MappingFinder.java

  1. /*
  2.  * *************************************************************************************************************************************************************
  3.  *
  4.  * TheseFoolishThings: Miscellaneous utilities
  5.  * http://tidalwave.it/projects/thesefoolishthings
  6.  *
  7.  * Copyright (C) 2009 - 2025 by Tidalwave s.a.s. (http://tidalwave.it)
  8.  *
  9.  * *************************************************************************************************************************************************************
  10.  *
  11.  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
  12.  * You may obtain a copy of the License at
  13.  *
  14.  *     http://www.apache.org/licenses/LICENSE-2.0
  15.  *
  16.  * 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
  17.  * CONDITIONS OF ANY KIND, either express or implied.  See the License for the specific language governing permissions and limitations under the License.
  18.  *
  19.  * *************************************************************************************************************************************************************
  20.  *
  21.  * git clone https://bitbucket.org/tidalwave/thesefoolishthings-src
  22.  * git clone https://github.com/tidalwave-it/thesefoolishthings-src
  23.  *
  24.  * *************************************************************************************************************************************************************
  25.  */
  26. package it.tidalwave.util.impl.finder;

  27. // import javax.annotation.concurrent.Immutable;
  28. import jakarta.annotation.Nonnull;
  29. import java.util.List;
  30. import java.util.function.Function;
  31. import it.tidalwave.util.Finder;
  32. import it.tidalwave.util.spi.SimpleFinderSupport;
  33. import static java.util.stream.Collectors.*;

  34. /***************************************************************************************************************************************************************
  35.  *
  36.  * A {@link it.tidalwave.util.Finder} which retrieves results from another instance applying a mapper {@link Function}. Don't use directly; use
  37.  * {@link it.tidalwave.util.Finder#mapping(Finder, Function)} instead.
  38.  *
  39.  * @param   <T>   the mapped type
  40.  * @param   <U>   the type of the delegate Finder
  41.  * @author  Fabrizio Giudici
  42.  *
  43.  **************************************************************************************************************************************************************/
  44. /* @Immutable */
  45. public final class MappingFinder<T, U> extends SimpleFinderSupport<T>
  46.   {
  47.     private static final long serialVersionUID = -6359683808082070089L;

  48.     @Nonnull
  49.     private final Finder<? extends U> delegate;

  50.     @Nonnull
  51.     private final Function<? super U, ? extends T> mapper;

  52.     /***********************************************************************************************************************************************************
  53.      * Creates a new instance given a delegate and a mapper function.
  54.      * @param   delegate    the delegate
  55.      * @param   mapper      the mapper function
  56.      **********************************************************************************************************************************************************/
  57.     public MappingFinder (@Nonnull final Finder<? extends U> delegate, @Nonnull final Function<? super U, ? extends T> mapper)
  58.       {
  59.         this.delegate = delegate;
  60.         this.mapper = mapper;
  61.       }

  62.     /***********************************************************************************************************************************************************
  63.      * The special Finder copy constructor.
  64.      * @param   other       the finder to copy
  65.      * @param   override    the overriding object
  66.      **********************************************************************************************************************************************************/
  67.     @SuppressWarnings("unchecked")
  68.     public MappingFinder (@Nonnull final MappingFinder<T, ?> other, @Nonnull final Object override)
  69.       {
  70.         super(other, override);
  71.         final var source = getSource(MappingFinder.class, other, override);
  72.         this.delegate = source.delegate;
  73.         this.mapper = source.mapper;
  74.       }

  75.     /***********************************************************************************************************************************************************
  76.      * {@inheritDoc}
  77.      **********************************************************************************************************************************************************/
  78.     @Override @Nonnull
  79.     protected List<T> computeResults()
  80.       {
  81.         return delegate.results().stream().map(mapper).collect(toList());
  82.       }
  83.   }