1 files changed, 87 insertions, 0 deletions
diff --git a/src/main/java/org/whispersystems/libaxolotl/util/guava/Absent.java b/src/main/java/org/whispersystems/libaxolotl/util/guava/Absent.java
new file mode 100644
index 00000000..bd06ded9
--- /dev/null
+++ b/src/main/java/org/whispersystems/libaxolotl/util/guava/Absent.java
@@ -0,0 +1,87 @@
+/*
+ * 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 org.whispersystems.libaxolotl.util.guava;
+
+import static org.whispersystems.libaxolotl.util.guava.Preconditions.checkNotNull;
+
+
+
+import java.util.Collections;
+import java.util.Set;
+
+
+/**
+ * Implementation of an {@link Optional} not containing a reference.
+ */
+
+final class Absent extends Optional<Object> {
+  static final Absent INSTANCE = new Absent();
+
+  @Override public boolean isPresent() {
+    return false;
+  }
+
+  @Override public Object get() {
+    throw new IllegalStateException("value is absent");
+  }
+
+  @Override public Object or(Object defaultValue) {
+    return checkNotNull(defaultValue, "use orNull() instead of or(null)");
+  }
+
+  @SuppressWarnings("unchecked") // safe covariant cast
+  @Override public Optional<Object> or(Optional<?> secondChoice) {
+    return (Optional) checkNotNull(secondChoice);
+  }
+
+  @Override public Object or(Supplier<?> supplier) {
+    return checkNotNull(supplier.get(),
+        "use orNull() instead of a Supplier that returns null");
+  }
+
+  @Override public Object orNull() {
+    return null;
+  }
+
+  @Override public Set<Object> asSet() {
+    return Collections.emptySet();
+  }
+
+  @Override
+  public <V> Optional<V> transform(Function<? super Object, V> function) {
+    checkNotNull(function);
+    return Optional.absent();
+  }
+
+  @Override public boolean equals(Object object) {
+    return object == this;
+  }
+
+  @Override public int hashCode() {
+    return 0x598df91c;
+  }
+
+  @Override public String toString() {
+    return "Optional.absent()";
+  }
+
+  private Object readResolve() {
+    return INSTANCE;
+  }
+
+  private static final long serialVersionUID = 0;
+}