ca.uqac.dim.turtledb

Class RelationStreamIterator

java.lang.Object

ca.uqac.dim.turtledb.RelationStreamIterator

All Implemented Interfaces:

RelationIterator, java.util.Iterator<Tuple>

Direct Known Subclasses:

BinaryRelation.BinaryRelationStreamIterator, NAryRelation.NAryRelationStreamIterator, Table.TableStreamIterator, UnaryRelation.UnaryRelationStreamIterator

public abstract class RelationStreamIterator
extends java.lang.Object
implements RelationIterator

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	m_internalNextCalled
protected Tuple	m_nextTuple
protected java.util.List<Tuple>	m_outputTuples

Constructor Summary

Constructors

Constructor and Description
RelationStreamIterator()

Method Summary

Modifier and Type	Method and Description
boolean	hasNext()
protected abstract Tuple	internalNext() Method that must be implemented by every non-abstract relation; it returns the next tuple of the enumeration, if any.
Tuple	next()
void	remove()
void	reset() Resets the enumeration of tuples, i.e.

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

m_outputTuples

protected java.util.List<Tuple> m_outputTuples

m_nextTuple

protected Tuple m_nextTuple

m_internalNextCalled

protected boolean m_internalNextCalled

Constructor Detail

RelationStreamIterator

public RelationStreamIterator()

Method Detail

hasNext

public final boolean hasNext()

Specified by:

hasNext in interface java.util.Iterator<Tuple>

next

public final Tuple next()

Specified by:

next in interface java.util.Iterator<Tuple>

internalNext

protected abstract Tuple internalNext()

Method that must be implemented by every non-abstract relation; it returns the next tuple of the enumeration, if any. Methods next and hasNext use the return value of internalNext and additionally remove any duplicate tuples from the output enumeration. Hence a call to next may result in multiple calls to the relation's internalNext, if the tuples returned are already part of the result (this is especially true of Projections.

Returns:

The next tuple, null if no such tuple exists

remove

public final void remove()

Specified by:

remove in interface java.util.Iterator<Tuple>

reset

public void reset()

Resets the enumeration of tuples, i.e. starts back at the first tuple of the relation.

Specified by:

reset in interface RelationIterator