org.fcrepo.kernel.rdf.impl.mappings

Class PropertyToTriple

java.lang.Object

org.fcrepo.kernel.rdf.impl.mappings.PropertyToTriple

All Implemented Interfaces:

com.google.common.base.Function<javax.jcr.Property,com.google.common.base.Function<Iterator<javax.jcr.Value>,Iterator<com.hp.hpl.jena.graph.Triple>>>

public class PropertyToTriple
extends Object
implements com.google.common.base.Function<javax.jcr.Property,com.google.common.base.Function<Iterator<javax.jcr.Value>,Iterator<com.hp.hpl.jena.graph.Triple>>>

Utility for moving from JCR properties to RDF triples.

Author:

ajs6f

Constructor Summary

Constructors

Constructor and Description
PropertyToTriple(org.fcrepo.kernel.rdf.IdentifierTranslator graphSubjects) Default constructor.

Method Summary

Methods

Modifier and Type	Method and Description
com.google.common.base.Function<Iterator<javax.jcr.Value>,Iterator<com.hp.hpl.jena.graph.Triple>>	apply(javax.jcr.Property p) This nightmare of Java signature verbosity is a curried transformation.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.google.common.base.Function

equals

Constructor Detail

PropertyToTriple

public PropertyToTriple(org.fcrepo.kernel.rdf.IdentifierTranslator graphSubjects)

Default constructor. We require a IdentifierTranslator in order to construct the externally-meaningful RDF subjects of our triples.

Parameters:

graphSubjects -

Method Detail

apply

public com.google.common.base.Function<Iterator<javax.jcr.Value>,Iterator<com.hp.hpl.jena.graph.Triple>> apply(javax.jcr.Property p)

This nightmare of Java signature verbosity is a curried transformation. We want to go from an iterator of JCR Properties to an iterator of RDF Triples. An annoyance: some properties may produce several triples (multi-valued properties). So we cannot find a simple Property -> Triple mapping. Instead, we wax clever and offer a function from any specific property to a new function, one that takes multiple values (such as occur in our multi-valued properties) to multiple triples. In other words, this is a function the outputs of which are functions specific to a given JCR property. Each output knows how to take any specific value of its specific property to a triple representing the fact that its specific property obtains that specific value on the node to which that property belongs. All of this is useful because with these operations represented as functions instead of ordinary methods, which may have side-effects, we can use efficient machinery to manipulate iterators of the objects in which we are interested, and that's exactly what we want to do in this class. See PropertiesRdfContext#triplesFromProperties for an example of the use of this class with ZippingIterator.

Specified by:

apply in interface com.google.common.base.Function<javax.jcr.Property,com.google.common.base.Function<Iterator<javax.jcr.Value>,Iterator<com.hp.hpl.jena.graph.Triple>>>

See Also:

Currying