cascading.nested.core.aggregate

Class BaseNumberNestedAggregate<Node,Type,Context extends BaseNumberNestedAggregate.BaseContext<Type,Node>>

java.lang.Object

cascading.nested.core.aggregate.BaseNumberNestedAggregate<Node,Type,Context>

All Implemented Interfaces:

NestedAggregate<Node,Context>, java.io.Serializable

Direct Known Subclasses:

AverageDoubleNestedAggregate, SumDoubleNestedAggregate, SumLongNestedAggregate

public abstract class BaseNumberNestedAggregate<Node,Type,Context extends BaseNumberNestedAggregate.BaseContext<Type,Node>>
extends java.lang.Object
implements NestedAggregate<Node,Context>

Class BaseNumberNestedAggregate is the base class used to create number oriented aggregation operations.

Subclasses can optimize based on an expected primitive type while still honoring the Long.class and Long.TYPE semantics around null or 0 empty values.

Note that subclasses can also be independent of the Node type (JSON etc). All Node specific operations are passed back to the NestedCoercibleType instance.

See Also:

SumLongNestedAggregate, SumDoubleNestedAggregate, AverageDoubleNestedAggregate, Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BaseNumberNestedAggregate.BaseContext<Type,Node>

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.Class<Type>	aggregateType
protected cascading.tuple.Fields	fieldDeclaration

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BaseNumberNestedAggregate()
protected	BaseNumberNestedAggregate(cascading.tuple.Fields fieldDeclaration, java.lang.Class<Type> defaultType)

Method Summary

Modifier and Type	Method and Description
void	aggregate(Context context, Node node) This method receives each collected value to be applied to the current aggregation.
cascading.tuple.Tuple	complete(Context context) This method completes the aggregate operation and insert the results into a Tuple instance.
protected boolean	discardNullValues()
cascading.tuple.Fields	getFieldDeclaration()
Context	resetContext(Context context) This method is called after NestedAggregate.complete(Object) so that any resources can be freed and the result context instance can be used in the next aggregation.
protected boolean	returnNullForEmpty()

Methods inherited from class java.lang.Object

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

Methods inherited from interface cascading.nested.core.NestedAggregate

createContext

Field Detail

fieldDeclaration

protected cascading.tuple.Fields fieldDeclaration

aggregateType

protected java.lang.Class<Type> aggregateType

Constructor Detail

BaseNumberNestedAggregate

protected BaseNumberNestedAggregate()

BaseNumberNestedAggregate

protected BaseNumberNestedAggregate(cascading.tuple.Fields fieldDeclaration,
                                    java.lang.Class<Type> defaultType)

Method Detail

getFieldDeclaration

public cascading.tuple.Fields getFieldDeclaration()

Specified by:

getFieldDeclaration in interface NestedAggregate<Node,Context extends BaseNumberNestedAggregate.BaseContext<Type,Node>>

Returns:

the fields this aggregate function will return

returnNullForEmpty

protected boolean returnNullForEmpty()

discardNullValues

protected boolean discardNullValues()

aggregate

public void aggregate(Context context,
                      Node node)

Description copied from interface: NestedAggregate

This method receives each collected value to be applied to the current aggregation.

Specified by:

aggregate in interface NestedAggregate<Node,Context extends BaseNumberNestedAggregate.BaseContext<Type,Node>>

Parameters:

context - the context object created by NestedAggregate.createContext(CoercibleType)

node - the Node container object that should be aggregated

complete

public cascading.tuple.Tuple complete(Context context)

Description copied from interface: NestedAggregate

This method completes the aggregate operation and insert the results into a Tuple instance.

Note the Tuple may be created (indirectly) by the NestedAggregate.createContext(CoercibleType) method and reused.

Specified by:

complete in interface NestedAggregate<Node,Context extends BaseNumberNestedAggregate.BaseContext<Type,Node>>

Parameters:

context - the context object created by NestedAggregate.createContext(CoercibleType)

Returns:

a Tuple containing the aggregate value(s), the Tuple may be reused

resetContext

public Context resetContext(Context context)

Description copied from interface: NestedAggregate

This method is called after NestedAggregate.complete(Object) so that any resources can be freed and the result context instance can be used in the next aggregation.

Specified by:

resetContext in interface NestedAggregate<Node,Context extends BaseNumberNestedAggregate.BaseContext<Type,Node>>

Parameters:

context - the context object created by NestedAggregate.createContext(CoercibleType)

Returns:

either a cleared or new context instance to be used in further aggregations