1 /* 2 * Copyright (C) 2011 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package org.whispersystems.libsignal.util.guava; 18 19 import static org.whispersystems.libsignal.util.guava.Preconditions.checkNotNull; 20 21 import java.util.Collections; 22 import java.util.Set; 23 24 /** 25 * Implementation of an {@link Optional} containing a reference. 26 */ 27 28 final class Present<T> extends Optional<T> { 29 private final T reference; 30 Present(T reference)31 Present(T reference) { 32 this.reference = reference; 33 } 34 isPresent()35 @Override public boolean isPresent() { 36 return true; 37 } 38 get()39 @Override public T get() { 40 return reference; 41 } 42 or(T defaultValue)43 @Override public T or(T defaultValue) { 44 checkNotNull(defaultValue, "use orNull() instead of or(null)"); 45 return reference; 46 } 47 or(Optional<? extends T> secondChoice)48 @Override public Optional<T> or(Optional<? extends T> secondChoice) { 49 checkNotNull(secondChoice); 50 return this; 51 } 52 or(Supplier<? extends T> supplier)53 @Override public T or(Supplier<? extends T> supplier) { 54 checkNotNull(supplier); 55 return reference; 56 } 57 orNull()58 @Override public T orNull() { 59 return reference; 60 } 61 asSet()62 @Override public Set<T> asSet() { 63 return Collections.singleton(reference); 64 } 65 transform(Function<? super T, V> function)66 @Override public <V> Optional<V> transform(Function<? super T, V> function) { 67 return new Present<V>(checkNotNull(function.apply(reference), 68 "Transformation function cannot return null.")); 69 } 70 equals(Object object)71 @Override public boolean equals(Object object) { 72 if (object instanceof Present) { 73 Present<?> other = (Present<?>) object; 74 return reference.equals(other.reference); 75 } 76 return false; 77 } 78 hashCode()79 @Override public int hashCode() { 80 return 0x598df91c + reference.hashCode(); 81 } 82 toString()83 @Override public String toString() { 84 return "Optional.of(" + reference + ")"; 85 } 86 87 private static final long serialVersionUID = 0; 88 } 89