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 interface 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]$"}.
033 * </li>
034 * </ul>
035 * <p>
036 * An example of how to configure the check is:
037 * </p>
038 * <pre>
039 * &lt;module name="InterfaceTypeParameterName"/&gt;
040 * </pre>
041 * <p>Code Example:</p>
042 * <pre>
043 * interface FirstInterface&lt;T&gt; {} // OK
044 * interface SecondInterface&lt;t&gt; {} // violation, name 't' must match pattern '^[A-Z]$'
045 * </pre>
046 * <p>
047 * An example of how to configure the check for names that are only a single
048 * letter is:
049 * </p>
050 * <pre>
051 * &lt;module name="InterfaceTypeParameterName"&gt;
052 *    &lt;property name="format" value="^[a-zA-Z]$"/&gt;
053 * &lt;/module&gt;
054 * </pre>
055 * <p>Code Example:</p>
056 * <pre>
057 * interface FirstInterface&lt;T&gt; {} // OK
058 * interface SecondInterface&lt;t&gt; {} // OK
059 * interface ThirdInterface&lt;type&gt; {} // violation, name 'type' must
060 *                                         // match pattern '^[a-zA-Z]$'
061 * </pre>
062 *
063 * @since 5.8
064 */
065public class InterfaceTypeParameterNameCheck
066    extends AbstractNameCheck {
067
068    /** Creates a new {@code InterfaceTypeParameterNameCheck} instance. */
069    public InterfaceTypeParameterNameCheck() {
070        super("^[A-Z]$");
071    }
072
073    @Override
074    public int[] getDefaultTokens() {
075        return getRequiredTokens();
076    }
077
078    @Override
079    public int[] getAcceptableTokens() {
080        return getRequiredTokens();
081    }
082
083    @Override
084    public int[] getRequiredTokens() {
085        return new int[] {
086            TokenTypes.TYPE_PARAMETER,
087        };
088    }
089
090    @Override
091    protected final boolean mustCheckName(DetailAST ast) {
092        final DetailAST location =
093            ast.getParent().getParent();
094        return location.getType() == TokenTypes.INTERFACE_DEF;
095    }
096
097}