AbstractClassNameCheck.java
////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2021 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.checks.naming;
import java.util.regex.Pattern;
import com.puppycrawl.tools.checkstyle.StatelessCheck;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
/**
* <p>
* Ensures that the names of abstract classes conforming to some regular
* expression and check that {@code abstract} modifier exists.
* </p>
* <p>
* Rationale: Abstract classes are convenience base class implementations of
* interfaces, not types as such. As such they should be named to indicate this.
* Also if names of classes starts with 'Abstract' it's very convenient that
* they will have abstract modifier.
* </p>
* <ul>
* <li>
* Property {@code format} - Specify valid identifiers.
* Type is {@code java.util.regex.Pattern}.
* Default value is {@code "^Abstract.+$"}.</li>
* <li>
* Property {@code ignoreModifier} - Control whether to ignore checking for the
* {@code abstract} modifier on classes that match the name.
* Type is {@code boolean}.
* Default value is {@code false}.</li>
* <li>
* Property {@code ignoreName} - Control whether to ignore checking the name.
* Realistically only useful if using the check to identify that match name and
* do not have the {@code abstract} modifier.
* Type is {@code boolean}.
* Default value is {@code false}.
* </li>
* </ul>
* <p>
* To configure the check:
* </p>
* <pre>
* <module name="AbstractClassName"/>
* </pre>
* <p>Example:</p>
* <pre>
* abstract class AbstractFirstClass {} // OK
* abstract class SecondClass {} // violation, it should match pattern "^Abstract.+$"
* class AbstractThirdClass {} // violation, must be declared 'abstract'
* class FourthClass {} // OK
* </pre>
* <p>
* To configure the check so that it check name
* but ignore {@code abstract} modifier:
* </p>
* <pre>
* <module name="AbstractClassName">
* <property name="ignoreModifier" value="true"/>
* </module>
* </pre>
* <p>Example:</p>
* <pre>
* abstract class AbstractFirstClass {} // OK
* abstract class SecondClass {} // violation, it should match pattern "^Abstract.+$"
* class AbstractThirdClass {} // OK, no "abstract" modifier
* class FourthClass {} // OK
* </pre>
* <p>
* To configure the check to ignore name
* validation when class declared as 'abstract'
* </p>
* <pre>
* <module name="AbstractClassName">
* <property name="ignoreName" value="true"/>
* </module>
* </pre>
* <p>Example:</p>
* <pre>
* abstract class AbstractFirstClass {} // OK
* abstract class SecondClass {} // OK, name validation is ignored
* class AbstractThirdClass {} // violation, must be declared as 'abstract'
* class FourthClass {} // OK, no "abstract" modifier
* </pre>
* <p>
* To configure the check
* with {@code format}:
* </p>
* <pre>
* <module name="AbstractClassName">
* <property name="format" value="^Generator.+$"/>
* </module>
* </pre>
* <p>Example:</p>
* <pre>
* abstract class GeneratorFirstClass {} // OK
* abstract class SecondClass {} // violation, must match pattern '^Generator.+$'
* class GeneratorThirdClass {} // violation, must be declared 'abstract'
* class FourthClass {} // OK, no "abstract" modifier
* </pre>
* <p>
* Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
* </p>
* <p>
* Violation Message Keys:
* </p>
* <ul>
* <li>
* {@code illegal.abstract.class.name}
* </li>
* <li>
* {@code no.abstract.class.modifier}
* </li>
* </ul>
*
* @since 3.2
*/
@StatelessCheck
public final class AbstractClassNameCheck extends AbstractCheck {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_ILLEGAL_ABSTRACT_CLASS_NAME = "illegal.abstract.class.name";
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_NO_ABSTRACT_CLASS_MODIFIER = "no.abstract.class.modifier";
/**
* Control whether to ignore checking for the {@code abstract} modifier on
* classes that match the name.
*/
private boolean ignoreModifier;
/**
* Control whether to ignore checking the name. Realistically only useful
* if using the check to identify that match name and do not have the
* {@code abstract} modifier.
*/
private boolean ignoreName;
/** Specify valid identifiers. */
private Pattern format = Pattern.compile("^Abstract.+$");
/**
* Setter to control whether to ignore checking for the {@code abstract} modifier on
* classes that match the name.
*
* @param value new value
*/
public void setIgnoreModifier(boolean value) {
ignoreModifier = value;
}
/**
* Setter to control whether to ignore checking the name. Realistically only useful if
* using the check to identify that match name and do not have the {@code abstract} modifier.
*
* @param value new value.
*/
public void setIgnoreName(boolean value) {
ignoreName = value;
}
/**
* Setter to specify valid identifiers.
*
* @param pattern the new pattern
*/
public void setFormat(Pattern pattern) {
format = pattern;
}
@Override
public int[] getDefaultTokens() {
return getRequiredTokens();
}
@Override
public int[] getRequiredTokens() {
return new int[] {TokenTypes.CLASS_DEF};
}
@Override
public int[] getAcceptableTokens() {
return getRequiredTokens();
}
@Override
public void visitToken(DetailAST ast) {
visitClassDef(ast);
}
/**
* Checks class definition.
*
* @param ast class definition for check.
*/
private void visitClassDef(DetailAST ast) {
final String className =
ast.findFirstToken(TokenTypes.IDENT).getText();
if (isAbstract(ast)) {
// if class has abstract modifier
if (!ignoreName && !isMatchingClassName(className)) {
log(ast, MSG_ILLEGAL_ABSTRACT_CLASS_NAME, className, format.pattern());
}
}
else if (!ignoreModifier && isMatchingClassName(className)) {
log(ast, MSG_NO_ABSTRACT_CLASS_MODIFIER, className);
}
}
/**
* Checks if declared class is abstract or not.
*
* @param ast class definition for check.
* @return true if a given class declared as abstract.
*/
private static boolean isAbstract(DetailAST ast) {
final DetailAST abstractAST = ast.findFirstToken(TokenTypes.MODIFIERS)
.findFirstToken(TokenTypes.ABSTRACT);
return abstractAST != null;
}
/**
* Returns true if class name matches format of abstract class names.
*
* @param className class name for check.
* @return true if class name matches format of abstract class names.
*/
private boolean isMatchingClassName(String className) {
return format.matcher(className).find();
}
}