Coverage Summary for Class: PatternFilenameFilter (com.google.common.io)

1 /*
2  * Copyright (C) 2006 The Guava Authors
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5  * in compliance with the License. You may obtain a copy of the License at
6  *
7  * http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software distributed under the License
10  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11  * or implied. See the License for the specific language governing permissions and limitations under
12  * the License.
13  */
14 
15 package com.google.common.io;
16 
17 import com.google.common.annotations.Beta;
18 import com.google.common.annotations.GwtIncompatible;
19 import com.google.common.base.Preconditions;
20 import java.io.File;
21 import java.io.FilenameFilter;
22 import java.util.regex.Pattern;
23 import java.util.regex.PatternSyntaxException;
24 import javax.annotation.CheckForNull;
25 
26 /**
27  * File name filter that only accepts files matching a regular expression. This class is thread-safe
28  * and immutable.
29  *
30  * @author Apple Chow
31  * @since 1.0
32  */
33 @Beta
34 @GwtIncompatible
35 @ElementTypesAreNonnullByDefault
36 public final class PatternFilenameFilter implements FilenameFilter {
37 
38   private final Pattern pattern;
39 
40   /**
41    * Constructs a pattern file name filter object.
42    *
43    * @param patternStr the pattern string on which to filter file names
44    * @throws PatternSyntaxException if pattern compilation fails (runtime)
45    */
46   public PatternFilenameFilter(String patternStr) {
47     this(Pattern.compile(patternStr));
48   }
49 
50   /**
51    * Constructs a pattern file name filter object.
52    *
53    * @param pattern the pattern on which to filter file names
54    */
55   public PatternFilenameFilter(Pattern pattern) {
56     this.pattern = Preconditions.checkNotNull(pattern);
57   }
58 
59   /*
60    * Our implementation works fine with a null `dir`. However, there's nothing in the documentation
61    * of the supertype that suggests that implementations are expected to tolerate null. That said, I
62    * see calls in Google code that pass a null `dir` to a FilenameFilter.... So let's declare the
63    * parameter as non-nullable (since passing null to a FilenameFilter is unsafe in general), but if
64    * someone still manages to pass null, let's continue to have the method work.
65    *
66    * (OK, I haven't done that yet, but I will when I follow through on the TODO below after updating
67    * callers.)
68    *
69    * (PatternFilenameFilter is of course one of those classes that shouldn't be a publicly visible
70    * class to begin with but rather something returned from a static factory method whose declared
71    * return type is plain FilenameFilter. If we made such a change, then the annotation we choose
72    * here would have no significance to end users, who would be forced to conform to the signature
73    * used in FilenameFilter.)
74    */
75   @Override
76   @SuppressWarnings("nullness")
77   public boolean accept(
78       // TODO(b/147136275): Remove @CheckForNull, and remove suppression.
79       @CheckForNull File dir, String fileName) {
80     return pattern.matcher(fileName).matches();
81   }
82 }