Class RestartableIteratorTupleIter

  extended by org.eigenbase.runtime.AbstractTupleIter
      extended by 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.

$Id: //open/dev/farrago/src/org/eigenbase/runtime/ $
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
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
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail


private final RestartableIterator iterator
Constructor Detail


public RestartableIteratorTupleIter(RestartableIterator iterator)
Method Detail


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().

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


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
restart in class AbstractTupleIter


public void closeAllocation()
Description copied from interface: ClosableAllocation
Closes this object.