1 files changed, 30 insertions, 0 deletions
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/ListenableOldValue.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/ListenableOldValue.java
new file mode 100644
index 0000000000..5c3e12770e
--- /dev/null
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/ListenableOldValue.java
@@ -0,0 +1,30 @@
+// Copyright (C) 2012 The Android Open Source Project
+//
+// 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.gerrit.client.ui;
+
+public class ListenableOldValue<T> extends ListenableValue<T> {
+
+  private T oldValue;
+
+  public T getOld() {
+    return oldValue;
+  }
+
+  public void set(final T value) {
+    oldValue = get();
+    super.set(value);
+    oldValue = null; // allow it to be gced before the next event
+  }
+}