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

Unicode::Collate(3p) Perl Programmers Reference Guide Unicode::Collate(3p) #

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

NNAAMMEE #

 Unicode::Collate - Unicode Collation Algorithm

SSYYNNOOPPSSIISS #

   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.

 NNoottee:: 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.

DDEESSCCRRIIPPTTIIOONN #

 This module is an implementation of Unicode Technical Standard #10
 (a.k.a. UTS #10) - Unicode Collation Algorithm (a.k.a. UCA).

CCoonnssttrruuccttoorr aanndd TTaaiilloorriinngg The “new” method returns a collator object. If nneeww(()) 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 #

     NNOOTTEE:: The code point in the UCA file format (before ';') mmuusstt 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 _t_h_e _U_n_i_c_o_d_e _S_t_a_n_d_a_r_d and _H_a_n_g_u_l_S_y_l_l_a_b_l_e_T_y_p_e_._t_x_t.

     IImmpplleemmeennttaattiioonn NNoottee:: (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.

     NNOOTTEE: "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.

     NNOOTTEE: 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.

     NNOOTTEE:: 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.

     DDeeffaauulltt:: 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.

     LLiimmiittaattiioonn:: 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.

     NNoottee:: 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) })"
     iiss nnoott 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) })" iiss equivalent to
     "(normalization => 'NFD')".  If source strings are finely
     prenormalized, "(normalization => 'prenormalized')" may save time for
     normalization.

     Except "(normalization => undef)", UUnniiccooddee::::NNoorrmmaalliizzee is required
     (see also CCAAVVEEAATT).

 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.

     NNoottee:: 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.

NNOOTTEE AABBOOUUTT UU++FFFFFFDD:: #

     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);

     NNoottee:: 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).

     AAccccoorrddiinngg ttoo tthhee vveerrssiioonn 99 ooff UUCCAA,, tthhiiss ppaarraammeetteerr sshhaallll nnoott bbee uusseedd;;
     bbuutt iitt iiss nnoott wwaarrnneedd aatt pprreesseenntt..

 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.

     NNOOTTEE: "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. #

     NNOOTTEE: 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 _U_n_i_c_o_d_e_/_C_o_l_l_a_t_e directory on
     @INC. Say, if the filename is _F_o_o_._t_x_t, the table file is searched as
     _U_n_i_c_o_d_e_/_C_o_l_l_a_t_e_/_F_o_o_._t_x_t in @INC.

     By default, _a_l_l_k_e_y_s_._t_x_t (as the filename of DUCET) is used.  If you
     will prepare your own table file, any name other than _a_l_l_k_e_y_s_._t_x_t may
     be better to avoid namespace conflict.

     NNOOTTEE: 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.

     NNOOTTEE: 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 _a_l_l_k_e_y_s_._t_x_t).

        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.

MMeetthhooddss ffoorr CCoollllaattiioonn “@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

MMeetthhooddss ffoorr SSeeaarrcchhiinngg 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.

 DDIISSCCLLAAIIMMEERR:: 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 $string, in scalar context, returns aa
     rreeffeerreennccee ttoo the first occurrence of the matching part ($match_ref is
     always true if matches, since every reference is ttrruuee); 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.

OOtthheerr MMeetthhooddss “%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 nnoott 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.

EEXXPPOORRTT #

 No method will be exported.

IINNSSTTAALLLL #

 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.

CCAAVVEEAATTSS #

 Normalization
     Use of the "normalization" parameter requires the UUnniiccooddee::::NNoorrmmaalliizzee
     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 _C_o_l_l_a_t_i_o_n_T_e_s_t___S_H_I_F_T_E_D_._t_x_t, a collator via "Unicode::Collate->new(
     )" should be used; for _C_o_l_l_a_t_i_o_n_T_e_s_t___N_O_N___I_G_N_O_R_A_B_L_E_._t_x_t, 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.

     UUnniiccooddee::::NNoorrmmaalliizzee iiss rreeqquuiirreedd ttoo ttrryy TThhee CCoonnffoorrmmaannccee TTeesstt..

EEBBCCDDIICC--SSUUPPPPOORRTT IISS EEXXPPEERRIIMMEENNTTAALL.. #

AAUUTTHHOORR,, CCOOPPYYRRIIGGHHTT AANNDD LLIICCEENNSSEE #

 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>

SSEEEE AALLSSOO #

 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 v5.36.3 2023-02-15 Unicode::Collate(3p)