001 /*
002 * Java Genetic Algorithm Library (jenetics-5.2.0).
003 * Copyright (c) 2007-2020 Franz Wilhelmstötter
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 *
017 * Author:
018 * Franz Wilhelmstötter (franz.wilhelmstoetter@gmail.com)
019 */
020 package io.jenetics.ext.util;
021
022 import static java.lang.String.format;
023 import static java.util.Objects.requireNonNull;
024
025 import java.io.IOException;
026 import java.io.InvalidObjectException;
027 import java.io.ObjectInput;
028 import java.io.ObjectInputStream;
029 import java.io.ObjectOutput;
030 import java.io.Serializable;
031 import java.util.ArrayList;
032 import java.util.List;
033 import java.util.Optional;
034 import java.util.function.Function;
035
036 import io.jenetics.util.Copyable;
037 import io.jenetics.util.ISeq;
038
039 /**
040 * A general purpose node in a tree data-structure. The {@code TreeNode} is a
041 * mutable implementation of the {@link Tree} interface.
042 *
043 * @param <T> the value type of the tree node
044 *
045 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
046 * @version 5.2
047 * @since 3.9
048 */
049 public final class TreeNode<T>
050 implements
051 Tree<T, TreeNode<T>>,
052 Iterable<TreeNode<T>>,
053 Copyable<TreeNode<T>>,
054 Serializable
055 {
056 private static final long serialVersionUID = 2L;
057
058 private T _value;
059 private TreeNode<T> _parent;
060 private List<TreeNode<T>> _children;
061
062 /**
063 * Create a new tree node with no parent and children, but with the given
064 * user {@code value}.
065 *
066 * @param value the user value of the new tree node
067 */
068 private TreeNode(final T value) {
069 _value = value;
070 }
071
072
073 /* *************************************************************************
074 * Basic operations
075 **************************************************************************/
076
077 /**
078 * Sets the user object for this node.
079 *
080 * @param value the node {@code value}
081 */
082 public void value(final T value) {
083 _value = value;
084 }
085
086 /**
087 * Sets the user object for this node.
088 *
089 * @param value the node {@code value}
090 * @deprecated Use {@link #value(Object)} instead
091 */
092 @Deprecated
093 public void setValue(final T value) {
094 _value = value;
095 }
096
097 /**
098 * Return the node value
099 *
100 * @return the node value
101 */
102 @Override
103 @Deprecated
104 public T getValue() {
105 return _value;
106 }
107
108 /**
109 * Returns this node's parent if available.
110 *
111 * @return the tree-node, or an empty value if this node has no parent
112 */
113 @Deprecated
114 @Override
115 public Optional<TreeNode<T>> getParent() {
116 return Optional.ofNullable(_parent);
117 }
118
119 /**
120 * Sets this node's parent, but does not change the parent's child array.
121 * This method is called from {@code insert()} and {@code remove()} to
122 * reassign a child's parent, and it should not be messaged from anywhere
123 * else.
124 *
125 * @param parent this node's new parent
126 */
127 void setParent(final TreeNode<T> parent) {
128 _parent = parent;
129 }
130
131 /**
132 * Returns the child at the specified index in this node's child array.
133 *
134 * @param index an index into this node's child array
135 * @return the tree-node in this node's child array at the specified index
136 * @throws ArrayIndexOutOfBoundsException if the {@code index} is out of
137 * bounds
138 */
139 @Override
140 public TreeNode<T> childAt(final int index) {
141 if (_children == null) {
142 throw new ArrayIndexOutOfBoundsException(format(
143 "Child index is out of bounds: %s", index
144 ));
145 }
146
147 return _children.get(index);
148 }
149
150 @Override
151 public int childCount() {
152 return _children != null ? _children.size() : 0;
153 }
154
155 /**
156 * Removes the {@code child} from its present parent (if it has one), sets
157 * the child's parent to this node, and then adds the child to this node's
158 * child array at index {@code index}. The new {@code child} must not be
159 * {@code null} and must not be an ancestor of {@code this} node.
160 *
161 * @param index the index in the child array where this node is to be
162 * inserted
163 * @param child the sub-node to be inserted
164 * @return {@code this} tree-node, for method chaining
165 * @throws ArrayIndexOutOfBoundsException if {@code index} is out of bounds
166 * @throws IllegalArgumentException if {@code child} is an ancestor of
167 * {@code this} node
168 * @throws NullPointerException if the given {@code child} is {@code null}
169 */
170 public TreeNode<T> insert(final int index, final TreeNode<T> child) {
171 requireNonNull(child);
172 if (isAncestor(child)) {
173 throw new IllegalArgumentException("The new child is an ancestor.");
174 }
175
176 if (child._parent != null) {
177 child._parent.remove(child);
178 }
179
180 child.setParent(this);
181 createChildrenIfMissing();
182 _children.add(index, child);
183
184 return this;
185 }
186
187 // Only entry point for checking and creating non-existing children list.
188 private void createChildrenIfMissing() {
189 if (_children == null) {
190 _children = new ArrayList<>(2);
191 }
192 }
193
194 /**
195 * Replaces the child at the give index with the given {@code child}
196 *
197 * @param index the index of the child which will be replaced
198 * @param child the new child
199 * @return {@code this} tree-node, for method chaining
200 * @throws ArrayIndexOutOfBoundsException if the {@code index} is out of
201 * bounds
202 * @throws IllegalArgumentException if {@code child} is an ancestor of
203 * {@code this} node
204 * @throws NullPointerException if the given {@code child} is {@code null}
205 */
206 public TreeNode<T> replace(final int index, final TreeNode<T> child) {
207 requireNonNull(child);
208 if (_children == null) {
209 throw new ArrayIndexOutOfBoundsException(format(
210 "Child index is out of bounds: %s", index
211 ));
212 }
213 if (isAncestor(child)) {
214 throw new IllegalArgumentException("The new child is an ancestor.");
215 }
216
217 final TreeNode<T> oldChild = _children.set(index, child);
218 assert oldChild != null;
219 assert oldChild._parent == this;
220
221 oldChild.setParent(null);
222 child.setParent(this);
223
224 return this;
225 }
226
227 /**
228 * Removes the child at the specified index from this node's children and
229 * sets that node's parent to {@code null}.
230 *
231 * @param index the index in this node's child array of the child to remove
232 * @return {@code this} tree-node, for method chaining
233 * @throws ArrayIndexOutOfBoundsException if the {@code index} is out of
234 * bounds
235 */
236 public TreeNode<T> remove(final int index) {
237 if (_children == null) {
238 throw new ArrayIndexOutOfBoundsException(format(
239 "Child index is out of bounds: %s", index
240 ));
241 }
242
243 final TreeNode<T> child = _children.remove(index);
244 assert child._parent == this;
245 child.setParent(null);
246
247 if (_children.isEmpty()) {
248 _children = null;
249 }
250
251 return this;
252 }
253
254 /**
255 * Removes the child at the given {@code path}. If no child exists at the
256 * given path, nothing is removed.
257 *
258 * @since 4.4
259 *
260 * @param path the path of the child to replace
261 * @return {@code true} if a child at the given {@code path} existed and
262 * has been removed
263 * @throws NullPointerException if one of the given argument is {@code null}
264 */
265 public boolean removeAtPath(final Path path) {
266 final Optional<TreeNode<T>> parent = childAtPath(path)
267 .flatMap(Tree::parent);
268
269 parent.ifPresent(p -> p.remove(path.get(path.length() - 1)));
270 return parent.isPresent();
271 }
272
273 /**
274 * Replaces the child at the given {@code path} with the given new
275 * {@code child}. If no child exists at the given path, nothing is replaced.
276 *
277 * @since 4.4
278 *
279 * @param path the path of the child to replace
280 * @param child the new child
281 * @return {@code true} if a child at the given {@code path} existed and
282 * has been replaced
283 * @throws NullPointerException if one of the given argument is {@code null}
284 */
285 public boolean replaceAtPath(final Path path, final TreeNode<T> child) {
286 requireNonNull(path);
287 requireNonNull(child);
288
289 final Optional<TreeNode<T>> old = childAtPath(path);
290 final Optional<TreeNode<T>> parent = old.flatMap(TreeNode::parent);
291
292 if (parent.isPresent()) {
293 parent.orElseThrow(AssertionError::new)
294 .replace(path.get(path.length() - 1), child);
295 } else {
296 removeAllChildren();
297 value(child.value());
298
299 final ISeq<TreeNode<T>> nodes = child.childStream()
300 .collect(ISeq.toISeq());
301
302 for (TreeNode<T> node : nodes) {
303 attach(node);
304 }
305 }
306
307 return old.isPresent();
308 }
309
310 /* *************************************************************************
311 * Derived operations
312 **************************************************************************/
313
314 /**
315 * Detaches the subtree rooted at {@code this} node from the tree, giving
316 * {@code this} node a {@code null} parent. Does nothing if {@code this}
317 * node is the root of its tree.
318 *
319 * @return {@code this}
320 */
321 public TreeNode<T> detach() {
322 if (_parent != null) {
323 _parent.remove(this);
324 }
325
326 return this;
327 }
328
329 /**
330 * Remove the {@code child} from {@code this} node's child array, giving it
331 * a {@code null} parent.
332 *
333 * @param child the child of this node to remove
334 * @throws NullPointerException if the given {@code child} is {@code null}
335 * @throws IllegalArgumentException if the given {@code child} is not a
336 * child of this node
337 */
338 public void remove(final Tree<?, ?> child) {
339 requireNonNull(child);
340
341 if (!isChild(child)) {
342 throw new IllegalArgumentException("The given child is not a child.");
343 }
344 remove(indexOf(child));
345 }
346
347 /**
348 * Removes all children fo {@code this} node and setting their parents to
349 * {@code null}. If {@code this} node has no children, this method does
350 * nothing.
351 */
352 public void removeAllChildren() {
353 if (_children != null) {
354 for (TreeNode<T> child : _children) {
355 child.setParent(null);
356 }
357
358 _children = null;
359 }
360 }
361
362 /**
363 * Remove the given {@code child} from its parent and makes it a child of
364 * this node by adding it to the end of this node's child array.
365 *
366 * @param child the new child added to this node
367 * @return {@code this} tree-node, for method chaining
368 * @throws NullPointerException if the given {@code child} is {@code null}
369 */
370 public TreeNode<T> attach(final TreeNode<T> child) {
371 requireNonNull(child);
372
373 if (child._parent == this) {
374 insert(childCount() - 1, child);
375 } else {
376 insert(childCount(), child);
377 }
378
379 return this;
380 }
381
382 /**
383 * Attaches the given {@code children} to {@code this} node.
384 *
385 * @param children the children to attach to {@code this} node
386 * @return {@code this} tree-node, for method chaining
387 * @throws NullPointerException if the given {@code children} array is
388 * {@code null}
389 */
390 @SafeVarargs
391 public final TreeNode<T> attach(final T... children) {
392 for (T child : children) {
393 attach(TreeNode.of(child));
394 }
395
396 return this;
397 }
398
399 /**
400 * Attaches the given {@code child} to {@code this} node.
401 *
402 * @param child the child to attach to {@code this} node
403 * @return {@code this} tree-node, for method chaining
404 */
405 public TreeNode<T> attach(final T child) {
406 return attach(TreeNode.of(child));
407 }
408
409 @Override
410 public TreeNode<T> copy() {
411 return ofTree(this);
412 }
413
414 /**
415 * Returns a new {@code TreeNode} consisting of all nodes of {@code this}
416 * tree, but with a different value type, created by applying the given
417 * function to the node values of {@code this} tree.
418 *
419 * @param mapper the node value mapper
420 * @param <B> the new node type
421 * @return a new tree consisting of all nodes of {@code this} tree
422 * @throws NullPointerException if the given {@code mapper} function is
423 * {@code null}
424 */
425 public <B> TreeNode<B> map(final Function<? super T, ? extends B> mapper) {
426 final TreeNode<B> target = TreeNode.of(mapper.apply(value()));
427 fill(this, target, mapper);
428 return target;
429 }
430
431
432 @Override
433 public int hashCode() {
434 return Tree.hashCode(this);
435 }
436
437 @Override
438 public boolean equals(final Object obj) {
439 return obj == this ||
440 obj instanceof TreeNode &&
441 Tree.equals(this, (TreeNode)obj);
442 }
443
444 @Override
445 public String toString() {
446 return toParenthesesString();
447 }
448
449
450
451 /* *************************************************************************
452 * Static factory methods.
453 **************************************************************************/
454
455 /**
456 * Return a new {@code TreeNode} with a {@code null} tree value.
457 *
458 * @param <T> the tree-node type
459 * @return a new tree-node
460 */
461 public static <T> TreeNode<T> of() {
462 return TreeNode.of(null);
463 }
464
465 /**
466 * Return a new {@code TreeNode} with the given node {@code value}.
467 *
468 * @param value the node value
469 * @param <T> the tree-node type
470 * @return a new tree-node
471 */
472 public static <T> TreeNode<T> of(final T value) {
473 return new TreeNode<>(value);
474 }
475
476 /**
477 * Return a new {@code TreeNode} from the given source {@code tree}. The
478 * whole tree is copied.
479 *
480 * @param tree the source tree the new tree-node is created from
481 * @param mapper the tree value mapper function
482 * @param <T> the current tree value type
483 * @param <B> the mapped tree value type
484 * @return a new {@code TreeNode} from the given source {@code tree}
485 * @throws NullPointerException if one of the arguments is {@code null}
486 */
487 public static <T, B> TreeNode<B> ofTree(
488 final Tree<? extends T, ?> tree,
489 final Function<? super T, ? extends B> mapper
490 ) {
491 final TreeNode<B> target = of(mapper.apply(tree.value()));
492 fill(tree, target, mapper);
493 return target;
494 }
495
496 private static <T, B> void fill(
497 final Tree<? extends T, ?> source,
498 final TreeNode<B> target,
499 final Function<? super T, ? extends B> mapper
500 ) {
501 source.childStream().forEachOrdered(child -> {
502 final TreeNode<B> targetChild = of(mapper.apply(child.value()));
503 target.attach(targetChild);
504 fill(child, targetChild, mapper);
505 });
506 }
507
508 /**
509 * Return a new {@code TreeNode} from the given source {@code tree}. The
510 * whole tree is copied.
511 *
512 * @param tree the source tree the new tree-node is created from
513 * @param <T> the current tree value type
514 * @return a new {@code TreeNode} from the given source {@code tree}
515 * @throws NullPointerException if the source {@code tree} is {@code null}
516 */
517 public static <T> TreeNode<T> ofTree(final Tree<? extends T, ?> tree) {
518 return ofTree(tree, Function.identity());
519 }
520
521 /**
522 * Parses a (parentheses) tree string, created with
523 * {@link Tree#toParenthesesString()}. The tree string might look like this:
524 * <pre>
525 * mul(div(cos(1.0),cos(π)),sin(mul(1.0,z)))
526 * </pre>
527 *
528 * The parse method doesn't strip the whitespace between the parentheses and
529 * the commas. If you want to remove this <em>formatting</em> whitespaces,
530 * you should do the parsing with an addition <em>mapper</em> function.
531 * <pre>{@code
532 * final TreeNode<String> tree = TreeNode.parse(
533 * "mul( div(cos( 1.0) , cos(π )), sin(mul(1.0, z) ) )",
534 * String::trim
535 * );
536 * }</pre>
537 * The code above will trim all tree nodes during the parsing process.
538 *
539 * @see Tree#toParenthesesString(Function)
540 * @see Tree#toParenthesesString()
541 * @see TreeNode#parse(String, Function)
542 *
543 * @since 4.3
544 *
545 * @param tree the parentheses tree string
546 * @return the parsed tree
547 * @throws NullPointerException if the given {@code tree} string is
548 * {@code null}
549 * @throws IllegalArgumentException if the given tree string could not be
550 * parsed
551 */
552 public static TreeNode<String> parse(final String tree) {
553 return TreeParser.parse(tree, Function.identity());
554 }
555
556 /**
557 * Parses a (parentheses) tree string, created with
558 * {@link Tree#toParenthesesString()}. The tree string might look like this
559 * <pre>
560 * 0(1(4,5),2(6),3(7(10,11),8,9))
561 * </pre>
562 * and can be parsed to an integer tree with the following code:
563 * <pre>{@code
564 * final Tree<Integer, ?> tree = TreeNode.parse(
565 * "0(1(4,5),2(6),3(7(10,11),8,9))",
566 * Integer::parseInt
567 * );
568 * }</pre>
569 *
570 * @see Tree#toParenthesesString(Function)
571 * @see Tree#toParenthesesString()
572 * @see TreeNode#parse(String)
573 *
574 * @since 4.3
575 *
576 * @param <B> the tree node value type
577 * @param tree the parentheses tree string
578 * @param mapper the mapper which converts the serialized string value to
579 * the desired type
580 * @return the parsed tree object
581 * @throws NullPointerException if one of the arguments is {@code null}
582 * @throws IllegalArgumentException if the given parentheses tree string
583 * doesn't represent a valid tree
584 */
585 public static <B> TreeNode<B> parse(
586 final String tree,
587 final Function<? super String, ? extends B> mapper
588 ) {
589 return TreeParser.parse(tree, mapper);
590 }
591
592
593 /* *************************************************************************
594 * Java object serialization
595 * ************************************************************************/
596
597 private Object writeReplace() {
598 return new Serial(Serial.TREE_NODE, this);
599 }
600
601 private void readObject(final ObjectInputStream stream)
602 throws InvalidObjectException
603 {
604 throw new InvalidObjectException("Serialization proxy required.");
605 }
606
607
608 void write(final ObjectOutput out) throws IOException {
609 FlatTreeNode.of(this).write(out);
610 }
611
612 @SuppressWarnings({"rawtypes", "unchecked"})
613 static TreeNode read(final ObjectInput in)
614 throws IOException, ClassNotFoundException
615 {
616 return TreeNode.ofTree(FlatTreeNode.read(in));
617 }
618
619 }
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