001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2024 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 * <p>
028 * Checks that local, non-{@code final} variable names conform to a specified pattern.
029 * A catch parameter is considered to be
030 * a local variable.
031 * </p>
032 * <ul>
033 * <li>
034 * Property {@code allowOneCharVarInForLoop} - Allow one character variable name in
035 * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
036 * initialization expressions</a>
037 * in FOR loop if one char variable name is prohibited by {@code format} regexp.
038 * Type is {@code boolean}.
039 * Default value is {@code false}.
040 * </li>
041 * <li>
042 * Property {@code format} - Sets the pattern to match valid identifiers.
043 * Type is {@code java.util.regex.Pattern}.
044 * Default value is {@code "^[a-z][a-zA-Z0-9]*$"}.
045 * </li>
046 * </ul>
047 * <p>
048 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
049 * </p>
050 * <p>
051 * Violation Message Keys:
052 * </p>
053 * <ul>
054 * <li>
055 * {@code name.invalidPattern}
056 * </li>
057 * </ul>
058 *
059 * @since 3.0
060 */
061public class LocalVariableNameCheck
062    extends AbstractNameCheck {
063
064    /**
065     * Allow one character variable name in
066     * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
067     * initialization expressions</a>
068     * in FOR loop if one char variable name is prohibited by {@code format} regexp.
069     */
070    private boolean allowOneCharVarInForLoop;
071
072    /** Creates a new {@code LocalVariableNameCheck} instance. */
073    public LocalVariableNameCheck() {
074        super("^[a-z][a-zA-Z0-9]*$");
075    }
076
077    /**
078     * Setter to allow one character variable name in
079     * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
080     * initialization expressions</a>
081     * in FOR loop if one char variable name is prohibited by {@code format} regexp.
082     *
083     * @param allow Flag for allowing or not one character name in FOR loop.
084     * @since 5.8
085     */
086    public final void setAllowOneCharVarInForLoop(boolean allow) {
087        allowOneCharVarInForLoop = allow;
088    }
089
090    @Override
091    public int[] getDefaultTokens() {
092        return getRequiredTokens();
093    }
094
095    @Override
096    public int[] getAcceptableTokens() {
097        return getRequiredTokens();
098    }
099
100    @Override
101    public int[] getRequiredTokens() {
102        return new int[] {
103            TokenTypes.VARIABLE_DEF,
104        };
105    }
106
107    @Override
108    protected final boolean mustCheckName(DetailAST ast) {
109        final boolean result;
110        if (allowOneCharVarInForLoop && isForLoopVariable(ast)) {
111            final String variableName = ast.findFirstToken(TokenTypes.IDENT).getText();
112            result = variableName.length() != 1;
113        }
114        else {
115            final DetailAST modifiersAST = ast.findFirstToken(TokenTypes.MODIFIERS);
116            final boolean isFinal = modifiersAST.findFirstToken(TokenTypes.FINAL) != null;
117            result = !isFinal && ScopeUtil.isLocalVariableDef(ast);
118        }
119        return result;
120    }
121
122    /**
123     * Checks if a variable is the loop's one.
124     *
125     * @param variableDef variable definition.
126     * @return true if a variable is the loop's one.
127     */
128    private static boolean isForLoopVariable(DetailAST variableDef) {
129        final int parentType = variableDef.getParent().getType();
130        return parentType == TokenTypes.FOR_INIT
131                || parentType == TokenTypes.FOR_EACH_CLAUSE;
132    }
133
134}