com.hp.hpl.jena.util
Class ResourceUtils

java.lang.Object
  com.hp.hpl.jena.util.ResourceUtils

public class ResourceUtils
extends java.lang.Object

General utility methods that operate on RDF resources, but which are not specific to a given model.

Version:

CVS $Id: ResourceUtils.java,v 1.16 2008/01/02 12:07:44 andy_seaborne Exp $

Author:

Ian Dickinson, HP Labs (email)

Constructor Summary

ResourceUtils()

Method Summary

static java.util.List	maximalLowerElements(java.util.Collection resources, Property rel, boolean inverse) Answer the maximal lower elements of the given collection, given the partial ordering rel.
static java.util.List	maximalLowerElements(java.util.Iterator resources, Property rel, boolean inverse) Given a collection of resources, and a relation defining a partial order over those resources, answer the sub-collection that contains only those elements that appear in the maximal generator of the relation.
static java.util.List	partition(java.util.List l, Property p) Answer a list of lists, which is a partition of the given input list of resources.
static Model	reachableClosure(Resource root) Answer a model that contains all of the resources reachable from a given resource by any property, transitively.
static java.util.List	removeEquiv(java.util.List l, Property p, Resource ref) Remove from the given list l of Resources, any Resource that is equivalent to the reference resource ref under the relation p.
static Resource	renameResource(Resource old, java.lang.String uri) Answer a new resource that occupies the same position in the graph as the current resource old, but that has the given URI.

Methods inherited from class java.lang.Object

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

Constructor Detail

ResourceUtils

public ResourceUtils()

Method Detail

maximalLowerElements

public static java.util.List maximalLowerElements(java.util.Collection resources,
                                                  Property rel,
                                                  boolean inverse)

Answer the maximal lower elements of the given collection, given the partial ordering rel. See maximalLowerElements( Iterator, Property, boolean ) for details.

Parameters:

resources - A collection of resources

rel - A property defining a partial-ordering on resources

inverse - If true, we invert the given property (by reversing the order of the arguments), which allows us to use eg subClassOf as a partial order operator for both sub-class and super-class relationships

Returns:

The collection that contains only those resources are not greater than another resource under the partial order.

maximalLowerElements

public static java.util.List maximalLowerElements(java.util.Iterator resources,
                                                  Property rel,
                                                  boolean inverse)

Given a collection of resources, and a relation defining a partial order over those resources, answer the sub-collection that contains only those elements that appear in the maximal generator of the relation. Specifically, a resource x is excluded from the return value if there is another resource y in the input collection such that y Rel x holds.

Parameters:

resources - An iterator over a collection of resources

rel - A property defining a partial-ordering on resources

inverse - If true, we invert the given property (by reversing the order of the arguments), which allows us to use eg subClassOf as a partial order operator for both sub-class and super-class relationships

Returns:

The list that contains only those resources are not greater than another resource under the partial order.

removeEquiv

public static java.util.List removeEquiv(java.util.List l,
                                         Property p,
                                         Resource ref)

Remove from the given list l of Resources, any Resource that is equivalent to the reference resource ref under the relation p. Typically, p will be owl:subClassOf or owl:subPropertyOf or some similar predicate. A resource R is defined to be equivalent to ref iff R p ref is true and ref p R is true.

The equivalent resources are removed from list l in place, the return value is the list of removed resources.

Parameters:

l - A list of resources from which the resources equivalent to ref will be removed

p - An equivalence predicate

ref - A reference resource

Returns:

A list of the resources removed from the parameter list l

partition

public static java.util.List partition(java.util.List l,
                                       Property p)

Answer a list of lists, which is a partition of the given input list of resources. The equivalence relation is the predicate p. So, two resources a and b will be in the same partition iff (a p b) && (b p a).

Parameters:

l - A list of resources

p - An equivalence predicate

Returns:

A list of lists which are the partitions of l under p

renameResource

public static Resource renameResource(Resource old,
                                      java.lang.String uri)

Answer a new resource that occupies the same position in the graph as the current resource old, but that has the given URI. In the process, the existing statements referring to old are removed. Since Jena does not allow the identity of a resource to change, this is the closest approximation to a rename operation that works.

Notes: This method does minimal checking, so renaming a resource to its own URI is unpredictable. Furthermore, it is a general and simple approach, and in given applications it may be possible to do this operation more efficiently. Finally, if res is a property, existing statements that use the property will not be renamed, nor will occurrences of res in other models.

Parameters:

old - An existing resource in a given model

uri - A new URI for resource old, or null to rename old to a bNode

Returns:

A new resource that occupies the same position in the graph as old, but which has the new given URI.

reachableClosure

public static Model reachableClosure(Resource root)

Answer a model that contains all of the resources reachable from a given resource by any property, transitively. The returned graph is the sub-graph of the parent graph of root, whose root node is the given root. Cycles are permitted in the sub-graph.

Parameters:

root - The root node of the sub-graph to extract

Returns:

A model containing all reachable RDFNodes from root by any property.