001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2020 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 specified pattern.
028 * </p>
029 * <p>
030 * Default pattern has the following characteristic:
031 * </p>
032 * <ul>
033 * <li>allows names beginning with two lowercase letters followed by at least one uppercase or
034 * lowercase letter</li>
035 * <li>allows {@code e} abbreviation (suitable for exceptions end errors)</li>
036 * <li>allows {@code ex} abbreviation (suitable for exceptions)</li>
037 * <li>allows {@code t} abbreviation (suitable for throwables)</li>
038 * <li>prohibits numbered abbreviations like {@code e1} or {@code t2}</li>
039 * <li>prohibits one letter prefixes like {@code pException}</li>
040 * <li>prohibits two letter abbreviations like {@code ie} or {@code ee}</li>
041 * <li>prohibits any other characters than letters</li>
042 * </ul>
043 * <ul>
044 * <li>
045 * Property {@code format} - Specifies valid identifiers. Default value is
046 * {@code "^(e|t|ex|[a-z][a-z][a-zA-Z]+)$"}.
047 * </li>
048 * </ul>
049 * <p>
050 * An example of how to configure the check is:
051 * </p>
052 * <pre>
053 * &lt;module name="CatchParameterName"/&gt;
054 * </pre>
055 * <p>
056 * An example of how to configure the check for names that begin with a lower case letter,
057 * followed by any letters or digits is:
058 * </p>
059 * <p>Configuration:</p>
060 * <pre>
061 * &lt;module name="CatchParameterName"&gt;
062 *   &lt;property name="format" value="^[a-z][a-zA-Z0-9]+$"/&gt;
063 * &lt;/module&gt;
064 * </pre>
065 * <p>Example:</p>
066 * <pre>
067 * public class MyTest {
068 *   public void myTest() {
069 *     try {
070 *       // ...
071 *     } catch (ArithmeticException ex) { //OK
072 *       // ...
073 *     } catch (ArrayIndexOutOfBoundsException ex2) { //OK
074 *       // ...
075 *     } catch (IOException thirdException) { //OK
076 *       // ...
077 *     } catch (Exception FourthException) { // violation, the initial letter
078 *                                           // should be lowercase
079 *       // ...
080 *     }
081 *   }
082 * }
083 * </pre>
084 * @since 6.14
085 */
086public class CatchParameterNameCheck extends AbstractNameCheck {
087
088    /**
089     * Creates a new {@code CatchParameterNameCheck} instance.
090     */
091    public CatchParameterNameCheck() {
092        super("^(e|t|ex|[a-z][a-z][a-zA-Z]+)$");
093    }
094
095    @Override
096    public int[] getDefaultTokens() {
097        return getRequiredTokens();
098    }
099
100    @Override
101    public int[] getAcceptableTokens() {
102        return getRequiredTokens();
103    }
104
105    @Override
106    public int[] getRequiredTokens() {
107        return new int[] {TokenTypes.PARAMETER_DEF};
108    }
109
110    @Override
111    protected boolean mustCheckName(DetailAST ast) {
112        return ast.getParent().getType() == TokenTypes.LITERAL_CATCH;
113    }
114
115}