001/////////////////////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code and other text files for adherence to a set of rules. 003// Copyright (C) 2001-2024 the original author or authors. 004// 005// This library is free software; you can redistribute it and/or 006// modify it under the terms of the GNU Lesser General Public 007// License as published by the Free Software Foundation; either 008// version 2.1 of the License, or (at your option) any later version. 009// 010// This library is distributed in the hope that it will be useful, 011// but WITHOUT ANY WARRANTY; without even the implied warranty of 012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 013// Lesser General Public License for more details. 014// 015// You should have received a copy of the GNU Lesser General Public 016// License along with this library; if not, write to the Free Software 017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 018/////////////////////////////////////////////////////////////////////////////////////////////// 019 020package com.puppycrawl.tools.checkstyle.utils; 021 022import java.io.IOException; 023import java.lang.reflect.Constructor; 024import java.lang.reflect.Modifier; 025import java.util.Collection; 026import java.util.Set; 027import java.util.stream.Collectors; 028 029import com.google.common.reflect.ClassPath; 030import com.puppycrawl.tools.checkstyle.AbstractAutomaticBean; 031import com.puppycrawl.tools.checkstyle.TreeWalkerFilter; 032import com.puppycrawl.tools.checkstyle.api.AbstractCheck; 033import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck; 034import com.puppycrawl.tools.checkstyle.api.AuditListener; 035import com.puppycrawl.tools.checkstyle.api.BeforeExecutionFileFilter; 036import com.puppycrawl.tools.checkstyle.api.Filter; 037import com.puppycrawl.tools.checkstyle.api.RootModule; 038 039/** 040 * Contains utility methods for module reflection. 041 */ 042public final class ModuleReflectionUtil { 043 044 /** Prevent instantiation. */ 045 private ModuleReflectionUtil() { 046 } 047 048 /** 049 * Gets checkstyle's modules classes (directly, not recursively) in the given packages. 050 * 051 * @param packages the collection of package names to use 052 * @param loader the class loader used to load Checkstyle package names 053 * @return the set of checkstyle's module classes 054 * @throws IOException if the attempt to read class path resources failed 055 * @see #isCheckstyleModule(Class) 056 */ 057 public static Set<Class<?>> getCheckstyleModules( 058 Collection<String> packages, ClassLoader loader) throws IOException { 059 final ClassPath classPath = ClassPath.from(loader); 060 return packages.stream() 061 .flatMap(pkg -> classPath.getTopLevelClasses(pkg).stream()) 062 .map(ClassPath.ClassInfo::load) 063 .filter(ModuleReflectionUtil::isCheckstyleModule) 064 .collect(Collectors.toUnmodifiableSet()); 065 } 066 067 /** 068 * Checks whether a class may be considered as a checkstyle module. 069 * Checkstyle's modules are classes which extend 'AutomaticBean', is 070 * non-abstract, and has a default constructor. 071 * 072 * @param clazz class to check. 073 * @return true if a class may be considered a valid production class. 074 */ 075 public static boolean isCheckstyleModule(Class<?> clazz) { 076 return AbstractAutomaticBean.class.isAssignableFrom(clazz) 077 && !Modifier.isAbstract(clazz.getModifiers()) 078 && hasDefaultConstructor(clazz) 079 && isNotXpathFileGenerator(clazz); 080 } 081 082 /** 083 * Checks if the class has a default constructor. 084 * 085 * @param clazz class to check 086 * @return true if the class has a default constructor. 087 */ 088 private static boolean hasDefaultConstructor(Class<?> clazz) { 089 boolean result = false; 090 for (Constructor<?> constructor : clazz.getDeclaredConstructors()) { 091 if (constructor.getParameterCount() == 0) { 092 result = true; 093 break; 094 } 095 } 096 return result; 097 } 098 099 /** 100 * Checks whether a class may be considered as the checkstyle check 101 * which has TreeWalker as a parent. 102 * Checkstyle's checks are classes which implement 'AbstractCheck' interface. 103 * 104 * @param clazz class to check. 105 * @return true if a class may be considered as the checkstyle check. 106 */ 107 public static boolean isCheckstyleTreeWalkerCheck(Class<?> clazz) { 108 return AbstractCheck.class.isAssignableFrom(clazz); 109 } 110 111 /** 112 * Checks whether a class may be considered as the checkstyle file set. 113 * Checkstyle's file sets are classes which implement 'AbstractFileSetCheck' interface. 114 * 115 * @param clazz class to check. 116 * @return true if a class may be considered as the checkstyle file set. 117 */ 118 public static boolean isFileSetModule(Class<?> clazz) { 119 return AbstractFileSetCheck.class.isAssignableFrom(clazz); 120 } 121 122 /** 123 * Checks whether a class may be considered as the checkstyle filter. 124 * Checkstyle's filters are classes which implement 'Filter' interface. 125 * 126 * @param clazz class to check. 127 * @return true if a class may be considered as the checkstyle filter. 128 */ 129 public static boolean isFilterModule(Class<?> clazz) { 130 return Filter.class.isAssignableFrom(clazz); 131 } 132 133 /** 134 * Checks whether a class may be considered as the checkstyle file filter. 135 * Checkstyle's file filters are classes which implement 'BeforeExecutionFileFilter' interface. 136 * 137 * @param clazz class to check. 138 * @return true if a class may be considered as the checkstyle file filter. 139 */ 140 public static boolean isFileFilterModule(Class<?> clazz) { 141 return BeforeExecutionFileFilter.class.isAssignableFrom(clazz); 142 } 143 144 /** 145 * Checks whether a class may be considered as the checkstyle audit listener module. 146 * Checkstyle's audit listener modules are classes which implement 'AuditListener' interface. 147 * 148 * @param clazz class to check. 149 * @return true if a class may be considered as the checkstyle audit listener module. 150 */ 151 public static boolean isAuditListener(Class<?> clazz) { 152 return AuditListener.class.isAssignableFrom(clazz); 153 } 154 155 /** 156 * Checks whether a class may be considered as the checkstyle root module. 157 * Checkstyle's root modules are classes which implement 'RootModule' interface. 158 * 159 * @param clazz class to check. 160 * @return true if a class may be considered as the checkstyle root module. 161 */ 162 public static boolean isRootModule(Class<?> clazz) { 163 return RootModule.class.isAssignableFrom(clazz); 164 } 165 166 /** 167 * Checks whether a class may be considered as the checkstyle {@code TreeWalker} filter. 168 * Checkstyle's {@code TreeWalker} filters are classes which implement 'TreeWalkerFilter' 169 * interface. 170 * 171 * @param clazz class to check. 172 * @return true if a class may be considered as the checkstyle {@code TreeWalker} filter. 173 */ 174 public static boolean isTreeWalkerFilterModule(Class<?> clazz) { 175 return TreeWalkerFilter.class.isAssignableFrom(clazz); 176 } 177 178 /** 179 * Checks whether a class is {@code XpathFileGeneratorAstFilter} or 180 * {@code XpathFileGeneratorAuditListener}. 181 * See issue <a href="https://github.com/checkstyle/checkstyle/issues/102">#102</a> 182 * 183 * @param clazz class to check. 184 * @return true if a class name starts with `XpathFileGenerator`. 185 */ 186 private static boolean isNotXpathFileGenerator(Class<?> clazz) { 187 return !clazz.getSimpleName().startsWith("XpathFileGenerator"); 188 } 189}