Author: skestle Date: Tue Apr 1 14:36:59 2008 New Revision: 643590

URL: http://svn.apache.org/viewvc?rev=643590&view=rev Log: Added Equator interface for COLLECTIONS-242.

Added: commons/proper/collections/branches/collections_jdk5_branch/src/java/org/apache/commons/collections/functors/Equator.java

Added:
commons/proper/collections/branches/collections_jdk5_branch/src/java/org/apache/commons/collections/functors/Equator.java URL:
http://svn.apache.org/viewvc/commons/proper/collections/branches/collections_jdk5_branch/src/java/org/apache/commons/collections/functors/Equator.java?rev=643590&view=auto ============================================================================== ---
commons/proper/collections/branches/collections_jdk5_branch/src/java/org/apache/commons/collections/functors/Equator.java
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commons/proper/collections/branches/collections_jdk5_branch/src/java/org/apache/commons/collections/functors/Equator.java
Tue Apr 1 14:36:59 2008 @@ -0,0 +1,48 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more
contributor license + * agreements. See the NOTICE file distributed with this work for additional
information regarding + * copyright ownership. The ASF licenses this file to You 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.apache.commons.collections.functors; + +import org.apache.commons.collections.map.HashedMap; + +/** + * <p> + * An equation function, which determines equality between objects of type T. + * </p> + * <p> + * It is the functional sibling of {@link java.util.Comparator}; {@link
Equator} is to + * {@link Object} as {@link java.util.Comparator} is to {@link
java.lang.Comparable}. + * </p> + * + * @param <T> the types of object this {@link Equator} can evaluate. + * @author Stephen Kestle + * @since 4.0 + */ +public interface Equator<T> { + /** + * Evaluates the two arguments for their equality. + * + * @param o1 the first object to be equated. + * @param o2 the second object to be equated. + * @return whether the two objects are equal. + */ + boolean equate(T o1, T o2); + + /** + * Calculates the hash for the object, based on the method of equality
used in the equate + * method. This is used for classes that delegate their {@link
#equals(Object)} method to an + * Equator (and so must also delegate their {@link #hashCode()} method),
or for implementations + * of {@link HashedMap} that use an Equator for the key objects. + * + * @param o the object to calculate the hash for. + * @return the hash of the object. + */ + int hash(T o); +}