cascading.operation.expression

Class ScriptFilter

java.lang.Object

cascading.operation.BaseOperation<ScriptOperation.Context>

cascading.operation.expression.ScriptOperation

cascading.operation.expression.ScriptFilter

All Implemented Interfaces:

cascading.flow.planner.DeclaresResults, cascading.operation.Filter<ScriptOperation.Context>, cascading.operation.Operation<ScriptOperation.Context>, cascading.util.Traceable, java.io.Serializable

public class ScriptFilter
extends ScriptOperation
implements cascading.operation.Filter<ScriptOperation.Context>

Class ScriptFilter dynamically resolves a given expression using argument Tuple values. This Filter is based on the Janino compiler.

Specifically this filter uses the ScriptEvaluator, thus the syntax from that class is inherited here.

A script may use field names directly as parameters in the expression, or field positions with the syntax "$n", where n is an integer.

Given an argument tuple with the fields "a" and "b", the following script returns true:
boolean result = (a + b == $0 + $1);
return boolean;

Unlike an "expression" used by ExpressionFilter, a "script" requires each line to end in an semi-colon (@{code ;}) and the final line to be a return statement.

Further, the types of the tuple elements will be coerced into the given parameterTypes. Regardless of the actual tuple element values, they will be converted to the types expected by the script if possible.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class cascading.operation.expression.ScriptOperation

ScriptOperation.Context, ScriptOperation.Evaluator

Field Summary

Fields inherited from class cascading.operation.expression.ScriptOperation

block, parameterNames, parameterTypes, returnType

Fields inherited from class cascading.operation.BaseOperation

fieldDeclaration, numArgs, trace

Fields inherited from interface cascading.operation.Operation

ANY

Constructor Summary

Constructors

Constructor and Description
ScriptFilter(java.lang.String script) Constructor ScriptFilter creates a new ScriptFilter instance.
ScriptFilter(java.lang.String script, java.lang.Class[] expectedTypes) Constructor ScriptFilter creates a new ScriptFilter instance.
ScriptFilter(java.lang.String script, java.lang.String[] parameterNames, java.lang.Class[] parameterTypes) Constructor ScriptFilter creates a new ScriptFilter instance.
ScriptFilter(java.lang.String script, java.lang.String parameterName, java.lang.Class parameterType) Constructor ScriptFilter creates a new ScriptFilter instance.

Method Summary

Modifier and Type	Method and Description
java.lang.String	getScript()
boolean	isRemove(cascading.flow.FlowProcess flowProcess, cascading.operation.FilterCall<ScriptOperation.Context> filterCall)

Methods inherited from class cascading.operation.expression.ScriptOperation

equals, evaluate, getBlock, getEvaluator, getExtendedClass, getParameterNames, getParameterTypes, getReturnType, guessParameterNames, hashCode, prepare

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, prepare

Constructor Detail

ScriptFilter

@ConstructorProperties(value="script")
public ScriptFilter(java.lang.String script)

Constructor ScriptFilter creates a new ScriptFilter instance.

Parameters:

script - of type String

ScriptFilter

@ConstructorProperties(value={"script","parameterName","parameterType"})
public ScriptFilter(java.lang.String script,
                                                                                             java.lang.String parameterName,
                                                                                             java.lang.Class parameterType)

Constructor ScriptFilter creates a new ScriptFilter instance.

Parameters:

script - of type String

parameterName - of type String

parameterType - of type Class

ScriptFilter

@ConstructorProperties(value={"script","expectedTypes"})
public ScriptFilter(java.lang.String script,
                                                                             java.lang.Class[] expectedTypes)

Constructor ScriptFilter creates a new ScriptFilter instance.

This constructor will use the runtime OperationCall.getArgumentFields() to source the parameterNames and parameterTypes required by the other constructors, but use expectedTypes to coerce the incoming types to before passing as parameters to the expression.

Parameters:

script - of type String

expectedTypes - of type Class[]

ScriptFilter

@ConstructorProperties(value={"script","parameterNames","parameterTypes"})
public ScriptFilter(java.lang.String script,
                                                                                               java.lang.String[] parameterNames,
                                                                                               java.lang.Class[] parameterTypes)

Constructor ScriptFilter creates a new ScriptFilter instance.

Parameters:

script - of type String

parameterNames - of type String[]

parameterTypes - of type Class[]

Method Detail

getScript

public java.lang.String getScript()

isRemove

public boolean isRemove(cascading.flow.FlowProcess flowProcess,
                        cascading.operation.FilterCall<ScriptOperation.Context> filterCall)

Specified by:

isRemove in interface cascading.operation.Filter<ScriptOperation.Context>