/*
* Copyright 2008, Unitils.org
*
* 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.unitils.reflectionassert.comparator;
import org.unitils.reflectionassert.ReflectionComparator;
import org.unitils.reflectionassert.difference.Difference;
/**
* Interface for comparing 2 given objects.
* <p/>
* One should always first call canCompare before calling compare to perform the actual comparison.
* If canCompare returns false, the comparator implementation is not suited to compare the given objects and compare
* should not be called.
*
* @author Tim Ducheyne
* @author Filip Neven
*/
public interface Comparator {
/**
* Checks whether this comparator can compare the given objects.
* <p/>
* This method should always be called before calling the compare method. If false is returned compare
* should not be invoked.
*
* @param left The left object
* @param right The right object
* @return True if compare can be called, false otherwise
*/
boolean canCompare(Object left, Object right);
/**
* Compares the given objects and returns the difference (if any).
* <p/>
* The reflection comparator is passed as an argument and can be used to perform inner comparisons.
* E.g. during the comparison of an object the given comparator can be used to compare the instance
* fields of the object.
*
* @param left The left object
* @param right The right object
* @param onlyFirstDifference True if only the first difference should be returned
* @param reflectionComparator The root comparator for inner comparisons, not null
* @return The difference, null if a match is found
*/
Difference compare(Object left, Object right, boolean onlyFirstDifference, ReflectionComparator reflectionComparator);
}