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.
046 * Type is {@code java.util.regex.Pattern}.
047 * Default value is {@code "^(e|t|ex|[a-z][a-z][a-zA-Z]+)$"}.
048 * </li>
049 * </ul>
050 * <p>
051 * An example of how to configure the check is:
052 * </p>
053 * <pre>
054 * &lt;module name="CatchParameterName"/&gt;
055 * </pre>
056 * <p>Example:</p>
057 * <pre>
058 * public class MyTest {
059 *   public void myTest() {
060 *     try {
061 *       // ...
062 *     } catch (ArithmeticException e) { // OK
063 *       // ...
064 *     } catch (ArrayIndexOutOfBoundsException ex) { // OK
065 *       // ...
066 *     } catch (Throwable t) { // OK
067 *       // ...
068 *     } catch (IndexOutOfBoundsException e123) { // violation, digits
069 *                                // not allowed
070 *       // ...
071 *     } catch (NullPointerException ab) { // violation, should have at least
072 *                              // three characters if not e|t|ex
073 *       // ...
074 *     } catch (ArrayStoreException abc) { // OK
075 *       // ...
076 *     } catch (InterruptedException aBC) { // violation, first two characters
077 *                               // should be in lowercase
078 *       // ...
079 *     } catch (RuntimeException abC) { // OK
080 *       // ...
081 *     } catch (Exception abCD) { // OK
082 *       // ...
083 *     }
084 *   }
085 * }
086 * </pre>
087 * <p>
088 * An example of how to configure the check for names that begin with a lower case letter,
089 * followed by any letters or digits is:
090 * </p>
091 * <p>Configuration:</p>
092 * <pre>
093 * &lt;module name="CatchParameterName"&gt;
094 *   &lt;property name="format" value="^[a-z][a-zA-Z0-9]+$"/&gt;
095 * &lt;/module&gt;
096 * </pre>
097 * <p>Example:</p>
098 * <pre>
099 * public class MyTest {
100 *   public void myTest() {
101 *     try {
102 *       // ...
103 *     } catch (ArithmeticException ex) { // OK
104 *       // ...
105 *     } catch (ArrayIndexOutOfBoundsException ex2) { // OK
106 *       // ...
107 *     } catch (IOException thirdException) { // OK
108 *       // ...
109 *     } catch (Exception FourthException) { // violation, the initial letter
110 *                                           // should be lowercase
111 *       // ...
112 *     }
113 *   }
114 * }
115 * </pre>
116 * <p>
117 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
118 * </p>
119 * <p>
120 * Violation Message Keys:
121 * </p>
122 * <ul>
123 * <li>
124 * {@code name.invalidPattern}
125 * </li>
126 * </ul>
127 *
128 * @since 6.14
129 */
130public class CatchParameterNameCheck extends AbstractNameCheck {
131
132    /**
133     * Creates a new {@code CatchParameterNameCheck} instance.
134     */
135    public CatchParameterNameCheck() {
136        super("^(e|t|ex|[a-z][a-z][a-zA-Z]+)$");
137    }
138
139    @Override
140    public int[] getDefaultTokens() {
141        return getRequiredTokens();
142    }
143
144    @Override
145    public int[] getAcceptableTokens() {
146        return getRequiredTokens();
147    }
148
149    @Override
150    public int[] getRequiredTokens() {
151        return new int[] {TokenTypes.PARAMETER_DEF};
152    }
153
154    @Override
155    protected boolean mustCheckName(DetailAST ast) {
156        return ast.getParent().getType() == TokenTypes.LITERAL_CATCH;
157    }
158
159}