NAME

       XML::Atom::OWL - parse an Atom file into RDF

SYNOPSIS

        use XML::Atom::OWL;

        $parser = XML::Atom::OWL->new($xml, $baseuri);
        $graph  = $parser->graph;

DESCRIPTION

       This has a pretty similar interface to RDF::RDFa::Parser.

   Constructor
       "new($xml, $baseuri, \%options, $storage)"
           This method creates a new XML::Atom::OWL object and returns it.

           The $xml variable may contain an XML (Atom) string, or an XML::LibXML::Document
           object. If a string, the document is parsed using XML::LibXML, which will throw an
           exception if it is not well-formed. XML::Atom::OWL does not catch the exception.

           The base URI is used to resolve relative URIs found in the document.

           Currently only one option is defined, 'no_fetch_content_src', a boolean indicating
           whether <content src> URLs should be automatically fetched and added to the model as
           if inline content had been provided. They are fetched by default, but it's pretty rare
           for feeds to include this attribute.

           $storage is an RDF::Trine::Storage object. If undef, then a new temporary store is
           created.

   Public Methods
       "uri"
           Returns the base URI of the document being parsed. This will usually be the same as
           the base URI provided to the constructor.

           Optionally it may be passed a parameter - an absolute or relative URI - in which case
           it returns the same URI which it was passed as a parameter, but as an absolute URI,
           resolved relative to the document's base URI.

           This seems like two unrelated functions, but if you consider the consequence of
           passing a relative URI consisting of a zero-length string, it in fact makes sense.

       "dom"
           Returns the parsed XML::LibXML::Document.

       "graph"
           This method will return an RDF::Trine::Model object with all statements of the full
           graph.

           This method automatically calls "consume".

       "root_identifier"
           Returns the blank node or URI for the root element of the Atom document as an
           RDF::Trine::Node

           Calls "consume" automatically.

       "set_callbacks(\%callbacks)"
           Set callback functions for the parser to call on certain events. These are only
           necessary if you want to do something especially unusual.

             $p->set_callbacks({
               'pretriple_resource' => sub { ... } ,
               'pretriple_literal'  => sub { ... } ,
               'ontriple'           => undef ,
               });

           For details of the callback functions, see the section CALLBACKS. "set_callbacks" must
           be used before "consume". "set_callbacks" itself returns a reference to the parser
           object itself.

       "consume"
           The document is parsed. Triples extracted from the document are passed to the
           callbacks as each one is found; triples are made available in the model returned by
           the "graph" method.

           This function returns the parser object itself, making it easy to abbreviate several
           of XML::Atom::OWL's functions:

             my $iterator = XML::Atom::OWL->new(undef, $uri)
                            ->consume->graph->as_stream;

           You probably only need to call this explicitly if you're using callbacks.

CALLBACKS

       Several callback functions are provided. These may be set using the "set_callbacks"
       function, which taskes a hashref of keys pointing to coderefs. The keys are named for the
       event to fire the callback on.

   pretriple_resource
       This is called when a triple has been found, but before preparing the triple for adding to
       the model. It is only called for triples with a non-literal object value.

       The parameters passed to the callback function are:

       •   A reference to the "XML::Atom::OWL" object

       •   A reference to the "XML::LibXML::Element" being parsed

       •   Subject URI or bnode (string)

       •   Predicate URI (string)

       •   Object URI or bnode (string)

       •   Graph URI or bnode (string or undef)

       The callback should return 1 to tell the parser to skip this triple (not add it to the
       graph); return 0 otherwise.

   pretriple_literal
       This is the equivalent of pretriple_resource, but is only called for triples with a
       literal object value.

       The parameters passed to the callback function are:

       •   A reference to the "XML::Atom::OWL" object

       •   A reference to the "XML::LibXML::Element" being parsed

       •   Subject URI or bnode (string)

       •   Predicate URI (string)

       •   Object literal (string)

       •   Datatype URI (string or undef)

       •   Language (string or undef)

       •   Graph URI or bnode (string or undef)

       Beware: sometimes both a datatype and a language will be passed.  This goes beyond the
       normal RDF data model.)

       The callback should return 1 to tell the parser to skip this triple (not add it to the
       graph); return 0 otherwise.

   ontriple
       This is called once a triple is ready to be added to the graph. (After the pretriple
       callbacks.) The parameters passed to the callback function are:

       •   A reference to the "XML::Atom::OWL" object

       •   A reference to the "XML::LibXML::Element" being parsed

       •   An RDF::Trine::Statement object.

       The callback should return 1 to tell the parser to skip this triple (not add it to the
       graph); return 0 otherwise. The callback may modify the RDF::Trine::Statement object.

BUGS

       Please report any bugs to <http://rt.cpan.org/>.

SEE ALSO

       RDF::Trine, XML::Atom::FromOWL.

       <http://www.perlrdf.org/>.

AUTHOR

       Toby Inkster <tobyink@cpan.org>.

COPYRIGHT AND LICENCE

       Copyright 2010-2011 Toby Inkster

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

DISCLAIMER OF WARRANTIES

       THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
       WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
       PURPOSE.