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