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/*
* Copyright (c) 2017 Cisco and/or its affiliates.
*
* 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 io.fd.honeycomb.translate.util;
import java.util.Iterator;
import org.jgrapht.experimental.dag.DirectedAcyclicGraph;
import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
/**
* Directed acyclic graph representing ordering relationships between schema nodes represented as wildcarded
* InstanceIdentifiers. Maintains topological order of vertices. Feature is used by translation layer if more nodes are
* affected in single read/write transaction.
*/
public final class YangDAG {
private final DirectedAcyclicGraph<InstanceIdentifier<?>, Edge>
dag = new DirectedAcyclicGraph<>((sourceVertex, targetVertex) -> new Edge());
/**
* Adds the vertex if it wasn't already in the graph.
*
* @param vertex vertex to be added
*/
public void addVertex(final InstanceIdentifier<?> vertex) {
dag.addVertex(vertex);
}
/**
* Adds edge between source and target vertices.
*
* @param source source vertex of the edge
* @param target target vertex of the edge
* @throws IllegalArgumentException if the edge would induce a cycle in the graph
*/
public void addEdge(final InstanceIdentifier<?> source, final InstanceIdentifier<?> target) {
try {
dag.addDagEdge(source, target);
} catch (DirectedAcyclicGraph.CycleFoundException e) {
throw new IllegalArgumentException(String.format(
"Unable to add writer with relation: %s -> %s. Loop detected", source, target), e);
}
}
/**
* Traverses schema nodes in topological order.
*
* @return an iterator that will traverse the graph in topological order.
*/
public Iterator<InstanceIdentifier<?>> iterator() {
return dag.iterator();
}
private static final class Edge {
}
}
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