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1   ////////////////////////////////////////////////////////////////////////////////
2   // checkstyle: Checks Java source code for adherence to a set of rules.
3   // Copyright (C) 2001-2017 the original author or authors.
4   //
5   // This library is free software; you can redistribute it and/or
6   // modify it under the terms of the GNU Lesser General Public
7   // License as published by the Free Software Foundation; either
8   // version 2.1 of the License, or (at your option) any later version.
9   //
10  // This library is distributed in the hope that it will be useful,
11  // but WITHOUT ANY WARRANTY; without even the implied warranty of
12  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13  // Lesser General Public License for more details.
14  //
15  // You should have received a copy of the GNU Lesser General Public
16  // License along with this library; if not, write to the Free Software
17  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18  ////////////////////////////////////////////////////////////////////////////////
19  
20  package com.puppycrawl.tools.checkstyle.checks.naming;
21  
22  import com.puppycrawl.tools.checkstyle.api.DetailAST;
23  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
24  
25  /**
26   * <p>
27   * Checks that {@code catch} parameter names conform to a format specified by the format property.
28   * The format is a {@link java.util.regex.Pattern regular expression} and defaults to
29   * <strong>^(e|t|ex|[a-z][a-z][a-zA-Z]+)$</strong>.
30   * </p>
31   * <p>
32   * Default pattern has the following characteristic:
33   * </p>
34   * <ul>
35   * <li>allows names beginning with two lowercase letters followed by at least one uppercase or
36   * lowercase letter</li>
37   * <li>allows {@code e} abbreviation (suitable for exceptions end errors)</li>
38   * <li>allows {@code ex} abbreviation (suitable for exceptions)</li>
39   * <li>allows {@code t} abbreviation (suitable for throwables)</li>
40   * <li>prohibits numbered abbreviations like {@code e1} or {@code t2}</li>
41   * <li>prohibits one letter prefixes like {@code pException}</li>
42   * <li>prohibits two letter abbreviations like {@code ie} or {@code ee}</li>
43   * <li>prohibits any other characters than letters</li>
44   * </ul>
45   * <p>
46   * An example of how to configure the check is:
47   * </p>
48   * <pre>
49   * &lt;module name="CatchParameterName"/&gt;
50   * </pre>
51   * <p>
52   * An example of how to configure the check for names that begin with a lower case letter,
53   * followed by any letters or digits is:
54   * </p>
55   * <pre>
56   * &lt;module name="CatchParameterName"&gt;
57   *    &lt;property name="format" value="^[a-z][a-zA-Z0-9]+$"/&gt;
58   * &lt;/module&gt;
59   * </pre>
60   *
61   * @author Michal Kordas
62   */
63  public class CatchParameterNameCheck extends AbstractNameCheck {
64  
65      /**
66       * Creates a new {@code CatchParameterNameCheck} instance.
67       */
68      public CatchParameterNameCheck() {
69          super("^(e|t|ex|[a-z][a-z][a-zA-Z]+)$");
70      }
71  
72      @Override
73      public int[] getDefaultTokens() {
74          return getRequiredTokens();
75      }
76  
77      @Override
78      public int[] getAcceptableTokens() {
79          return getRequiredTokens();
80      }
81  
82      @Override
83      public int[] getRequiredTokens() {
84          return new int[] {TokenTypes.PARAMETER_DEF};
85      }
86  
87      @Override
88      protected boolean mustCheckName(DetailAST ast) {
89          return ast.getParent().getType() == TokenTypes.LITERAL_CATCH;
90      }
91  }