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]+)$"}.
047 * </li>
048 * </ul>
049 * <p>
050 * An example of how to configure the check is:
051 * </p>
052 * <pre>
053 * &lt;module name="CatchParameterName"/&gt;
054 * </pre>
055 * <p>Example:</p>
056 * <pre>
057 * public class MyTest {
058 *   public void myTest() {
059 *     try {
060 *       // ...
061 *     } catch (ArithmeticException e) { // OK
062 *       // ...
063 *     } catch (ArrayIndexOutOfBoundsException ex) { // OK
064 *       // ...
065 *     } catch (Throwable t) { // OK
066 *       // ...
067 *     } catch (IndexOutOfBoundsException e123) { // violation, digits
068 *                                // not allowed
069 *       // ...
070 *     } catch (NullPointerException ab) { // violation, should have at least
071 *                              // three characters if not e|t|ex
072 *       // ...
073 *     } catch (ArrayStoreException abc) { // OK
074 *       // ...
075 *     } catch (InterruptedException aBC) { // violation, first two characters
076 *                               // should be in lowercase
077 *       // ...
078 *     } catch (RuntimeException abC) { // OK
079 *       // ...
080 *     } catch (Exception abCD) { // OK
081 *       // ...
082 *     }
083 *   }
084 * }
085 * </pre>
086 * <p>
087 * An example of how to configure the check for names that begin with a lower case letter,
088 * followed by any letters or digits is:
089 * </p>
090 * <p>Configuration:</p>
091 * <pre>
092 * &lt;module name="CatchParameterName"&gt;
093 *   &lt;property name="format" value="^[a-z][a-zA-Z0-9]+$"/&gt;
094 * &lt;/module&gt;
095 * </pre>
096 * <p>Example:</p>
097 * <pre>
098 * public class MyTest {
099 *   public void myTest() {
100 *     try {
101 *       // ...
102 *     } catch (ArithmeticException ex) { // OK
103 *       // ...
104 *     } catch (ArrayIndexOutOfBoundsException ex2) { // OK
105 *       // ...
106 *     } catch (IOException thirdException) { // OK
107 *       // ...
108 *     } catch (Exception FourthException) { // violation, the initial letter
109 *                                           // should be lowercase
110 *       // ...
111 *     }
112 *   }
113 * }
114 * </pre>
115 *
116 * @since 6.14
117 */
118public class CatchParameterNameCheck extends AbstractNameCheck {
119
120    /**
121     * Creates a new {@code CatchParameterNameCheck} instance.
122     */
123    public CatchParameterNameCheck() {
124        super("^(e|t|ex|[a-z][a-z][a-zA-Z]+)$");
125    }
126
127    @Override
128    public int[] getDefaultTokens() {
129        return getRequiredTokens();
130    }
131
132    @Override
133    public int[] getAcceptableTokens() {
134        return getRequiredTokens();
135    }
136
137    @Override
138    public int[] getRequiredTokens() {
139        return new int[] {TokenTypes.PARAMETER_DEF};
140    }
141
142    @Override
143    protected boolean mustCheckName(DetailAST ast) {
144        return ast.getParent().getType() == TokenTypes.LITERAL_CATCH;
145    }
146
147}