1 ////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code for adherence to a set of rules.
3 // Copyright (C) 2001-2019 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.utils;
21
22 import java.io.IOException;
23 import java.lang.reflect.Constructor;
24 import java.lang.reflect.Modifier;
25 import java.util.Collection;
26 import java.util.Set;
27 import java.util.stream.Collectors;
28
29 import com.google.common.reflect.ClassPath;
30 import com.puppycrawl.tools.checkstyle.TreeWalkerFilter;
31 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
32 import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck;
33 import com.puppycrawl.tools.checkstyle.api.AuditListener;
34 import com.puppycrawl.tools.checkstyle.api.AutomaticBean;
35 import com.puppycrawl.tools.checkstyle.api.BeforeExecutionFileFilter;
36 import com.puppycrawl.tools.checkstyle.api.Filter;
37 import com.puppycrawl.tools.checkstyle.api.RootModule;
38
39 /**
40 * Contains utility methods for module reflection.
41 */
42 public final class ModuleReflectionUtil {
43
44 /** Prevent instantiation. */
45 private ModuleReflectionUtil() {
46 }
47
48 /**
49 * Gets checkstyle's modules (directly, not recursively) in the given packages.
50 * @param packages the collection of package names to use
51 * @param loader the class loader used to load Checkstyle package names
52 * @return the set of checkstyle's module classes
53 * @throws IOException if the attempt to read class path resources failed
54 * @see #isCheckstyleModule(Class)
55 */
56 public static Set<Class<?>> getCheckstyleModules(
57 Collection<String> packages, ClassLoader loader) throws IOException {
58 final ClassPath classPath = ClassPath.from(loader);
59 return packages.stream()
60 .flatMap(pkg -> classPath.getTopLevelClasses(pkg).stream())
61 .map(ClassPath.ClassInfo::load)
62 .filter(ModuleReflectionUtil::isCheckstyleModule)
63 .collect(Collectors.toSet());
64 }
65
66 /**
67 * Checks whether a class may be considered as a checkstyle module. Checkstyle's modules are
68 * non-abstract classes, which are either checkstyle's checks, file sets, filters, file filters,
69 * {@code TreeWalker} filters, audit listener, or root module.
70 * @param clazz class to check.
71 * @return true if the class may be considered as the checkstyle module.
72 */
73 public static boolean isCheckstyleModule(Class<?> clazz) {
74 return isValidCheckstyleClass(clazz)
75 && (isCheckstyleTreeWalkerCheck(clazz)
76 || isFileSetModule(clazz)
77 || isFilterModule(clazz)
78 || isFileFilterModule(clazz)
79 || isTreeWalkerFilterModule(clazz)
80 || isAuditListener(clazz)
81 || isRootModule(clazz));
82 }
83
84 /**
85 * Checks whether a class extends 'AutomaticBean', is non-abstract, and has a default
86 * constructor.
87 * @param clazz class to check.
88 * @return true if a class may be considered a valid production class.
89 */
90 public static boolean isValidCheckstyleClass(Class<?> clazz) {
91 return AutomaticBean.class.isAssignableFrom(clazz)
92 && !Modifier.isAbstract(clazz.getModifiers())
93 && hasDefaultConstructor(clazz)
94 && isNotXpathFileGenerator(clazz);
95 }
96
97 /**
98 * Checks if the class has a default constructor.
99 * @param clazz class to check
100 * @return true if the class has a default constructor.
101 */
102 private static boolean hasDefaultConstructor(Class<?> clazz) {
103 boolean result = false;
104 for (Constructor<?> constructor : clazz.getDeclaredConstructors()) {
105 if (constructor.getParameterCount() == 0) {
106 result = true;
107 break;
108 }
109 }
110 return result;
111 }
112
113 /**
114 * Checks whether a class may be considered as the checkstyle check
115 * which has TreeWalker as a parent.
116 * Checkstyle's checks are classes which implement 'AbstractCheck' interface.
117 * @param clazz class to check.
118 * @return true if a class may be considered as the checkstyle check.
119 */
120 public static boolean isCheckstyleTreeWalkerCheck(Class<?> clazz) {
121 return AbstractCheck.class.isAssignableFrom(clazz);
122 }
123
124 /**
125 * Checks whether a class may be considered as the checkstyle file set.
126 * Checkstyle's file sets are classes which implement 'AbstractFileSetCheck' interface.
127 * @param clazz class to check.
128 * @return true if a class may be considered as the checkstyle file set.
129 */
130 public static boolean isFileSetModule(Class<?> clazz) {
131 return AbstractFileSetCheck.class.isAssignableFrom(clazz);
132 }
133
134 /**
135 * Checks whether a class may be considered as the checkstyle filter.
136 * Checkstyle's filters are classes which implement 'Filter' interface.
137 * @param clazz class to check.
138 * @return true if a class may be considered as the checkstyle filter.
139 */
140 public static boolean isFilterModule(Class<?> clazz) {
141 return Filter.class.isAssignableFrom(clazz);
142 }
143
144 /**
145 * Checks whether a class may be considered as the checkstyle file filter.
146 * Checkstyle's file filters are classes which implement 'BeforeExecutionFileFilter' interface.
147 * @param clazz class to check.
148 * @return true if a class may be considered as the checkstyle file filter.
149 */
150 public static boolean isFileFilterModule(Class<?> clazz) {
151 return BeforeExecutionFileFilter.class.isAssignableFrom(clazz);
152 }
153
154 /**
155 * Checks whether a class may be considered as the checkstyle audit listener module.
156 * Checkstyle's audit listener modules are classes which implement 'AuditListener' interface.
157 * @param clazz class to check.
158 * @return true if a class may be considered as the checkstyle audit listener module.
159 */
160 public static boolean isAuditListener(Class<?> clazz) {
161 return AuditListener.class.isAssignableFrom(clazz);
162 }
163
164 /**
165 * Checks whether a class may be considered as the checkstyle root module.
166 * Checkstyle's root modules are classes which implement 'RootModule' interface.
167 * @param clazz class to check.
168 * @return true if a class may be considered as the checkstyle root module.
169 */
170 public static boolean isRootModule(Class<?> clazz) {
171 return RootModule.class.isAssignableFrom(clazz);
172 }
173
174 /**
175 * Checks whether a class may be considered as the checkstyle {@code TreeWalker} filter.
176 * Checkstyle's {@code TreeWalker} filters are classes which implement 'TreeWalkerFilter'
177 * interface.
178 * @param clazz class to check.
179 * @return true if a class may be considered as the checkstyle {@code TreeWalker} filter.
180 */
181 public static boolean isTreeWalkerFilterModule(Class<?> clazz) {
182 return TreeWalkerFilter.class.isAssignableFrom(clazz);
183 }
184
185 /**
186 * Checks whether a class is {@code XpathFileGeneratorAstFilter} or
187 * {@code XpathFileGeneratorAuditListener}.
188 * See issue #102 https://github.com/checkstyle/checkstyle/issues/102
189 * @param clazz class to check.
190 * @return true if a class name starts with `XpathFileGenerator`.
191 */
192 private static boolean isNotXpathFileGenerator(Class<?> clazz) {
193 return !clazz.getSimpleName().startsWith("XpathFileGenerator");
194 }
195 }