content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one
   *  or more contributor license agreements.  See the NOTICE file
   *  distributed with this work for additional information
   *  regarding copyright ownership.  The ASF licenses this file
   *  to you 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.apache.causeway.commons.internal.binding;
  
  import java.util.function.BooleanSupplier;
  
  import org.springframework.util.function.ThrowingSupplier;
  
  import org.apache.causeway.commons.internal.base._Lazy;
  
  /**
   * <h1>- internal use only -</h1>
   *
   * <p>
   * <b>WARNING</b>: Do <b>NOT</b> use any of the classes provided by this package! <br/>
   * These may be changed or removed without notice!
   * </p>
   *
   * @since 2.0
   */
  public class _Observables {
  
      public static class LazyObservable<T> extends _BindableAbstract<T> {
  
          private final _Lazy<T> lazyValue;
  
          public LazyObservable(final ThrowingSupplier<T> factory) {
              this.lazyValue = _Lazy.threadSafe(factory);
          }
  
          @Override
          public T getValue() {
              return lazyValue.get();
          }
  
          public void invalidate() {
              lazyValue.clear();
              super.fireValueChanged();
          }
  
          @Override
          public void setValue(final T newValue) {
              // just ignore
          }
  
      }
  
      public static <T> LazyObservable<T> lazy(final ThrowingSupplier<T> factory) {
          return new LazyObservable<T>(factory);
      }
  
      public static class BooleanObservable extends LazyObservable<Boolean> {
  
          public BooleanObservable(final BooleanSupplier factory) {
              super(()->factory.getAsBoolean());
          }
  
          public boolean booleanValue() {
              return super.getValue().booleanValue();
          }
      }
  
      public static BooleanObservable lazyBoolean(final BooleanSupplier factory) {
          return new BooleanObservable(factory);
      }
  
  }
  