PredicateExhaustiveSelector

PredicateExhaustiveSelector.java

import org.jetbrains.annotations.NotNull;

import java.util.HashMap;
import java.util.Objects;
import java.util.function.Predicate;

public class PredicateExhaustiveSelector<O, V> extends HashMap<Predicate<O>, V> {

    /**
     * Returns the value to which the specified object is true for the mapped predicate,
     * or {@code null} if this map contains no mapping for the key. if multiple predicates are
     * true throws NonExhaustiveSelectionException exception
     * .
     * @param object which used to evaluate the predicates
     * @return Returns the value to which the specified object is true for the mapped predicate
     * @throws NonExhaustiveSelectionException
     */
    @Override
    @SuppressWarnings("unchecked")
    public V get(@NotNull Object object) {

        V value = null;

        for (var entry : entrySet()) {
            if (!entry.getKey().test((O) object)) {
                continue;
            }
            if (Objects.isNull(value)) {
                value = entry.getValue();
            } else {
                throw new NonExhaustiveSelectionException();
            }
        }
        return value;
    }

}