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 java.util.Objects;
023
024import com.puppycrawl.tools.checkstyle.api.DetailAST;
025import com.puppycrawl.tools.checkstyle.api.TokenTypes;
026import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
027
028/**
029 * <div>
030 * Checks lambda parameter names.
031 * </div>
032 * <ul>
033 * <li>
034 * Property {@code format} - Sets the pattern to match valid identifiers.
035 * Type is {@code java.util.regex.Pattern}.
036 * Default value is {@code "^([a-z][a-zA-Z0-9]*|_)$"}.
037 * </li>
038 * </ul>
039 *
040 * <p>
041 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
042 * </p>
043 *
044 * <p>
045 * Violation Message Keys:
046 * </p>
047 * <ul>
048 * <li>
049 * {@code name.invalidPattern}
050 * </li>
051 * </ul>
052 *
053 * @since 8.11
054 */
055public class LambdaParameterNameCheck extends AbstractNameCheck {
056
057    /** Creates new instance of {@code LambdaParameterNameCheck}. */
058    public LambdaParameterNameCheck() {
059        super("^([a-z][a-zA-Z0-9]*|_)$");
060    }
061
062    @Override
063    public int[] getDefaultTokens() {
064        return getRequiredTokens();
065    }
066
067    @Override
068    public int[] getAcceptableTokens() {
069        return getRequiredTokens();
070    }
071
072    @Override
073    public int[] getRequiredTokens() {
074        return new int[] {
075            TokenTypes.LAMBDA,
076        };
077    }
078
079    @Override
080    public void visitToken(DetailAST ast) {
081        final boolean isInSwitchRule = ast.getParent().getType() == TokenTypes.SWITCH_RULE;
082
083        if (Objects.nonNull(ast.findFirstToken(TokenTypes.PARAMETERS))) {
084            final DetailAST parametersNode = ast.findFirstToken(TokenTypes.PARAMETERS);
085            TokenUtil.forEachChild(parametersNode, TokenTypes.PARAMETER_DEF, super::visitToken);
086        }
087        else if (!isInSwitchRule) {
088            super.visitToken(ast);
089        }
090    }
091
092    @Override
093    protected boolean mustCheckName(DetailAST ast) {
094        return true;
095    }
096
097}