/**
 * Copyright 2005 JBoss Inc
 *
 * 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.drools.common;


import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

import org.drools.FactHandle;
import org.drools.core.util.AbstractHashTable.ObjectComparator;

public class IdentityAssertMapComparator
    implements
    ObjectComparator {
    /**
     *
     */
    private static final long serialVersionUID = 510l;

    public IdentityAssertMapComparator() {
    }

    public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
    }

    public void writeExternal(ObjectOutput out) throws IOException {
    }

    public int hashCodeOf(final Object obj) {
        Object realObject = obj;
        if ( realObject instanceof FactHandle ) {
            return rehash( ((InternalFactHandle) obj).getIdentityHashCode() );
        } else {
            return rehash( System.identityHashCode( realObject ) );
        }
    }

    public int rehash(int h) {
        h += ~(h << 9);
        h ^= (h >>> 14);
        h += (h << 4);
        h ^= (h >>> 10);
        return h;
    }

    /**
     * Special comparator that allows FactHandles to be keys, but always  checks
     * like for like.
     */
    public boolean equal(final Object o1,
                         final Object o2) {
        if ( o1 instanceof InternalFactHandle ) {
            return ((InternalFactHandle) o1).getId() == ((InternalFactHandle) o2).getId();
        }
        Object left = o1;
        final InternalFactHandle handle = ((InternalFactHandle) o2);

        return left == handle.getObject();
    }

    public int compare(final Object o1,
                       final Object o2) {
        return ((Comparable) o1).compareTo( o2 );
    }

    public String toString() {
        return "identity";
    }
}