/**
* Copyright (C) 2015 Valkyrie RCP
*
* 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.valkyriercp.rules.constraint;
import org.springframework.util.comparator.ComparableComparator;
import org.springframework.util.comparator.NullSafeComparator;
import org.valkyriercp.rules.constraint.property.AbstractBinaryConstraint;
import java.util.Comparator;
/**
* Abstract helper superclass for binary predicates involved in comparison
* operations.
*
* @author Keith Donald
*/
public abstract class ComparisonBinaryPredicate extends AbstractBinaryConstraint {
private static final NullSafeComparator COMPARATOR = new NullSafeComparator(new ComparableComparator(), true);
private Comparator comparator;
/**
* Creates a comparing binary predicate which operates on
* <code>Comparable</code> objects.
*/
protected ComparisonBinaryPredicate() {
}
/**
* Creates a comparing binary predicate which compares using the provided
* <code>Comparator</code>.
*
* @param comparator
* the comparator, may be null
*/
protected ComparisonBinaryPredicate(Comparator comparator) {
if (!(comparator instanceof NullSafeComparator)) {
this.comparator = new NullSafeComparator(comparator, true);
}
else {
this.comparator = comparator;
}
}
/**
* Returns the comparator which is used to compare the arguments
*
* @return null if no custom comparator is defined
*/
public Comparator getComparator() {
return comparator;
}
/**
* Tests two arguments against a comparsion expression. This method
* delegates to the {@link #testCompareResult(int)}template method to
* evaluate the compareTo result.
*
* @param argument1
* the first argument
* @param argument2
* the second argument
* @return true if the comparsion result passes, false otherwise
*/
public boolean test(Object argument1, Object argument2) {
if (getComparator() != null)
return testCompareResult(getComparator().compare(argument1, argument2));
return testCompareResult(COMPARATOR.compare(argument1, argument2));
}
/**
* Template method for evaluating the compare result.
*
* @param result
* The compare result
* @return true or false
*/
protected abstract boolean testCompareResult(int result);
}