/*
* Copyright 2015 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 org.optaplanner.core.impl.heuristic.move.Move;
import org.optaplanner.core.impl.heuristic.selector.entity.EntitySelector;
import org.optaplanner.core.impl.heuristic.selector.value.ValueSelector;
public abstract class AbstractRandomChangeIterator<S extends Move> extends UpcomingSelectionIterator<S> {
private final EntitySelector entitySelector;
private final ValueSelector valueSelector;
private Iterator<Object> entityIterator;
public AbstractRandomChangeIterator(EntitySelector entitySelector, ValueSelector valueSelector) {
this.entitySelector = entitySelector;
this.valueSelector = valueSelector;
entityIterator = entitySelector.iterator();
// Don't do hasNext() in constructor (to avoid upcoming selections breaking mimic recording)
}
@Override
protected S createUpcomingSelection() {
// Ideally, this code should have read:
// Object entity = entityIterator.next();
// Iterator<Object> valueIterator = valueSelector.iterator(entity);
// Object toValue = valueIterator.next();
// But empty selectors and ending selectors (such as non-random or shuffled) make it more complex
if (!entityIterator.hasNext()) {
entityIterator = entitySelector.iterator();
if (!entityIterator.hasNext()) {
return noUpcomingSelection();
}
}
Object entity = entityIterator.next();
Iterator<Object> valueIterator = valueSelector.iterator(entity);
int entityIteratorCreationCount = 0;
// This loop is mostly only relevant when the entityIterator or valueIterator is non-random or shuffled
while (!valueIterator.hasNext()) {
// Try the next entity
if (!entityIterator.hasNext()) {
entityIterator = entitySelector.iterator();
entityIteratorCreationCount++;
if (entityIteratorCreationCount >= 2) {
// All entity-value combinations have been tried (some even more than once)
return noUpcomingSelection();
}
}
entity = entityIterator.next();
valueIterator = valueSelector.iterator(entity);
}
Object toValue = valueIterator.next();
return newChangeSelection(entity, toValue);
}
protected abstract S newChangeSelection(Object entity, Object toValue);
}