Unicode::Collate - Unicode Collation Algorithm |
Unicode::Collate - Unicode Collation Algorithm
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.
The new
method returns a collator object.
$Collator = Unicode::Collate->new( 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.
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 ignorable at levels 1 through 3; considered at the 4th level.
'Non-ignorable' Variable elements are not reset to ignorable.
'Shifted' Variable elements are 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 => $levelNumber or \@levelNumbers
Weights in reverse order; ex. level 2 (diacritic ordering) in French. If omitted, forwards at all the levels.
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
Makes the entry in the table ignorable. If a collation element is ignorable, it is ignored as if the element had been deleted from there.
E.g. when 'a' and 'e' are ignorable, 'element' is equal to 'lament' (or 'lmnt').
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.
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.
By default, mapping of CJK Unified Ideographs uses the Unicode codepoint order. But the mapping of CJK Unified Ideographs may 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 assignment of weight for CJK Unified Ideographs
in table or entry is still valid.
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.
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/\b(?:an?|the)\s+//gi; $str; },
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.
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 );
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.
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, UTR #10. If you define your collation elements which violates this, these tags doesn't work validly.
@sorted = $Collator->sort(@not_sorted)
$result = $Collator->cmp($a, $b)
$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)
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)
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)
'['
and ']'
and level boundaries are denoted by '|'
.
use Unicode::Collate; my $c = Unicode::Collate->new(); print $c->viewSortKey("Perl"),"\n";
# output: # [09B3 08B1 09CB 094F|0020 0020 0020 0020|0008 0002 0002 0002|FFFF FFFF FFFF FFFF] # Level 1 Level 2 Level 3 Level 4
$position = $Collator->index($string, $substring)
($position, $length) = $Collator->index($string, $substring)
If $substring
matches a part of $string
, returns
the position of the first occurrence of the matching part in scalar context;
in list context, returns a two-element list of
the position and the length of the matching part.
Notice that the length of the matching part may differ from
the length of $substring
.
Note that the position and the length are counted on the string
after the process of preprocess, normalization, and rearrangement.
Therefore, in case the specified string is not binary equal to
the preprocessed/normalized/rearranged string, the position and the length
may differ form those on the specified string. But it is guaranteed
that, if matched, it returns a non-negative value as $position
.
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 ); my $str = "Ich mu\x{00DF} studieren."; my $sub = "m\x{00FC}ss"; my $match; if (my($pos,$len) = $Collator->index($str, $sub)) { $match = substr($str, $pos, $len); }
and get "mu\x{00DF}"
in $match
since "mu
ß"
is primary equal to "m
üss"
.
None by default.
Unicode::Collate has not been ported to EBCDIC. The code mostly would work just fine but a decision needs to be made: how the module should work in EBCDIC? Should the low 256 characters be understood as Unicode or as EBCDIC code points? Should one be chosen or should there be a way to do either? Or should such translation be left outside the module for the user to do, for example by using Encode::from_to()? (or utf8::unicode_to_native()/utf8::native_to_unicode()?)
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, UTR #10.
index()
is an experimental method and
its return value may be unreliable.
The correct implementation for index()
must be based
on Locale-Sensitive Support: Level 3 in UTR #18,
Unicode Regular Expression Guidelines.
See also 4.2 Locale-Dependent Graphemes in UTR #18.
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.
Unicode::Collate - Unicode Collation Algorithm |