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Unicode::GCString(3)  User Contributed Perl Documentation Unicode::GCString(3)




NAME

       Unicode::GCString - String as Sequence of UAX #29 Grapheme Clusters


SYNOPSIS

           use Unicode::GCString;
           $gcstring = Unicode::GCString->new($string);


DESCRIPTION

       Unicode::GCString treats Unicode string as a sequence of extended
       grapheme clusters defined by Unicode Standard Annex #29 [UAX #29].

       Grapheme cluster is a sequence of Unicode character(s) that consists of
       one grapheme base and optional grapheme extender and/or aprependa
       character.  It is close in that people consider as character.

   Public Interface
       Constructors

       new (STRING, [KEY => VALUE, ...])
       new (STRING, [LINEBREAK])
           Constructor.  Create new grapheme cluster string (Unicode::GCString
           object) from Unicode string STRING.

           About optional KEY => VALUE pairs see "Options" in
           Unicode::LineBreak.  On second form, Unicode::LineBreak object
           LINEBREAK controls breaking features.

           Note: The first form was introduced by release 2012.10.

       copy
           Copy constructor.  Create a copy of grapheme cluster string.  Next
           position of new string is set at beginning.

       Sizes

       chars
           Instance method.  Returns number of Unicode characters grapheme
           cluster string includes, i.e. length as Unicode string.

       columns
           Instance method.  Returns total number of columns of grapheme
           clusters defined by built-in character database.  For more details
           see "DESCRIPTION" in Unicode::LineBreak.

       length
           Instance method.  Returns number of grapheme clusters contained in
           grapheme cluster string.

       Operations as String

       as_string
       """OBJECT"""
           Instance method.  Convert grapheme cluster string to Unicode string
           explicitly.

       cmp (STRING)
       STRING "cmp" STRING
           Instance method.  Compare strings.  There are no oddities.  One of
           each STRING may be Unicode string.

       concat (STRING)
       STRING "." STRING
           Instance method.  Concatenate STRINGs.  One of each STRING may be
           Unicode string.  Note that number of columns (see columns()) or
           grapheme clusters (see length()) of resulting string is not always
           equal to sum of both strings.  Next position of new string is that
           set on the left value.

       join ([STRING, ...])
           Instance method.  Join STRINGs inserting grapheme cluster string.
           Any of STRINGs may be Unicode string.

       substr (OFFSET, [LENGTH, [REPLACEMENT]])
           Instance method.  Returns substring of grapheme cluster string.
           OFFSET and LENGTH are based on grapheme clusters.  If REPLACEMENT
           is specified, substring is replaced by it.  REPLACEMENT may be
           Unicode string.

           Note: This method cannot return the lvalue, unlike built-in
           substr().

       Operations as Sequence of Grapheme Clusters

       as_array
       "@{"OBJECT"}"
       as_arrayref
           Instance method.  Convert grapheme cluster string to an array of
           grapheme clusters.

       eos Instance method.  Test if current position is at end of grapheme
           cluster string.

       item ([OFFSET])
           Instance method.  Returns OFFSET-th grapheme cluster.  If OFFSET
           was not specified, returns next grapheme cluster.

       next
       "<"OBJECT">"
           Instance method, iterative.  Returns next grapheme cluster and
           increment next position.

       pos ([OFFSET])
           Instance method.  If optional OFFSET is specified, set next
           position by it.  Returns next position of grapheme cluster string.

       Miscelaneous

       lbc Instance method.  Returns Line Breaking Class (See
           Unicode::LineBreak) of the first character of first grapheme
           cluster.

       lbcext
           Instance method.  Returns Line Breaking Class (See
           Unicode::LineBreak) of the last grapheme extender of last grapheme
           cluster.  If there are no grapheme extenders or its class is CM,
           value of last grapheme base will be returned.


CAVEATS

       o   The grapheme cluster should not be referred to as "grapheme" even
           though Larry does.

       o   On Perl around 5.10.1, implicit conversion from Unicode::GCString
           object to Unicode string sometimes let "utf8_mg_pos_cache_update"
           cache be confused.

           For example, instead of doing

               $sub = substr($gcstring, $i, $j);

           do

               $sub = substr("$gcstring", $i, $j);

               $sub = substr($gcstring->as_string, $i, $j);

       o   This module implements default algorithm for determining grapheme
           cluster boundaries.  Tailoring mechanism has not been supported
           yet.


VERSION

       Consult $VERSION variable.

   Incompatible Changes
       Release 2013.10
           o   The new() method can take non-Unicode string argument.  In this
               case it will be decoded by iso-8859-1 (Latin 1) character set.
               That method of former releases would die with non-Unicode
               inputs.


SEE ALSO

       [UAX #29] Mark Davis (ed.) (2009-2013).  Unicode Standard Annex #29:
       Unicode Text Segmentation, Revisions 15-23.
       <http://www.unicode.org/reports/tr29/>.


AUTHOR

       Hatuka*nezumi - IKEDA Soji <hatuka(at)nezumi.nu>


COPYRIGHT

       Copyright (C) 2009-2013 Hatuka*nezumi - IKEDA Soji.

       This program is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.



perl v5.30.0                      2017-04-11              Unicode::GCString(3)

unicode-linebreak 2019.1.0 - Generated Fri Jun 11 14:27:51 CDT 2021
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