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;
024import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
025import com.puppycrawl.tools.checkstyle.utils.ScopeUtil;
026
027/**
028 * <p>
029 * Checks that local final variable names conform to a specified pattern.
030 *  A catch parameter and resources in try statements
031 * are considered to be a local, final variables.
032 * </p>
033 * <ul>
034 * <li>
035 * Property {@code format} - Specifies valid identifiers.
036 * Type is {@code java.util.regex.Pattern}.
037 * Default value is {@code "^[a-z][a-zA-Z0-9]*$"}.
038 * </li>
039 * <li>
040 * Property {@code tokens} - tokens to check
041 * Type is {@code int[]}.
042 * Default value is:
043 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#VARIABLE_DEF">
044 * VARIABLE_DEF</a>,
045 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#PARAMETER_DEF">
046 * PARAMETER_DEF</a>,
047 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#RESOURCE">
048 * RESOURCE</a>.
049 * </li>
050 * </ul>
051 * <p>
052 * An example of how to configure the check is:
053 * </p>
054 * <pre>
055 * &lt;module name="LocalFinalVariableName"/&gt;
056 * </pre>
057 * <p>
058 * An example of how to configure the check for names that are only upper case
059 * letters and digits is:
060 * </p>
061 * <pre>
062 * &lt;module name="LocalFinalVariableName"&gt;
063 *   &lt;property name="format" value="^[A-Z][A-Z0-9]*$"/&gt;
064 * &lt;/module&gt;
065 * </pre>
066 * <p>Code Example:</p>
067 * <pre>
068 * class MyClass {
069 *   void MyMethod() {
070 *     try {
071 *       final int VAR1 = 5; // OK
072 *       final int var1 = 10; // violation,  name 'var1' must match pattern "^[A-Z][A-Z0-9]*$"
073 *     } catch (Exception ex) {
074 *       final int VAR2 = 15; // OK
075 *       final int var2 = 20; // violation,  name 'var2' must match pattern "^[A-Z][A-Z0-9]*$"
076 *     }
077 *   }
078 * }
079 * </pre>
080 * <p>
081 * An example of how to configure the check for names of local final parameters and
082 * resources in try statements (without checks on variables):
083 * </p>
084 * <pre>
085 * &lt;module name=&quot;LocalFinalVariableName&quot;&gt;
086 *   &lt;property name="format" value="^[A-Z][A-Z0-9]*$"/&gt;
087 *   &lt;property name="tokens" value="PARAMETER_DEF,RESOURCE"/&gt;
088 * &lt;/module&gt;
089 * </pre>
090 * <p>Code Example:</p>
091 * <pre>
092 * class MyClass {
093 *   void MyMethod() {
094 *     try(Scanner scanner = new Scanner()) { // violation, name 'scanner' must
095 *                                            // match pattern '^[A-Z][A-Z0-9]*$'
096 *       final int VAR1 = 5; // OK
097 *       final int var1 = 10; // OK
098 *     } catch (final Exception ex) { // violation, name 'ex'
099 *                                    // must match pattern '^[A-Z][A-Z0-9]*$'
100 *       final int VAR2 = 15; // OK
101 *       final int var2 = 20; // OK
102 *     }
103 *   }
104 * }
105 * </pre>
106 * <p>
107 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
108 * </p>
109 * <p>
110 * Violation Message Keys:
111 * </p>
112 * <ul>
113 * <li>
114 * {@code name.invalidPattern}
115 * </li>
116 * </ul>
117 *
118 * @since 3.0
119 */
120public class LocalFinalVariableNameCheck
121    extends AbstractNameCheck {
122
123    /** Creates a new {@code LocalFinalVariableNameCheck} instance. */
124    public LocalFinalVariableNameCheck() {
125        super("^[a-z][a-zA-Z0-9]*$");
126    }
127
128    @Override
129    public int[] getDefaultTokens() {
130        return getAcceptableTokens();
131    }
132
133    @Override
134    public int[] getAcceptableTokens() {
135        return new int[] {
136            TokenTypes.VARIABLE_DEF,
137            TokenTypes.PARAMETER_DEF,
138            TokenTypes.RESOURCE,
139        };
140    }
141
142    @Override
143    public int[] getRequiredTokens() {
144        return CommonUtil.EMPTY_INT_ARRAY;
145    }
146
147    @Override
148    protected final boolean mustCheckName(DetailAST ast) {
149        final DetailAST modifiersAST =
150            ast.findFirstToken(TokenTypes.MODIFIERS);
151        final boolean isFinal = ast.getType() == TokenTypes.RESOURCE
152            || modifiersAST.findFirstToken(TokenTypes.FINAL) != null;
153        return isFinal && ScopeUtil.isLocalVariableDef(ast);
154    }
155
156}