org.gcube.data.streams
Class LookAheadStream<E>

java.lang.Object
  org.gcube.data.streams.LookAheadStream<E>

Type Parameters:

E - the type of stream elements

All Implemented Interfaces:

Iterator<E>, Stream<E>

Direct Known Subclasses:

FoldedStream, GuardedStream, MonitoredStream, PipedStream, ResultsetStream, UnfoldedStream

public abstract class LookAheadStream<E>
extends Object
implements Stream<E>

Partial Stream implementation based on look-ahead operations over an underlying stream.

The implementation attempts to prefetch the output of next() in hasNext(). If a failure occurs, hasNext():

keeps consuming the underlying stream as long as the failure is a StreamSkipSignal;

consults a FaultHandler for all the other failures. If the FaultHandler re-throws the same or a different exception, the implementation throws it at the following next().

Author:

Fabio Simeoni

Field Summary

protected E	element
protected Boolean	hasNext

Constructor Summary

LookAheadStream()

Method Summary

protected abstract boolean	delegateHasNext() Returns true if the underlying stream has more elements.
protected abstract E	delegateNext() Returns an element of the underlying stream
boolean	hasNext()
E	next()
void	setHandler(FaultHandler handler) Sets the FaultHandler for the iteration

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.gcube.data.streams.Stream

close, isClosed, locator

Methods inherited from interface java.util.Iterator

remove

Field Detail

hasNext

protected Boolean hasNext

element

protected E element

Constructor Detail

LookAheadStream

public LookAheadStream()

Method Detail

setHandler

public void setHandler(FaultHandler handler)
                throws IllegalArgumentException

Sets the FaultHandler for the iteration

Parameters:

handler - the handler

Throws:

IllegalArgumentException - if the handler is null

hasNext

public final boolean hasNext()

Specified by:

hasNext in interface Iterator<E>

Specified by:

hasNext in interface Stream<E>

next

public final E next()

Specified by:

next in interface Iterator<E>

Specified by:

next in interface Stream<E>

delegateNext

protected abstract E delegateNext()

Returns an element of the underlying stream

Returns:

the element

delegateHasNext

protected abstract boolean delegateHasNext()

Returns true if the underlying stream has more elements.

Returns:

true if the underlying stream has more elements