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.
032 * Type is {@code java.util.regex.Pattern}.
033 * Default value is {@code "^[A-Z]$"}.
034 * </li>
035 * </ul>
036 * <p>
037 * To configure the check:
038 * </p>
039 * <pre>
040 * &lt;module name="InterfaceTypeParameterName"/&gt;
041 * </pre>
042 * <p>Code Example:</p>
043 * <pre>
044 * interface FirstInterface&lt;T&gt; {} // OK
045 * interface SecondInterface&lt;t&gt; {} // violation, name 't' must match pattern '^[A-Z]$'
046 * </pre>
047 * <p>
048 * An example of how to configure the check for names that are only a single
049 * letter is:
050 * </p>
051 * <pre>
052 * &lt;module name="InterfaceTypeParameterName"&gt;
053 *    &lt;property name="format" value="^[a-zA-Z]$"/&gt;
054 * &lt;/module&gt;
055 * </pre>
056 * <p>Code Example:</p>
057 * <pre>
058 * interface FirstInterface&lt;T&gt; {} // OK
059 * interface SecondInterface&lt;t&gt; {} // OK
060 * interface ThirdInterface&lt;type&gt; {} // violation, name 'type' must
061 *                                         // match pattern '^[a-zA-Z]$'
062 * </pre>
063 * <p>
064 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
065 * </p>
066 * <p>
067 * Violation Message Keys:
068 * </p>
069 * <ul>
070 * <li>
071 * {@code name.invalidPattern}
072 * </li>
073 * </ul>
074 *
075 * @since 5.8
076 */
077public class InterfaceTypeParameterNameCheck
078    extends AbstractNameCheck {
079
080    /** Creates a new {@code InterfaceTypeParameterNameCheck} instance. */
081    public InterfaceTypeParameterNameCheck() {
082        super("^[A-Z]$");
083    }
084
085    @Override
086    public int[] getDefaultTokens() {
087        return getRequiredTokens();
088    }
089
090    @Override
091    public int[] getAcceptableTokens() {
092        return getRequiredTokens();
093    }
094
095    @Override
096    public int[] getRequiredTokens() {
097        return new int[] {
098            TokenTypes.TYPE_PARAMETER,
099        };
100    }
101
102    @Override
103    protected final boolean mustCheckName(DetailAST ast) {
104        final DetailAST location =
105            ast.getParent().getParent();
106        return location.getType() == TokenTypes.INTERFACE_DEF;
107    }
108
109}