001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2017 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 * <p>
027 * Checks that {@code catch} parameter names conform to a format specified by the format property.
028 * The format is a {@link java.util.regex.Pattern regular expression} and defaults to
029 * <strong>^(e|t|ex|[a-z][a-z][a-zA-Z]+)$</strong>.
030 * </p>
031 * <p>
032 * Default pattern has the following characteristic:
033 * </p>
034 * <ul>
035 * <li>allows names beginning with two lowercase letters followed by at least one uppercase or
036 * lowercase letter</li>
037 * <li>allows {@code e} abbreviation (suitable for exceptions end errors)</li>
038 * <li>allows {@code ex} abbreviation (suitable for exceptions)</li>
039 * <li>allows {@code t} abbreviation (suitable for throwables)</li>
040 * <li>prohibits numbered abbreviations like {@code e1} or {@code t2}</li>
041 * <li>prohibits one letter prefixes like {@code pException}</li>
042 * <li>prohibits two letter abbreviations like {@code ie} or {@code ee}</li>
043 * <li>prohibits any other characters than letters</li>
044 * </ul>
045 * <p>
046 * An example of how to configure the check is:
047 * </p>
048 * <pre>
049 * &lt;module name="CatchParameterName"/&gt;
050 * </pre>
051 * <p>
052 * An example of how to configure the check for names that begin with a lower case letter,
053 * followed by any letters or digits is:
054 * </p>
055 * <pre>
056 * &lt;module name="CatchParameterName"&gt;
057 *    &lt;property name="format" value="^[a-z][a-zA-Z0-9]+$"/&gt;
058 * &lt;/module&gt;
059 * </pre>
060 *
061 * @author Michal Kordas
062 */
063public class CatchParameterNameCheck extends AbstractNameCheck {
064
065    /**
066     * Creates a new {@code CatchParameterNameCheck} instance.
067     */
068    public CatchParameterNameCheck() {
069        super("^(e|t|ex|[a-z][a-z][a-zA-Z]+)$");
070    }
071
072    @Override
073    public int[] getDefaultTokens() {
074        return getRequiredTokens();
075    }
076
077    @Override
078    public int[] getAcceptableTokens() {
079        return getRequiredTokens();
080    }
081
082    @Override
083    public int[] getRequiredTokens() {
084        return new int[] {TokenTypes.PARAMETER_DEF};
085    }
086
087    @Override
088    protected boolean mustCheckName(DetailAST ast) {
089        return ast.getParent().getType() == TokenTypes.LITERAL_CATCH;
090    }
091}