1 files changed, 43 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/skyframe/Evaluator.java b/src/main/java/com/google/devtools/build/skyframe/Evaluator.java
new file mode 100644
index 0000000000..342eff132c
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/skyframe/Evaluator.java
@@ -0,0 +1,43 @@
+// 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.
+package com.google.devtools.build.skyframe;
+
+import com.google.devtools.build.lib.events.EventHandler;
+
+/**
+ * An interface for the evaluator for a particular graph version.
+ */
+public interface Evaluator {
+  /**
+   * Factory to create Evaluator instances.
+   */
+  interface Factory {
+    /**
+     * @param graph the graph to operate on
+     * @param graphVersion the version at which to write entries in the graph.
+     * @param reporter where to write warning/error/progress messages.
+     * @param keepGoing whether {@link #eval} should continue if building a {link Value} fails.
+     *                  Otherwise, we throw an exception on failure.
+     */
+    Evaluator create(ProcessableGraph graph, long graphVersion, EventHandler reporter,
+        boolean keepGoing);
+  }
+
+  /**
+   * Evaluates a set of values. Returns an {@link EvaluationResult}. All elements of skyKeys must
+   * be keys for Values of subtype T.
+   */
+  <T extends SkyValue> EvaluationResult<T> eval(Iterable<SkyKey> skyKeys)
+      throws InterruptedException;
+}