NAME

       RDF::Trine::Store::LanguagePreference - RDF Store proxy for filtering language tagged
       literals

VERSION

       This document describes RDF::Trine::Store::LanguagePreference version 1.019

SYNOPSIS

        use RDF::Trine::Store::LanguagePreference;

DESCRIPTION

       RDF::Trine::Store::LanguagePreference provides a RDF::Trine::Store API to filter the
       statements made available from some underlying store object based on a users' language
       preferences (e.g. coming from an Accept-Language HTTP header value).

METHODS

       Beyond the methods documented below, this class inherits methods from the
       RDF::Trine::Store class.

       "new ( $store, { $lang1 => $q1, $lang2 => $q2, ... } )"
           Returns a new storage object that will act as a proxy for the $store object, filtering
           language literals based on the expressed language preferences.

       "new_with_config ( $hashref )"
           Returns a new storage object configured with a hashref with certain keys as arguments.

           The "storetype" key must be "LanguagePreference" for this backend.

           The following key must also be used:

           "store"
               A configuration hash for the underlying store object.

           "preferred_languages"
               A hash reference mapping language tags to quality values in the range [0, 1].  The
               referent may be changed between operations to change the set of preferred
               languages used in statement matching.

       "new_with_config ( \%config )"
           Returns a new RDF::Trine::Store object based on the supplied configuration hashref.

       "language_preferences"
           Returns a hash of the language preference quality values.

       "language_preference( $lang )"
           Return the quality value preference for the given language.

       "update_language_preference( $lang => $qvalue )"
           Update the quality value preference for the given language.

       "get_statements ( $subject, $predicate, $object [, $context] )"
           Returns a stream object of all statements matching the specified subject, predicate
           and objects. Any of the arguments may be undef to match any value.

       "count_statements ( $subject, $predicate, $object, $context )"
           Returns a count of all the statements matching the specified subject, predicate,
           object, and context. Any of the arguments may be undef to match any value.

       "qvalueForLanguage ( $language, \%cache )"
           Returns the q-value for $language based on the current language preference. %cache is
           used across multiple calls to this method for performance reasons.

       "siteQValueForLanguage ( $language )"
           Returns an implementation-specific q-value preference for the given $language. This
           method may be overridden by subclasses to control the default preferred language.

       "availableLanguagesForStatement( $statement )"
           Returns a list of language tags that are available in the underlying store for the
           given statement object. For example, if $statement represented the triple:

            dbpedia:Los_Angeles rdf:label "Los Angeles"@en

           and the underlying store contains the triples:

            dbpedia:Los_Angeles rdf:label "Los Angeles"@en
            dbpedia:Los_Angeles rdf:label "ロサンゼルス"@ja
            dbpedia:Los_Angeles rdf:label "Лос-Анджелес"@ru

           then the return value would be "('en', 'ja', 'ru')".

       "languagePreferenceAllowsStatement ( $statement, \%cache )"
           Returns true if the $statement is allowed by the current language preference. %cache
           is used across multiple calls to this method for performance reasons.

       "supports ( [ $feature ] )"
           If $feature is specified, returns true if the feature is supported by the store, false
           otherwise. If $feature is not specified, returns a list of supported features.

BUGS

       Please report any bugs or feature requests to through the GitHub web interface at
       <https://github.com/kasei/perlrdf/issues>.

AUTHOR

       Gregory Todd Williams  "<gwilliams@cpan.org>"

COPYRIGHT

       Copyright (c) 2006-2012 Gregory Todd Williams. This program is free software; you can
       redistribute it and/or modify it under the same terms as Perl itself.