EqualityPolicy.java

/*
 * Copyright 2000-2016 JetBrains s.r.o.
 *
 * 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 com.intellij.util.containers.hash;


public interface EqualityPolicy<T> {
  EqualityPolicy<?> IDENTITY = new EqualityPolicy() {

    public int getHashCode(Object value) {
      return System.identityHashCode(value);
    }

    public boolean isEqual(Object val1, Object val2) {
      return val1 == val2;
    }
  };

  EqualityPolicy<?> CANONICAL = new EqualityPolicy() {

    public int getHashCode(Object value) {
      return value != null ? value.hashCode() : 0;
    }

    public boolean isEqual(Object val1, Object val2) {
      return val1 != null ? val1.equals(val2) : val2 == null;
    }
  };

  int getHashCode(T value);

  boolean isEqual(T val1, T val2);
}