LatestOperationHolder.java

/*
 * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.yangtools.yang.data.impl.schema.tree;

/**
 * Holder and factory for upgradable root modifications
 *
 * This class is factory for upgradable root modifications and provides an
 * access to set latest backing implementation.
 */
final class LatestOperationHolder {

    private ModificationApplyOperation current = AlwaysFailOperation.INSTANCE;

    /**
     * Return latest backing implemenation
     *
     * @return
     */
    ModificationApplyOperation getCurrent() {
        return current;
    }

    /**
     * Sets latest backing implementation of associated
     * {@link RootModificationApplyOperation}.
     * <p>
     * Note: This does not result in upgrading implementation of already
     * existing {@link RootModificationApplyOperation}. Users, which
     * obtained instances using {@link #newSnapshot()}, deriving
     * {@link RootModificationApplyOperation} from this modification must
     * explicitly invoke
     * {@link RootModificationApplyOperation#upgradeIfPossible()} on their
     * instance to be updated to latest backing implementation.
     *
     * @param newApplyOper
     *            New backing implementation
     */
    void setCurrent(final ModificationApplyOperation newApplyOper) {
        current = newApplyOper;
    }

    /**
     *
     * Creates new upgradable {@link RootModificationApplyOperation}
     * associated with holder.
     *
     * @return New upgradable {@link RootModificationApplyOperation} with
     *         {@link #getCurrent()} used as backing implementation.
     */
    RootModificationApplyOperation newSnapshot() {
        return new UpgradableModificationApplyOperation(this, current);
    }

}