org.eigenbase.runtime
Class RestartableIteratorTupleIter

java.lang.Object
  org.eigenbase.runtime.AbstractTupleIter
      org.eigenbase.runtime.RestartableIteratorTupleIter

All Implemented Interfaces:

TupleIter, ClosableAllocation

public class RestartableIteratorTupleIter
extends AbstractTupleIter

RestartableIteratorTupleIter adapts an underlying RestartableIterator as a TupleIter. It is an imperfect adaptor; fetchNext() blocks when a real TupleIter would return TupleIter.NoDataReason.UNDERFLOW.

Version:

$Id: //open/dev/farrago/src/org/eigenbase/runtime/RestartableIteratorTupleIter.java#8 $

Author:

John V. Sichi

Nested Class Summary

Nested classes/interfaces inherited from interface org.eigenbase.runtime.TupleIter

TupleIter.NoDataReason, TupleIter.TimeoutException

Field Summary

private RestartableIterator

iterator

Fields inherited from interface org.eigenbase.runtime.TupleIter

EMPTY_ITERATOR

Constructor Summary

RestartableIteratorTupleIter(RestartableIterator iterator)

Method Summary

void	closeAllocation() Closes this object.
Object	fetchNext() Returns the next element in the iteration.
void	restart() Restarts this iterator, so that a subsequent call to TupleIter.fetchNext() returns the first element in the collection being iterated.

Methods inherited from class org.eigenbase.runtime.AbstractTupleIter

setTimeout

Methods inherited from class java.lang.Object

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

Field Detail

iterator

private final RestartableIterator iterator

Constructor Detail

RestartableIteratorTupleIter

public RestartableIteratorTupleIter(RestartableIterator iterator)

Method Detail

fetchNext

public Object fetchNext()

Description copied from interface: TupleIter

Returns the next element in the iteration. If there is no next value, it returns a value from the TupleIter.NoDataReason enumeration indicating why no data was returned.

If this method returns TupleIter.NoDataReason.END_OF_DATA, no further data will be returned by this iterator unless TupleIter.restart() is called.

If this method returns TupleIter.NoDataReason.UNDERFLOW, no data is currently available, but may be come available in the future. It is possible for consecutive calls to return UNDERFLOW and then END_OF_DATA.

The object returned by this method may be re-used for each subsequent call to fetchNext(). In other words, callers must either make certain that the returned value is no longer needed or is copied before any subsequent calls to fetchNext().

Returns:

the next element in the iteration, or an instance of TupleIter.NoDataReason.

restart

public void restart()

Description copied from interface: TupleIter

Restarts this iterator, so that a subsequent call to TupleIter.fetchNext() returns the first element in the collection being iterated.

Specified by:

restart in interface TupleIter

Overrides:

restart in class AbstractTupleIter

closeAllocation

public void closeAllocation()

Description copied from interface: ClosableAllocation

Closes this object.