Pull cacheinvalidations code directory into chromium repo.

third_party/cacheinvalidation/src/java/com/google/ipc/invalidation/util/Box.java

+/*
+ * Copyright 2011 Google Inc.
+ *
+ * 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.ipc.invalidation.util;
+
+/**
+ * Container for a single arbitrary value. Useful when a nested callback needs
+ * to modify a primitive type, which is ordinarily not possible as variables
+ * available to nested callbacks need to be declared final.
+ *
+ * @param <T> Type of the value being boxed.
+ *
+ */
+public class Box<T> {
+
+  /** Contents of the box. */
+  private T value;
+
+  /** Constructs a box with the given initial {@code value}. */
+  public Box(T value) {
+    this.value = value;
+  }
+
+  /** Constructs a Box with {@code null} as the value. */
+  public Box() {
+    this.value = null;
+  }
+
+  /** Constructs and returns a {@code Box} that wraps {@code objectValue}. */
+  public static <T> Box<T> of(T objectValue) {
+    return new Box<T>(objectValue);
+  }
+
+  public void set(T objectValue) {
+    this.value = objectValue;
+  }
+
+  public T get() {
+    return value;
+  }
+
+  @Override
+  public String toString() {
+    return (value == null) ? null : value.toString();
+  }
+}