cascading.operation
Class Identity

java.lang.Object
  cascading.operation.BaseOperation<cascading.operation.Identity.Functor>
      cascading.operation.Identity

All Implemented Interfaces:

DeclaresResults, Function<cascading.operation.Identity.Functor>, Operation<cascading.operation.Identity.Functor>, Traceable, Serializable

public class Identity
extends BaseOperation<cascading.operation.Identity.Functor>
implements Function<cascading.operation.Identity.Functor>

The Identity function simply passes incoming arguments back out again. Optionally argument fields can be renamed, and/or coerced into specific types.

During coercion, if the given type is a primitive (long), and the tuple value is null, 0 is returned. If the type is an Object (java.lang.Long), and the tuple value is null, null is returned.

See Also:

Serialized Form

Field Summary

Fields inherited from class cascading.operation.BaseOperation

fieldDeclaration, numArgs, trace

Fields inherited from interface cascading.operation.Operation

ANY

Constructor Summary

Identity()
Constructor Identity creates a new Identity instance that will pass the argument values to its output.

Identity(Class... types)
Constructor Identity creates a new Identity instance that will coerce the values to the give types.

Identity(Fields fieldDeclaration)
Constructor Identity creates a new Identity instance that will rename the argument fields to the given fieldDeclaration.

Identity(Fields fieldDeclaration, Class... types)
Constructor Identity creates a new Identity instance that will rename the argument fields to the given fieldDeclaration, and coerce the values to the give types.

Method Summary

boolean	equals(Object object)
Type[]	getTypes()
int	hashCode()
void	operate(FlowProcess flowProcess, FunctionCall<cascading.operation.Identity.Functor> functionCall) Method operate provides the implementation of this Function.
void	prepare(FlowProcess flowProcess, OperationCall<cascading.operation.Identity.Functor> operationCall) Method prepare does nothing, and may safely be overridden.

Methods inherited from class cascading.operation.BaseOperation

cleanup, flush, getFieldDeclaration, getNumArgs, getTrace, isSafe, printOperationInternal, toString, toStringInternal

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface cascading.operation.Operation

cleanup, flush, getFieldDeclaration, getNumArgs, isSafe

Constructor Detail

Identity

public Identity()

Constructor Identity creates a new Identity instance that will pass the argument values to its output. Use this constructor for a simple copy Pipe.

Identity

@ConstructorProperties(value="types")
public Identity(Class... types)

Constructor Identity creates a new Identity instance that will coerce the values to the give types.

Parameters:

types - of type Class...

Identity

@ConstructorProperties(value="fieldDeclaration")
public Identity(Fields fieldDeclaration)

Constructor Identity creates a new Identity instance that will rename the argument fields to the given fieldDeclaration.

Parameters:

fieldDeclaration - of type Fields

Identity

@ConstructorProperties(value={"fieldDeclaration","types"})
public Identity(Fields fieldDeclaration,
                                           Class... types)

Constructor Identity creates a new Identity instance that will rename the argument fields to the given fieldDeclaration, and coerce the values to the give types.

Parameters:

fieldDeclaration - of type Fields

types - of type Class...

Method Detail

getTypes

public Type[] getTypes()

prepare

public void prepare(FlowProcess flowProcess,
                    OperationCall<cascading.operation.Identity.Functor> operationCall)

Description copied from class: BaseOperation

Method prepare does nothing, and may safely be overridden.

Specified by:

prepare in interface Operation<cascading.operation.Identity.Functor>

Overrides:

prepare in class BaseOperation<cascading.operation.Identity.Functor>

operate

public void operate(FlowProcess flowProcess,
                    FunctionCall<cascading.operation.Identity.Functor> functionCall)

Description copied from interface: Function

Method operate provides the implementation of this Function.

Specified by:

operate in interface Function<cascading.operation.Identity.Functor>

Parameters:

flowProcess - of type FlowProcess

functionCall - of type FunctionCall

equals

public boolean equals(Object object)

Overrides:

equals in class BaseOperation<cascading.operation.Identity.Functor>

hashCode

public int hashCode()

Overrides:

hashCode in class BaseOperation<cascading.operation.Identity.Functor>