/*
* Copyright 2012 Red Hat, Inc. and/or its affiliates.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.optaplanner.core.impl.heuristic.selector.common.iterator;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.optaplanner.core.impl.heuristic.move.Move;
import org.optaplanner.core.impl.heuristic.selector.Selector;
import org.optaplanner.core.impl.heuristic.selector.entity.mimic.MimicReplayingEntitySelector;
/**
* IMPORTANT: The constructor of any subclass of this abstract class, should never call any of its child
* {@link Selector}'s {@link Iterator#hasNext()} or {@link Iterator#next()} methods,
* because that can cause descendant {@link Selector}s to be selected too early
* (which breaks {@link MimicReplayingEntitySelector}).
* @param <S> Selection type, for example a {@link Move} class, an entity class or a value class.
*/
public abstract class UpcomingSelectionIterator<S> extends SelectionIterator<S> {
protected boolean upcomingCreated = false;
protected boolean hasUpcomingSelection = true;
protected S upcomingSelection;
@Override
public boolean hasNext() {
if (!upcomingCreated) {
upcomingSelection = createUpcomingSelection();
upcomingCreated = true;
}
return hasUpcomingSelection;
}
@Override
public S next() {
if (!hasUpcomingSelection) {
throw new NoSuchElementException();
}
if (!upcomingCreated) {
upcomingSelection = createUpcomingSelection();
}
upcomingCreated = false;
return upcomingSelection;
}
protected abstract S createUpcomingSelection();
protected S noUpcomingSelection() {
hasUpcomingSelection = false;
return null;
}
@Override
public String toString() {
if (!upcomingCreated) {
return "Next upcoming (?)";
} else if (!hasUpcomingSelection) {
return "No next upcoming";
} else {
return "Next upcoming (" + upcomingSelection + ")";
}
}
}