'NFKD' for Normalization Form KD
If omitted, the string is put into Normalization Form D.
If "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).
see CAVEAT.
overrideCJK
-- see 7.1 Derived Collation Elements, UTS #10.
By default, mapping of CJK Unified Ideographs uses the Unicode codepoint order. But the mapping of CJK Unified Ideographs may be over-
rided.
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("Pex{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 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. But the mapping of Hangul Syllables may be overrided.
This tag works like overrideCJK, so see there for examples.
If you want to override the mapping of Hangul Syllables, the Normalization Forms D and KD are not appropriate (they will be decomposed
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".
preprocess => sub {
my $str = shift;
$str =~ s/(?:an?|the)s+//gi;
$str;
},
rearrange
-- see 3.1.3 Rearrangement, UTS #10.
Characters that are not coded in logical order and to be rearranged. By default,
rearrange => [ 0x0E40..0x0E44, 0x0EC0..0x0EC4 ],
If you want to disallow any rearrangement, pass "undef" or "[]" (a reference to an empty list) as the value for this key.
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 element table if desired. The table file must be in your "lib/Unicode/Collate" directory.
By default, the file "lib/Unicode/Collate/allkeys.txt" is used.
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
);
undefName
undefChar
-- 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 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 codepoint order among the unassigned characters). But, it'd be better to ignore
characters unfamiliar to you and maybe never used.
katakana_before_hiragana
upper_before_lower
-- see 6.6 Case Comparisons; 7.3.1 Tertiary Weight Table, UTS #10.
By default, lowercase is before uppercase and hiragana is before katakana.
If the tag is made true, this is reversed.
NOTE: These tags simplemindedly assume any lowercase/uppercase or hiragana/katakana distinctions should occur in level 3, and their
weights at level 3 should be same as those mentioned in 7.3.1, UTS #10. If you define your collation elements which violates this,
these tags don't work validly.
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 a sort key for each string, 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)"
use Unicode::Collate;
my $c = Unicode::Collate->new();
print $c->viewSortKey("Perl"),"
";
# 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
(If C<UCA_Version> is 8, the output is slightly different.)
Methods for Searching
DISCLAIMER: If "preprocess" or "normalization" tag is true for $Collator, calling these methods ("index", "match", "gmatch", "subst",
"gsubst") is croaked, as the position and the length might differ from those on the specified string. (And the "rearrange" tag is
neglected.)
The "match", "gmatch", "subst", "gsubst" methods work like "m//", "m//g", "s///", "s///g", respectively, but they are not aware of any pat-
tern, but only a literal substring.
"$position = $Collator->index($string, $substring[, $position])"
"($position, $length) = $Collator->index($string, $substring[, $position])"
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 muB studieren Perl.";
my $sub = "MUSS";
my $match;
if (my($pos,$len) = $Collator->index($str, $sub)) {
$match = substr($str, $pos, $len);
}
and get "muB" in $match since "muB" is primary equal to "MUSS".
"$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 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].
";
} else {
print "doesn't match.
";
}
or
if (($match) = $Collator->match($str, $sub)) { # list context
print "matches [$match].
";
} else {
print "doesn't match.
";
}
"@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 ass camex{301}l CAMEL horse cAm E L...";
$Collator->gsubst($str, "camel", sub { "<b>$_[0]</b>" });
# now $str is "<b>Camel</b> ass <b>camex{301}l</b> <b>CAMEL</b> horse <b>cAm E L</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).
$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
UCA_Version
Returns the version number of UTS #10 this module consults.
Base_Unicode_Version
Returns the version number of the Unicode Standard this module is based on.
EXPORT
None by default.
TODO
Unicode::Collate has not been ported to EBCDIC. IMHO, use of utf8::unicode_to_native()/utf8::native_to_unicode() at the proper postions
should allow this module to work on EBCDIC platform...
CAVEAT
Use of the "normalization" parameter requires the Unicode::Normalize module.
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 provided in <http://www.unicode.org/reports/tr10/CollationTest.html> and <http://www.uni-
code.org/reports/tr10/CollationTest.zip>
For CollationTest_SHIFTED.txt, a collator via "Unicode::Collate->new( )" should be used; for CollationTest_NON_IGNORABLE.txt, a collator
via "Unicode::Collate->new(alternate => "non-ignorable", level => 3)".
Unicode::Normalize is required to try The Conformance Test.
AUTHOR
SADAHIRO Tomoyuki, <SADAHIRO@cpan.org>
http://homepage1.nifty.com/nomenclator/perl/
Copyright(C) 2001-2002, SADAHIRO Tomoyuki. Japan. All rights reserved.
This library is free software; you can redistribute it
and/or modify it under the same terms as Perl itself.
SEE ALSO
http://www.unicode.org/reports/tr10/
Unicode Collation Algorithm - UTS #10
http://www.unicode.org/reports/tr10/allkeys.txt
The Default Unicode Collation Element Table
http://www.unicode.org/reports/tr10/CollationTest.html http://www.unicode.org/reports/tr10/CollationTest.zip
The latest versions of the conformance test for the UCA
http://www.unicode.org/reports/tr15/
Unicode Normalization Forms - UAX #15
Unicode::Normalize
perl v5.8.0 2002-06-01 Unicode::Collate(3pm)