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;
024
025/**
026 * <div>
027 * Checks that {@code catch} parameter names conform to a specified pattern.
028 * </div>
029 *
030 * <p>
031 * Default pattern has the following characteristic:
032 * </p>
033 * <ul>
034 * <li>allows names beginning with two lowercase letters followed by at least one uppercase or
035 * lowercase letter</li>
036 * <li>allows {@code e} abbreviation (suitable for exceptions end errors)</li>
037 * <li>allows {@code ex} abbreviation (suitable for exceptions)</li>
038 * <li>allows {@code t} abbreviation (suitable for throwables)</li>
039 * <li>allows {@code _} for unnamed catch parameters</li>
040 * <li>prohibits numbered abbreviations like {@code e1} or {@code t2}</li>
041 * <li>prohibits one letter prefixes like {@code pException}</li>
042 * <li>prohibits two letter abbreviations like {@code ie} or {@code ee}</li>
043 * <li>prohibits any other characters than letters</li>
044 * </ul>
045 *
046 * @since 6.14
047 */
048public class CatchParameterNameCheck extends AbstractNameCheck {
049
050    /**
051     * A key is pointing to the warning message text in "messages.properties"
052     * file.
053     */
054    public static final String MSG_INVALID_PATTERN = "name.invalidPattern";
055
056    /**
057     * Creates a new {@code CatchParameterNameCheck} instance.
058     */
059    public CatchParameterNameCheck() {
060        super("^(e|t|ex|[a-z][a-z][a-zA-Z]+|_)$", MSG_INVALID_PATTERN);
061    }
062
063    @Override
064    public int[] getDefaultTokens() {
065        return getRequiredTokens();
066    }
067
068    @Override
069    public int[] getAcceptableTokens() {
070        return getRequiredTokens();
071    }
072
073    @Override
074    public int[] getRequiredTokens() {
075        return new int[] {TokenTypes.PARAMETER_DEF};
076    }
077
078    @Override
079    protected boolean mustCheckName(DetailAST ast) {
080        return ast.getParent().getType() == TokenTypes.LITERAL_CATCH;
081    }
082
083}