001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2015 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 org.apache.commons.lang3.ArrayUtils;
025
026import com.puppycrawl.tools.checkstyle.api.DetailAST;
027import com.puppycrawl.tools.checkstyle.api.TokenTypes;
028import com.puppycrawl.tools.checkstyle.utils.ScopeUtils;
029
030/**
031 * <p>
032 * Checks that local, non-final variable names conform to a format specified
033 * by the format property. A catch parameter is considered to be
034 * a local variable. The format is a
035 * {@link Pattern regular expression}
036 * and defaults to
037 * <strong>^[a-z][a-zA-Z0-9]*$</strong>.
038 * </p>
039 * <p>
040 * An example of how to configure the check is:
041 * </p>
042 * <pre>
043 * &lt;module name="LocalVariableName"/&gt;
044 * </pre>
045 * <p>
046 * An example of how to configure the check for names that begin with a lower
047 * case letter, followed by letters, digits, and underscores is:
048 * </p>
049 * <pre>
050 * &lt;module name="LocalVariableName"&gt;
051 *    &lt;property name="format" value="^[a-z](_?[a-zA-Z0-9]+)*$"/&gt;
052 * &lt;/module&gt;
053 * </pre>
054 * <p>
055 * An example of one character variable name in
056 * initialization expression(like "i") in FOR loop:
057 * </p>
058 * <pre>
059 * for(int i = 1; i &lt; 10; i++) {}
060 * </pre>
061 * <p>
062 * An example of how to configure the check to allow one char variable name in
063 * <a href="http://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html">
064 * initialization expressions</a> in FOR loop:
065 * </p>
066 * <pre>
067 * &lt;module name="LocalVariableName"&gt;
068 *    &lt;property name="allowOneCharVarInForLoop" value="true"/&gt;
069 * &lt;/module&gt;
070 * </pre>
071 *
072 * @author Rick Giles
073 * @author maxvetrenko
074 */
075public class LocalVariableNameCheck
076    extends AbstractNameCheck {
077    /** Regexp for one-char loop variables. */
078    private static final Pattern SINGLE_CHAR = Pattern.compile("^[a-z]$");
079
080    /**
081     * Allow one character name for initialization expression in FOR loop.
082     */
083    private boolean allowOneCharVarInForLoop;
084
085    /** Creates a new {@code LocalVariableNameCheck} instance. */
086    public LocalVariableNameCheck() {
087        super("^[a-z][a-zA-Z0-9]*$");
088    }
089
090    /**
091     * Sets whether to allow one character name in FOR loop or not.
092     *
093     * @param allow Flag for allowing or not one character name in FOR loop.
094     */
095    public final void setAllowOneCharVarInForLoop(boolean allow) {
096        allowOneCharVarInForLoop = allow;
097    }
098
099    @Override
100    public int[] getDefaultTokens() {
101        return getAcceptableTokens();
102    }
103
104    @Override
105    public int[] getAcceptableTokens() {
106        return new int[] {
107            TokenTypes.VARIABLE_DEF,
108            TokenTypes.PARAMETER_DEF,
109        };
110    }
111
112    @Override
113    public int[] getRequiredTokens() {
114        return ArrayUtils.EMPTY_INT_ARRAY;
115    }
116
117    @Override
118    protected final boolean mustCheckName(DetailAST ast) {
119        if (allowOneCharVarInForLoop && isForLoopVariable(ast)) {
120            final String variableName =
121                    ast.findFirstToken(TokenTypes.IDENT).getText();
122            return !SINGLE_CHAR.matcher(variableName).find();
123        }
124        final DetailAST modifiersAST =
125            ast.findFirstToken(TokenTypes.MODIFIERS);
126        final boolean isFinal = modifiersAST.branchContains(TokenTypes.FINAL);
127        return !isFinal && ScopeUtils.isLocalVariableDef(ast);
128    }
129
130    /**
131     * Checks if a variable is the loop's one.
132     * @param variableDef variable definition.
133     * @return true if a variable is the loop's one.
134     */
135    private static boolean isForLoopVariable(DetailAST variableDef) {
136        final int parentType = variableDef.getParent().getType();
137        return parentType == TokenTypes.FOR_INIT
138                || parentType == TokenTypes.FOR_EACH_CLAUSE;
139    }
140}