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 “prepend” 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

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

       •   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);

       •   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
           •   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.