WeakCopyFunctionSupport.java

  1. /*
  2.  * *************************************************************************************************************************************************************
  3.  *
  4.  * SteelBlue: DCI User Interfaces
  5.  * http://tidalwave.it/projects/steelblue
  6.  *
  7.  * Copyright (C) 2015 - 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/steelblue-src
  22.  * git clone https://github.com/tidalwave-it/steelblue-src
  23.  *
  24.  * *************************************************************************************************************************************************************
  25.  */
  26. package it.tidalwave.ui.core.function;

  27. import jakarta.annotation.Nonnull;
  28. import it.tidalwave.ui.core.role.Changeable;
  29. import it.tidalwave.ui.core.ChangingSource;
  30. import lombok.extern.slf4j.Slf4j;

  31. /***************************************************************************************************************************************************************
  32.  *
  33.  * Changes the destination only at a certain condition in function of the target.
  34.  *
  35.  * @since   2.0-ALPHA-1
  36.  * @author  Fabrizio Giudici
  37.  *
  38.  **************************************************************************************************************************************************************/
  39. @Slf4j
  40. public abstract class WeakCopyFunctionSupport<T> extends UnaryBoundFunctionSupport<T, T> implements Changeable<T>
  41.   {
  42.     @Nonnull
  43.     protected T targetValue;

  44.     protected WeakCopyFunctionSupport (@Nonnull final ChangingSource<T> source)
  45.       {
  46.         super(source);
  47.       }

  48.     @Override
  49.     protected void onSourceChange (@Nonnull final T oldSourceValue, @Nonnull final T newSourceValue)
  50.       {
  51.         final var oldValue = function(oldSourceValue);
  52.         final var newValue = function(newSourceValue);

  53.         if (shouldChange(oldValue, newValue))
  54.           {
  55.             value = newValue;
  56.             fireValueChanged(oldValue, newValue);
  57.           }
  58.       }

  59.     @Override
  60.     public void set (final T value)
  61.       {
  62.         this.targetValue = value;
  63.       }

  64.     protected abstract boolean shouldChange (T oldValue, T newValue);

  65.     @Override @Nonnull
  66.     protected T function (@Nonnull final T value)
  67.       {
  68.         return value;
  69.       }
  70.   }