Unicode::Collate(3perl) Perl Programmers Reference GuideUnicode::Collate(3perl)
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 43.
UCA Unicode Standard DUCET (@version)
-------------------------------------------------------
8 3.1 3.0.1 (3.0.1d9)
9 3.1 with Corrigendum 3 3.1.1
11 4.0.0
14 4.1.0
16 5.0.0
18 5.1.0
20 5.2.0
22 6.0.0
24 6.1.0
26 6.2.0
28 6.3.0
30 7.0.0
32 8.0.0
34 9.0.0
36 10.0.0
38 11.0.0
40 12.0.0
41 12.1.0
43 13.0.0
* See below for "long_contraction" with "UCA_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 on "UCA_Version".
* Many hangul jamo are assigned at "UCA_Version" 20, that will
affect "hangul_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 for "variable".
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 is "undef" 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. 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 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 2.4 Tailored noncharacter weights, UTS #35 (LDML) Part 5:
Collation.
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. $str may be
"abcd", "abc012", but should not include "U+FFFF" such as
"abc\x{FFFF}xyz".
"$coll->le($str, "abc\x{FFFF}")" works like "$coll->lt($str, "abd")"
almost, but the latter has a problem that you should know which
letter is next to "c". For a certain language where "ch" as the next
letter, "abch" is greater than "abc\x{FFFF}", but less than "abd".
Note: This is equivalent to "(entry => 'FFFF ;
[.FFFE.0020.0005.FFFF]')". Any other character than "U+FFFF" can be
tailored by "entry".
identical
-- see A.3 Deterministic Comparison, UTS #10.
By default, strings whose weights are equal should be equal, even
though their code points are not equal. Completely ignorable
characters are ignored.
If the parameter is made true, a final, tie-breaking level is used.
If no difference of weights is found after the comparison through
all the level specified by "level", the comparison with code points
will be performed. For the tie-breaking comparison, the sort key
has code points of the original string appended. Completely
ignorable characters are not ignored.
If "preprocess" and/or "normalization" is applied, the code points
of the string after them (in NFD by default) are used.
ignoreChar
ignoreName
-- see 3.6 Variable Weighting, UTS #10.
Makes the entry in the table completely ignorable; i.e. as if the
weights were zero at all level.
Through "ignoreChar", any character matching "qr/$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').
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
of "long_contraction" is not specified in new(), a true value is set
implicitly. This is a workaround to pass Conformance Tests for
Unicode 6.0.0 and 6.1.0.
change() handles "long_contraction" explicitly only. If
"long_contraction" is not specified in change(), even though
"UCA_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" with "COMBINING TILDE
OVERLAY" ("U+0344") is "0FB2 0344 0F71 0F80" in NFD. In this case
"0FB2 0F80" ("TIBETAN VOWEL SIGN VOCALIC R") is detected, instead of
"0FB2 0F71 0F80". Inserted 0344 makes "0FB2 0F71 0F80"
discontiguous and lack of contraction "0FB2 0F71" prohibits "0FB2
0F71 0F80" from being detected.
minimalFFFE
-- see 1.1.1 U+FFFE, UTS #35 (LDML) Part 5: Collation.
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 than "U+FFFE" can be
tailored by "entry".
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::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 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 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 to 30.
U+4E00..U+9FD5 if UCA_Version is 32 or 34.
U+4E00..U+9FEA if UCA_Version is 36.
U+4E00..U+9FEF if UCA_Version is 38, 40 or 41.
U+4E00..U+9FFC if UCA_Version is 43.
In the CJK Unified Ideographs Extension blocks:
Ext.A (U+3400..U+4DB5) if UCA_Version is 8 to 41.
Ext.A (U+3400..U+4DBF) if UCA_Version is 43.
Ext.B (U+20000..U+2A6D6) if UCA_Version is 8 to 41.
Ext.B (U+20000..U+2A6DD) if UCA_Version is 43.
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.
Ext.E (U+2B820..U+2CEA1) if UCA_Version is 32 or later.
Ext.F (U+2CEB0..U+2EBE0) if UCA_Version is 36 or later.
Ext.G (U+30000..U+3134A) if UCA_Version is 43.
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" or
"entry" is still valid. If "undef" is passed explicitly as the
value for this key, weights for CJK unified ideographs are treated
as undefined. However when "UCA_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 via
"overrideCJK" when you use DUCET, as the table includes weights for
them. "table" or "entry" has priority over "overrideCJK".
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. "$Collator->change(overrideHangul => 0)" resets the old
one.
If "undef" is passed explicitly as the value for this key, weight
for Hangul syllables is treated as undefined without decomposition
into Hangul Jamo. But definition of weight for Hangul syllables in
"table" or "entry" is still valid.
overrideOut
-- see 7.1.1 Handling Ill-Formed Code Unit Sequences, UTS #10.
Perl seems to allow out-of-range values (greater than 0x10FFFF). By
default, out-of-range values are replaced with "U+FFFD" (REPLACEMENT
CHARACTER) when "UCA_Version" >= 22, or ignored when "UCA_Version"
<= 20.
When "UCA_Version" >= 22, the weights of out-of-range values can be
overridden. Though "table" or "entry" are available for them, out-
of-range values are too many.
"overrideOut" can perform it algorithmically. This parameter works
like "overrideCJK", so see there for examples.
ex. ignores all out-of-range values.
overrideOut => sub {()}, # CODEREF returning empty list
If a false value (including "undef") is passed, "overrideOut" has no
effect. "$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 when "variable" isn't "Non-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 before "normalization" (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" or
"entry". 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 3.12 Special-Purpose Commands, UTS #35 (LDML) Part 5:
Collation.
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" will 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 using
"ignoreChar", "ignoreName", "undefChar", "undefName" or "rewrite"
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 via "entry").
A typical way to define a collation element table without any file
of table:
$onlyABC = Unicode::Collate->new(
table => undef,
entry => << 'ENTRIES',
0061 ; [.0101.0020.0002.0061] # LATIN SMALL LETTER A
0041 ; [.0101.0020.0008.0041] # LATIN CAPITAL LETTER A
0062 ; [.0102.0020.0002.0062] # LATIN SMALL LETTER B
0042 ; [.0102.0020.0008.0042] # LATIN CAPITAL LETTER B
0063 ; [.0103.0020.0002.0063] # LATIN SMALL LETTER C
0043 ; [.0103.0020.0008.0043] # LATIN CAPITAL LETTER C
ENTRIES
);
If "ignoreName" or "undefName" is used, character names should be
specified as a comment (following "#") on each line.
undefChar
undefName
-- see 6.3.3 Reducing the Repertoire, UTS #10.
Undefines the collation element as if it were unassigned in the
"table". This reduces the size of the table. If an unassigned
character appears in the string to be collated, the sort key is made
from its codepoint as a single-character collation element, as it is
greater than any other assigned collation elements (in the codepoint
order among the unassigned characters). But, it'd be better to
ignore characters unfamiliar to you and maybe never used.
Through "undefChar", any character matching "qr/$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
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"ß" studieren Perl."", you
say the following where $sub is ""M"ü"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"ß""" in $match, since ""mu"ß""" is primary equal to
""M"ü"SS"".
"$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 $string, returns "undef" in
scalar context and an empty list in list context.
e.g.
if ($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
$count (always equals to 1) is returned.
$replacement can be a "CODEREF", taking the matching part as an
argument, and returning a string to replace the matching part (a bit
similar to "s/(..)/$coderef->($1)/e").
"$count = $Collator->gsubst($string, $substring, $replacement)"
If $substring matches a part of $string, all the occurrences of the
matching part are replaced by $replacement ($string is modified) and
$count is returned.
$replacement can be a "CODEREF", taking the matching part as an
argument, and returning a string to replace the matching part (a bit
similar to "s/(..)/$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.
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 via
"Unicode::Collate->new(variable => "non-ignorable", level => 3)".
If "UCA_Version" is 26 or later, the "identical" level is preferred;
"Unicode::Collate->new(identical => 1)" and
"Unicode::Collate->new(identical => 1," "variable =>
"non-ignorable", level => 3)" should be used.
Unicode::Normalize is required to try The Conformance Test.
EBCDIC-SUPPORT IS EXPERIMENTAL.
AUTHOR, COPYRIGHT AND LICENSE
The Unicode::Collate module for perl was written by SADAHIRO Tomoyuki,
<SADAHIRO@cpan.org>. This module is Copyright(C) 2001-2021, 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/13.0.0/allkeys.txt>. For this file,
Copyright (c) 2020 Unicode, Inc.; distributed under the Terms of Use in
<http://www.unicode.org/terms_of_use.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/>
Unicode Locale Data Markup Language (LDML) - UTS #35
<http://www.unicode.org/reports/tr35/>
perl v5.40.1 2026-08-30 Unicode::Collate(3perl)
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