17dd252788645e940eada959bdde927426e2531c9Paul Duffin/* 27dd252788645e940eada959bdde927426e2531c9Paul Duffin * Copyright (C) 2011 The Guava Authors 37dd252788645e940eada959bdde927426e2531c9Paul Duffin * 47dd252788645e940eada959bdde927426e2531c9Paul Duffin * Licensed under the Apache License, Version 2.0 (the "License"); 57dd252788645e940eada959bdde927426e2531c9Paul Duffin * you may not use this file except in compliance with the License. 67dd252788645e940eada959bdde927426e2531c9Paul Duffin * You may obtain a copy of the License at 77dd252788645e940eada959bdde927426e2531c9Paul Duffin * 87dd252788645e940eada959bdde927426e2531c9Paul Duffin * http://www.apache.org/licenses/LICENSE-2.0 97dd252788645e940eada959bdde927426e2531c9Paul Duffin * 107dd252788645e940eada959bdde927426e2531c9Paul Duffin * Unless required by applicable law or agreed to in writing, software 117dd252788645e940eada959bdde927426e2531c9Paul Duffin * distributed under the License is distributed on an "AS IS" BASIS, 127dd252788645e940eada959bdde927426e2531c9Paul Duffin * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 137dd252788645e940eada959bdde927426e2531c9Paul Duffin * See the License for the specific language governing permissions and 147dd252788645e940eada959bdde927426e2531c9Paul Duffin * limitations under the License. 157dd252788645e940eada959bdde927426e2531c9Paul Duffin */ 167dd252788645e940eada959bdde927426e2531c9Paul Duffin 177dd252788645e940eada959bdde927426e2531c9Paul Duffinpackage com.google.common.base; 187dd252788645e940eada959bdde927426e2531c9Paul Duffin 197dd252788645e940eada959bdde927426e2531c9Paul Duffinimport static com.google.common.base.Preconditions.checkNotNull; 207dd252788645e940eada959bdde927426e2531c9Paul Duffin 217dd252788645e940eada959bdde927426e2531c9Paul Duffinimport com.google.common.annotations.GwtCompatible; 227dd252788645e940eada959bdde927426e2531c9Paul Duffin 237dd252788645e940eada959bdde927426e2531c9Paul Duffinimport java.util.Collections; 247dd252788645e940eada959bdde927426e2531c9Paul Duffinimport java.util.Set; 257dd252788645e940eada959bdde927426e2531c9Paul Duffin 267dd252788645e940eada959bdde927426e2531c9Paul Duffinimport javax.annotation.Nullable; 277dd252788645e940eada959bdde927426e2531c9Paul Duffin 287dd252788645e940eada959bdde927426e2531c9Paul Duffin/** 297dd252788645e940eada959bdde927426e2531c9Paul Duffin * Implementation of an {@link Optional} containing a reference. 307dd252788645e940eada959bdde927426e2531c9Paul Duffin */ 317dd252788645e940eada959bdde927426e2531c9Paul Duffin@GwtCompatible 327dd252788645e940eada959bdde927426e2531c9Paul Duffinfinal class Present<T> extends Optional<T> { 337dd252788645e940eada959bdde927426e2531c9Paul Duffin private final T reference; 347dd252788645e940eada959bdde927426e2531c9Paul Duffin 357dd252788645e940eada959bdde927426e2531c9Paul Duffin Present(T reference) { 367dd252788645e940eada959bdde927426e2531c9Paul Duffin this.reference = reference; 377dd252788645e940eada959bdde927426e2531c9Paul Duffin } 387dd252788645e940eada959bdde927426e2531c9Paul Duffin 390888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public boolean isPresent() { 407dd252788645e940eada959bdde927426e2531c9Paul Duffin return true; 417dd252788645e940eada959bdde927426e2531c9Paul Duffin } 427dd252788645e940eada959bdde927426e2531c9Paul Duffin 430888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public T get() { 447dd252788645e940eada959bdde927426e2531c9Paul Duffin return reference; 457dd252788645e940eada959bdde927426e2531c9Paul Duffin } 467dd252788645e940eada959bdde927426e2531c9Paul Duffin 470888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public T or(T defaultValue) { 487dd252788645e940eada959bdde927426e2531c9Paul Duffin checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)"); 497dd252788645e940eada959bdde927426e2531c9Paul Duffin return reference; 507dd252788645e940eada959bdde927426e2531c9Paul Duffin } 517dd252788645e940eada959bdde927426e2531c9Paul Duffin 520888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public Optional<T> or(Optional<? extends T> secondChoice) { 537dd252788645e940eada959bdde927426e2531c9Paul Duffin checkNotNull(secondChoice); 547dd252788645e940eada959bdde927426e2531c9Paul Duffin return this; 557dd252788645e940eada959bdde927426e2531c9Paul Duffin } 567dd252788645e940eada959bdde927426e2531c9Paul Duffin 570888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public T or(Supplier<? extends T> supplier) { 587dd252788645e940eada959bdde927426e2531c9Paul Duffin checkNotNull(supplier); 597dd252788645e940eada959bdde927426e2531c9Paul Duffin return reference; 607dd252788645e940eada959bdde927426e2531c9Paul Duffin } 617dd252788645e940eada959bdde927426e2531c9Paul Duffin 620888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public T orNull() { 637dd252788645e940eada959bdde927426e2531c9Paul Duffin return reference; 647dd252788645e940eada959bdde927426e2531c9Paul Duffin } 657dd252788645e940eada959bdde927426e2531c9Paul Duffin 660888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public Set<T> asSet() { 677dd252788645e940eada959bdde927426e2531c9Paul Duffin return Collections.singleton(reference); 687dd252788645e940eada959bdde927426e2531c9Paul Duffin } 690888a09821a98ac0680fad765217302858e70fa4Paul Duffin 700888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public <V> Optional<V> transform(Function<? super T, V> function) { 717dd252788645e940eada959bdde927426e2531c9Paul Duffin return new Present<V>(checkNotNull(function.apply(reference), 727dd252788645e940eada959bdde927426e2531c9Paul Duffin "the Function passed to Optional.transform() must not return null.")); 737dd252788645e940eada959bdde927426e2531c9Paul Duffin } 747dd252788645e940eada959bdde927426e2531c9Paul Duffin 750888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public boolean equals(@Nullable Object object) { 767dd252788645e940eada959bdde927426e2531c9Paul Duffin if (object instanceof Present) { 777dd252788645e940eada959bdde927426e2531c9Paul Duffin Present<?> other = (Present<?>) object; 787dd252788645e940eada959bdde927426e2531c9Paul Duffin return reference.equals(other.reference); 797dd252788645e940eada959bdde927426e2531c9Paul Duffin } 807dd252788645e940eada959bdde927426e2531c9Paul Duffin return false; 817dd252788645e940eada959bdde927426e2531c9Paul Duffin } 827dd252788645e940eada959bdde927426e2531c9Paul Duffin 830888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public int hashCode() { 847dd252788645e940eada959bdde927426e2531c9Paul Duffin return 0x598df91c + reference.hashCode(); 857dd252788645e940eada959bdde927426e2531c9Paul Duffin } 867dd252788645e940eada959bdde927426e2531c9Paul Duffin 870888a09821a98ac0680fad765217302858e70fa4Paul Duffin @Override public String toString() { 887dd252788645e940eada959bdde927426e2531c9Paul Duffin return "Optional.of(" + reference + ")"; 897dd252788645e940eada959bdde927426e2531c9Paul Duffin } 907dd252788645e940eada959bdde927426e2531c9Paul Duffin 917dd252788645e940eada959bdde927426e2531c9Paul Duffin private static final long serialVersionUID = 0; 927dd252788645e940eada959bdde927426e2531c9Paul Duffin} 93