001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2025 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.checks.naming;
021
022import com.puppycrawl.tools.checkstyle.api.DetailAST;
023import com.puppycrawl.tools.checkstyle.api.TokenTypes;
024import com.puppycrawl.tools.checkstyle.utils.ScopeUtil;
025
026/**
027 * <div>
028 * Checks that local, non-{@code final} variable names conform to a specified pattern.
029 * A catch parameter is considered to be a local variable.
030 * </div>
031 *
032 * <p>
033 * This check does not support pattern variables. Instead, use
034 * <a href="https://checkstyle.org/checks/naming/patternvariablename.html#PatternVariableName">
035 * PatternVariableName</a>.
036 * </p>
037 * <ul>
038 * <li>
039 * Property {@code allowOneCharVarInForLoop} - Allow one character variable name in
040 * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
041 * initialization expressions</a>
042 * in FOR loop if one char variable name is prohibited by {@code format} regexp.
043 * Type is {@code boolean}.
044 * Default value is {@code false}.
045 * </li>
046 * <li>
047 * Property {@code format} - Sets the pattern to match valid identifiers.
048 * Type is {@code java.util.regex.Pattern}.
049 * Default value is {@code "^([a-z][a-zA-Z0-9]*|_)$"}.
050 * </li>
051 * </ul>
052 *
053 * <p>
054 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
055 * </p>
056 *
057 * <p>
058 * Violation Message Keys:
059 * </p>
060 * <ul>
061 * <li>
062 * {@code name.invalidPattern}
063 * </li>
064 * </ul>
065 *
066 * @since 3.0
067 */
068public class LocalVariableNameCheck
069    extends AbstractNameCheck {
070
071    /**
072     * Allow one character variable name in
073     * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
074     * initialization expressions</a>
075     * in FOR loop if one char variable name is prohibited by {@code format} regexp.
076     */
077    private boolean allowOneCharVarInForLoop;
078
079    /** Creates a new {@code LocalVariableNameCheck} instance. */
080    public LocalVariableNameCheck() {
081        super("^([a-z][a-zA-Z0-9]*|_)$");
082    }
083
084    /**
085     * Setter to allow one character variable name in
086     * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
087     * initialization expressions</a>
088     * in FOR loop if one char variable name is prohibited by {@code format} regexp.
089     *
090     * @param allow Flag for allowing or not one character name in FOR loop.
091     * @since 5.8
092     */
093    public final void setAllowOneCharVarInForLoop(boolean allow) {
094        allowOneCharVarInForLoop = allow;
095    }
096
097    @Override
098    public int[] getDefaultTokens() {
099        return getRequiredTokens();
100    }
101
102    @Override
103    public int[] getAcceptableTokens() {
104        return getRequiredTokens();
105    }
106
107    @Override
108    public int[] getRequiredTokens() {
109        return new int[] {
110            TokenTypes.VARIABLE_DEF,
111        };
112    }
113
114    @Override
115    protected final boolean mustCheckName(DetailAST ast) {
116        final boolean result;
117        if (allowOneCharVarInForLoop && isForLoopVariable(ast)) {
118            final String variableName = ast.findFirstToken(TokenTypes.IDENT).getText();
119            result = variableName.length() != 1;
120        }
121        else {
122            final DetailAST modifiersAST = ast.findFirstToken(TokenTypes.MODIFIERS);
123            final boolean isFinal = modifiersAST.findFirstToken(TokenTypes.FINAL) != null;
124            result = !isFinal && ScopeUtil.isLocalVariableDef(ast);
125        }
126        return result;
127    }
128
129    /**
130     * Checks if a variable is the loop's one.
131     *
132     * @param variableDef variable definition.
133     * @return true if a variable is the loop's one.
134     */
135    private static boolean isForLoopVariable(DetailAST variableDef) {
136        final int parentType = variableDef.getParent().getType();
137        return parentType == TokenTypes.FOR_INIT
138                || parentType == TokenTypes.FOR_EACH_CLAUSE;
139    }
140
141}