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.function;
27
28 import jakarta.annotation.Nonnull;
29 import it.tidalwave.ui.core.role.Changeable;
30 import it.tidalwave.ui.core.ChangingSource;
31 import lombok.extern.slf4j.Slf4j;
32
33 /***************************************************************************************************************************************************************
34 *
35 * @since 2.0-ALPHA-1
36 * Changes the destination only at a certain condition in function of the target.
37 *
38 * @author Fabrizio Giudici
39 *
40 **************************************************************************************************************************************************************/
41 @Slf4j
42 public abstract class WeakCopyFunctionSupport<T> extends UnaryBoundFunctionSupport<T, T> implements Changeable<T>
43 {
44 @Nonnull
45 protected T targetValue;
46
47 public WeakCopyFunctionSupport (@Nonnull final ChangingSource<T> source)
48 {
49 super(source);
50 }
51
52 @Override
53 protected void onSourceChange (@Nonnull final T oldSourceValue, @Nonnull final T newSourceValue)
54 {
55 final var oldValue = function(oldSourceValue);
56 final var newValue = function(newSourceValue);
57
58 if (shouldChange(oldValue, newValue))
59 {
60 value = newValue;
61 fireValueChanged(oldValue, newValue);
62 }
63 }
64
65 @Override
66 public void set (final T value)
67 {
68 this.targetValue = value;
69 }
70
71 protected abstract boolean shouldChange (T oldValue, T newValue);
72
73 @Override @Nonnull
74 protected T function (@Nonnull final T value)
75 {
76 return value;
77 }
78 }