ModuleReflectionUtil.java
///////////////////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
// Copyright (C) 2001-2024 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
///////////////////////////////////////////////////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.utils;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.Modifier;
import java.util.Collection;
import java.util.Set;
import java.util.stream.Collectors;
import com.google.common.reflect.ClassPath;
import com.puppycrawl.tools.checkstyle.AbstractAutomaticBean;
import com.puppycrawl.tools.checkstyle.TreeWalkerFilter;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck;
import com.puppycrawl.tools.checkstyle.api.AuditListener;
import com.puppycrawl.tools.checkstyle.api.BeforeExecutionFileFilter;
import com.puppycrawl.tools.checkstyle.api.Filter;
import com.puppycrawl.tools.checkstyle.api.RootModule;
/**
* Contains utility methods for module reflection.
*/
public final class ModuleReflectionUtil {
/** Prevent instantiation. */
private ModuleReflectionUtil() {
}
/**
* Gets checkstyle's modules classes (directly, not recursively) in the given packages.
*
* @param packages the collection of package names to use
* @param loader the class loader used to load Checkstyle package names
* @return the set of checkstyle's module classes
* @throws IOException if the attempt to read class path resources failed
* @see #isCheckstyleModule(Class)
*/
public static Set<Class<?>> getCheckstyleModules(
Collection<String> packages, ClassLoader loader) throws IOException {
final ClassPath classPath = ClassPath.from(loader);
return packages.stream()
.flatMap(pkg -> classPath.getTopLevelClasses(pkg).stream())
.map(ClassPath.ClassInfo::load)
.filter(ModuleReflectionUtil::isCheckstyleModule)
.collect(Collectors.toUnmodifiableSet());
}
/**
* Checks whether a class may be considered as a checkstyle module.
* Checkstyle's modules are classes which extend 'AutomaticBean', is
* non-abstract, and has a default constructor.
*
* @param clazz class to check.
* @return true if a class may be considered a valid production class.
*/
public static boolean isCheckstyleModule(Class<?> clazz) {
return AbstractAutomaticBean.class.isAssignableFrom(clazz)
&& !Modifier.isAbstract(clazz.getModifiers())
&& hasDefaultConstructor(clazz)
&& isNotXpathFileGenerator(clazz);
}
/**
* Checks if the class has a default constructor.
*
* @param clazz class to check
* @return true if the class has a default constructor.
*/
private static boolean hasDefaultConstructor(Class<?> clazz) {
boolean result = false;
for (Constructor<?> constructor : clazz.getDeclaredConstructors()) {
if (constructor.getParameterCount() == 0) {
result = true;
break;
}
}
return result;
}
/**
* Checks whether a class may be considered as the checkstyle check
* which has TreeWalker as a parent.
* Checkstyle's checks are classes which implement 'AbstractCheck' interface.
*
* @param clazz class to check.
* @return true if a class may be considered as the checkstyle check.
*/
public static boolean isCheckstyleTreeWalkerCheck(Class<?> clazz) {
return AbstractCheck.class.isAssignableFrom(clazz);
}
/**
* Checks whether a class may be considered as the checkstyle file set.
* Checkstyle's file sets are classes which implement 'AbstractFileSetCheck' interface.
*
* @param clazz class to check.
* @return true if a class may be considered as the checkstyle file set.
*/
public static boolean isFileSetModule(Class<?> clazz) {
return AbstractFileSetCheck.class.isAssignableFrom(clazz);
}
/**
* Checks whether a class may be considered as the checkstyle filter.
* Checkstyle's filters are classes which implement 'Filter' interface.
*
* @param clazz class to check.
* @return true if a class may be considered as the checkstyle filter.
*/
public static boolean isFilterModule(Class<?> clazz) {
return Filter.class.isAssignableFrom(clazz);
}
/**
* Checks whether a class may be considered as the checkstyle file filter.
* Checkstyle's file filters are classes which implement 'BeforeExecutionFileFilter' interface.
*
* @param clazz class to check.
* @return true if a class may be considered as the checkstyle file filter.
*/
public static boolean isFileFilterModule(Class<?> clazz) {
return BeforeExecutionFileFilter.class.isAssignableFrom(clazz);
}
/**
* Checks whether a class may be considered as the checkstyle audit listener module.
* Checkstyle's audit listener modules are classes which implement 'AuditListener' interface.
*
* @param clazz class to check.
* @return true if a class may be considered as the checkstyle audit listener module.
*/
public static boolean isAuditListener(Class<?> clazz) {
return AuditListener.class.isAssignableFrom(clazz);
}
/**
* Checks whether a class may be considered as the checkstyle root module.
* Checkstyle's root modules are classes which implement 'RootModule' interface.
*
* @param clazz class to check.
* @return true if a class may be considered as the checkstyle root module.
*/
public static boolean isRootModule(Class<?> clazz) {
return RootModule.class.isAssignableFrom(clazz);
}
/**
* Checks whether a class may be considered as the checkstyle {@code TreeWalker} filter.
* Checkstyle's {@code TreeWalker} filters are classes which implement 'TreeWalkerFilter'
* interface.
*
* @param clazz class to check.
* @return true if a class may be considered as the checkstyle {@code TreeWalker} filter.
*/
public static boolean isTreeWalkerFilterModule(Class<?> clazz) {
return TreeWalkerFilter.class.isAssignableFrom(clazz);
}
/**
* Checks whether a class is {@code XpathFileGeneratorAstFilter} or
* {@code XpathFileGeneratorAuditListener}.
* See issue <a href="https://github.com/checkstyle/checkstyle/issues/102">#102</a>
*
* @param clazz class to check.
* @return true if a class name starts with `XpathFileGenerator`.
*/
private static boolean isNotXpathFileGenerator(Class<?> clazz) {
return !clazz.getSimpleName().startsWith("XpathFileGenerator");
}
}