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    • com.apollographql.apollo.api.internal.Absent Maven / Gradle / Ivy

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    /**
 * Copyright 2018-2019 Amazon.com,
 * Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Amazon Software License (the "License").
 * You may not use this file except in compliance with the
 * License. A copy of the License is located at
 *
 *     http://aws.amazon.com/asl/
 *
 * or in the "license" file accompanying this file. This file is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
 * CONDITIONS OF ANY KIND, express or implied. See the License
 * for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * 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 com.apollographql.apollo.api.internal;


import java.util.Collections;
import java.util.Set;

import javax.annotation.Nullable;

import static com.apollographql.apollo.api.internal.Utils.checkNotNull;

/**
 * Implementation of an {@link Optional} not containing a reference.
 */

final class Absent extends Optional {
  static final Absent INSTANCE = new Absent();

  @SuppressWarnings("unchecked") // implementation is "fully variant"
  static  Optional withType() {
    return (Optional) INSTANCE;
  }

  private Absent() {
  }

  @Override
  public boolean isPresent() {
    return false;
  }

  @Override
  public T get() {
    throw new IllegalStateException("Optional.get() cannot be called on an absent value");
  }

  @Override
  public T or(T defaultValue) {
    return checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");
  }

  @SuppressWarnings("unchecked") // safe covariant cast
  @Override
  public Optional or(Optional secondChoice) {
    return (Optional) checkNotNull(secondChoice);
  }

  @Override
  @Nullable
  public T orNull() {
    return null;
  }

  @Override
  public  Optional transform(Function function) {
    checkNotNull(function);
    return Optional.absent();
  }

  @Override public  Optional map(Function function) {
    checkNotNull(function);
    return Optional.absent();
  }

  @Override public  Optional flatMap(Function> function) {
    checkNotNull(function);
    return Optional.absent();
  }

  @Override public Optional apply(Action action) {
    checkNotNull(action);
    return Optional.absent();
  }

  @Override
  public Set asSet() {
    return Collections.emptySet();
  }

  @Override
  public boolean equals(@Nullable Object object) {
    return object == this;
  }

  @Override
  public int hashCode() {
    return 0x79a31aac;
  }

  @Override
  public String toString() {
    return "Optional.absent()";
  }

  private Object readResolve() {
    return INSTANCE;
  }

  private static final long serialVersionUID = 0;
}
    
    
    
    

    




    
    
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