de.team33.libs.decision.v1

Class Choice<P,R>

java.lang.Object

de.team33.libs.decision.v1.Choice<P,R>

Type Parameters:

P - The parameter type

R - The result type

All Implemented Interfaces:

Function<P,R>

public class Choice<P,R>
extends Object
implements Function<P,R>

A functional implementation of a simple decision.

Typically used to implement multiple choices, e.g. based on an enum:

 public enum Signum implements Function<Integer, Integer> {

     POSITIVE(any -> 1),

     NON_ZERO(Choice.on(Condition.IS_POSITIVE).apply(POSITIVE).orReply(-1)),

     ANY(Choice.on(Condition.IS_ZERO).reply(0).orApply(NON_ZERO));

     private final Function<Integer, Integer> backing;

     Signum(final Function<Integer, Integer> backing) {
         this.backing = backing;
     }

     public static int map(final int input) {
         return ANY.apply(input);
     }

     @Override
     public Integer apply(final Integer input) {
         return backing.apply(input);
     }

     interface Condition extends Predicate<Integer> {

         Condition IS_ZERO = input -> input == 0;
         Condition IS_POSITIVE = input -> input > 0;
     }
 }
 

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Choice.Condition<P> Represents the start of the creation of a Choice on a given condition.
static interface	Choice.Consequence<P,R> Represents the preliminary stage of a Choice that is only missing a negative result.

Method Summary

Modifier and Type	Method and Description
R	apply(P parameter)
static <P> Choice.Condition<P>	on(Predicate<P> condition) Starts the creation of a Choice giving a condition.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.function.Function

andThen, compose, identity

Method Detail

on

public static <P> Choice.Condition<P> on(Predicate<P> condition)

Starts the creation of a Choice giving a condition.

apply

public final R apply(P parameter)

Specified by:

apply in interface Function<P,R>