Move ordering logic out of AbstractSubtreeManagerRegistryBuilderBuilder

Introduces YangDAG that maintains topological order for yang schema
nodes and can be used by other components to read additional graph edges,
e.g. from file (HONEYCOMB-365).

Change-Id: Ia3046d38ffb4ca222412309f6c4391afc9315bd2
Signed-off-by: Marek Gradzki <mgradzki@cisco.com>

1 files changed, 69 insertions, 0 deletions

diff --git a/infra/translate-utils/src/main/java/io/fd/honeycomb/translate/util/YangDAG.java b/infra/translate-utils/src/main/java/io/fd/honeycomb/translate/util/YangDAG.java
new file mode 100644
index 000000000..2269adbff
--- /dev/null
+++ b/infra/translate-utils/src/main/java/io/fd/honeycomb/translate/util/YangDAG.java
@@ -0,0 +1,69 @@
+/*
+ * 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 {
+    }
+}