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