/*
* 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;
public abstract class AbstractRandomSwapIterator<S, SubS> extends UpcomingSelectionIterator<S> {
protected final Iterable<SubS> leftSubSelector;
protected final Iterable<SubS> rightSubSelector;
protected Iterator<SubS> leftSubSelectionIterator;
protected Iterator<SubS> rightSubSelectionIterator;
public AbstractRandomSwapIterator(Iterable<SubS> leftSubSelector,
Iterable<SubS> rightSubSelector) {
this.leftSubSelector = leftSubSelector;
this.rightSubSelector = rightSubSelector;
leftSubSelectionIterator = this.leftSubSelector.iterator();
rightSubSelectionIterator = this.rightSubSelector.iterator();
// Don't do hasNext() in constructor (to avoid upcoming selections breaking mimic recording)
}
@Override
protected S createUpcomingSelection() {
// Ideally, this code should have read:
// SubS leftSubSelection = leftSubSelectionIterator.next();
// SubS rightSubSelection = rightSubSelectionIterator.next();
// But empty selectors and ending selectors (such as non-random or shuffled) make it more complex
if (!leftSubSelectionIterator.hasNext()) {
leftSubSelectionIterator = leftSubSelector.iterator();
if (!leftSubSelectionIterator.hasNext()) {
return noUpcomingSelection();
}
}
SubS leftSubSelection = leftSubSelectionIterator.next();
if (!rightSubSelectionIterator.hasNext()) {
rightSubSelectionIterator = rightSubSelector.iterator();
if (!rightSubSelectionIterator.hasNext()) {
return noUpcomingSelection();
}
}
SubS rightSubSelection = rightSubSelectionIterator.next();
return newSwapSelection(leftSubSelection, rightSubSelection);
}
protected abstract S newSwapSelection(SubS leftSubSelection, SubS rightSubSelection);
}