cascading.operation.expression
Class ExpressionOperation

java.lang.Object
  cascading.operation.BaseOperation<ExpressionOperation.Context>
      cascading.operation.expression.ExpressionOperation

All Implemented Interfaces:

Operation<ExpressionOperation.Context>, Serializable

Direct Known Subclasses:

AssertExpression, ExpressionFilter, ExpressionFunction

public class ExpressionOperation
extends BaseOperation<ExpressionOperation.Context>

Class ExpressionOperation is the base class for ExpressionFunction, ExpressionFilter, AssertExpression.

See Also:

Serialized Form

Nested Class Summary

static class

ExpressionOperation.Context

Field Summary

protected String

expression Field expression

Fields inherited from class cascading.operation.BaseOperation

fieldDeclaration, numArgs, trace

Fields inherited from interface cascading.operation.Operation

ANY

Constructor Summary

protected	ExpressionOperation(Fields fieldDeclaration, String expression)
protected	ExpressionOperation(Fields fieldDeclaration, String expression, Class parameterType)
protected	ExpressionOperation(Fields fieldDeclaration, String expression, String[] parameterNames, Class[] parameterTypes)
protected	ExpressionOperation(String expression, Class parameterType)
protected	ExpressionOperation(String expression, String[] parameterNames, Class[] parameterTypes)

Method Summary

protected Comparable	evaluate(ExpressionOperation.Context context, TupleEntry input) Performs the actual expression evaluation.
void	prepare(FlowProcess flowProcess, OperationCall<ExpressionOperation.Context> operationCall) Method prepare does nothing, and may safely be overridden.

Methods inherited from class cascading.operation.BaseOperation

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

Methods inherited from class java.lang.Object

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

Field Detail

expression

protected String expression

Field expression

Constructor Detail

ExpressionOperation

protected ExpressionOperation(Fields fieldDeclaration,
                              String expression)

ExpressionOperation

protected ExpressionOperation(Fields fieldDeclaration,
                              String expression,
                              Class parameterType)

ExpressionOperation

protected ExpressionOperation(Fields fieldDeclaration,
                              String expression,
                              String[] parameterNames,
                              Class[] parameterTypes)

ExpressionOperation

protected ExpressionOperation(String expression,
                              Class parameterType)

ExpressionOperation

protected ExpressionOperation(String expression,
                              String[] parameterNames,
                              Class[] parameterTypes)

Method Detail

prepare

public void prepare(FlowProcess flowProcess,
                    OperationCall<ExpressionOperation.Context> operationCall)

Description copied from class: BaseOperation

Method prepare does nothing, and may safely be overridden.

Specified by:

prepare in interface Operation<ExpressionOperation.Context>

Overrides:

prepare in class BaseOperation<ExpressionOperation.Context>

evaluate

protected Comparable evaluate(ExpressionOperation.Context context,
                              TupleEntry input)

Performs the actual expression evaluation.

Parameters:

context -

input - of type TupleEntry @return Comparable