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ca.uqac.dim.ddb.Union Class Reference
Inheritance diagram for ca.uqac.dim.ddb.Union:
ca.uqac.dim.ddb.NAryRelation ca.uqac.dim.ddb.Relation

List of all members.

Public Member Functions

 Union ()
void accept (QueryVisitor v) throws VisitorException
void reset ()

Protected Member Functions

Tuple internalNext ()

Protected Attributes

int m_relationCursor

Constructor & Destructor Documentation


Member Function Documentation

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.

Returns:
The next tuple, null if no such tuple exists

Implements ca.uqac.dim.ddb.Relation.

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

Reimplemented from ca.uqac.dim.ddb.Relation.


Member Data Documentation


The documentation for this class was generated from the following file: