1 files changed, 74 insertions, 0 deletions
diff --git a/guava/src/com/google/common/collect/BstModificationResult.java b/guava/src/com/google/common/collect/BstModificationResult.java
new file mode 100644
index 0000000..2c7c036
--- /dev/null
+++ b/guava/src/com/google/common/collect/BstModificationResult.java
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2011 The Guava Authors
+ *
+ * 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.common.collect;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import com.google.common.annotations.GwtCompatible;
+
+import javax.annotation.Nullable;
+
+/**
+ * The result of a {@code BstModifier}.
+ *
+ * @author Louis Wasserman
+ */
+@GwtCompatible
+final class BstModificationResult<N extends BstNode<?, N>> {
+  enum ModificationType {
+    IDENTITY, REBUILDING_CHANGE, REBALANCING_CHANGE;
+  }
+
+  static <N extends BstNode<?, N>> BstModificationResult<N> identity(@Nullable N target) {
+    return new BstModificationResult<N>(target, target, ModificationType.IDENTITY);
+  }
+
+  static <N extends BstNode<?, N>> BstModificationResult<N> rebuildingChange(
+      @Nullable N originalTarget, @Nullable N changedTarget) {
+    return new BstModificationResult<N>(
+        originalTarget, changedTarget, ModificationType.REBUILDING_CHANGE);
+  }
+
+  static <N extends BstNode<?, N>> BstModificationResult<N> rebalancingChange(
+      @Nullable N originalTarget, @Nullable N changedTarget) {
+    return new BstModificationResult<N>(
+        originalTarget, changedTarget, ModificationType.REBALANCING_CHANGE);
+  }
+
+  @Nullable private final N originalTarget;
+  @Nullable private final N changedTarget;
+  private final ModificationType type;
+
+  private BstModificationResult(
+      @Nullable N originalTarget, @Nullable N changedTarget, ModificationType type) {
+    this.originalTarget = originalTarget;
+    this.changedTarget = changedTarget;
+    this.type = checkNotNull(type);
+  }
+
+  @Nullable
+  N getOriginalTarget() {
+    return originalTarget;
+  }
+
+  @Nullable
+  N getChangedTarget() {
+    return changedTarget;
+  }
+
+  ModificationType getType() {
+    return type;
+  }
+}