LocalVariableNameCheck.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 com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.utils.ScopeUtil;
/**
* <p>
* Checks that local, non-{@code final} variable names conform to a specified pattern.
* A catch parameter is considered to be
* a local variable.
* </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]*$"}.
* </li>
* <li>
* Property {@code allowOneCharVarInForLoop} - Allow one character variable name in
* <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
* initialization expressions</a>
* in FOR loop if one char variable name is prohibited by {@code format} regexp.
* Type is {@code boolean}.
* Default value is {@code false}.
* </li>
* </ul>
* <p>
* To configure the check:
* </p>
* <pre>
* <module name="LocalVariableName"/>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* void MyMethod() {
* for (int var = 1; var < 10; var++) {} // OK
* for (int VAR = 1; VAR < 10; VAR++) {} // violation, name 'VAR' must match
* // pattern '^[a-z][a-zA-Z0-9]*$'
* for (int i = 1; i < 10; i++) {} // OK
* for (int var_1 = 0; var_1 < 10; var_1++) {} // violation, name 'var_1' must match
* // pattern '^[a-z][a-zA-Z0-9]*$'
* }
* }
* </pre>
* <p>
* An example of how to configure the check for names that begin with a lower
* case letter, followed by letters, digits, and underscores is:
* </p>
* <pre>
* <module name="LocalVariableName">
* <property name="format" value="^[a-z](_?[a-zA-Z0-9]+)*$"/>
* </module>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* void MyMethod() {
* for (int var = 1; var < 10; var++) {} // OK
* for (int VAR = 1; VAR < 10; VAR++) {} // violation, name 'VAR' must match
* // pattern '^[a-z](_?[a-zA-Z0-9]+)*$'
* for (int i = 1; i < 10; i++) {} // OK
* for (int var_1 = 0; var_1 < 10; var_1++) {} // OK
* }
* }
* </pre>
* <p>
* An example of one character variable name in
* initialization expression(like "i") in FOR loop:
* </p>
* <pre>
* for(int i = 1; i < 10; i++) {}
* for(int K = 1; K < 10; K++) {}
* List list = new ArrayList();
* for (Object o : list) {}
* for (Object O : list) {}
* </pre>
* <p>
* An example of how to configure the check to allow one character variable name in
* <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
* initialization expressions</a> in FOR loop, where regexp allows 2 or more chars:
* </p>
* <pre>
* <module name="LocalVariableName">
* <property name="format" value="^[a-z][_a-zA-Z0-9]+$"/>
* <property name="allowOneCharVarInForLoop" value="true"/>
* </module>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* void MyMethod() {
* int good = 1;
* int g = 0; // violation
* for (int v = 1; v < 10; v++) { // OK
* int a = 1; // violation
* }
* for (int V = 1; V < 10; V++) { // OK
* int I = 1; // violation
* }
* List list = new ArrayList();
* for (Object o : list) { // OK
* String a = ""; // violation
* }
* for (Object O : list) { // OK
* String A = ""; // violation
* }
* }
* }
* </pre>
* <p>
* An example of how to configure the check to that all variables have 3 or more chars in name:
* </p>
* <pre>
* <module name="LocalVariableName">
* <property name="format" value="^[a-z][_a-zA-Z0-9]{2,}$"/>
* </module>
* </pre>
* <p>Code Example:</p>
* <pre>
* class MyClass {
* void MyMethod() {
* int goodName = 0;
* int i = 1; // violation
* for (int var = 1; var < 10; var++) { //OK
* int j = 1; // violation
* }
* }
* }
* </pre>
* <p>
* Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
* </p>
* <p>
* Violation Message Keys:
* </p>
* <ul>
* <li>
* {@code name.invalidPattern}
* </li>
* </ul>
*
* @since 3.0
*/
public class LocalVariableNameCheck
extends AbstractNameCheck {
/**
* Allow one character variable name in
* <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
* initialization expressions</a>
* in FOR loop if one char variable name is prohibited by {@code format} regexp.
*/
private boolean allowOneCharVarInForLoop;
/** Creates a new {@code LocalVariableNameCheck} instance. */
public LocalVariableNameCheck() {
super("^[a-z][a-zA-Z0-9]*$");
}
/**
* Setter to allow one character variable name in
* <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
* initialization expressions</a>
* in FOR loop if one char variable name is prohibited by {@code format} regexp.
*
* @param allow Flag for allowing or not one character name in FOR loop.
*/
public final void setAllowOneCharVarInForLoop(boolean allow) {
allowOneCharVarInForLoop = allow;
}
@Override
public int[] getDefaultTokens() {
return getRequiredTokens();
}
@Override
public int[] getAcceptableTokens() {
return getRequiredTokens();
}
@Override
public int[] getRequiredTokens() {
return new int[] {
TokenTypes.VARIABLE_DEF,
};
}
@Override
protected final boolean mustCheckName(DetailAST ast) {
final boolean result;
if (allowOneCharVarInForLoop && isForLoopVariable(ast)) {
final String variableName = ast.findFirstToken(TokenTypes.IDENT).getText();
result = variableName.length() != 1;
}
else {
final DetailAST modifiersAST = ast.findFirstToken(TokenTypes.MODIFIERS);
final boolean isFinal = modifiersAST.findFirstToken(TokenTypes.FINAL) != null;
result = !isFinal && ScopeUtil.isLocalVariableDef(ast);
}
return result;
}
/**
* Checks if a variable is the loop's one.
*
* @param variableDef variable definition.
* @return true if a variable is the loop's one.
*/
private static boolean isForLoopVariable(DetailAST variableDef) {
final int parentType = variableDef.getParent().getType();
return parentType == TokenTypes.FOR_INIT
|| parentType == TokenTypes.FOR_EACH_CLAUSE;
}
}