001 /*
002 * Java Genetic Algorithm Library (jenetics-4.2.0).
003 * Copyright (c) 2007-2018 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
025 import java.io.Serializable;
026 import java.lang.reflect.Array;
027 import java.util.Objects;
028 import java.util.Random;
029
030 import io.jenetics.util.ISeq;
031 import io.jenetics.util.RandomRegistry;
032
033 import io.jenetics.ext.util.FlatTree;
034 import io.jenetics.ext.util.Tree;
035 import io.jenetics.ext.util.TreeNode;
036
037 /**
038 * This class composes a given operation tree to a new operation. which can
039 * serve as a sub <em>program</em> in an other operation tree.
040 *
041 * @param <T> the argument type of the operation
042 *
043 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
044 * @version 4.1
045 * @since 3.9
046 */
047 public class Program<T> implements Op<T>, Serializable {
048
049 private static final long serialVersionUID = 1L;
050
051 private final String _name;
052 private final int _arity;
053 private final Tree<? extends Op<T>, ?> _tree;
054
055 /**
056 * Create a new program with the given name and the given operation tree.
057 * The arity of the program is calculated from the given operation tree and
058 * set to the maximal arity of the operations of the tree.
059 *
060 * @param name the program name
061 * @param tree the operation tree
062 * @throws NullPointerException if one of the given arguments is {@code null}
063 * @throws IllegalArgumentException if the given operation tree is invalid,
064 * which means there is at least one node where the operation arity
065 * and the node child count differ.
066 */
067 public Program(final String name, final Tree<? extends Op<T>, ?> tree) {
068 _name = requireNonNull(name);
069 _tree = requireNonNull(tree);
070 check(tree);
071 _arity = tree.breadthFirstStream()
072 .filter(t -> t.getValue() instanceof Var)
073 .mapToInt(v -> ((Var)v.getValue()).index() + 1)
074 .max()
075 .orElse(0);
076 }
077
078 @Override
079 public String name() {
080 return _name;
081 }
082
083 @Override
084 public int arity() {
085 return _arity;
086 }
087
088 /**
089 * Return the underlying expression tree.
090 *
091 * @since 4.1
092 *
093 * @return the underlying expression tree
094 */
095 public Tree<? extends Op<T>, ?> tree() {
096 return TreeNode.ofTree(_tree);
097 }
098
099 @Override
100 public T apply(final T[] args) {
101 if (args.length < arity()) {
102 throw new IllegalArgumentException(format(
103 "Arguments length is smaller than program arity: %d < %d",
104 args.length, arity()
105 ));
106 }
107
108 return eval(_tree, args);
109 }
110
111 /**
112 * Convenient method, which lets you apply the program function without
113 * explicitly create a wrapper array.
114 *
115 * @see #apply(Object[])
116 *
117 * @param args the function arguments
118 * @return the evaluated value
119 * @throws NullPointerException if the given variable array is {@code null}
120 * @throws IllegalArgumentException if the length of the arguments array
121 * is smaller than the program arity
122 */
123 @SafeVarargs
124 public final T eval(final T... args) {
125 return apply(args);
126 }
127
128 @Override
129 public int hashCode() {
130 int hash = 17;
131 hash += 31*Objects.hashCode(_name) + 37;
132 hash += 31*Integer.hashCode(_arity) + 37;
133 hash += 31*Objects.hashCode(_tree) + 37;
134 return hash;
135 }
136
137 @Override
138 public boolean equals(final Object obj) {
139 return obj == this ||
140 obj instanceof Program &&
141 Objects.equals(((Program)obj)._name, _name) &&
142 ((Program)obj)._arity == _arity &&
143 Objects.equals(((Program)obj)._tree, _tree);
144 }
145
146 @Override
147 public String toString() {
148 return _name;
149 }
150
151
152 /* *************************************************************************
153 * Static helper methods.
154 * ************************************************************************/
155
156 /**
157 * Evaluates the given operation tree with the given variables.
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 requireNonNull(tree);
173 requireNonNull(variables);
174
175 final Op<T> op = tree.getValue();
176 return op.isTerminal()
177 ? eval(op, variables)
178 : eval(op,
179 tree.childStream()
180 .map(child -> eval(child, variables))
181 .toArray(size -> newArray(variables.getClass(), size))
182 );
183 }
184
185 @SafeVarargs
186 private static <T> T eval(final Op<T> op, final T... variables) {
187 if (op instanceof Var && ((Var) op).index() >= variables.length) {
188 throw new IllegalArgumentException(format(
189 "No value for variable '%s' given.", op
190 ));
191 }
192
193 return op.apply(variables);
194 }
195
196 @SuppressWarnings("unchecked")
197 private static <T> T[] newArray(final Class<?> arrayType, final int size) {
198 return (T[])Array.newInstance(arrayType.getComponentType(), size);
199 }
200
201 /**
202 * Validates the given program tree.
203 *
204 * @param program the program to validate
205 * @throws NullPointerException if the given {@code program} is {@code null}
206 * @throws IllegalArgumentException if the given operation tree is invalid,
207 * which means there is at least one node where the operation arity
208 * and the node child count differ.
209 */
210 public static void check(final Tree<? extends Op<?>, ?> program) {
211 requireNonNull(program);
212 program.forEach(Program::checkArity);
213 }
214
215 private static void checkArity(final Tree<? extends Op<?>, ?> node) {
216 if (node.getValue() != null &&
217 node.getValue().arity() != node.childCount())
218 {
219 throw new IllegalArgumentException(format(
220 "Op arity != child count: %d != %d",
221 node.getValue().arity(), node.childCount()
222 ));
223 }
224 }
225
226 /**
227 * Create a new, random program from the given (non) terminal operations
228 * with the desired depth. The created program tree is a <em>full</em> tree.
229 *
230 * @since 4.1
231 *
232 * @param name the program name
233 * @param depth the desired depth of the program tree
234 * @param operations the list of <em>non</em>-terminal operations
235 * @param terminals the list of terminal operations
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 ) {
249 return new Program<>(name, of(depth, operations, terminals));
250 }
251
252 /**
253 * Create a new, random program from the given (non) terminal operations
254 * with the desired depth. The created program tree is a <em>full</em> tree.
255 *
256 * @since 4.1
257 *
258 * @param name the program name
259 * @param depth the desired depth of the program tree
260 * @param operations the list of <em>non</em>-terminal operations
261 * @param terminals the list of terminal operations
262 * @param random the random engine used for creating the program
263 * @param <A> the operational type
264 * @return a new program
265 * @throws NullPointerException if one of the given operations is
266 * {@code null}
267 * @throws IllegalArgumentException if the given tree depth is smaller than
268 * zero
269 */
270 public static <A> Program<A> of(
271 final String name,
272 final int depth,
273 final ISeq<? extends Op<A>> operations,
274 final ISeq<? extends Op<A>> terminals,
275 final Random random
276 ) {
277 return new Program<>(name, of(depth, operations, terminals, random));
278 }
279
280 /**
281 * Create a new, random program tree from the given (non) terminal
282 * operations with the desired depth. The created program tree is a
283 * <em>full</em> tree.
284 *
285 * @param depth the desired depth of the program tree
286 * @param operations the list of <em>non</em>-terminal operations
287 * @param terminals the list of terminal operations
288 * @param <A> the operational type
289 * @return a new program tree
290 * @throws NullPointerException if one of the given operations is
291 * {@code null}
292 * @throws IllegalArgumentException if the given tree depth is smaller than
293 * zero
294 */
295 public static <A> TreeNode<Op<A>> of(
296 final int depth,
297 final ISeq<? extends Op<A>> operations,
298 final ISeq<? extends Op<A>> terminals
299 ) {
300 return of(depth, operations, terminals, RandomRegistry.getRandom());
301 }
302
303 /**
304 * Create a new, random program tree from the given (non) terminal
305 * operations with the desired depth. The created program tree is a
306 * <em>full</em> tree.
307 *
308 * @since 4.1
309 *
310 * @param depth the desired depth of the program tree
311 * @param operations the list of <em>non</em>-terminal operations
312 * @param terminals the list of terminal operations
313 * @param random the random engine used for creating the program
314 * @param <A> the operational type
315 * @return a new program tree
316 * @throws NullPointerException if one of the given operations is
317 * {@code null}
318 * @throws IllegalArgumentException if the given tree depth is smaller than
319 * zero
320 */
321 public static <A> TreeNode<Op<A>> of(
322 final int depth,
323 final ISeq<? extends Op<A>> operations,
324 final ISeq<? extends Op<A>> terminals,
325 final Random random
326 ) {
327 if (depth < 0) {
328 throw new IllegalArgumentException(
329 "Tree depth is smaller than zero: " + depth
330 );
331 }
332 if (!operations.forAll(o -> !o.isTerminal())) {
333 throw new IllegalArgumentException(
334 "Operation list contains terminal op."
335 );
336 }
337 if (!terminals.forAll(o -> o.isTerminal())) {
338 throw new IllegalArgumentException(
339 "Terminal list contains non-terminal op."
340 );
341 }
342
343 final TreeNode<Op<A>> root = TreeNode.of();
344 fill(depth, root, operations, terminals, random);
345 return root;
346 }
347
348 private static <A> void fill(
349 final int level,
350 final TreeNode<Op<A>> tree,
351 final ISeq<? extends Op<A>> operations,
352 final ISeq<? extends Op<A>> terminals,
353 final Random random
354 ) {
355 final Op<A> op = level == 0
356 ? terminals.get(random.nextInt(terminals.size()))
357 : operations.get(random.nextInt(operations.size()));
358
359 tree.setValue(op);
360
361 if (level > 1) {
362 for (int i = 0; i < op.arity(); ++i) {
363 final TreeNode<Op<A>> node = TreeNode.of();
364 fill(level - 1, node, operations, terminals, random);
365 tree.attach(node);
366 }
367 } else {
368 for (int i = 0; i < op.arity(); ++i) {
369 final Op<A> term = terminals.get(random.nextInt(terminals.size()));
370 tree.attach(TreeNode.of(term));
371 }
372 }
373 }
374
375 /**
376 * Creates a valid program tree from the given flattened sequence of
377 * op nodes. The given {@code operations} and {@code termination} nodes are
378 * used for <em>repairing</em> the program tree, if necessary.
379 *
380 * @param nodes the flattened, possible corrupt, program tree
381 * @param terminals the usable non-terminal operation nodes to use for
382 * reparation
383 * @param <A> the operation argument type
384 * @return a new valid program tree build from the flattened program tree
385 * @throws NullPointerException if one of the arguments is {@code null}
386 * @throws IllegalArgumentException if the {@code nodes} sequence is empty
387 */
388 public static <A> TreeNode<Op<A>> toTree(
389 final ISeq<? extends FlatTree<? extends Op<A>, ?>> nodes,
390 final ISeq<? extends Op<A>> terminals
391 ) {
392 if (nodes.isEmpty()) {
393 throw new IllegalArgumentException("Tree nodes must not be empty.");
394 }
395
396 final Op<A> op = requireNonNull(nodes.get(0).getValue());
397 final TreeNode<Op<A>> tree = TreeNode.of(op);
398 return toTree(
399 tree,
400 0,
401 nodes,
402 offsets(nodes),
403 terminals,
404 RandomRegistry.getRandom()
405 );
406 }
407
408 private static <A> TreeNode<Op<A>> toTree(
409 final TreeNode<Op<A>> root,
410 final int index,
411 final ISeq<? extends FlatTree<? extends Op<A>, ?>> nodes,
412 final int[] offsets,
413 final ISeq<? extends Op<A>> terminals,
414 final Random random
415 ) {
416 if (index < nodes.size()) {
417 final FlatTree<? extends Op<A>, ?> node = nodes.get(index);
418 final Op<A> op = node.getValue();
419
420 for (int i = 0; i < op.arity(); ++i) {
421 assert offsets[index] != -1;
422
423 final TreeNode<Op<A>> treeNode = TreeNode.of();
424 if (offsets[index] + i < nodes.size()) {
425 treeNode.setValue(nodes.get(offsets[index] + i).getValue());
426 } else {
427 treeNode.setValue(terminals.get(random.nextInt(terminals.size())));
428 }
429
430 toTree(
431 treeNode,
432 offsets[index] + i,
433 nodes,
434 offsets,
435 terminals,
436 random
437 );
438 root.attach(treeNode);
439 }
440 }
441
442 return root;
443 }
444
445 /**
446 * Create the offset array for the given nodes. The offsets are calculated
447 * using the arity of the stored operations.
448 *
449 * @param nodes the flattened tree nodes
450 * @return the offset array for the given nodes
451 */
452 static int[]
453 offsets(final ISeq<? extends FlatTree<? extends Op<?>, ?>> nodes) {
454 final int[] offsets = new int[nodes.size()];
455
456 int offset = 1;
457 for (int i = 0; i < offsets.length; ++i) {
458 final Op<?> op = nodes.get(i).getValue();
459
460 offsets[i] = op.isTerminal() ? -1 : offset;
461 offset += op.arity();
462 }
463
464 return offsets;
465 }
466
467 }
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