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 interface 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]$"}.
032 * </li>
033 * </ul>
034 * <p>
035 * An example of how to configure the check is:
036 * </p>
037 * <pre>
038 * &lt;module name="InterfaceTypeParameterName"/&gt;
039 * </pre>
040 * <p>Code Example:</p>
041 * <pre>
042 * interface FirstInterface&lt;T&gt; {} // OK
043 * interface SecondInterface&lt;t&gt; {} // violation, name 't' must match pattern '^[A-Z]$'
044 * </pre>
045 * <p>
046 * An example of how to configure the check for names that are only a single
047 * letter is:
048 * </p>
049 * <pre>
050 * &lt;module name="InterfaceTypeParameterName"&gt;
051 *    &lt;property name="format" value="^[a-zA-Z]$"/&gt;
052 * &lt;/module&gt;
053 * </pre>
054 * <p>Code Example:</p>
055 * <pre>
056 * interface FirstInterface&lt;T&gt; {} // OK
057 * interface SecondInterface&lt;t&gt; {} // OK
058 * interface ThirdInterface&lt;type&gt; {} // violation, name 'type' must
059 *                                         // match pattern '^[a-zA-Z]$'
060 * </pre>
061 *
062 * @since 5.8
063 */
064public class InterfaceTypeParameterNameCheck
065    extends AbstractNameCheck {
066
067    /** Creates a new {@code InterfaceTypeParameterNameCheck} instance. */
068    public InterfaceTypeParameterNameCheck() {
069        super("^[A-Z]$");
070    }
071
072    @Override
073    public int[] getDefaultTokens() {
074        return getRequiredTokens();
075    }
076
077    @Override
078    public int[] getAcceptableTokens() {
079        return getRequiredTokens();
080    }
081
082    @Override
083    public int[] getRequiredTokens() {
084        return new int[] {
085            TokenTypes.TYPE_PARAMETER,
086        };
087    }
088
089    @Override
090    protected final boolean mustCheckName(DetailAST ast) {
091        final DetailAST location =
092            ast.getParent().getParent();
093        return location.getType() == TokenTypes.INTERFACE_DEF;
094    }
095
096}