org.universAAL.middleware.util

Class GraphIterator

java.lang.Object

org.universAAL.middleware.util.GraphIterator

All Implemented Interfaces:

Iterator

Direct Known Subclasses:

GraphIterator.GraphIteratorResources

public class GraphIterator
extends Object
implements Iterator

Iterate over all Resources of an RDF graph.

Author:

Carsten Stockloew

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	GraphIterator.GraphIteratorResources A specialized iterator to iterate only over instances of Resource .
static class	GraphIterator.ObjectEqualsResource A class that links to a resource but overrides the equals-method to return true iff the objects are equal (instead of the URI as it is defined for Resource).
protected static class	GraphIterator.StackElement Element to be stored in the stack.

Field Summary

Fields

Modifier and Type	Field and Description
protected GraphIterator.ObjectEqualsResource	idxdummy A dummy object for performance that is only used to call the contains-method of visitedResources.
protected GraphIteratorElement	nextElement The next element as being returned by next().
protected GraphIterator.StackElement	se The current information at a certain depth.
protected Stack<GraphIterator.StackElement>	stack The stack contains information for previous depth.
protected Set<GraphIterator.ObjectEqualsResource>	visitedResources The set of resources that have been visited before.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	GraphIterator(Resource root)

Method Summary

Modifier and Type	Method and Description
protected void	createNext()
protected void	createResult()
static Iterator<GraphIteratorElement>	getIterator(Resource root) Create a new Iterator that iterates over all triples of the graph.
protected Enumeration	getPropertyEnumeration(Resource r)
static Iterator<Resource>	getResourceIterator(Resource root) Create a new Iterator that iterates over all Resources of the graph.
boolean	hasNext()
Object	next()
void	remove()
protected void	stepDeeper(Resource root)
protected boolean	stepHigher()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

forEachRemaining

Field Detail

visitedResources

protected Set<GraphIterator.ObjectEqualsResource> visitedResources

The set of resources that have been visited before. During iteration, this will be used to avoid endless loop in case of cycles.

idxdummy

protected GraphIterator.ObjectEqualsResource idxdummy

A dummy object for performance that is only used to call the contains-method of visitedResources.

se

protected GraphIterator.StackElement se

The current information at a certain depth.

stack

protected Stack<GraphIterator.StackElement> stack

The stack contains information for previous depth. When going one level deeper into the graph, the information about the current state, e.g. the enumerator of properties, is stored in the stack to be restored when all child nodes have been processed.

nextElement

protected GraphIteratorElement nextElement

The next element as being returned by next(). It can be calculated by next() and by hasNext().

Constructor Detail

GraphIterator

protected GraphIterator(Resource root)

Method Detail

getIterator

public static Iterator<GraphIteratorElement> getIterator(Resource root)

Create a new Iterator that iterates over all triples of the graph.

Parameters:

root - the Resource that is the root of the graph.

Returns:

an Iterator to iterate over elements of the graph.

getResourceIterator

public static Iterator<Resource> getResourceIterator(Resource root)

Create a new Iterator that iterates over all Resources of the graph. This iterator differentiates between different Java objects. Thus, it might be that more than one resource with the same URI is returned if the Java objects are different.

Parameters:

root - the Resource that is the root of the graph.

Returns:

an Iterator to iterate over elements of the graph.

getPropertyEnumeration

protected Enumeration getPropertyEnumeration(Resource r)

stepDeeper

protected final void stepDeeper(Resource root)

stepHigher

protected final boolean stepHigher()

createResult

protected final void createResult()

createNext

protected void createNext()

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator

See Also:

Iterator.hasNext()

next

public Object next()

Specified by:

next in interface Iterator

Returns:

the next element of the iterator. The type of the return value depends on the type of the iterator.

See Also:

Iterator.next()

remove

public final void remove()

Specified by:

remove in interface Iterator

See Also:

Iterator.remove()