1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.collections4;
19
20 import java.util.Collection;
21
22 import org.apache.commons.collections4.functors.AllPredicate;
23 import org.apache.commons.collections4.functors.AndPredicate;
24 import org.apache.commons.collections4.functors.AnyPredicate;
25 import org.apache.commons.collections4.functors.EqualPredicate;
26 import org.apache.commons.collections4.functors.ExceptionPredicate;
27 import org.apache.commons.collections4.functors.FalsePredicate;
28 import org.apache.commons.collections4.functors.IdentityPredicate;
29 import org.apache.commons.collections4.functors.InstanceofPredicate;
30 import org.apache.commons.collections4.functors.InvokerTransformer;
31 import org.apache.commons.collections4.functors.NonePredicate;
32 import org.apache.commons.collections4.functors.NotNullPredicate;
33 import org.apache.commons.collections4.functors.NotPredicate;
34 import org.apache.commons.collections4.functors.NullIsExceptionPredicate;
35 import org.apache.commons.collections4.functors.NullIsFalsePredicate;
36 import org.apache.commons.collections4.functors.NullIsTruePredicate;
37 import org.apache.commons.collections4.functors.NullPredicate;
38 import org.apache.commons.collections4.functors.OnePredicate;
39 import org.apache.commons.collections4.functors.OrPredicate;
40 import org.apache.commons.collections4.functors.TransformedPredicate;
41 import org.apache.commons.collections4.functors.TransformerPredicate;
42 import org.apache.commons.collections4.functors.TruePredicate;
43 import org.apache.commons.collections4.functors.UniquePredicate;
44
45 /**
46 * {@code PredicateUtils} provides reference implementations and utilities for the Predicate functor interface. The supplied predicates are:
47 * <ul>
48 * <li>Invoker - returns the result of a method call on the input object</li>
49 * <li>InstanceOf - true if the object is an instanceof a class</li>
50 * <li>Equal - true if the object equals() a specified object</li>
51 * <li>Identity - true if the object == a specified object</li>
52 * <li>Null - true if the object is null</li>
53 * <li>NotNull - true if the object is not null</li>
54 * <li>Unique - true if the object has not already been evaluated</li>
55 * <li>And/All - true if all of the predicates are true</li>
56 * <li>Or/Any - true if any of the predicates is true</li>
57 * <li>Either/One - true if only one of the predicate is true</li>
58 * <li>Neither/None - true if none of the predicates are true</li>
59 * <li>Not - true if the predicate is false, and vice versa</li>
60 * <li>Transformer - wraps a Transformer as a Predicate</li>
61 * <li>True - always return true</li>
62 * <li>False - always return false</li>
63 * <li>Exception - always throws an exception</li>
64 * <li>NullIsException/NullIsFalse/NullIsTrue - check for null input</li>
65 * <li>Transformed - transforms the input before calling the predicate</li>
66 * </ul>
67 * <p>
68 * All the supplied predicates are Serializable.
69 * </p>
70 *
71 * @since 3.0
72 */
73 public class PredicateUtils {
74
75 /**
76 * Creates a new Predicate that returns true only if all of the specified predicates are true. The predicates are checked in iterator order. If the
77 * collection of predicates is empty, then this predicate returns true.
78 *
79 * @param <T> the type that the predicate queries.
80 * @param predicates A collection of predicates to check, may not be null.
81 * @return The {@code all} predicate.
82 * @throws NullPointerException if the predicates collection is null.
83 * @throws NullPointerException if any predicate in the collection is null.
84 * @see AllPredicate
85 */
86 public static <T> Predicate<T> allPredicate(final Collection<? extends Predicate<? super T>> predicates) {
87 return AllPredicate.allPredicate(predicates);
88 }
89
90 /**
91 * Creates a new Predicate that returns true only if all of the specified predicates are true. If the array of predicates is empty, then this predicate
92 * returns true.
93 *
94 * @param <T> the type that the predicate queries.
95 * @param predicates An array of predicates to check, may not be null.
96 * @return The {@code all} predicate.
97 * @throws NullPointerException if the predicates array is null.
98 * @throws NullPointerException if any predicate in the array is null.
99 * @see AllPredicate
100 */
101 public static <T> Predicate<T> allPredicate(final Predicate<? super T>... predicates) {
102 return AllPredicate.allPredicate(predicates);
103 }
104
105 /**
106 * Creates a new Predicate that returns true only if both of the specified predicates are true.
107 *
108 * @param <T> the type that the predicate queries.
109 * @param predicate1 The first predicate, may not be null.
110 * @param predicate2 The second predicate, may not be null.
111 * @return The {@code and} predicate.
112 * @throws NullPointerException if either predicate is null.
113 * @see AndPredicate
114 */
115 public static <T> Predicate<T> andPredicate(final Predicate<? super T> predicate1, final Predicate<? super T> predicate2) {
116 return AndPredicate.andPredicate(predicate1, predicate2);
117 }
118
119 /**
120 * Creates a new Predicate that returns true if any of the specified predicates are true. The predicates are checked in iterator order. If the collection of
121 * predicates is empty, then this predicate returns false.
122 *
123 * @param <T> the type that the predicate queries.
124 * @param predicates A collection of predicates to check, may not be null.
125 * @return The {@code any} predicate.
126 * @throws NullPointerException if the predicates collection is null.
127 * @throws NullPointerException if any predicate in the collection is null.
128 * @see AnyPredicate
129 */
130 public static <T> Predicate<T> anyPredicate(final Collection<? extends Predicate<? super T>> predicates) {
131 return AnyPredicate.anyPredicate(predicates);
132 }
133
134 /**
135 * Creates a new Predicate that returns true if any of the specified predicates are true. If the array of predicates is empty, then this predicate returns
136 * false.
137 *
138 * @param <T> the type that the predicate queries.
139 * @param predicates An array of predicates to check, may not be null.
140 * @return The {@code any} predicate.
141 * @throws NullPointerException if the predicates array is null.
142 * @throws NullPointerException if any predicate in the array is null.
143 * @see AnyPredicate
144 */
145 public static <T> Predicate<T> anyPredicate(final Predicate<? super T>... predicates) {
146 return AnyPredicate.anyPredicate(predicates);
147 }
148
149 /**
150 * Creates a new Predicate that wraps a Transformer. The Transformer must return either {@link Boolean#TRUE} or {@link Boolean#FALSE} otherwise a
151 * PredicateException will be thrown.
152 *
153 * @param <T> the type that the predicate queries.
154 * @param transformer The transformer to wrap, may not be null.
155 * @return The transformer wrapping predicate.
156 * @throws NullPointerException if the transformer is null.
157 * @see TransformerPredicate
158 */
159 public static <T> Predicate<T> asPredicate(final Transformer<? super T, Boolean> transformer) {
160 return TransformerPredicate.transformerPredicate(transformer);
161 }
162
163 /**
164 * Creates a new Predicate that returns true if one, but not both, of the specified predicates are true. XOR
165 *
166 * @param <T> the type that the predicate queries.
167 * @param predicate1 The first predicate, may not be null.
168 * @param predicate2 The second predicate, may not be null.
169 * @return The {@code either} predicate.
170 * @throws NullPointerException if either predicate is null.
171 * @see OnePredicate
172 */
173 public static <T> Predicate<T> eitherPredicate(final Predicate<? super T> predicate1, final Predicate<? super T> predicate2) {
174 @SuppressWarnings("unchecked")
175 final Predicate<T> onePredicate = onePredicate(predicate1, predicate2);
176 return onePredicate;
177 }
178
179 /**
180 * Creates a Predicate that checks if the input object is equal to the specified object using equals().
181 *
182 * @param <T> the type that the predicate queries.
183 * @param value The value to compare against.
184 * @return The predicate.
185 * @see EqualPredicate
186 */
187 public static <T> Predicate<T> equalPredicate(final T value) {
188 return EqualPredicate.equalPredicate(value);
189 }
190
191 /**
192 * Gets a Predicate that always throws an exception. This could be useful during testing as a placeholder.
193 *
194 * @param <T> the type that the predicate queries.
195 * @return The predicate.
196 * @see ExceptionPredicate
197 */
198 public static <T> Predicate<T> exceptionPredicate() {
199 return ExceptionPredicate.exceptionPredicate();
200 }
201
202 /**
203 * Gets a Predicate that always returns false.
204 *
205 * @param <T> the type that the predicate queries.
206 * @return The predicate.
207 * @see FalsePredicate
208 */
209 public static <T> Predicate<T> falsePredicate() {
210 return FalsePredicate.falsePredicate();
211 }
212
213 /**
214 * Creates a Predicate that checks if the input object is equal to the specified object by identity.
215 *
216 * @param <T> the type that the predicate queries.
217 * @param value The value to compare against.
218 * @return The predicate.
219 * @see IdentityPredicate
220 */
221 public static <T> Predicate<T> identityPredicate(final T value) {
222 return IdentityPredicate.identityPredicate(value);
223 }
224
225 /**
226 * Creates a Predicate that checks if the object passed in is of a particular type, using instanceof. A {@code null} input object will return {@code false}.
227 *
228 * @param type The type to check for, may not be null.
229 * @return The predicate.
230 * @throws NullPointerException if the class is null.
231 * @see InstanceofPredicate
232 */
233 public static Predicate<Object> instanceofPredicate(final Class<?> type) {
234 return InstanceofPredicate.instanceOfPredicate(type);
235 }
236
237 /**
238 * Creates a Predicate that invokes a method on the input object. The method must return either a boolean or a non-null Boolean, and have no parameters. If
239 * the input object is null, a PredicateException is thrown.
240 * <p>
241 * For ePredicateUtils.invokerPredicate("isEmpty");} will call the {@code isEmpty} method on the input object to determine the predicate result.
242 *
243 * @param <T> the type that the predicate queries.
244 * @param methodName The method name to call on the input object, may not be null.
245 * @return The predicate.
246 * @throws NullPointerException if the methodName is null.
247 * @see InvokerTransformer
248 * @see TransformerPredicate
249 */
250 public static <T> Predicate<T> invokerPredicate(final String methodName) {
251 // reuse transformer as it has caching - this is lazy really, should have inner class here
252 return asPredicate(InvokerTransformer.<Object, Boolean>invokerTransformer(methodName));
253 }
254
255 /**
256 * Creates a Predicate that invokes a method on the input object. The method must return either a boolean or a non-null Boolean, and have no parameters. If
257 * the input object is null, a PredicateException is thrown.
258 * <p>
259 * For example, {@code PredicateUtils.invokerPredicate("isEmpty");} will call the {@code isEmpty} method on the input object to determine the predicate
260 * result.
261 * </p>
262 *
263 * @param <T> the type that the predicate queries.
264 * @param methodName The method name to call on the input object, may not be null.
265 * @param paramTypes The parameter types.
266 * @param args The arguments.
267 * @return The predicate.
268 * @throws NullPointerException if the method name is null.
269 * @throws IllegalArgumentException if the paramTypes and args don't match.
270 * @see InvokerTransformer
271 * @see TransformerPredicate
272 */
273 public static <T> Predicate<T> invokerPredicate(final String methodName, final Class<?>[] paramTypes, final Object[] args) {
274 // reuse transformer as it has caching - this is lazy really, should have inner class here
275 return asPredicate(InvokerTransformer.<Object, Boolean>invokerTransformer(methodName, paramTypes, args));
276 }
277
278 /**
279 * Creates a new Predicate that returns true if neither of the specified predicates are true.
280 *
281 * @param <T> the type that the predicate queries.
282 * @param predicate1 The first predicate, may not be null.
283 * @param predicate2 The second predicate, may not be null.
284 * @return The {@code neither} predicate.
285 * @throws NullPointerException if either predicate is null.
286 * @see NonePredicate
287 */
288 public static <T> Predicate<T> neitherPredicate(final Predicate<? super T> predicate1, final Predicate<? super T> predicate2) {
289 @SuppressWarnings("unchecked")
290 final Predicate<T> nonePredicate = nonePredicate(predicate1, predicate2);
291 return nonePredicate;
292 }
293
294 /**
295 * Creates a new Predicate that returns true if none of the specified predicates are true. The predicates are checked in iterator order. If the collection
296 * of predicates is empty, then this predicate returns true.
297 *
298 * @param <T> the type that the predicate queries.
299 * @param predicates A collection of predicates to check, may not be null.
300 * @return The {@code none} predicate.
301 * @throws NullPointerException if the predicates collection is null.
302 * @throws NullPointerException if any predicate in the collection is null.
303 * @see NonePredicate
304 */
305 public static <T> Predicate<T> nonePredicate(final Collection<? extends Predicate<? super T>> predicates) {
306 return NonePredicate.nonePredicate(predicates);
307 }
308
309 /**
310 * Creates a new Predicate that returns true if none of the specified predicates are true. If the array of predicates is empty, then this predicate returns
311 * true.
312 *
313 * @param <T> the type that the predicate queries.
314 * @param predicates An array of predicates to check, may not be null.
315 * @return The {@code none} predicate.
316 * @throws NullPointerException if the predicates array is null.
317 * @throws NullPointerException if any predicate in the array is null.
318 * @see NonePredicate
319 */
320 public static <T> Predicate<T> nonePredicate(final Predicate<? super T>... predicates) {
321 return NonePredicate.nonePredicate(predicates);
322 }
323
324 /**
325 * Gets a Predicate that checks if the input object passed in is not null.
326 *
327 * @param <T> the type that the predicate queries.
328 * @return The predicate.
329 * @see NotNullPredicate
330 */
331 public static <T> Predicate<T> notNullPredicate() {
332 return NotNullPredicate.notNullPredicate();
333 }
334
335 /**
336 * Creates a new Predicate that returns true if the specified predicate returns false and vice versa.
337 *
338 * @param <T> the type that the predicate queries.
339 * @param predicate The predicate to not.
340 * @return The {@code not} predicate.
341 * @throws NullPointerException if the predicate is null.
342 * @see NotPredicate
343 */
344 public static <T> Predicate<T> notPredicate(final Predicate<? super T> predicate) {
345 return NotPredicate.notPredicate(predicate);
346 }
347
348 /**
349 * Gets a Predicate that throws an exception if the input object is null, otherwise it calls the specified Predicate. This allows null handling behavior to
350 * be added to Predicates that don't support nulls.
351 *
352 * @param <T> the type that the predicate queries.
353 * @param predicate The predicate to wrap, may not be null.
354 * @return A new predicate that throws a NullPointerException if the input is null, otherwise delegates to the given predicate.
355 * @throws NullPointerException if the predicate is null.
356 * @see NullIsExceptionPredicate
357 */
358 public static <T> Predicate<T> nullIsExceptionPredicate(final Predicate<? super T> predicate) {
359 return NullIsExceptionPredicate.nullIsExceptionPredicate(predicate);
360 }
361
362 /**
363 * Gets a Predicate that returns false if the input object is null, otherwise it calls the specified Predicate. This allows null handling behavior to be
364 * added to Predicates that don't support nulls.
365 *
366 * @param <T> the type that the predicate queries.
367 * @param predicate The predicate to wrap, may not be null.
368 * @return A new predicate that returns false if the input is null, otherwise delegates to the given predicate.
369 * @throws NullPointerException if the predicate is null.
370 * @see NullIsFalsePredicate
371 */
372 public static <T> Predicate<T> nullIsFalsePredicate(final Predicate<? super T> predicate) {
373 return NullIsFalsePredicate.nullIsFalsePredicate(predicate);
374 }
375
376 /**
377 * Gets a Predicate that returns true if the input object is null, otherwise it calls the specified Predicate. This allows null handling behavior to be
378 * added to Predicates that don't support nulls.
379 *
380 * @param <T> the type that the predicate queries.
381 * @param predicate The predicate to wrap, may not be null.
382 * @return A new predicate that returns true if the input is null, otherwise delegates to the given predicate.
383 * @throws NullPointerException if the predicate is null.
384 * @see NullIsTruePredicate
385 */
386 public static <T> Predicate<T> nullIsTruePredicate(final Predicate<? super T> predicate) {
387 return NullIsTruePredicate.nullIsTruePredicate(predicate);
388 }
389
390 /**
391 * Gets a Predicate that checks if the input object passed in is null.
392 *
393 * @param <T> the type that the predicate queries.
394 * @return The predicate.
395 * @see NullPredicate
396 */
397 public static <T> Predicate<T> nullPredicate() {
398 return NullPredicate.nullPredicate();
399 }
400
401 /**
402 * Creates a new Predicate that returns true if only one of the specified predicates are true. The predicates are checked in iterator order. If the
403 * collection of predicates is empty, then this predicate returns false.
404 *
405 * @param <T> the type that the predicate queries.
406 * @param predicates A collection of predicates to check, may not be null.
407 * @return The {@code one} predicate.
408 * @throws NullPointerException if the predicates collection is null.
409 * @throws NullPointerException if any predicate in the collection is null.
410 * @see OnePredicate
411 */
412 public static <T> Predicate<T> onePredicate(final Collection<? extends Predicate<? super T>> predicates) {
413 return OnePredicate.onePredicate(predicates);
414 }
415
416 /**
417 * Creates a new Predicate that returns true if only one of the specified predicates are true. If the array of predicates is empty, then this predicate
418 * returns false.
419 *
420 * @param <T> the type that the predicate queries.
421 * @param predicates An array of predicates to check, may not be null.
422 * @return The {@code one} predicate.
423 * @throws NullPointerException if the predicates array is null.
424 * @throws NullPointerException if any predicate in the array is null.
425 * @see OnePredicate
426 */
427 public static <T> Predicate<T> onePredicate(final Predicate<? super T>... predicates) {
428 return OnePredicate.onePredicate(predicates);
429 }
430
431 /**
432 * Creates a new Predicate that returns true if either of the specified predicates are true.
433 *
434 * @param <T> the type that the predicate queries.
435 * @param predicate1 The first predicate, may not be null.
436 * @param predicate2 The second predicate, may not be null.
437 * @return The {@code or} predicate.
438 * @throws NullPointerException if either predicate is null.
439 * @see OrPredicate
440 */
441 public static <T> Predicate<T> orPredicate(final Predicate<? super T> predicate1, final Predicate<? super T> predicate2) {
442 return OrPredicate.orPredicate(predicate1, predicate2);
443 }
444
445 /**
446 * Creates a predicate that transforms the input object before passing it to the predicate.
447 *
448 * @param <T> the type that the predicate queries.
449 * @param transformer The transformer to call first.
450 * @param predicate The predicate to call with the result of the transform.
451 * @return A new predicate that transforms the input object using the given transformer and then passes the result to the given predicate.
452 * @throws NullPointerException if the transformer or the predicate is null.
453 * @see TransformedPredicate
454 * @since 3.1
455 */
456 public static <T> Predicate<T> transformedPredicate(final Transformer<? super T, ? extends T> transformer, final Predicate<? super T> predicate) {
457 return TransformedPredicate.transformedPredicate(transformer, predicate);
458 }
459
460 /**
461 * Gets a Predicate that always returns true.
462 *
463 * @param <T> the type that the predicate queries.
464 * @return The predicate.
465 * @see TruePredicate
466 */
467 public static <T> Predicate<T> truePredicate() {
468 return TruePredicate.truePredicate();
469 }
470
471 /**
472 * Creates a Predicate that returns true the first time an object is encountered, and false if the same object is received again. The comparison is by
473 * equals(). A {@code null} input object is accepted and will return true the first time, and false subsequently as well.
474 *
475 * @param <T> the type that the predicate queries.
476 * @return The predicate.
477 * @see UniquePredicate
478 */
479 public static <T> Predicate<T> uniquePredicate() {
480 // must return new instance each time
481 return UniquePredicate.uniquePredicate();
482 }
483
484 /**
485 * Don't allow instances.
486 */
487 private PredicateUtils() {
488 // empty
489 }
490 }