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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:
•
"literal_canonical($lit)"
Given an RDF::Trine::Node::Literal, returns a literal with the canonical lexical value for its given datatype. If the literal is not a valid lexical form for its datatype throws an Error.
If the literal is a plain literal, returns an rdf:PlainLiteral typed literal; if the literal is of an unrecognised datatype, simply returns the original literal.
Note that as per OWL 2 RL rules, xsd:dateTime literals are not shifted to UTC, even though XSD says that UTC is the canonical form. By setting the "force_utc" to true, you can force XSD-style canonicalisation. (See the object-oriented interface.)
•
"literal_canonical_safe($lit)"
As per "literal_canonical", but in the case where a literal is not a valid lexical form, simply returns the original literal.
•
"literal_valid($lit)"
Returns true iff the literal is a valid lexical form for its datatype. An example of an invalid literal might be: 
  "2011-02-29"^^xsd:date
•
"literals_identical($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".
•
"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:
•
The Artistic License 1.0 <http://www.perlfoundation.org/artistic_license_1_0>.
•
The GNU General Public License Version 1 <http://www.gnu.org/licenses/old-licenses/gpl-1.0.txt>, or (at your option) any later version.
•
The W3C Software Notice and License <http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231>.
•
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.
2012-06-28 perl v5.18.2