/*
* 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.value;
import java.util.Iterator;
import org.optaplanner.core.api.domain.valuerange.ValueRangeProvider;
import org.optaplanner.core.api.domain.variable.PlanningVariable;
import org.optaplanner.core.impl.domain.variable.descriptor.GenuineVariableDescriptor;
import org.optaplanner.core.impl.heuristic.selector.IterableSelector;
import org.optaplanner.core.impl.heuristic.selector.Selector;
/**
* Selects values from the {@link ValueRangeProvider} for a {@link PlanningVariable} annotated property.
* @see AbstractValueSelector
*/
public interface ValueSelector extends Selector {
/**
* @return never null
*/
GenuineVariableDescriptor getVariableDescriptor();
/**
* Similar to {@link IterableSelector#getSize()}, but requires an entity.
* @param entity never null
* @return the approximate number of elements generated by this {@link Selector}, always {@code >= 0}
* @throws IllegalStateException if {@link #isCountable} returns false,
* but not if only {@link #isNeverEnding()} returns true
*/
long getSize(Object entity);
/**
* Similar to {@link IterableSelector#iterator()}, but requires an entity.
* @param entity never null
* @return never null
*/
Iterator<Object> iterator(Object entity);
/**
* If {@link #isNeverEnding()} is true, then {@link #iterator(Object)} will never end.
* This returns an ending {@link Iterator}, that tries to match {@link #iterator(Object)} as much as possible,
* but return each distinct element only once
* and therefore it might not respect the configuration of this {@link ValueSelector} entirely.
* @param entity never null
* @return never null
* @see #iterator(Object)
*/
Iterator<Object> endingIterator(Object entity);
}