openjpa-kernel/src/main/java/org/apache/openjpa/util/ProxyManager.java

/*
 * 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.openjpa.util;

import java.util.Calendar;
import java.util.Collection;
import java.util.Comparator;
import java.util.Date;
import java.util.Map;
import java.util.TimeZone;

/**
 * Manager for copying and proxying second class objects. Second class
 * objects are those that are often used as fields of persistent or
 * transactional instances, and which can themselves be modified without
 * resetting the owning class' field. Because these types can change without
 * an explicit call to the owning persistence capable instance, special care
 * must be taken to ensure that their state is managed correctly.
 * Specifically, they must be copied when saving state for rollback, and they
 * must be proxied for any instance whose state is managed by a state manager,
 * where proxying involves creating a second class object that automaticlly
 * notifies its owning instance whenever it is modified. Generally, this
 * factory is only used by the implementation; second class object handling
 * is transparent to client code.
 *
 * @author Abe White
 */
public interface ProxyManager {

    /**
     * Return a new array of the same component type as the given array
     * and containing the same elements. Works for both primitive and
     * object array types.
     */
    Object copyArray(Object orig);

    /**
     * Return a copy of the given date with the same information.
     */
    Date copyDate(Date orig);

    /**
     * Return a new date proxy.
     */
    Proxy newDateProxy(Class type);

    /**
     * Return a copy of the given calendar with the same information.
     */
    Calendar copyCalendar(Calendar orig);

    /**
     * Return a new calendar proxy.
     */
    Proxy newCalendarProxy(Class type, TimeZone timeZone);

    /**
     * Return a new collection of the same type as the given one
     * with a copy of all contained elements.
     */
    Collection copyCollection(Collection orig);

    /**
     * Return a proxy for the given collection type. The returned collection
     * will allow only addition of elements assignable from the given
     * element type and will use the given comparator, if it is not null.
     */
    Proxy newCollectionProxy(Class type, Class elementType,
        Comparator compare, boolean autoOff);

    /**
     * Return a new map of the same type as the given one
     * with a copy of all contained key/value pairs.
     */
    Map copyMap(Map orig);

    /**
     * Return a proxy for the given map type. The returned map will
     * allow only addition of keys/values assignable from the given
     * keyType/valueType, and will use the given comparator, if it is not null.
     */
    Proxy newMapProxy(Class type, Class keyType, Class valueType,
        Comparator compare, boolean autoOff);

    /**
     * Return a copy of the given object with the same information, or null if
     * this manager cannot copy the object.
     *
     * @since 0.2.5
     */
    Object copyCustom(Object orig);

    /**
     * Return a proxy for the given object, or null if this manager cannot
     * proxy the object.
     *
     * @since 0.2.5
     */
    Proxy newCustomProxy (Object obj, boolean autoOff);

    /**
     * Returns whether this proxy manager is enabled for delayed collection
     * loading.  Delayed collection loading provides the ability to do simple,
     * non-indexed add or remove operations on a lazy collection without
     * loading the collection.  The collection is loaded when necessary, such
     * as iteration, indexed operations, isEmpty, or size.
     *
     * @since 2.2.1
     */
    boolean getDelayCollectionLoading();
}