1 /*
2 * Copyright (c) 2010, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25 package javafx.collections.transformation;
26
27 import javafx.collections.ListChangeListener.Change;
28 import java.util.List;
29 import javafx.collections.ListChangeListener;
30 import javafx.collections.ObservableList;
31 import javafx.collections.ObservableListBase;
32 import javafx.collections.WeakListChangeListener;
33
34 /**
35 * A base class for all lists that wrap another list in a way that changes
36 * (transforms) the wrapped list's elements, order, size, or structure.
37 *
38 * If the source list is observable, a listener is automatically added to it
39 * and the events are delegated to {@link #sourceChanged(javafx.collections.ListChangeListener.Change)}
40 *
41 * @param <E> the type parameter of this list
42 * @param <F> the upper bound of the type of the source list
43 * @since JavaFX 8.0
44 */
45 public abstract class TransformationList<E, F> extends ObservableListBase<E> implements ObservableList<E> {
46
47 /**
48 * Contains the source list of this transformation list.
49 * This is never null and should be used to directly access source list content
50 */
51 private ObservableList<? extends F> source;
52 /**
53 * This field contains the result of expression "source instanceof {@link javafx.collections.ObservableList}".
54 * If this is true, it is possible to do transforms online.
55 */
56 private ListChangeListener<F> sourceListener;
57
58 /**
59 * Creates a new Transformation list wrapped around the source list.
60 * @param source the wrapped list
61 */
62 @SuppressWarnings("unchecked")
63 protected TransformationList(ObservableList<? extends F> source) {
64 if (source == null) {
65 throw new NullPointerException();
66 }
67 this.source = source;
68 source.addListener(new WeakListChangeListener<>(getListener()));
69 }
70
71 /**
72 * The source list specified in the constructor of this transformation list.
73 * @return The List that is directly wrapped by this TransformationList
74 */
75 public final ObservableList<? extends F> getSource() {
76 return source;
77 }
78
79 /**
80 * Checks whether the provided list is in the chain under this
81 * {@code TransformationList}.
82 *
83 * This means the list is either the direct source as returned by
84 * {@link #getSource()} or the direct source is a {@code TransformationList},
85 * and the list is in it's transformation chain.
86 * @param list the list to check
87 * @return true if the list is in the transformation chain as specified above.
88 */
89 public final boolean isInTransformationChain(ObservableList<?> list) {
90 if (source == list) {
91 return true;
92 }
93 List<?> currentSource = source;
94 while(currentSource instanceof TransformationList) {
95 currentSource = ((TransformationList)currentSource).source;
96 if (currentSource == list) {
97 return true;
98 }
99 }
100 return false;
101 }
102
103 private ListChangeListener<F> getListener() {
104 if (sourceListener == null) {
105 sourceListener = c -> {
106 TransformationList.this.sourceChanged(c);
107 };
108 }
109 return sourceListener;
110 }
111
112 /**
113 * Called when a change from the source is triggered.
114 * @param c the change
115 */
116 protected abstract void sourceChanged(Change<? extends F> c);
117
118 /**
119 * Maps the index of this list's element to an index in the direct source list.
120 * @param index the index in this list
121 * @return the index of the element's origin in the source list
122 * @see #getSource()
123 */
124 public abstract int getSourceIndex(int index);
125
126 /**
127 * Maps the index of this list's element to an index of the provided {@code list}.
128 *
129 * The {@code list} must be in the transformation chain.
130 *
131 * @param list a list from the transformation chain
132 * @param index the index of an element in this list
133 * @return the index of the element's origin in the provided list
134 * @see #isInTransformationChain(javafx.collections.ObservableList)
135 */
136 public final int getSourceIndexFor(ObservableList<?> list, int index) {
137 if (!isInTransformationChain(list)) {
138 throw new IllegalArgumentException("Provided list is not in the transformation chain of this"
139 + "transformation list");
140 }
141 List<?> currentSource = source;
142 int idx = getSourceIndex(index);
143 while(currentSource != list && currentSource instanceof TransformationList) {
144 final TransformationList tSource = (TransformationList)currentSource;
145 idx = tSource.getSourceIndex(idx);
146 currentSource = tSource.source;
147 }
148 return idx;
149 }
150
151 /**
152 * Maps the index of the direct source list's element to an index in this list.
153 * @param index the index in the source list
154 * @return the index of the element in this list if it is contained
155 * in this list or negative value otherwise
156 * @see #getSource()
157 * @see #getSourceIndex(int)
158 *
159 * @since 9
160 */
161 public abstract int getViewIndex(int index);
162 }