001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2017 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 java.util.regex.Pattern;
023
024import com.puppycrawl.tools.checkstyle.api.DetailAST;
025import com.puppycrawl.tools.checkstyle.api.TokenTypes;
026import com.puppycrawl.tools.checkstyle.utils.ScopeUtils;
027
028/**
029 * <p>
030 * Checks that local, non-final variable names conform to a format specified
031 * by the format property. A catch parameter is considered to be
032 * a local variable. The format is a
033 * {@link Pattern regular expression}
034 * and defaults to
035 * <strong>^[a-z][a-zA-Z0-9]*$</strong>.
036 * </p>
037 * <p>
038 * An example of how to configure the check is:
039 * </p>
040 * <pre>
041 * &lt;module name="LocalVariableName"/&gt;
042 * </pre>
043 * <p>
044 * An example of how to configure the check for names that begin with a lower
045 * case letter, followed by letters, digits, and underscores is:
046 * </p>
047 * <pre>
048 * &lt;module name="LocalVariableName"&gt;
049 *    &lt;property name="format" value="^[a-z](_?[a-zA-Z0-9]+)*$"/&gt;
050 * &lt;/module&gt;
051 * </pre>
052 * <p>
053 * An example of one character variable name in
054 * initialization expression(like "i") in FOR loop:
055 * </p>
056 * <pre>
057 * for(int i = 1; i &lt; 10; i++) {}
058 * </pre>
059 * <p>
060 * An example of how to configure the check to allow one char variable name in
061 * <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
062 * initialization expressions</a> in FOR loop:
063 * </p>
064 * <pre>
065 * &lt;module name="LocalVariableName"&gt;
066 *    &lt;property name="allowOneCharVarInForLoop" value="true"/&gt;
067 * &lt;/module&gt;
068 * </pre>
069 *
070 * @author Rick Giles
071 * @author maxvetrenko
072 */
073public class LocalVariableNameCheck
074    extends AbstractNameCheck {
075    /** Regexp for one-char loop variables. */
076    private static final Pattern SINGLE_CHAR = Pattern.compile("^[a-z]$");
077
078    /**
079     * Allow one character name for initialization expression in FOR loop.
080     */
081    private boolean allowOneCharVarInForLoop;
082
083    /** Creates a new {@code LocalVariableNameCheck} instance. */
084    public LocalVariableNameCheck() {
085        super("^[a-z][a-zA-Z0-9]*$");
086    }
087
088    /**
089     * Sets whether to allow one character name in FOR loop or not.
090     *
091     * @param allow Flag for allowing or not one character name in FOR loop.
092     */
093    public final void setAllowOneCharVarInForLoop(boolean allow) {
094        allowOneCharVarInForLoop = allow;
095    }
096
097    @Override
098    public int[] getDefaultTokens() {
099        return getAcceptableTokens();
100    }
101
102    @Override
103    public int[] getAcceptableTokens() {
104        return new int[] {
105            TokenTypes.VARIABLE_DEF,
106        };
107    }
108
109    @Override
110    public int[] getRequiredTokens() {
111        return getAcceptableTokens();
112    }
113
114    @Override
115    protected final boolean mustCheckName(DetailAST ast) {
116        final boolean result;
117        if (allowOneCharVarInForLoop && isForLoopVariable(ast)) {
118            final String variableName = ast.findFirstToken(TokenTypes.IDENT).getText();
119            result = !SINGLE_CHAR.matcher(variableName).find();
120        }
121        else {
122            final DetailAST modifiersAST = ast.findFirstToken(TokenTypes.MODIFIERS);
123            final boolean isFinal = modifiersAST.findFirstToken(TokenTypes.FINAL) != null;
124            result = !isFinal && ScopeUtils.isLocalVariableDef(ast);
125        }
126        return result;
127    }
128
129    /**
130     * Checks if a variable is the loop's one.
131     * @param variableDef variable definition.
132     * @return true if a variable is the loop's one.
133     */
134    private static boolean isForLoopVariable(DetailAST variableDef) {
135        final int parentType = variableDef.getParent().getType();
136        return parentType == TokenTypes.FOR_INIT
137                || parentType == TokenTypes.FOR_EACH_CLAUSE;
138    }
139}