com.almworks.jira.structure.api.attribute.loader.reduce

Class ReducingAggregateLoader<T>

Object

AbstractAttributeLoader<T>

AbstractAggregateLoader<T>

ReducingAggregateLoader<T>

Type Parameters:

T - type of reduced values

All Implemented Interfaces:

AggregateAttributeLoader<T>, AttributeLoader<T>, MultiRowAttributeLoader<T>, ValueReducer<T>, RowAttributeLoader<T>

Direct Known Subclasses:

SingleDependencyReducingAggregateLoader

public abstract class ReducingAggregateLoader<T>
extends AbstractAggregateLoader<T>
implements ValueReducer<T>

A base class for aggregate loaders that calculate values using only the specified part of subtree. The part of subtree to use is defined by ReductionStrategy, which is specified by type parameter in the attribute specification.

Here and in other classes, the process of combining the current value with values calculated for partial subtree into one value is called reduction.

This class:

1. checks for errors,
2. filters out values for generator rows,
3. passes values to the reduction strategy.

See Also:

ValueReducer, ReductionStrategy

Field Summary

Fields inherited from class AbstractAttributeLoader

mySpec

Constructor Summary

Constructors

Constructor and Description
ReducingAggregateLoader(AttributeSpec<T> spec)

Method Summary

Modifier and Type	Method and Description
protected abstract AttributeValue<T>	getSelfValue(AggregateAttributeContext context)
AttributeValue<T>	loadValue(List<AttributeValue<T>> childrenValues, AggregateAttributeContext context) Performs aggregate loading.

Methods inherited from class AbstractAggregateLoader

firstChildError

Methods inherited from class AbstractAttributeLoader

getAttributeSpec, toString

Methods inherited from class Object

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

Methods inherited from interface ValueReducer

convert, merge, merge, reduce

Methods inherited from interface MultiRowAttributeLoader

getCachingStrategy

Methods inherited from interface RowAttributeLoader

isWholeForestDependent, preload

Methods inherited from interface AttributeLoader

getAttributeDependencies, getAttributeSpec, getContextDependencies, getGlobalTrail

Constructor Detail

ReducingAggregateLoader

public ReducingAggregateLoader(AttributeSpec<T> spec)

Method Detail

loadValue

public AttributeValue<T> loadValue(List<AttributeValue<T>> childrenValues,
                                   AggregateAttributeContext context)

Description copied from interface: AggregateAttributeLoader

Performs aggregate loading.

If the value is missing or empty, the loader should return AttributeValue.undefined(). If for some reason this loader is not applicable for the given row, it should return null. (Note, however, that if multiple aggregate loaders work on the same attribute, it could be tricky and lead to unexpected results.)

Note: children values may contain loop markers

Specified by:

loadValue in interface AggregateAttributeLoader<T>

Parameters:

childrenValues - the values of this attribute for all children rows, in the same order as the children rows

context - loading context

Returns:

the calculated value

getSelfValue

@NotNull
protected abstract AttributeValue<T> getSelfValue(AggregateAttributeContext context)