/*
* 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.api.schema.tree;
/**
* Enumeration of all possible node modification states. These are used in
* data tree modification context to quickly assess what sort of modification
* the node is undergoing.
*/
public enum ModificationType {
/**
* Node is currently unmodified.
*/
UNMODIFIED,
/**
* A child node, either direct or indirect, has been modified. This means
* that the data representation of this node has potentially changed.
*/
SUBTREE_MODIFIED,
/**
* This node has been placed into the tree, potentially completely replacing
* pre-existing contents.
*/
WRITE,
/**
* This node has been deleted along with any of its child nodes.
*/
DELETE,
/**
* This node has appeared because it is implied by one of its children. This type is usually produced when a
* structural container is created to host some leaf entries. It does not have an associated before-image.
*
* Its semantics is a combination of SUBTREE_MODIFIED and WRITE, depending on which context it is being interpreted.
*
* Users who track the value of the node can treat it as a WRITE. Users transforming a {@link DataTreeCandidate} to
* operations on a {@link DataTreeModification} should interpret it as a SUBTREE_MODIFIED and examine its children.
* This is needed to correctly deal with concurrent operations on the nodes children, as issuing a write on the
* DataTreeModification could end up removing any leaves which have not been present at the DataTree which emitted
* this event.
*/
APPEARED,
/**
* This node has disappeared because it is no longer implied by any children. This type is usually produced when a
* structural container is removed because it has become empty. It does not have an associated after-image.
*
* Its semantics is a combination of SUBTREE_MODIFIED and DELETE, depending on which context it is being interpreted.
* Users who track the value of the node can treat it as a DELETE, as the container has disappeared. Users
* transforming a {@link DataTreeCandidate} to operations on a {@link DataTreeModification} should interpret it as
* a SUBTREE_MODIFIED and examine its children.
*
* This is needed to correctly deal with concurrent operations on the nodes children, as issuing a delete on the
* DataTreeModification would end up removing any leaves which have not been present at the DataTree which emitted
* this event.
*/
DISAPPEARED,
}