diff options
author | Moxie Marlinspike <moxie@thoughtcrime.org> | 2014-11-24 12:54:30 -0800 |
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committer | Moxie Marlinspike <moxie@thoughtcrime.org> | 2014-11-24 12:54:30 -0800 |
commit | 60800e155612bea797eed93c67046a23d26054cc (patch) | |
tree | d88368c1c26162e27e790195133ca2b526597afe /src/main/java/org/whispersystems/libaxolotl/util/guava/Absent.java |
Break out into separate repo.
Diffstat (limited to 'src/main/java/org/whispersystems/libaxolotl/util/guava/Absent.java')
-rw-r--r-- | src/main/java/org/whispersystems/libaxolotl/util/guava/Absent.java | 87 |
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; +} |