001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2026 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">
035 * PatternVariableName</a>.
036 * </p>
037 *
038 * @since 3.0
039 */
040public class LocalVariableNameCheck
041    extends AbstractNameCheck {
042
043    /**
044     * A key is pointing to the warning message text in "messages.properties"
045     * file.
046     */
047    public static final String MSG_INVALID_PATTERN = "name.invalidPattern";
048
049    /**
050     * Allow one character variable name in
051     * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
052     * initialization expressions</a>
053     * in FOR loop if one char variable name is prohibited by {@code format} regexp.
054     */
055    private boolean allowOneCharVarInForLoop;
056
057    /** Creates a new {@code LocalVariableNameCheck} instance. */
058    public LocalVariableNameCheck() {
059        super("^([a-z][a-zA-Z0-9]*|_)$", MSG_INVALID_PATTERN);
060    }
061
062    /**
063     * Setter to allow one character variable name in
064     * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
065     * initialization expressions</a>
066     * in FOR loop if one char variable name is prohibited by {@code format} regexp.
067     *
068     * @param allow Flag for allowing or not one character name in FOR loop.
069     * @since 5.8
070     */
071    public final void setAllowOneCharVarInForLoop(boolean allow) {
072        allowOneCharVarInForLoop = allow;
073    }
074
075    @Override
076    public int[] getDefaultTokens() {
077        return getRequiredTokens();
078    }
079
080    @Override
081    public int[] getAcceptableTokens() {
082        return getRequiredTokens();
083    }
084
085    @Override
086    public int[] getRequiredTokens() {
087        return new int[] {
088            TokenTypes.VARIABLE_DEF,
089        };
090    }
091
092    @Override
093    protected final boolean mustCheckName(DetailAST ast) {
094        final boolean result;
095        if (allowOneCharVarInForLoop && isForLoopVariable(ast)) {
096            final String variableName = ast.findFirstToken(TokenTypes.IDENT).getText();
097            result = variableName.length() != 1;
098        }
099        else {
100            final DetailAST modifiersAST = ast.findFirstToken(TokenTypes.MODIFIERS);
101            final boolean isFinal = modifiersAST.findFirstToken(TokenTypes.FINAL) != null;
102            result = !isFinal && ScopeUtil.isLocalVariableDef(ast);
103        }
104        return result;
105    }
106
107    /**
108     * Checks if a variable is the loop's one.
109     *
110     * @param variableDef variable definition.
111     * @return true if a variable is the loop's one.
112     */
113    private static boolean isForLoopVariable(DetailAST variableDef) {
114        final int parentType = variableDef.getParent().getType();
115        return parentType == TokenTypes.FOR_INIT
116                || parentType == TokenTypes.FOR_EACH_CLAUSE;
117    }
118
119}