RDF::Closure::DatatypeHandling(3pm)			User Contributed Perl Documentation		       RDF::Closure::DatatypeHandling(3pm)

NAME

       RDF::Closure::DatatypeHandling - validate and canonicalise typed literals

ANALOGOUS PYTHON

       RDFClosure/DatatypeHandling.py

DESCRIPTION

       Provides datatype handling functions for OWL 2 RL and RDFS datatypes.

   Functional Interface
       This module can export four functions:

       o   "literal_canonical($lit)"

	   Given an RDF::Trine::Node::Literal, returns a literal with the canonical lexical value for its given datatype. If the literal is not a
	   valid lexical form for its datatype throws an Error.

	   If the literal is a plain literal, returns an rdf:PlainLiteral typed literal; if the literal is of an unrecognised datatype, simply
	   returns the original literal.

	   Note that as per OWL 2 RL rules, xsd:dateTime literals are not shifted to UTC, even though XSD says that UTC is the canonical form. By
	   setting the "force_utc" to true, you can force XSD-style canonicalisation. (See the object-oriented interface.)

       o   "literal_canonical_safe($lit)"

	   As per "literal_canonical", but in the case where a literal is not a valid lexical form, simply returns the original literal.

       o   "literal_valid($lit)"

	   Returns true iff the literal is a valid lexical form for its datatype. An example of an invalid literal might be:

	     "2011-02-29"^^xsd:date

       o   "literals_identical($lit1, $lit2)"

	   Returns true iff the two literals are identical according to OWL 2 RL. Here are some example pairs that are identical:

	     # integers and decimals are drawn from the same pool of values
	     "1.000"^^xsd:decimal
	     "1"^^xsd:integer

	     # different ways of writing the same datetime
	     "2010-01-01T12:00:00.000Z"^^xsd:dateTime
	     "2010-01-01T12:00:00+00:00"^^xsd:dateTime

	   Here are some example literals that are not identical:

	     # floats and decimals are drawn from different pools of values
	     "1.000"^^xsd:float
	     "1"^^xsd:integer

	     # according to OWL 2 these are "equal but not identical".
	     "2010-01-01T12:00:00+00:00"^^xsd:dateTime
	     "2010-01-01T11:00:00-01:00"^^xsd:dateTime

	   This latter example is affected by "force_utc".

       o   "literal_to_perl($lit)"

	   Returns a scalar value for the literal, or an appropriate object with overloaded operators (e.g. DateTime, Math::BigInt).

       Variables $RDF, $RDFS, $OWL and $XSD may also be exported as a convenience. These are RDF::Trine::Namespace objects. Don't modify them.

   Object-Oriented Interface
	 use RDF::Trine;
	 use RDF::Closure::DatatypeHandling qw[$XSD];

	 my $lit     = RDF::Trine::Node::Literal->new(
	   "2010-01-01T11:00:00-01:00", undef, $XSD->dateTime);
	 my $handler = RDF::Closure::DatatypeHandling->new(force_utc => 1);
	 print $handler->literal_canonical($lit)->as_ntriples;

SEE ALSO

       RDF::Closure.

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

AUTHOR

       Toby Inkster <tobyink@cpan.org>.

COPYRIGHT

       Copyright 2008-2011 Ivan Herman

       Copyright 2011-2012 Toby Inkster

       This library is free software; you can redistribute it and/or modify it under any of the following licences:

       o   The Artistic License 1.0 <http://www.perlfoundation.org/artistic_license_1_0>.

       o   The GNU General Public License Version 1 http://www.gnu.org/licenses/old-licenses/gpl-1.0.txt <http://www.gnu.org/licenses/old-
	   licenses/gpl-1.0.txt>, or (at your option) any later version.

       o   The W3C Software Notice and License http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
	   <http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231>.

       o   The Clarified Artistic License <http://www.ncftp.com/ncftp/doc/LICENSE.txt>.

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.

perl v5.14.2							    2012-06-28				       RDF::Closure::DatatypeHandling(3pm)