/*
* Copyright (C) 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.jboss.errai.ioc.client;
import java.lang.annotation.Annotation;
/**
* A simple comparator interface used by the {@link QualifierEqualityFactory} generator to create comparators for
* testing the equality of qualifiers at runtime.
* <p>
* NOTE: This interface is only for tested the attribute-equality of like-typed annotations. For instance, you can
* only compare an annotation of type <tt>Foo</tt> with another annotation of type <tt>Foo</tt>. You cannot
* compare the equality of <tt>Foo</tt> with <tt>Bar</tt>. Attempting to do so will simply result in a
* <tt>ClassCastException</tt>.
*
* @author Mike Brock
*/
public interface AnnotationComparator<T extends Annotation> {
/**
* Tests the equality of two qualifiers. Does not accept null values.
*
* @param a1 an annotation to be compared. cannot be null.
* @param a2 an annotation to be compared. cannot be null.
* @return true if the annotations match.
*/
public boolean isEqual(T a1, T a2);
/**
* Creates a consistent hashCode based on the attribute values of the annotation.
*
* @param a1 the annotation to have a hashCode generated for. cannot be null.
* @return a consistent hash code.
*/
public int hashCodeOf(T a1);
}