com.metamatrix.query.function.aggregate
Interface AggregateFunction

All Known Implementing Classes:

Avg, ConstantFunction, Count, DuplicateFilter, Max, Min, NullFilter, Sum

public interface AggregateFunction

This represents the interface for an aggregate function. The basic lifecycle is that the AggregateFunction is initialize()'d with the type of the element being aggregated, then addInput() is called for every row in the group, then getResult() is called to retrieve the result.

Method Summary

void	addInput(java.lang.Object input) Called for the element value in every row of a group.
java.lang.Object	getResult() Called after all values have been processed to get the result.
void	initialize(java.lang.Class dataType) Called to initialize the function.
void	reset() Called to reset the state of the function.

Method Detail

initialize

void initialize(java.lang.Class dataType)

Called to initialize the function. In the future this may expand with additional information.

Parameters:

dataType - Data type of element begin aggregated

reset

void reset()

Called to reset the state of the function.

addInput

void addInput(java.lang.Object input)
              throws FunctionExecutionException,
                     ExpressionEvaluationException,
                     MetaMatrixComponentException

Called for the element value in every row of a group.

Parameters:

input - Input value, may be null

Throws:

FunctionExecutionException

ExpressionEvaluationException

MetaMatrixComponentException

getResult

java.lang.Object getResult()
                           throws FunctionExecutionException,
                                  ExpressionEvaluationException,
                                  MetaMatrixComponentException,
                                  MetaMatrixProcessingException

Called after all values have been processed to get the result.

Returns:

Result value

Throws:

MetaMatrixProcessingException

FunctionExecutionException

ExpressionEvaluationException

MetaMatrixComponentException