ParameterNameCheck.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.Arrays;
import java.util.Optional;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.utils.CheckUtil;
/**
* <p>
* Checks that method parameter names conform to a specified pattern.
* By using {@code accessModifiers} property it is possible
* to specify different formats for methods at different visibility levels.
* </p>
* <p>
* To validate {@code catch} parameters please use
* <a href="https://checkstyle.org/config_naming.html#CatchParameterName">CatchParameterName</a>.
* </p>
* <p>
* To validate lambda parameters please use
* <a href="https://checkstyle.org/config_naming.html#LambdaParameterName">LambdaParameterName</a>.
* </p>
* <ul>
* <li>
* Property {@code format} - Specifies valid identifiers.
* Type is {@code java.util.regex.Pattern}.
* Default value is {@code "^[a-z][a-zA-Z0-9]*$"}.
* </li>
* <li>
* Property {@code ignoreOverridden} - Allows to skip methods with Override annotation from
* validation.
* Type is {@code boolean}.
* Default value is {@code false}.
* </li>
* <li>
* Property {@code accessModifiers} - Access modifiers of methods where parameters are
* checked.
* Type is {@code com.puppycrawl.tools.checkstyle.checks.naming.AccessModifierOption[]}.
* Default value is {@code public, protected, package, private}.
* </li>
* </ul>
* <p>
* To configure the check:
* </p>
* <pre>
* <module name="ParameterName"/>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* void method1(int v1) {} // OK
* void method2(int V2) {} // violation, name 'V2' must match pattern '^[a-z][a-zA-Z0-9]*$'
* }
* </pre>
* <p>
* An example of how to configure the check for names that begin with
* a lower case letter, followed by letters, digits, and underscores:
* </p>
* <pre>
* <module name="ParameterName">
* <property name="format" value="^[a-z][_a-zA-Z0-9]+$"/>
* </module>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* void method1(int v1) {} // OK
* void method2(int v_2) {} // OK
* void method3(int V3) {} // violation, name 'V3' must match pattern '^[a-z][_a-zA-Z0-9]+$'
* }
* </pre>
* <p>
* An example of how to configure the check to skip methods with Override annotation from
* validation:
* </p>
* <pre>
* <module name="ParameterName">
* <property name="ignoreOverridden" value="true"/>
* </module>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* void method1(int v1) {} // OK
* void method2(int V2) {} // violation, name 'V2' must match pattern '^[a-z][a-zA-Z0-9]*$'
* @Override
* public boolean equals(Object V3) { // OK
* return true;
* }
* }
* </pre>
* <p>
* An example of how to configure the check for names that begin with a lower case letter, followed
* by letters and digits is:
* </p>
* <pre>
* <module name="ParameterName">
* <property name="format" value="^[a-z][a-zA-Z0-9]+$"/>
* </module>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* void method1(int v1) {} // OK
* void method2(int v_2) {} // violation, name 'v_2' must match pattern '^[a-z][a-zA-Z0-9]+$'
* void method3(int V3) {} // violation, name 'V3' must match pattern '^[a-z][a-zA-Z0-9]+$'
* }
* </pre>
* <p>
* The following configuration checks that the parameters always start with two lowercase
* characters and, in addition, that public method parameters cannot be one character long:
* </p>
* <pre>
* <module name="ParameterName">
* <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
* <property name="accessModifiers"
* value="protected, package, private"/>
* <message key="name.invalidPattern"
* value="Parameter name ''{0}'' must match pattern ''{1}''"/>
* </module>
* <module name="ParameterName">
* <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
* <property name="accessModifiers" value="public"/>
* <message key="name.invalidPattern"
* value="Parameter name ''{0}'' must match pattern ''{1}''"/>
* </module>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* void method1(int v1) {} // OK
* protected method2(int V2) {} // violation, Parameter name 'V2'
* // must match pattern '^[a-z]([a-z0-9][a-zA-Z0-9]*)?$'
* private method3(int a) {} // OK
* public method4(int b) {} // violation, Parameter name 'b'
* // must match pattern '^[a-z][a-z0-9][a-zA-Z0-9]*$'
* }
* </pre>
* <p>
* Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
* </p>
* <p>
* Violation Message Keys:
* </p>
* <ul>
* <li>
* {@code name.invalidPattern}
* </li>
* </ul>
*
* @since 3.0
*/
public class ParameterNameCheck extends AbstractNameCheck {
/**
* Allows to skip methods with Override annotation from validation.
*/
private boolean ignoreOverridden;
/** Access modifiers of methods where parameters are checked. */
private AccessModifierOption[] accessModifiers = {
AccessModifierOption.PUBLIC,
AccessModifierOption.PROTECTED,
AccessModifierOption.PACKAGE,
AccessModifierOption.PRIVATE,
};
/**
* Creates a new {@code ParameterNameCheck} instance.
*/
public ParameterNameCheck() {
super("^[a-z][a-zA-Z0-9]*$");
}
/**
* Setter to allows to skip methods with Override annotation from validation.
*
* @param ignoreOverridden Flag for skipping methods with Override annotation.
*/
public void setIgnoreOverridden(boolean ignoreOverridden) {
this.ignoreOverridden = ignoreOverridden;
}
/**
* Setter to access modifiers of methods where parameters are checked.
*
* @param accessModifiers access modifiers of methods which should be checked.
*/
public void setAccessModifiers(AccessModifierOption... accessModifiers) {
this.accessModifiers =
Arrays.copyOf(accessModifiers, accessModifiers.length);
}
@Override
public int[] getDefaultTokens() {
return getRequiredTokens();
}
@Override
public int[] getAcceptableTokens() {
return getRequiredTokens();
}
@Override
public int[] getRequiredTokens() {
return new int[] {TokenTypes.PARAMETER_DEF};
}
@Override
protected boolean mustCheckName(DetailAST ast) {
boolean checkName = true;
final DetailAST parent = ast.getParent();
if (ignoreOverridden && isOverriddenMethod(ast)
|| parent.getType() == TokenTypes.LITERAL_CATCH
|| parent.getParent().getType() == TokenTypes.LAMBDA
|| CheckUtil.isReceiverParameter(ast)
|| !matchAccessModifiers(
CheckUtil.getAccessModifierFromModifiersToken(parent.getParent()))) {
checkName = false;
}
return checkName;
}
/**
* Checks whether a method has the correct access modifier to be checked.
*
* @param accessModifier the access modifier of the method.
* @return whether the method matches the expected access modifier.
*/
private boolean matchAccessModifiers(final AccessModifierOption accessModifier) {
return Arrays.stream(accessModifiers)
.anyMatch(modifier -> modifier == accessModifier);
}
/**
* Checks whether a method is annotated with Override annotation.
*
* @param ast method parameter definition token.
* @return true if a method is annotated with Override annotation.
*/
private static boolean isOverriddenMethod(DetailAST ast) {
boolean overridden = false;
final DetailAST parent = ast.getParent().getParent();
final Optional<DetailAST> annotation =
Optional.ofNullable(parent.getFirstChild().getFirstChild());
if (annotation.isPresent()) {
final Optional<DetailAST> overrideToken =
Optional.ofNullable(annotation.get().findFirstToken(TokenTypes.IDENT));
if (overrideToken.isPresent() && "Override".equals(overrideToken.get().getText())) {
overridden = true;
}
}
return overridden;
}
}