001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2019 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 class type parameter names conform to a format specified
028 * by the format property.
029 * </p>
030 * <ul>
031 * <li>
032 * Property {@code format} - Specifies valid identifiers. Default value is {@code "^[A-Z]$"}.
033 * </li>
034 * </ul>
035 * <p>
036 * An example of how to configure the check is:
037 * </p>
038 * <pre>
039 * &lt;module name="ClassTypeParameterName"/&gt;
040 * </pre>
041 * <p>
042 * An example of how to configure the check for names that are only a single
043 * letter is:
044 * </p>
045 * <p>Configuration:</p>
046 * <pre>
047 * &lt;module name="ClassTypeParameterName"&gt;
048 *   &lt;property name="format" value="^[a-zA-Z]$"/&gt;
049 * &lt;/module&gt;
050 * </pre>
051 * <p>Example:</p>
052 * <pre>
053 * class MyClass1&lt;T&gt; {} // OK
054 * class MyClass2&lt;t&gt; {} // OK
055 * class MyClass3&lt;abc&gt; {} // violation, the class type parameter
056 *                              // name should match the regular expression "^[a-zA-Z]$"
057 * </pre>
058 * @since 5.0
059 */
060public class ClassTypeParameterNameCheck
061    extends AbstractNameCheck {
062
063    /** Creates a new {@code ClassTypeParameterNameCheck} instance. */
064    public ClassTypeParameterNameCheck() {
065        super("^[A-Z]$");
066    }
067
068    @Override
069    public int[] getDefaultTokens() {
070        return getRequiredTokens();
071    }
072
073    @Override
074    public final int[] getAcceptableTokens() {
075        return getRequiredTokens();
076    }
077
078    @Override
079    public int[] getRequiredTokens() {
080        return new int[] {
081            TokenTypes.TYPE_PARAMETER,
082        };
083    }
084
085    @Override
086    protected final boolean mustCheckName(DetailAST ast) {
087        final DetailAST location =
088            ast.getParent().getParent();
089        return location.getType() == TokenTypes.CLASS_DEF;
090    }
091
092}