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 method 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]$"}.
032 * </li>
033 * </ul>
034 * <p>
035 * An example of how to configure the check is:
036 * </p>
037 * <pre>
038 * &lt;module name=&quot;MethodTypeParameterName&quot;/&gt;
039 * </pre>
040 * <p>Code Example:</p>
041 * <pre>
042 * class MyClass {
043 *   public &lt;T&gt; void method1() {} // OK
044 *   public &lt;a&gt; void method2() {} // violation,  name 'a' must match pattern '^[A-Z]$'
045 *   public &lt;K, V&gt; void method3() {} // OK
046 *   public &lt;k, V&gt; void method4() {} // violation, name 'k' must match pattern '^[A-Z]$'
047 * }
048 * </pre>
049 * <p>
050 * An example of how to configure the check for names that are only a single letter is:
051 * </p>
052 * <pre>
053 * &lt;module name=&quot;MethodTypeParameterName&quot;&gt;
054 *    &lt;property name=&quot;format&quot; value=&quot;^[a-zA-Z]$&quot;/&gt;
055 * &lt;/module&gt;
056 * </pre>
057 * <p>Code Example:</p>
058 * <pre>
059 * class MyClass {
060 *   public &lt;T&gt; void method1() {} // OK
061 *   public &lt;a&gt; void method2() {} // OK
062 *   public &lt;K, V&gt; void method3() {} // OK
063 *   public &lt;k, V&gt; void method4() {} // OK
064 * }
065 * </pre>
066 *
067 * @since 5.0
068 */
069public class MethodTypeParameterNameCheck
070    extends AbstractNameCheck {
071
072    /** Creates a new {@code MethodTypeParameterNameCheck} instance. */
073    public MethodTypeParameterNameCheck() {
074        super("^[A-Z]$");
075    }
076
077    @Override
078    public int[] getDefaultTokens() {
079        return getRequiredTokens();
080    }
081
082    @Override
083    public int[] getAcceptableTokens() {
084        return getRequiredTokens();
085    }
086
087    @Override
088    public int[] getRequiredTokens() {
089        return new int[] {
090            TokenTypes.TYPE_PARAMETER,
091        };
092    }
093
094    @Override
095    protected final boolean mustCheckName(DetailAST ast) {
096        final DetailAST location =
097            ast.getParent().getParent();
098        return location.getType() == TokenTypes.METHOD_DEF;
099    }
100
101}