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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 }