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