1 files changed, 69 insertions, 0 deletions
diff --git a/src/tools/xcode-common/java/com/google/devtools/build/xcode/util/Value.java b/src/tools/xcode-common/java/com/google/devtools/build/xcode/util/Value.java
new file mode 100644
index 0000000000..6363af19a3
--- /dev/null
+++ b/src/tools/xcode-common/java/com/google/devtools/build/xcode/util/Value.java
@@ -0,0 +1,69 @@
+// 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.xcode.util;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+
+/**
+ * Represents a type whose equality, hash code, and string representation are defined by a single
+ * immutable array. This class is designed to be extended by a final class, and to pass the member
+ * data to this class's constructor.
+ *
+ * @param <V> the base class that extends {@code Value}
+ */
+public class Value<V extends Value<V>> {
+  private final Object memberData;
+
+  /**
+   * Constructs a new instance with the given member data. Generally, all member data should be
+   * reflected in final fields in the child class.
+   * @throws NullPointerException if any element in {@code memberData} is null
+   */
+  public Value(Object... memberData) {
+    Preconditions.checkArgument(memberData.length > 0);
+    this.memberData = (memberData.length == 1)
+        ? Preconditions.checkNotNull(memberData[0]) : ImmutableList.copyOf(memberData);
+  }
+
+  /**
+   * A type-safe alternative to calling {@code a.equals(b)}. When using {@code a.equals(b)},
+   * {@code b} may accidentally be a different class from {@code a}, in which case there will be no
+   * compiler warning and the result will always be false. This method requires both values to have
+   * compatible types and to be non-null.
+   */
+  public boolean equalsOther(V other) {
+    return equals(Preconditions.checkNotNull(other));
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if ((o == null) || (o.getClass() != getClass())) {
+      return false;
+    }
+    Value<?> other = (Value<?>) o;
+    return memberData.equals(other.memberData);
+  }
+
+  @Override
+  public int hashCode() {
+    return memberData.hashCode();
+  }
+
+  @Override
+  public String toString() {
+    return getClass().getSimpleName() + ":" + memberData.toString();
+  }
+}