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Berkeley DB Java Edition is a open source, transactional storage solution for Java applications. The Direct Persistence Layer (DPL) API is faster and easier to develop, deploy, and manage than serialized object files or ORM-based Java persistence solutions. The Collections API enhances the standard java.util.collections classes allowing them to be persisted to a local file system and accessed concurrently while protected by ACID transactions. Data is stored by serializing objects and managing class and instance data separately so as not to waste space. Berkeley DB Java Edition is the reliable drop-in solution for complex, fast, and scalable storage. Source for this release is in 'je-4.0.92-sources.jar', the Javadoc is located at 'http://download.oracle.com/berkeley-db/docs/je/4.0.92/'.

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/*-
 * Copyright (C) 2002, 2018, Oracle and/or its affiliates. All rights reserved.
 *
 * This file was distributed by Oracle as part of a version of Oracle Berkeley
 * DB Java Edition made available at:
 *
 * http://www.oracle.com/technetwork/database/database-technologies/berkeleydb/downloads/index.html
 *
 * Please see the LICENSE file included in the top-level directory of the
 * appropriate version of Oracle Berkeley DB Java Edition for a copy of the
 * license and additional information.
 */

package com.sleepycat.persist;

import com.sleepycat.bind.EntryBinding;
import com.sleepycat.je.DatabaseEntry;

/**
 * A ValueAdapter where the "value" is the data, although the data in this case
 * is the primary key in a KeysIndex.
 *
 * @author Mark Hayes
 */
class DataValueAdapter implements ValueAdapter {

    private EntryBinding dataBinding;

    DataValueAdapter(Class keyClass, EntryBinding dataBinding) {
        this.dataBinding = dataBinding;
    }

    public DatabaseEntry initKey() {
        return new DatabaseEntry();
    }

    public DatabaseEntry initPKey() {
        return null;
    }

    public DatabaseEntry initData() {
        return new DatabaseEntry();
    }

    public void clearEntries(DatabaseEntry key,
                             DatabaseEntry pkey,
                             DatabaseEntry data) {
        key.setData(null);
        data.setData(null);
    }

    public V entryToValue(DatabaseEntry key,
                          DatabaseEntry pkey,
                          DatabaseEntry data) {
        return (V) dataBinding.entryToObject(data);
    }

    public void valueToData(V value, DatabaseEntry data) {
        throw new UnsupportedOperationException
            ("Cannot change the data in a key-only index");
    }
}