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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.
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