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.
Note: Strings in @not_sorted
, $a
and $b
are interpreted according to Perl's Unicode support. See perlunicode, perluniintro, perlunitut, perlunifaq, utf8. Otherwise you can use preprocess
or should decode them before.
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. If new() is called with no parameters, the collator should do the default collation.
$Collator = Unicode::Collate->new( UCA_Version => $UCA_Version, alternate => $alternate, # alias for 'variable' backwards => $levelNumber, # or \@levelNumbers entry => $element, hangul_terminator => $term_primary_weight, highestFFFF => $bool, identical => $bool, ignoreName => qr/$ignoreName/, ignoreChar => qr/$ignoreChar/, ignore_level2 => $bool, katakana_before_hiragana => $bool, level => $collationLevel, long_contraction => $bool, minimalFFFE => $bool, normalization => $normalization_form, overrideCJK => \&overrideCJK, overrideHangul => \&overrideHangul, preprocess => \&preprocess, rearrange => \@charList, rewrite => \&rewrite, suppress => \@charList, table => $filename, undefName => qr/$undefName/, undefChar => qr/$undefChar/, upper_before_lower => $bool, variable => $variable, );
-
UCA_Version
If the revision (previously "tracking version") number of UCA is given, behavior of that revision is emulated on collating. If omitted, the return value of
UCA_Version()
is used.The following revisions are supported. The default is 30.
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) 16 5.0 5.0.0 (5.0.0) 18 5.1.0 5.1.0 (5.1.0) 20 5.2.0 5.2.0 (5.2.0) 22 6.0.0 6.0.0 (6.0.0) 24 6.1.0 6.1.0 (6.1.0) 26 6.2.0 6.2.0 (6.2.0) 28 6.3.0 6.3.0 (6.3.0) 30 7.0.0 7.0.0 (7.0.0)
* See below
long_contraction
withUCA_Version
22 and 24.* Noncharacters (e.g. U+FFFF) are not ignored, and can be overridden since
UCA_Version
22.* Out-of-range codepoints (greater than U+10FFFF) are not ignored, and can be overridden since
UCA_Version
22.* Fully ignorable characters were ignored, and would not interrupt contractions with
UCA_Version
9 and 11.* Treatment of ignorables after variables and some behaviors were changed at
UCA_Version
9.* Characters regarded as CJK unified ideographs (cf.
overrideCJK
) depend onUCA_Version
.* Many hangul jamo are assigned at
UCA_Version
20, that will affecthangul_terminator
. -
alternate
-- see 3.2.2 Alternate Weighting, version 8 of UTS #10
For backward compatibility,
alternate
(old name) can be used as an alias forvariable
. -
backwards
-- see 3.4 Backward Accents, UTS #10.
backwards => $levelNumber or \@levelNumbers
Weights in reverse order; ex. level 2 (diacritic ordering) in French. If omitted (or
$levelNumber
isundef
or\@levelNumbers
is[]
), forwards at all the levels. -
entry
-- see 5 Tailoring; 9.1 Allkeys 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 overridden. 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. So0063
must always denoteU+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 viatable
.In DUCET v4.0.0, primary weight of
C
is0E60
and that ofD
is0E6D
. So setting primary weight ofCH
to0E6A
(as a value between0E60
and0E6D
) makes ordering asC < CH < D
. Exactly speaking DUCET already has some characters betweenC
andD
:small capital C
(U+1D04
) with primary weight0E64
,c-hook/C-hook
(U+0188/U+0187
) with0E65
, andc-curl
(U+0255
) with0E69
. Then primary weight0E6A
forCH
makesCH
ordered betweenc-curl
andD
. -
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 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 automatically terminated with a terminator primary weight. These characters may need terminator included in a collation element table beforehand.
-
highestFFFF
-- see 5.14 Collation Elements, UTS #35.
If the parameter is made true,
U+FFFF
has a highest primary weight. When a boolean of$coll->ge($str, "abc")
and$coll->le($str, "abc\x{FFFF}")
is true, it is expected that$str
begins with"abc"
, or another primary equivalent.$str
may be"abcd"
,"abc012"
, but should not includeU+FFFF
such as"abc\x{FFFF}xyz"
.$coll->le($str, "abc\x{FFFF}")
works like$coll->lt($str, "abd")
almost, but the latter has a problem that you should know which letter is next toc
. For a certain language wherech
as the next letter,"abch"
is greater than"abc\x{FFFF}"
, but less than"abd"
.Note: This is equivalent to
(entry => 'FFFF ; [.FFFE.0020.0005.FFFF]')
. Any other character thanU+FFFF
can be tailored byentry
. -
identical
-- see A.3 Deterministic Comparison, UTS #10.
By default, strings whose weights are equal should be equal, even though their code points are not equal. Completely ignorable characters are ignored.
If the parameter is made true, a final, tie-breaking level is used. If no difference of weights is found after the comparison through all the level specified by
level
, the comparison with code points will be performed. For the tie-breaking comparison, the sort key has code points of the original string appended. Completely ignorable characters are not ignored.If
preprocess
and/ornormalization
is applied, the code points of the string after them (in NFD by default) are used. - ignoreChar
-
ignoreName
-- see 3.6 Variable Weighting, UTS #10.
Makes the entry in the table completely ignorable; i.e. as if the weights were zero at all level.
Through
ignoreChar
, any character matchingqr/$ignoreChar/
will be ignored. ThroughignoreName
, any character whose name (given in thetable
file as a comment) matchesqr/$ignoreName/
will be ignored.E.g. when 'a' and 'e' are ignorable, 'element' is equal to 'lament' (or 'lmnt').
-
ignore_level2
-- see 5.1 Parametric Tailoring, UTS #10.
By default, case-sensitive comparison (that is level 3 difference) won't ignore accents (that is level 2 difference).
If the parameter is made true, accents (and other primary ignorable characters) are ignored, even though cases are taken into account.
NOTE:
level
should be 3 or greater. -
katakana_before_hiragana
-- see 7.2 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 hiragana/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.
NOTE: The DUCET includes weights over 0xFFFF at the 4th level. But this module only uses weights within 0xFFFF. When
variable
is 'blanked' or 'non-ignorable' (other than 'shifted' and 'shift-trimmed'), the level 4 may be unreliable.See also
identical
. -
long_contraction
-- see 3.8.2 Well-Formedness of the DUCET, 4.2 Produce Array, UTS #10.
If the parameter is made true, for a contraction with three or more characters (here nicknamed "long contraction"), initial substrings will be handled. For example, a contraction ABC, where A is a starter, and B and C are non-starters (character with non-zero combining character class), will be detected even if there is not AB as a contraction.
Default: Usually false. If
UCA_Version
is 22 or 24, and the value oflong_contraction
is not specified innew()
, a true value is set implicitly. This is a workaround to pass Conformance Tests for Unicode 6.0.0 and 6.1.0.change()
handleslong_contraction
explicitly only. Iflong_contraction
is not specified inchange()
, even thoughUCA_Version
is changed,long_contraction
will not be changed.Limitation: Scanning non-starters is one-way (no back tracking). If AB is found but not ABC is not found, other long contraction where the first character is A and the second is not B may not be found.
Under
(normalization => undef)
, detection step of discontiguous contractions will be skipped.Note: The following contractions in DUCET are not considered in steps S2.1.1 to S2.1.3, where they are discontiguous.
0FB2 0F71 0F80 (TIBETAN VOWEL SIGN VOCALIC RR) 0FB3 0F71 0F80 (TIBETAN VOWEL SIGN VOCALIC LL)
For example
TIBETAN VOWEL SIGN VOCALIC RR
withCOMBINING TILDE OVERLAY
(U+0344
) is0FB2 0344 0F71 0F80
in NFD. In this case0FB2 0F80
(TIBETAN VOWEL SIGN VOCALIC R
) is detected, instead of0FB2 0F71 0F80
. Inserted0344
makes0FB2 0F71 0F80
discontiguous and lack of contraction0FB2 0F71
prohibits0FB2 0F71 0F80
from being detected. -
minimalFFFE
-- see 5.14 Collation Elements, UTS #35.
If the parameter is made true,
U+FFFE
has a minimal primary weight. The comparison between"$a1\x{FFFE}$a2"
and"$b1\x{FFFE}$b2"
first compares$a1
and$b1
at level 1, and then$a2
and$b2
at level 1, as followed."ab\x{FFFE}a" "Ab\x{FFFE}a" "ab\x{FFFE}c" "Ab\x{FFFE}c" "ab\x{FFFE}xyz" "abc\x{FFFE}def" "abc\x{FFFE}xYz" "aBc\x{FFFE}xyz" "abcX\x{FFFE}def" "abcx\x{FFFE}xyz" "b\x{FFFE}aaa" "bbb\x{FFFE}a"
Note: This is equivalent to
(entry => 'FFFE ; [.0001.0020.0005.FFFE]')
. Any other character thanU+FFFE
can be tailored byentry
. -
normalization
-- see 4.1 Normalize, UTS #10.
If specified, strings are normalized before preparation of sort keys (the normalization is executed after preprocess).
A form name
Unicode::Normalize::normalize()
accepts will be applied as$normalization_form
. Acceptable names include'NFD'
,'NFC'
,'NFKD'
, and'NFKC'
. SeeUnicode::Normalize::normalize()
for detail. If omitted,'NFD'
is used.normalization
is performed afterpreprocess
(if defined).Furthermore, special values,
undef
and"prenormalized"
, can be used, though they are not concerned withUnicode::Normalize::normalize()
.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(normalization => undef)
, only contiguous contractions are resolved; e.g. even ifA-ring
(andA-ring-cedilla
) is ordered afterZ
,A-cedilla-ring
would be primary equal toA
. 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 discontiguous contractions 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 those in the CJK Unified Ideographs block are less than those in the CJK Unified Ideographs Extension A etc.
In the CJK Unified Ideographs block: U+4E00..U+9FA5 if UCA_Version is 8, 9 or 11. U+4E00..U+9FBB if UCA_Version is 14 or 16. U+4E00..U+9FC3 if UCA_Version is 18. U+4E00..U+9FCB if UCA_Version is 20 or 22. U+4E00..U+9FCC if UCA_Version is 24 or later. In the CJK Unified Ideographs Extension blocks: Ext.A (U+3400..U+4DB5) and Ext.B (U+20000..U+2A6D6) in any UCA_Version. Ext.C (U+2A700..U+2B734) if UCA_Version is 20 or later. Ext.D (U+2B740..U+2B81D) if UCA_Version is 22 or later.
Through
overrideCJK
, ordering of CJK unified ideographs (including extensions) can be overridden.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 },
The return value may be an arrayref of 1st to 4th weights as shown above. The return value may be an integer as the primary weight as shown below. If
undef
is returned, the default derived collation element will be used.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 return $n; # return the primary weight },
The return value may be a list containing zero or more of an arrayref, an integer, or
undef
.ex. ignores all CJK unified ideographs.
overrideCJK => sub {()}, # CODEREF returning empty list # where ->eq("Pe\x{4E00}rl", "Perl") is true # as U+4E00 is a CJK unified ideograph and to be ignorable.
If a false value (including
undef
) is passed,overrideCJK
has no effect.$Collator->change(overrideCJK => 0)
resets the old one.But assignment of weight for CJK unified ideographs in
table
orentry
is still valid. Ifundef
is passed explicitly as the value for this key, weights for CJK unified ideographs are treated as undefined. However whenUCA_Version
> 8,(overrideCJK => undef)
has no special meaning.Note: In addition to them, 12 CJK compatibility ideographs (
U+FA0E
,U+FA0F
,U+FA11
,U+FA13
,U+FA14
,U+FA1F
,U+FA21
,U+FA23
,U+FA24
,U+FA27
,U+FA28
,U+FA29
) are also treated as CJK unified ideographs. But they can't be overridden viaoverrideCJK
when you use DUCET, as the table includes weights for them.table
orentry
has priority overoverrideCJK
. -
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 overridden.This parameter works like
overrideCJK
, so see there for examples.If you want to override the mapping of Hangul syllables, NFD and NFKD are not appropriate, since NFD and NFKD will decompose Hangul syllables before overriding. FCD may decompose Hangul syllables as the case may be.
If a false value (but not
undef
) is passed,overrideHangul
has no effect.$Collator->change(overrideHangul => 0)
resets the old one.If
undef
is passed explicitly as the value for this key, weight for Hangul syllables is treated as undefined without decomposition into Hangul Jamo. But definition of weight for Hangul syllables intable
orentry
is still valid. -
overrideOut
-- see 7.1.1 Handling Ill-Formed Code Unit Sequences, UTS #10.
Perl seems to allow out-of-range values (greater than 0x10FFFF). By default, out-of-range values are replaced with
U+FFFD
(REPLACEMENT CHARACTER) whenUCA_Version
>= 22, or ignored whenUCA_Version
<= 20.When
UCA_Version
>= 22, the weights of out-of-range values can be overridden. Thoughtable
orentry
are available for them, out-of-range values are too many.overrideOut
can perform it algorithmically. This parameter works likeoverrideCJK
, so see there for examples.ex. ignores all out-of-range values.
overrideOut => sub {()}, # CODEREF returning empty list
If a false value (including
undef
) is passed,overrideOut
has no effect.$Collator->change(overrideOut => 0)
resets the old one.NOTE ABOUT U+FFFD:
UCA recommends that out-of-range values should not be ignored for security reasons. Say,
"pe\x{110000}rl"
should not be equal to"perl"
. However,U+FFFD
is wrongly mapped to a variable collation element in DUCET for Unicode 6.0.0 to 6.2.0, that means out-of-range values will be ignored whenvariable
isn'tNon-ignorable
.The mapping of
U+FFFD
is corrected in Unicode 6.3.0. see http://www.unicode.org/reports/tr10/tr10-28.html#Trailing_Weights (7.1.4 Trailing Weights). Such a correction is reproduced by this.overrideOut => sub { 0xFFFD }, # CODEREF returning a very large integer
This workaround is unnecessary since Unicode 6.3.0.
-
preprocess
-- see 5.4 Preprocessing, UTS #10.
If specified, the coderef is used to preprocess each string 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/\b(?:an?|the)\s+//gi; return $str; },
preprocess
is performed beforenormalization
(if defined).ex. decoding strings in a legacy encoding such as shift-jis:
$sjis_collator = Unicode::Collate->new( preprocess => \&your_shiftjis_to_unicode_decoder, ); @result = $sjis_collator->sort(@shiftjis_strings);
Note: Strings returned from the coderef will be interpreted according to Perl's Unicode support. See perlunicode, perluniintro, perlunitut, perlunifaq, utf8.
-
rearrange
-- see 3.5 Rearrangement, UTS #10.
Characters that are not coded in logical order and to be rearranged. If
UCA_Version
is equal to or less 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 or greater than 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.
-
rewrite
If specified, the coderef is used to rewrite lines in
table
orentry
. The coderef will get each line, and then should return a rewritten line according to the UCA file format. If the coderef returns an empty line, the line will be skipped.e.g. any primary ignorable characters into tertiary ignorable:
rewrite => sub { my $line = shift; $line =~ s/\[\.0000\..{4}\..{4}\./[.0000.0000.0000./g; return $line; },
This example shows rewriting weights.
rewrite
is allowed to affect code points, weights, and the name.NOTE:
table
is available to use another table file; preparing a modified table once would be more efficient than rewriting lines on reading an unmodified table every time. -
suppress
-- see suppress contractions in 5.14.11 Special-Purpose Commands, UTS #35 (LDML).
Contractions beginning with the specified characters are suppressed, even if those contractions are defined in
table
.An example for Russian and some languages using the Cyrillic script:
suppress => [0x0400..0x0417, 0x041A..0x0437, 0x043A..0x045F],
where 0x0400 stands for
U+0400
, CYRILLIC CAPITAL LETTER IE WITH GRAVE.NOTE: Contractions via
entry
are not be suppressed. -
table
-- see 3.8 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.
NOTE: When XSUB is used, the DUCET is compiled on building this module, and it may save time at the run time. Explicit saying
(table => 'allkeys.txt')
, or using another table, or usingignoreChar
,ignoreName
,undefChar
,undefName
orrewrite
will prevent this module from using the compiled DUCET.If
undef
is passed explicitly as the value for this key, no file is read (but you can define collation elements viaentry
).A typical way to define a collation element table without any file of table:
$onlyABC = Unicode::Collate->new( table => undef, entry => << 'ENTRIES', 0061 ; [.0101.0020.0002.0061] # LATIN SMALL LETTER A 0041 ; [.0101.0020.0008.0041] # LATIN CAPITAL LETTER A 0062 ; [.0102.0020.0002.0062] # LATIN SMALL LETTER B 0042 ; [.0102.0020.0008.0042] # LATIN CAPITAL LETTER B 0063 ; [.0103.0020.0002.0063] # LATIN SMALL LETTER C 0043 ; [.0103.0020.0008.0043] # LATIN CAPITAL LETTER C ENTRIES );
If
ignoreName
orundefName
is used, character names should be specified as a comment (following#
) on each line. - undefChar
-
undefName
-- see 6.3.4 Reducing the Repertoire, UTS #10.
Undefines the collation element as if it were unassigned in the
table
. This reduces the size of the table. If an unassigned character appears in the string to be collated, the sort key is made from its codepoint as a single-character collation element, as it is greater than any other assigned collation elements (in the codepoint order among the unassigned characters). But, it'd be better to ignore characters unfamiliar to you and maybe never used.Through
undefChar
, any character matchingqr/$undefChar/
will be undefined. ThroughundefName
, any character whose name (given in thetable
file as a comment) matchesqr/$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 lowercase/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 3.6 Variable Weighting, UTS #10.
This key allows for variable weighting of variable collation elements, which are marked with an ASTERISK in the table (NOTE: Many punctuation 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$a
is less than$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 less than $b. le : whether $a is less 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_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
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.
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.
rearrange
and hangul_terminator
parameters are neglected. katakana_before_hiragana
and upper_before_lower
don't affect matching and searching, as it doesn't matter whether greater or less.
-
$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. when the content of
$str
is"Ich mu
code class="inline"> studieren Perl." , you say the following where$sub
is"M
code class="inline">SS" ,my $Collator = Unicode::Collate->new( normalization => undef, level => 1 ); # (normalization => undef) is REQUIRED. my $match; if (my($pos,$len) = $Collator->index($str, $sub)) { $match = substr($str, $pos, $len); }
and get
"mu
code class="inline">" in$match
, since"mu
code class="inline">" is primary equal to"M
code class="inline">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 matching part.If
$substring
does not match any part of$string
, returnsundef
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$count
(always equals to1
) is returned.$replacement
can be aCODEREF
, taking the matching part as an argument, and returning a string to replace the matching part (a bit similar tos/(..)/$coderef->($1)/e
). -
$count = $Collator->gsubst($string, $substring, $replacement)
If
$substring
matches a part of$string
, all the occurrences of the matching part are replaced by$replacement
($string
is modified) and$count
is returned.$replacement
can be aCODEREF
, taking the matching part as an argument, and returning a string to replace the matching part (a bit similar tos/(..)/$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. Examples: levels and ignore_level2 - what does camel match? --------------------------------------------------------------------------- level ignore_level2 | camel Camel came\x{301}l c-a-m-e-l cam\0e\0l -----------------------|--------------------------------------------------- 1 false | yes yes yes yes yes 2 false | yes yes no yes yes 3 false | yes no no yes yes 4 false | yes no no no yes -----------------------|--------------------------------------------------- 1 true | yes yes yes yes yes 2 true | yes yes yes yes yes 3 true | yes no yes yes yes 4 true | yes no yes no yes --------------------------------------------------------------------------- note: if variable => non-ignorable, camel doesn't match c-a-m-e-l at any level.
Other Methods
-
%old_tailoring = $Collator->change(%new_tailoring)
-
$modified_collator = $Collator->change(%new_tailoring)
Changes 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
-
$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 revision number of UTS #10 this module consults, that should correspond with the DUCET incorporated.
-
Base_Unicode_Version()
Returns the version number of UTS #10 this module consults, that should correspond with the DUCET incorporated.
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.
-
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 viaUnicode::Collate->new(variable => "non-ignorable", level => 3)
.If
UCA_Version
is 26 or later, theidentical
level is preferred;Unicode::Collate->new(identical => 1)
andUnicode::Collate->new(identical => 1,
variable => "non-ignorable", level => 3)
should be used.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) 2001-2014, 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 verbatim from http://www.unicode.org/Public/UCA/6.3.0/allkeys.txt. For this file, Copyright (c) 2001-2012 Unicode, Inc. Distributed under the Terms of Use in http://www.unicode.org/copyright.html.
SEE ALSO
- Unicode Collation Algorithm - UTS #10
- The Default Unicode Collation Element Table (DUCET)
- The conformance test for the UCA
-
Hangul Syllable Type
http://www.unicode.org/Public/UNIDATA/HangulSyllableType.txt
- Unicode Normalization Forms - UAX #15
- Unicode Locale Data Markup Language (LDML) - UTS #35
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