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

protected static class	GraphIterator.GraphIteratorResources A specialized iterator to iterate only over instances of Resource .
protected class	GraphIterator.StackElement Element to be stored in the stack.

Field Summary

protected GraphIteratorElement	nextElement The next element as being returned by next().
protected GraphIterator.StackElement	se The current information at a certain depth.
protected Stack	stack The stack contains information for previous depth.
protected Set	visitedResources The set of resources that have been visited before.

Constructor Summary

protected

GraphIterator(Resource root)

Method Summary

protected void	createNext()
protected void	createResult()
static Iterator	getIterator(Resource root) Create a new Iterator that iterates over all triples.
protected Enumeration	getPropertyEnumeration(Resource r)
static Iterator	getResourceIterator(Resource root) Create a new Iterator that iterates over all Resources.
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

Field Detail

visitedResources

protected Set visitedResources

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

se

protected GraphIterator.StackElement se

The current information at a certain depth.

stack

protected Stack 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 getIterator(Resource root)

Create a new Iterator that iterates over all triples. The return value of next() is of type GraphIteratorElement.

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 getResourceIterator(Resource root)

Create a new Iterator that iterates over all Resources. The return value of next() is of type Resource.

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 void stepDeeper(Resource root)

stepHigher

protected boolean stepHigher()

createResult

protected 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 void remove()

Specified by:

remove in interface Iterator

See Also:

Iterator.remove()