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)