uk.ac.ed.epcc.safe.accounting.db

Class ReductionHandler<E extends uk.ac.ed.epcc.webapp.model.data.DataObject & ExpressionTarget,F extends uk.ac.ed.epcc.webapp.model.data.DataObjectFactory<E> & ExpressionTargetFactory<E>>

java.lang.Object

uk.ac.ed.epcc.safe.accounting.db.ReductionHandler<E,F>

Type Parameters:

E - type of ExpressionTarget

All Implemented Interfaces:

ReductionProducer<E>

public class ReductionHandler<E extends uk.ac.ed.epcc.webapp.model.data.DataObject & ExpressionTarget,F extends uk.ac.ed.epcc.webapp.model.data.DataObjectFactory<E> & ExpressionTargetFactory<E>>
extends java.lang.Object
implements ReductionProducer<E>

A wrapper round an ExpressionTargetFactory that implements ReductionProducer

Author:

spb

Constructor Summary

Constructors

Constructor and Description
ReductionHandler(AccessorMap map, F fac)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	compatible(RecordSelector sel)
java.util.Map<ExpressionTuple,ReductionMapResult>	getIndexedReductionMap(java.util.Set<ReductionTarget> sum, RecordSelector selector) General reduction operation.
<R> R	getReduction(ReductionTarget<R> type, RecordSelector sel) Perform a reduction over a set of records
<I> java.util.Map<I,java.lang.Number>	getReductionMap(PropExpression<I> index, ReductionTarget<java.lang.Number> property, RecordSelector selector) sum the specified numerical quantity over all records that match the selector grouped by the other specified property

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ReductionHandler

public ReductionHandler(AccessorMap map,
                F fac)

Method Detail

compatible

public final boolean compatible(RecordSelector sel)

getIndexedReductionMap

public java.util.Map<ExpressionTuple,ReductionMapResult> getIndexedReductionMap(java.util.Set<ReductionTarget> sum,
                                                                       RecordSelector selector)
                                                                         throws java.lang.Exception

Description copied from interface: ReductionProducer

General reduction operation. The reduction is specified by a set of ReductionTarget objects. This method generates Maps from the requested ReductionTarget to the result of the corresponding reduction. If the list of ReductionTargets contains any IndexReduction objects then multiple results will be returned so these results are themselves returned as a Map indexed by PropertyTuple objects representing the Index values. If there are no IndexValues an empty PropertyTuple will be used. A non-index target that does not resolve may be ignored or return the default value for the ReductionTarget. This is so target set compatible with composite UsageProducers can contain targets only relevant to some of its parts without suppressing all output from the tables that don't support the property. This does run the risk that spurious index-tuples might be generated from tables that support none of the non-index targets. In that case the producer has to be tuned.

Specified by:

getIndexedReductionMap in interface ReductionProducer<E extends uk.ac.ed.epcc.webapp.model.data.DataObject & ExpressionTarget>

Throws:

java.lang.Exception

Returns:

Map

getReduction

public <R> R getReduction(ReductionTarget<R> type,
                 RecordSelector sel)
               throws java.lang.Exception

Description copied from interface: ReductionProducer

Perform a reduction over a set of records

Specified by:

getReduction in interface ReductionProducer<E extends uk.ac.ed.epcc.webapp.model.data.DataObject & ExpressionTarget>

Throws:

java.lang.Exception

Parameters:

type - ReductionTarget specifying reduction to perform

sel - RecordSelector to select target records

Returns:

result of reduction

getReductionMap

public <I> java.util.Map<I,java.lang.Number> getReductionMap(PropExpression<I> index,
                                                    ReductionTarget<java.lang.Number> property,
                                                    RecordSelector selector)
                                                  throws java.lang.Exception

Description copied from interface: ReductionProducer

sum the specified numerical quantity over all records that match the selector grouped by the other specified property

Specified by:

getReductionMap in interface ReductionProducer<E extends uk.ac.ed.epcc.webapp.model.data.DataObject & ExpressionTarget>

Throws:

java.lang.Exception

Returns:

Map