/* 
 * 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 com.googlecode.openbeans;

import com.googlecode.openbeans.Encoder;
import com.googlecode.openbeans.Expression;
import com.googlecode.openbeans.PersistenceDelegate;
import java.lang.reflect.Field;

/**
 * This is a persistence delegate for the {@link java.lang.reflect.Field} class.
 */
class FieldPersistenceDelegate extends PersistenceDelegate {
    @Override
    protected Expression instantiate(Object oldInstance, Encoder out) {
        // should not be null or have a type other than Field
        assert oldInstance instanceof Field : oldInstance;
        Field oldField = (Field) oldInstance;
        Class<?> declClass = oldField.getDeclaringClass();
        return new Expression(oldField, declClass, "getField", //$NON-NLS-1$
                new Object[] { oldField.getName() });
    }

    @Override
    protected void initialize(Class<?> type, Object oldInstance, Object newInstance, Encoder out) {
        // check for consistency
        assert oldInstance instanceof Field : oldInstance;
        assert newInstance instanceof Field : newInstance;
        assert newInstance.equals(oldInstance);
    }

    @Override
    protected boolean mutatesTo(Object oldInstance, Object newInstance) {
        assert oldInstance instanceof Field : oldInstance;
        if (!(newInstance instanceof Field)) {
            // if null or not a Field
            return false;
        }
        return oldInstance.equals(newInstance);
    }
}