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1   ///////////////////////////////////////////////////////////////////////////////////////////////
2   // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3   // Copyright (C) 2001-2025 the original author or authors.
4   //
5   // This library is free software; you can redistribute it and/or
6   // modify it under the terms of the GNU Lesser General Public
7   // License as published by the Free Software Foundation; either
8   // version 2.1 of the License, or (at your option) any later version.
9   //
10  // This library is distributed in the hope that it will be useful,
11  // but WITHOUT ANY WARRANTY; without even the implied warranty of
12  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13  // Lesser General Public License for more details.
14  //
15  // You should have received a copy of the GNU Lesser General Public
16  // License along with this library; if not, write to the Free Software
17  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18  ///////////////////////////////////////////////////////////////////////////////////////////////
19  
20  package com.puppycrawl.tools.checkstyle.checks.metrics;
21  
22  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
23  
24  /**
25   * <div>
26   * Checks the number of other types a given class/record/interface/enum/annotation
27   * relies on. Also, the square of this has been shown to indicate the amount
28   * of maintenance required in functional programs (on a file basis) at least.
29   * </div>
30   *
31   * <p>
32   * This check processes files in the following way:
33   * </p>
34   * <ol>
35   * <li>
36   * Iterates over all tokens that might contain type reference.
37   * </li>
38   * <li>
39   * If a class was imported with direct import (i.e. {@code import java.math.BigDecimal}),
40   * or the class was referenced with the package name (i.e. {@code java.math.BigDecimal value})
41   * and the package was added to the {@code excludedPackages} parameter,
42   * the class does not increase complexity.
43   * </li>
44   * <li>
45   * If a class name was added to the {@code excludedClasses} parameter,
46   * the class does not increase complexity.
47   * </li>
48   * </ol>
49   * <ul>
50   * <li>
51   * Property {@code excludeClassesRegexps} - Specify user-configured regular
52   * expressions to ignore classes.
53   * Type is {@code java.util.regex.Pattern[]}.
54   * Default value is {@code ^$}.
55   * Since version 7.7
56   * </li>
57   * <li>
58   * Property {@code excludedClasses} - Specify user-configured class names to ignore.
59   * Type is {@code java.lang.String[]}.
60   * Default value is {@code ArrayIndexOutOfBoundsException, ArrayList, Boolean, Byte,
61   * Character, Class, Collection, Deprecated, Deque, Double, DoubleStream, EnumSet, Exception,
62   * Float, FunctionalInterface, HashMap, HashSet, IllegalArgumentException, IllegalStateException,
63   * IndexOutOfBoundsException, IntStream, Integer, LinkedHashMap, LinkedHashSet, LinkedList, List,
64   * Long, LongStream, Map, NullPointerException, Object, Optional, OptionalDouble, OptionalInt,
65   * OptionalLong, Override, Queue, RuntimeException, SafeVarargs, SecurityException, Set, Short,
66   * SortedMap, SortedSet, Stream, String, StringBuffer, StringBuilder, SuppressWarnings, Throwable,
67   * TreeMap, TreeSet, UnsupportedOperationException, Void, boolean, byte, char, double,
68   * float, int, long, short, var, void}.
69   * Since version 5.7
70   * </li>
71   * <li>
72   * Property {@code excludedPackages} - Specify user-configured packages to ignore.
73   * Type is {@code java.lang.String[]}.
74   * Default value is {@code ""}.
75   * Since version 7.7
76   * </li>
77   * <li>
78   * Property {@code max} - Specify the maximum threshold allowed.
79   * Type is {@code int}.
80   * Default value is {@code 20}.
81   * </li>
82   * </ul>
83   *
84   * <p>
85   * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
86   * </p>
87   *
88   * <p>
89   * Violation Message Keys:
90   * </p>
91   * <ul>
92   * <li>
93   * {@code classFanOutComplexity}
94   * </li>
95   * </ul>
96   *
97   * @since 3.4
98   */
99  public final class ClassFanOutComplexityCheck extends AbstractClassCouplingCheck {
100 
101     /**
102      * A key is pointing to the warning message text in "messages.properties"
103      * file.
104      */
105     public static final String MSG_KEY = "classFanOutComplexity";
106 
107     /** Default value of max value. */
108     private static final int DEFAULT_MAX = 20;
109 
110     /** Creates new instance of this check. */
111     public ClassFanOutComplexityCheck() {
112         super(DEFAULT_MAX);
113     }
114 
115     @Override
116     public int[] getRequiredTokens() {
117         return new int[] {
118             TokenTypes.PACKAGE_DEF,
119             TokenTypes.IMPORT,
120             TokenTypes.CLASS_DEF,
121             TokenTypes.EXTENDS_CLAUSE,
122             TokenTypes.IMPLEMENTS_CLAUSE,
123             TokenTypes.ANNOTATION,
124             TokenTypes.INTERFACE_DEF,
125             TokenTypes.ENUM_DEF,
126             TokenTypes.TYPE,
127             TokenTypes.LITERAL_NEW,
128             TokenTypes.LITERAL_THROWS,
129             TokenTypes.ANNOTATION_DEF,
130             TokenTypes.RECORD_DEF,
131         };
132     }
133 
134     @Override
135     public int[] getAcceptableTokens() {
136         return getRequiredTokens();
137     }
138 
139     @Override
140     protected String getLogMessageId() {
141         return MSG_KEY;
142     }
143 
144 }