Package com.singularsys.extensions.stream

Class StreamCollector

java.lang.Object

com.singularsys.jep.functions.PostfixMathCommand

com.singularsys.jep.functions.UnaryFunction

com.singularsys.extensions.stream.StreamCollector

All Implemented Interfaces:

JepComponent, PostfixMathCommandI, Serializable

public class StreamCollector
extends UnaryFunction
implements JepComponent

Collects the elements of a stream into a list using a provided Collector.

For example, to join a stream of objects into a string, you could define a function like this:

Collector<Object, StringBuilder, String> join =
   Collector.of(
       StringBuilder::new,
       StringBuilder::append,
       (left, right) -> { left.append(right.toString()); return left; },
       StringBuilder::toString);

jep.addFunction("toString",
    new ChainedUnaryFunction(
        new StreamCollector(join)));

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class com.singularsys.jep.functions.UnaryFunction

UnaryFunction.FunctionWithException<T>

Field Summary

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

curNumberOfParameters, description, name, NaN, numberOfParameters

Constructor Summary

Constructors

Constructor	Description
StreamCollector(Collector<Object,?,?> collector2)

Method Summary

Modifier and Type	Method	Description
Object	eval(Object arg)	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.UnaryFunction

instanceOf, instanceOf, instanceOf, instanceOf, 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

StreamCollector

public StreamCollector(Collector<Object,?,?> collector2)

Method Details

eval

public Object eval(Object arg)
            throws EvaluationException

Description copied from class: UnaryFunction

Evaluate the function

Specified by:

eval in class UnaryFunction

Parameters:

arg - the single argument passed in

Returns:

the result of the function

Throws:

EvaluationException - on error

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'.