/*
* Copyright 2003-2012 JetBrains s.r.o.
*
* Licensed 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.jetbrains.mps.openapi.model;
import org.jetbrains.annotations.Nullable;
import org.jetbrains.mps.openapi.module.SRepository;
/**
* Represents a unique global reference to a node. SNodeReferences are the only recommended way to keep references
* to nodes across subsequent read or write actions. While direct memory references get obsolete once an action finishes,
* SNodeReferences will consistently retrieve the same node.
*/
public interface SNodeReference {
/**
* Find actual instance of the node represented by this pointer.
* @return node if known in the repository, or <code>null</code>
*/
@Nullable
SNode resolve(SRepository repo);
/**
* @return pointer to the node's model, if known, or <code>null</code>
*/
@Nullable
SModelReference getModelReference();
/**
* @return identity of the node, if known, or <code>null</code>
*/
@Nullable
SNodeId getNodeId();
}