Package com.singularsys.extensions.stream

Class StreamReduce

java.lang.Object

com.singularsys.jep.functions.PostfixMathCommand

com.singularsys.jep.functions.NaryFunction

com.singularsys.extensions.stream.StreamReduce

All Implemented Interfaces:

JepComponent, PostfixMathCommandI, Serializable

public class StreamReduce
extends NaryFunction
implements JepComponent

Reduce a list to a single value using a lambda function and an initial identity value.

For example:

 reduce(1, [x,y] => x*y, [1,2,3,4,5])
 

If the stream is empty, the identity value is returned if the stream has a single element, then the result of applying the lambda function to the identity value and the single element is returned. Hence, the initial value should be the identity value for the lambda function.

See Also:

• Serialized Form

Field Summary

Fields inherited from class com.singularsys.jep.functions.PostfixMathCommand

curNumberOfParameters, description, name, NaN, numberOfParameters

Constructor Summary

Constructors

Constructor	Description
StreamReduce()

Method Summary

Modifier and Type	Method	Description
Object	eval(Object[] args)	Evaluate the function
JepComponent	getLightWeightInstance()	Gets a light-weight instance suitable for using in multiple threads.
void	init(Jep jep)	Initialize the component.

Methods inherited from class com.singularsys.jep.functions.NaryFunction

run

Methods inherited from class com.singularsys.jep.functions.PostfixMathCommand

asArray, asBool, asDouble, asInt, asLong, asStrictInt, asString, asType, checkNumberOfParameters, getDescription, getDescription, getDescriptionWithType, getName, getNumberOfParameters, setCurNumberOfParameters, setDescription, setName, toString, toString

Methods inherited from class java.lang.Object

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

Constructor Details

StreamReduce

public StreamReduce()

Method Details

eval

public Object eval(Object[] args)
            throws EvaluationException

Description copied from class: NaryFunction

Evaluate the function

Specified by:

eval in class NaryFunction

Parameters:

args - arguments to the function

Returns:

value returned by the function

Throws:

EvaluationException - if the calculation cannot be performed

init

public void init(Jep jep)

Description copied from interface: JepComponent

Initialize the component. This method is called whenever a component is added to Jep. Hence, it allows components to keep track of the other components they may rely on.

Specified by:

init in interface JepComponent

Parameters:

jep - the current Jep instance

getLightWeightInstance

public JepComponent getLightWeightInstance()

Description copied from interface: JepComponent

Gets a light-weight instance suitable for using in multiple threads.

Specified by:

getLightWeightInstance in interface JepComponent

Returns:

either a new instance, null or 'this'.