001 /*
002 * Java Genetic Algorithm Library (jenetics-7.2.0).
003 * Copyright (c) 2007-2023 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.prog.op;
021
022 import static java.lang.String.format;
023 import static java.util.Objects.requireNonNull;
024 import static io.jenetics.internal.util.Hashes.hash;
025
026 import java.io.Serial;
027 import java.io.Serializable;
028 import java.util.Objects;
029 import java.util.function.BiFunction;
030 import java.util.function.Function;
031 import java.util.random.RandomGenerator;
032
033 import io.jenetics.util.ISeq;
034 import io.jenetics.util.RandomRegistry;
035
036 import io.jenetics.ext.util.FlatTree;
037 import io.jenetics.ext.util.Tree;
038 import io.jenetics.ext.util.TreeNode;
039
040 /**
041 * This class composes a given operation tree to a new operation, which can
042 * serve as a sub <em>program</em> in another operation tree.
043 *
044 * @param <T> the argument type of the operation
045 *
046 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
047 * @version 4.1
048 * @since 3.9
049 */
050 public class Program<T> implements Op<T>, Serializable {
051
052 @Serial
053 private static final long serialVersionUID = 1L;
054
055 private final String _name;
056 private final Tree<? extends Op<T>, ?> _tree;
057
058 /**
059 * Create a new program with the given name and the given operation tree.
060 * The arity of the program is calculated from the given operation tree and
061 * set to the maximal arity of the operations of the tree.
062 *
063 * @param name the program name
064 * @param tree the operation tree
065 * @throws NullPointerException if one of the given arguments is {@code null}
066 * @throws IllegalArgumentException if the given operation tree is invalid,
067 * which means there is at least one node where the operation arity
068 * and the node child count differ.
069 */
070 public Program(final String name, final Tree<? extends Op<T>, ?> tree) {
071 _name = requireNonNull(name);
072 _tree = requireNonNull(tree);
073 check(tree);
074 }
075
076 @Override
077 public String name() {
078 return _name;
079 }
080
081 @Override
082 public int arity() {
083 return 0;
084 }
085
086 /**
087 * Return the underlying expression tree.
088 *
089 * @since 4.1
090 *
091 * @return the underlying expression tree
092 */
093 public Tree<Op<T>, ?> tree() {
094 return TreeNode.ofTree(_tree);
095 }
096
097 @Override
098 public T apply(final T[] args) {
099 if (args.length < arity()) {
100 throw new IllegalArgumentException(format(
101 "Arguments length is smaller than program arity: %d < %d",
102 args.length, arity()
103 ));
104 }
105
106 return eval(_tree, args);
107 }
108
109 /**
110 * Convenient method, which lets you apply the program function without
111 * explicitly create a wrapper array.
112 *
113 * @see #apply(Object[])
114 *
115 * @param args the function arguments
116 * @return the evaluated value
117 * @throws NullPointerException if the given variable array is {@code null}
118 * @throws IllegalArgumentException if the length of the argument array
119 * is smaller than the program arity
120 */
121 @SafeVarargs
122 public final T eval(final T... args) {
123 return apply(args);
124 }
125
126 @Override
127 public int hashCode() {
128 return hash(_name, hash(_tree));
129 }
130
131 @Override
132 public boolean equals(final Object obj) {
133 return obj == this ||
134 obj instanceof Program<?> other &&
135 Objects.equals(other._name, _name) &&
136 Objects.equals(other._tree, _tree);
137 }
138
139 @Override
140 public String toString() {
141 return _name;
142 }
143
144
145 /* *************************************************************************
146 * Static helper methods.
147 * ************************************************************************/
148
149 /**
150 * Evaluates the given operation tree with the given variables. This method
151 * is equivalent to
152 * <pre>{@code
153 * final T result = tree.reduce(variables, Op::apply);
154 * }</pre>
155 * but handles the variable sized {@code variables} array more conveniently.
156 *
157 * @see Tree#reduce(Object[], BiFunction)
158 *
159 * @param <T> the argument type
160 * @param tree the operation tree
161 * @param variables the input variables
162 * @return the result of the operation tree evaluation
163 * @throws NullPointerException if one of the arguments is {@code null}
164 * @throws IllegalArgumentException if the length of the variable array
165 * is smaller than the program arity
166 */
167 @SafeVarargs
168 public static <T> T eval(
169 final Tree<? extends Op<T>, ?> tree,
170 final T... variables
171 ) {
172 return tree.reduce(variables, Function::apply);
173 }
174
175 /**
176 * Validates the given program tree.
177 *
178 * @param program the program to validate
179 * @throws NullPointerException if the given {@code program} is {@code null}
180 * @throws IllegalArgumentException if the given operation tree is invalid,
181 * which means there is at least one node where the operation arity
182 * and the node child count differ.
183 */
184 public static void check(final Tree<? extends Op<?>, ?> program) {
185 program.forEach(Program::checkArity);
186 }
187
188 private static void checkArity(final Tree<? extends Op<?>, ?> node) {
189 if (node.value() != null &&
190 node.value().arity() != node.childCount())
191 {
192 throw new IllegalArgumentException(format(
193 "Op arity != child count: %d != %d",
194 node.value().arity(), node.childCount()
195 ));
196 }
197 }
198
199 /**
200 * Create a new, random program from the given (non) terminal operations
201 * with the desired depth. The created program tree is a <em>full</em> tree.
202 *
203 * @since 4.1
204 *
205 * @param name the program name
206 * @param depth the desired depth of the program tree
207 * @param operations the list of <em>non</em>-terminal operations
208 * @param terminals the list of terminal operations
209 * @param <A> the operational type
210 * @return a new program
211 * @throws NullPointerException if one of the given operations is
212 * {@code null}
213 * @throws IllegalArgumentException if the given tree depth is smaller than
214 * zero
215 */
216 public static <A> Program<A> of(
217 final String name,
218 final int depth,
219 final ISeq<? extends Op<A>> operations,
220 final ISeq<? extends Op<A>> terminals
221 ) {
222 return new Program<>(name, of(depth, operations, terminals));
223 }
224
225 /**
226 * Create a new, random program from the given (non) terminal operations
227 * with the desired depth. The created program tree is a <em>full</em> tree.
228 *
229 * @since 4.1
230 *
231 * @param name the program name
232 * @param depth the desired depth of the program tree
233 * @param operations the list of <em>non</em>-terminal operations
234 * @param terminals the list of terminal operations
235 * @param random the random engine used for creating the program
236 * @param <A> the operational type
237 * @return a new program
238 * @throws NullPointerException if one of the given operations is
239 * {@code null}
240 * @throws IllegalArgumentException if the given tree depth is smaller than
241 * zero
242 */
243 public static <A> Program<A> of(
244 final String name,
245 final int depth,
246 final ISeq<? extends Op<A>> operations,
247 final ISeq<? extends Op<A>> terminals,
248 final RandomGenerator random
249 ) {
250 return new Program<>(name, of(depth, operations, terminals, random));
251 }
252
253 /**
254 * Create a new, random program tree from the given (non) terminal
255 * operations with the desired depth. The created program tree is a
256 * <em>full</em> tree.
257 *
258 * @param depth the desired depth of the program tree
259 * @param operations the list of <em>non</em>-terminal operations
260 * @param terminals the list of terminal operations
261 * @param <A> the operational type
262 * @return a new program tree
263 * @throws NullPointerException if one of the given operations is
264 * {@code null}
265 * @throws IllegalArgumentException if the given tree depth is smaller than
266 * zero
267 */
268 public static <A> TreeNode<Op<A>> of(
269 final int depth,
270 final ISeq<? extends Op<A>> operations,
271 final ISeq<? extends Op<A>> terminals
272 ) {
273 return of(depth, operations, terminals, RandomRegistry.random());
274 }
275
276 /**
277 * Create a new, random program tree from the given (non) terminal
278 * operations with the desired depth. The created program tree is a
279 * <em>full</em> tree.
280 *
281 * @since 4.1
282 *
283 * @param depth the desired depth of the program tree
284 * @param operations the list of <em>non</em>-terminal operations
285 * @param terminals the list of terminal operations
286 * @param random the random engine used for creating the program
287 * @param <A> the operational type
288 * @return a new program tree
289 * @throws NullPointerException if one of the given operations is
290 * {@code null}
291 * @throws IllegalArgumentException if the given tree depth is smaller than
292 * zero
293 */
294 public static <A> TreeNode<Op<A>> of(
295 final int depth,
296 final ISeq<? extends Op<A>> operations,
297 final ISeq<? extends Op<A>> terminals,
298 final RandomGenerator random
299 ) {
300 if (depth < 0) {
301 throw new IllegalArgumentException(
302 "Tree depth is smaller than zero: " + depth
303 );
304 }
305 if (!operations.forAll(o -> !o.isTerminal())) {
306 throw new IllegalArgumentException(
307 "Operation list contains terminal op."
308 );
309 }
310 if (!terminals.forAll(Op::isTerminal)) {
311 throw new IllegalArgumentException(
312 "Terminal list contains non-terminal op."
313 );
314 }
315
316 final TreeNode<Op<A>> root = TreeNode.of();
317 fill(depth, root, operations, terminals, random);
318 return root;
319 }
320
321 private static <A> void fill(
322 final int level,
323 final TreeNode<Op<A>> tree,
324 final ISeq<? extends Op<A>> operations,
325 final ISeq<? extends Op<A>> terminals,
326 final RandomGenerator random
327 ) {
328 final Op<A> op = level == 0
329 ? terminals.get(random.nextInt(terminals.size()))
330 : operations.get(random.nextInt(operations.size()));
331
332 tree.value(op);
333
334 if (level > 1) {
335 for (int i = 0; i < op.arity(); ++i) {
336 final TreeNode<Op<A>> node = TreeNode.of();
337 fill(level - 1, node, operations, terminals, random);
338 tree.attach(node);
339 }
340 } else {
341 for (int i = 0; i < op.arity(); ++i) {
342 final Op<A> term = terminals.get(random.nextInt(terminals.size()));
343 tree.attach(TreeNode.of(term));
344 }
345 }
346 }
347
348 /**
349 * Creates a valid program tree from the given flattened sequence of
350 * op nodes. The given {@code operations} and {@code termination} nodes are
351 * used for <em>repairing</em> the program tree, if necessary.
352 *
353 * @param nodes the flattened, possible corrupt, program tree
354 * @param terminals the usable non-terminal operation nodes to use for
355 * reparation
356 * @param <A> the operation argument type
357 * @return a new valid program tree build from the flattened program tree
358 * @throws NullPointerException if one of the arguments is {@code null}
359 * @throws IllegalArgumentException if the {@code nodes} sequence is empty
360 */
361 public static <A> TreeNode<Op<A>> toTree(
362 final ISeq<? extends FlatTree<? extends Op<A>, ?>> nodes,
363 final ISeq<? extends Op<A>> terminals
364 ) {
365 if (nodes.isEmpty()) {
366 throw new IllegalArgumentException("Tree nodes must not be empty.");
367 }
368
369 final Op<A> op = requireNonNull(nodes.get(0).value());
370 final TreeNode<Op<A>> tree = TreeNode.of(op);
371 return toTree(
372 tree,
373 0,
374 nodes,
375 offsets(nodes),
376 terminals,
377 RandomRegistry.random()
378 );
379 }
380
381 private static <A> TreeNode<Op<A>> toTree(
382 final TreeNode<Op<A>> root,
383 final int index,
384 final ISeq<? extends FlatTree<? extends Op<A>, ?>> nodes,
385 final int[] offsets,
386 final ISeq<? extends Op<A>> terminals,
387 final RandomGenerator random
388 ) {
389 if (index < nodes.size()) {
390 final FlatTree<? extends Op<A>, ?> node = nodes.get(index);
391 final Op<A> op = node.value();
392
393 for (int i = 0; i < op.arity(); ++i) {
394 assert offsets[index] != -1;
395
396 final TreeNode<Op<A>> treeNode = TreeNode.of();
397 if (offsets[index] + i < nodes.size()) {
398 treeNode.value(nodes.get(offsets[index] + i).value());
399 } else {
400 treeNode.value(terminals.get(random.nextInt(terminals.size())));
401 }
402
403 toTree(
404 treeNode,
405 offsets[index] + i,
406 nodes,
407 offsets,
408 terminals,
409 random
410 );
411 root.attach(treeNode);
412 }
413 }
414
415 return root;
416 }
417
418 /**
419 * Create the offset array for the given nodes. The offsets are calculated
420 * using the arity of the stored operations.
421 *
422 * @param nodes the flattened tree nodes
423 * @return the offset array for the given nodes
424 */
425 static int[]
426 offsets(final ISeq<? extends FlatTree<? extends Op<?>, ?>> nodes) {
427 final int[] offsets = new int[nodes.size()];
428
429 int offset = 1;
430 for (int i = 0; i < offsets.length; ++i) {
431 final Op<?> op = nodes.get(i).value();
432
433 offsets[i] = op.isTerminal() ? -1 : offset;
434 offset += op.arity();
435 }
436
437 return offsets;
438 }
439
440 }
|