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Unicode::Collate(Perl Programmers Reference GUnicode::Collate(3p)

       Unicode::Collate - Unicode Collation Algorithm

         use Unicode::Collate;

         $Collator = Unicode::Collate->new(%tailoring);

         @sorted = $Collator->sort(@not_sorted);

         $result = $Collator->cmp($a, $b); # returns 1, 0, or -1.

         # If %tailoring is false (i.e. empty),
         # $Collator should do the default collation.

       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, # deprecated: use of 'variable' is recommended.
             backwards => $levelNumber, # or \@levelNumbers
             entry => $element,
             hangul_terminator => $term_primary_weight,
             ignoreName => qr/$ignoreName/,
             ignoreChar => qr/$ignoreChar/,
             katakana_before_hiragana => $bool,
             level => $collationLevel,
             normalization  => $normalization_form,
             overrideCJK => \&overrideCJK,
             overrideHangul => \&overrideHangul,
             preprocess => \&preprocess,
             rearrange => \@charList,
             table => $filename,
             undefName => qr/$undefName/,
             undefChar => qr/$undefChar/,
             upper_before_lower => $bool,
             variable => $variable,

           If the tracking version number of the older UCA is
           given, the older behavior of that tracking version is
           emulated on collating.  If omitted, the return value
           of "UCA_Version()" is used.

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           The supported tracking version: 8, 9, or 11.

           This parameter may be removed in the future version,
           as switching the algorithm would affect the perfor-

           -- 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

           -- see 3.1 Linguistic Features; 3.2.1 File Format, UTS

           If the same character (or a sequence of characters)
           exists in the collation element table through "table",
           mapping to collation elements is overrided.  If it
           does not exist, the mapping is defined additionally.

               entry => <<'ENTRY', # for DUCET v4.0.0 (allkeys-4.0.0.txt)
           0063 0068 ; [.0E6A.0020.0002.0063] # ch
           0043 0068 ; [.0E6A.0020.0007.0043] # Ch
           0043 0048 ; [.0E6A.0020.0008.0043] # CH
           006C 006C ; [.0F4C.0020.0002.006C] # ll
           004C 006C ; [.0F4C.0020.0007.004C] # Ll
           004C 004C ; [.0F4C.0020.0008.004C] # LL
           00F1      ; [.0F7B.0020.0002.00F1] # n-tilde
           006E 0303 ; [.0F7B.0020.0002.00F1] # n-tilde
           00D1      ; [.0F7B.0020.0008.00D1] # N-tilde
           004E 0303 ; [.0F7B.0020.0008.00D1] # N-tilde

               entry => <<'ENTRY', # 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>

           NOTE: The code point in the UCA file format (before
           ';') must be a Unicode code point (defined as hexadec-
           imal), 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

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           "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".

           -- see Condition B.2. in 7.1.4 Trailing Weights, UTS

           If a true value is given (non-zero but should be posi-
           tive), it will be added as a terminator primary weight
           to the end of every standard Hangul syllable. Sec-
           ondary 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 accord-
           ing to conjoining Jamo behavior in the Unicode Stan-
           dard and HangulSyllableType.txt.

           Implementation Note: (1) For expansion mapping (Uni-
           code character mapped to a sequence of collation ele-
           ments), a terminator will not be added between colla-
           tion 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 automat-
           ically terminated with a terminator primary weight.
           These characters may need terminator included in a
           collation element table beforehand.

           -- 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').

           -- 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.

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             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.

           -- see 4.1 Normalize each input string, UTS #10.

           If specified, strings are normalized before prepara-
           tion of sort keys (the normalization is executed after

           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

           Furthermore, special values, "undef" and "prenormal-
           ized", can be used, though they are not concerned with

           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 non-contiguous
           contractions with combining characters are performed.
           Therefore "(normalization => 'prenormalized', prepro-
           cess => sub { NFD(shift) })" is equivalent to "(nor-
           malization => 'NFD')".  If source strings are finely
           prenormalized, "(normalization => 'prenormalized')"
           may save time for normalization.

           Except "(normalization => undef)", Unicode::Normalize
           is required (see also CAVEAT).

           -- see 7.1 Derived Collation Elements, UTS #10.

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           By default, CJK Unified Ideographs are ordered in Uni-
           code codepoint order (but "CJK Unified Ideographs"
           ["U+4E00" to "U+9FA5"]  are lesser than "CJK Unified
           Ideographs Extension" ["U+3400" to "U+4DB5" and
           "U+20000" to "U+2A6D6"].

           Through "overrideCJK", ordering of CJK Unified
           Ideographs can be overrided.

           ex. CJK Unified Ideographs in the JIS code point

             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.

           -- see 7.1 Derived Collation Elements, UTS #10.

           By default, Hangul Syllables are decomposed into
           Hangul Jamo, even if "(normalization => undef)".  But
           the mapping of Hangul Syllables may be overrided.

           This tag works like "overrideCJK", so see there for

           If you want to override the mapping of Hangul Sylla-
           bles, NFD, NFKD, and FCD are not appropriate, since
           they will decompose Hangul Syllables before overrid-

           If "undef" is passed explicitly as the value for this
           key, weight for Hangul Syllables is treated as unde-
           fined without decomposition into Hangul Jamo.  But
           definition of weight for Hangul Syllables in table or
           "entry" is still valid.

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           -- 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/\b(?:an?|the)\s+//gi;
                      return $str;

           "preprocess" is performed before "normalization" (if

           -- 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.

           -- see 3.2 Default Unicode Collation Element Table,
           UTS #10.

           You can use another collation element table if

           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

           By default, allkeys.txt (as the filename of DUCET) is

           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:

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              $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

           -- see 6.3.4 Reducing the Repertoire, UTS #10.

           Undefines the collation element as if it were unas-
           signed 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 ele-
           ments (in the codepoint order among the unassigned
           characters).  But, it'd be better to ignore characters
           unfamiliar to you and maybe never used.

           ex. Collation weights for beyond-BMP characters are
           not stored in object:

               undefChar => qr/[^\0-\x{fffd}]/,

           -- 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 lower-
           case/uppercase or 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, these tags don't work validly.

           -- see 3.2.2 Variable Weighting, UTS #10.

           (the title in UCA version 8: Alternate Weighting)

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           This key allows to variable 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).

              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.

           For backward compatibility, "alternate" can be used as
           an alias for "variable".

       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.

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           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"),"\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

               (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 "rearrange" and "hangul_terminator" tags are

       The "match", "gmatch", "subst", "gsubst" methods work like
       "m//", "m//g", "s///", "s///g", respectively, but they are
       not aware of any pattern, but only a literal substring.

       "$position = $Collator->index($string, $substring[, $posi-
       "($position, $length) = $Collator->index($string, $sub-
       string[, $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-ele-
           ment list of the position and the length of the match-
           ing 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

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             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 con-
           text, returns the first occurrence of the matching

           If $substring does not match any part of $string,
           returns "undef" in scalar context and an empty list in
           list context.


               if ($match_ref = $Collator->match($str, $sub)) { # scalar context
                   print "matches [$$match_ref].\n";
               } else {
                   print "doesn't match.\n";


               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 con-

           If $substring does not match any part of $string,
           returns an empty list.

       "$count = $Collator->subst($string, $substring, $replace-
           If $substring matches a part of $string, the first
           occurrence of the matching part is replaced by
           $replacement ($string is modified) and return $count

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           (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

       "$count = $Collator->gsubst($string, $substring, $replace-
           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


             my $Collator = Unicode::Collate->new( normalization => undef, level => 1 );
                                                # (normalization => undef) is REQUIRED.
             my $str = "Camel ass came\x{301}l CAMEL horse cAm\0E\0L...";
             $Collator->gsubst($str, "camel", sub { "<b>$_[0]</b>" });

             # now $str is "<b>Camel</b> ass <b>came\x{301}l</b> <b>CAMEL</b> horse <b>cAm\0E\0L</b>...";
             # i.e., all the camels are made bold-faced.

       Other Methods

       "%old_tailoring = $Collator->change(%new_tailoring)"
           Change the value of specified keys and returns the
           changed part.

               $Collator = Unicode::Collate->new(level => 4);

               $Collator->eq("perl", "PERL"); # false

               %old = $Collator->change(level => 2); # returns (level => 4).

               $Collator->eq("perl", "PERL"); # true

               $Collator->change(%old); # returns (level => 2).

               $Collator->eq("perl", "PERL"); # false

           Not all "(key,value)"s are allowed to be changed.  See
           also @Unicode::Collate::ChangeOK and @Unicode::Col-

           In the scalar context, returns the modified collator
           (but it is not a clone from the original).

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               $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

           Returns the tracking version number of UTS #10 this
           module consults.

           Returns the version number of UTS #10 this module con-


       None by default.


       Use of the "normalization" parameter requires the Uni-
       code::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 available under

       For CollationTest_SHIFTED.txt, a collator via "Uni-
       code::Collate->new( )" should be used; for Collation-
       Test_NON_IGNORABLE.txt, a collator via "Unicode::Col-
       late->new(variable => "non-ignorable", level => 3)".

       Unicode::Normalize is required to try The Conformance

       SADAHIRO Tomoyuki <SADAHIROATcpan.org>


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         Copyright(C) 2001-2004, 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 Collation Algorithm - UTS #10

       The Default Unicode Collation Element Table (DUCET)

       The conformance test for the UCA


       Hangul Syllable Type

       Unicode Normalization Forms - UAX #15


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