Update from Google.

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MOE_MIGRATED_REVID=85702957

1 files changed, 50 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/graph/GraphVisitor.java b/src/main/java/com/google/devtools/build/lib/graph/GraphVisitor.java
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index 0000000000..f7e0f62d9e
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+++ b/src/main/java/com/google/devtools/build/lib/graph/GraphVisitor.java
@@ -0,0 +1,50 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// 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.
+// All Rights Reserved.
+
+package com.google.devtools.build.lib.graph;
+
+/**
+ *  <p> An graph visitor interface; particularly useful for allowing subclasses
+ *  to specify how to output a graph.  The order in which node and edge
+ *  callbacks are made (DFS, BFS, etc) is defined by the choice of Digraph
+ *  visitation method used.  </p>
+ */
+public interface GraphVisitor<T> {
+
+  /**
+   *  Called before visitation commences.
+   */
+  void beginVisit();
+
+  /**
+   *  Called after visitation is complete.
+   */
+  void endVisit();
+
+  /**
+   *  <p> Called for each edge. </p>
+   *
+   *  TODO(bazel-team): This method is not essential, and in all known cases so
+   *  far, the visitEdge code can always be placed within visitNode.  Perhaps
+   *  we should remove it, and the begin/end methods, and make this just a
+   *  NodeVisitor?  Are there any algorithms for which edge-visitation order is
+   *  important?
+   */
+  void visitEdge(Node<T> lhs, Node<T> rhs);
+  /**
+   *  Called for each node.
+   */
+  void visitNode(Node<T> node);
+}