Turtle DB
A mini DDBMS
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Public Member Functions | |
Union () | |
void | accept (QueryVisitor v) throws VisitorException |
void | reset () |
Protected Member Functions | |
Tuple | internalNext () |
Protected Attributes | |
int | m_relationCursor |
void ca.uqac.dim.ddb.Union.accept | ( | QueryVisitor | v | ) | throws VisitorException [virtual] |
Implements ca.uqac.dim.ddb.Relation.
Tuple ca.uqac.dim.ddb.Union.internalNext | ( | ) | [protected, virtual] |
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.
null
if no such tuple exists Implements ca.uqac.dim.ddb.Relation.
void ca.uqac.dim.ddb.Union.reset | ( | ) |
Resets the enumeration of tuples, i.e. starts back at the first tuple of the relation.
Reimplemented from ca.uqac.dim.ddb.Relation.
int ca.uqac.dim.ddb.Union.m_relationCursor [protected] |