org.apache.cassandra.index.sasi.utils

Class AbstractIterator<T>

java.lang.Object

org.apache.cassandra.index.sasi.utils.AbstractIterator<T>

All Implemented Interfaces:

com.google.common.collect.PeekingIterator<T>, java.util.Iterator<T>

Direct Known Subclasses:

RangeIterator

public abstract class AbstractIterator<T>
extends java.lang.Object
implements com.google.common.collect.PeekingIterator<T>

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	AbstractIterator.State

Field Summary

Fields

Modifier and Type	Field and Description
protected T	next
protected AbstractIterator.State	state

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractIterator() Constructor for use by subclasses.

Method Summary

Modifier and Type	Method and Description
protected abstract T	computeNext() Returns the next element.
protected T	endOfData() Implementations of computeNext() must invoke this method when there are no elements left in the iteration.
boolean	hasNext()
T	next()
T	peek() Returns the next element in the iteration without advancing the iteration, according to the contract of PeekingIterator.peek().
void	remove()
protected boolean	tryToComputeNext()

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

state

protected AbstractIterator.State state

next

protected T next

Constructor Detail

AbstractIterator

protected AbstractIterator()

Constructor for use by subclasses.

Method Detail

computeNext

protected abstract T computeNext()

Returns the next element. Note: the implementation must call endOfData() when there are no elements left in the iteration. Failure to do so could result in an infinite loop.

The initial invocation of hasNext() or next() calls this method, as does the first invocation of hasNext or next following each successful call to next. Once the implementation either invokes endOfData or throws an exception, computeNext is guaranteed to never be called again.

If this method throws an exception, it will propagate outward to the hasNext or next invocation that invoked this method. Any further attempts to use the iterator will result in an IllegalStateException.

The implementation of this method may not invoke the hasNext, next, or peek() methods on this instance; if it does, an IllegalStateException will result.

Returns:

the next element if there was one. If endOfData was called during execution, the return value will be ignored.

Throws:

java.lang.RuntimeException - if any unrecoverable error happens. This exception will propagate outward to the hasNext(), next(), or peek() invocation that invoked this method. Any further attempts to use the iterator will result in an IllegalStateException.

endOfData

protected final T endOfData()

Implementations of computeNext() must invoke this method when there are no elements left in the iteration.

Returns:

null; a convenience so your computeNext implementation can use the simple statement return endOfData();

hasNext

public final boolean hasNext()

Specified by:

hasNext in interface java.util.Iterator<T>

tryToComputeNext

protected boolean tryToComputeNext()

next

public final T next()

Specified by:

next in interface com.google.common.collect.PeekingIterator<T>

Specified by:

next in interface java.util.Iterator<T>

remove

public void remove()

Specified by:

remove in interface com.google.common.collect.PeekingIterator<T>

Specified by:

remove in interface java.util.Iterator<T>

peek

public final T peek()

Returns the next element in the iteration without advancing the iteration, according to the contract of PeekingIterator.peek().

Implementations of AbstractIterator that wish to expose this functionality should implement PeekingIterator.

Specified by:

peek in interface com.google.common.collect.PeekingIterator<T>