1 files changed, 62 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/collect/nestedset/OnlyTransitivesNestedSet.java b/src/main/java/com/google/devtools/build/lib/collect/nestedset/OnlyTransitivesNestedSet.java
new file mode 100644
index 0000000000..5a570538c7
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/collect/nestedset/OnlyTransitivesNestedSet.java
@@ -0,0 +1,62 @@
+// 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.lib.collect.nestedset;
+
+import java.util.Arrays;
+import java.util.Objects;
+
+import javax.annotation.Nullable;
+
+/**
+ * Memory-efficient implementation for the case where we have one direct element and one
+ * transitive NestedSet.
+ */
+abstract class OnlyTransitivesNestedSet<E> extends MemoizedUniquefierNestedSet<E> {
+
+  private static final NestedSet[] EMPTY = new NestedSet[0];
+
+  private final NestedSet[] transitives;
+  private Object memo;
+
+  OnlyTransitivesNestedSet(NestedSet[] transitives) {
+    this.transitives = transitives;
+  }
+
+  @Override
+  Object getMemo() { return memo; }
+
+  @Override
+  void setMemo(Object memo) { this.memo = memo; }
+
+  @Override
+  Object[] directMembers() { return EMPTY; }
+
+  @Override
+  NestedSet[] transitiveSets() { return transitives; }
+
+  @Override
+  public boolean shallowEquals(@Nullable NestedSet<? extends E> other) {
+    if (this == other) {
+      return true;
+    }
+    return other != null
+        && getOrder().equals(other.getOrder())
+        && other instanceof OnlyTransitivesNestedSet
+        && Arrays.equals(transitives, ((OnlyTransitivesNestedSet) other).transitives);
+  }
+
+  @Override
+  public int shallowHashCode() {
+    return Objects.hash(getOrder(), Arrays.hashCode(transitives)); }
+}