Source code

001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2020 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.TreeWalkerFilter;
031import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
032import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck;
033import com.puppycrawl.tools.checkstyle.api.AuditListener;
034import com.puppycrawl.tools.checkstyle.api.AutomaticBean;
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 (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.toSet());
065    }
066
067    /**
068     * Checks whether a class may be considered as a checkstyle module. Checkstyle's modules are
069     * non-abstract classes, which are either checkstyle's checks, file sets, filters, file filters,
070     * {@code TreeWalker} filters, audit listener, or root module.
071     *
072     * @param clazz class to check.
073     * @return true if the class may be considered as the checkstyle module.
074     */
075    public static boolean isCheckstyleModule(Class<?> clazz) {
076        return isValidCheckstyleClass(clazz)
077            && (isCheckstyleTreeWalkerCheck(clazz)
078                    || isFileSetModule(clazz)
079                    || isFilterModule(clazz)
080                    || isFileFilterModule(clazz)
081                    || isTreeWalkerFilterModule(clazz)
082                    || isAuditListener(clazz)
083                    || isRootModule(clazz));
084    }
085
086    /**
087     * Checks whether a class extends 'AutomaticBean', is non-abstract, and has a default
088     * constructor.
089     *
090     * @param clazz class to check.
091     * @return true if a class may be considered a valid production class.
092     */
093    public static boolean isValidCheckstyleClass(Class<?> clazz) {
094        return AutomaticBean.class.isAssignableFrom(clazz)
095                && !Modifier.isAbstract(clazz.getModifiers())
096                && hasDefaultConstructor(clazz)
097                && isNotXpathFileGenerator(clazz);
098    }
099
100    /**
101     * Checks if the class has a default constructor.
102     *
103     * @param clazz class to check
104     * @return true if the class has a default constructor.
105     */
106    private static boolean hasDefaultConstructor(Class<?> clazz) {
107        boolean result = false;
108        for (Constructor<?> constructor : clazz.getDeclaredConstructors()) {
109            if (constructor.getParameterCount() == 0) {
110                result = true;
111                break;
112            }
113        }
114        return result;
115    }
116
117    /**
118     * Checks whether a class may be considered as the checkstyle check
119     * which has TreeWalker as a parent.
120     * Checkstyle's checks are classes which implement 'AbstractCheck' interface.
121     *
122     * @param clazz class to check.
123     * @return true if a class may be considered as the checkstyle check.
124     */
125    public static boolean isCheckstyleTreeWalkerCheck(Class<?> clazz) {
126        return AbstractCheck.class.isAssignableFrom(clazz);
127    }
128
129    /**
130     * Checks whether a class may be considered as the checkstyle file set.
131     * Checkstyle's file sets are classes which implement 'AbstractFileSetCheck' interface.
132     *
133     * @param clazz class to check.
134     * @return true if a class may be considered as the checkstyle file set.
135     */
136    public static boolean isFileSetModule(Class<?> clazz) {
137        return AbstractFileSetCheck.class.isAssignableFrom(clazz);
138    }
139
140    /**
141     * Checks whether a class may be considered as the checkstyle filter.
142     * Checkstyle's filters are classes which implement 'Filter' interface.
143     *
144     * @param clazz class to check.
145     * @return true if a class may be considered as the checkstyle filter.
146     */
147    public static boolean isFilterModule(Class<?> clazz) {
148        return Filter.class.isAssignableFrom(clazz);
149    }
150
151    /**
152     * Checks whether a class may be considered as the checkstyle file filter.
153     * Checkstyle's file filters are classes which implement 'BeforeExecutionFileFilter' interface.
154     *
155     * @param clazz class to check.
156     * @return true if a class may be considered as the checkstyle file filter.
157     */
158    public static boolean isFileFilterModule(Class<?> clazz) {
159        return BeforeExecutionFileFilter.class.isAssignableFrom(clazz);
160    }
161
162    /**
163     * Checks whether a class may be considered as the checkstyle audit listener module.
164     * Checkstyle's audit listener modules are classes which implement 'AuditListener' interface.
165     *
166     * @param clazz class to check.
167     * @return true if a class may be considered as the checkstyle audit listener module.
168     */
169    public static boolean isAuditListener(Class<?> clazz) {
170        return AuditListener.class.isAssignableFrom(clazz);
171    }
172
173    /**
174     * Checks whether a class may be considered as the checkstyle root module.
175     * Checkstyle's root modules are classes which implement 'RootModule' interface.
176     *
177     * @param clazz class to check.
178     * @return true if a class may be considered as the checkstyle root module.
179     */
180    public static boolean isRootModule(Class<?> clazz) {
181        return RootModule.class.isAssignableFrom(clazz);
182    }
183
184    /**
185     * Checks whether a class may be considered as the checkstyle {@code TreeWalker} filter.
186     * Checkstyle's {@code TreeWalker} filters are classes which implement 'TreeWalkerFilter'
187     * interface.
188     *
189     * @param clazz class to check.
190     * @return true if a class may be considered as the checkstyle {@code TreeWalker} filter.
191     */
192    public static boolean isTreeWalkerFilterModule(Class<?> clazz) {
193        return TreeWalkerFilter.class.isAssignableFrom(clazz);
194    }
195
196    /**
197     * Checks whether a class is {@code XpathFileGeneratorAstFilter} or
198     * {@code XpathFileGeneratorAuditListener}.
199     * See issue #102 https://github.com/checkstyle/checkstyle/issues/102
200     *
201     * @param clazz class to check.
202     * @return true if a class name starts with `XpathFileGenerator`.
203     */
204    private static boolean isNotXpathFileGenerator(Class<?> clazz) {
205        return !clazz.getSimpleName().startsWith("XpathFileGenerator");
206    }
207}