001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2014  Oliver Burn
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.blocks;
021
022
023import com.puppycrawl.tools.checkstyle.api.Check;
024import com.puppycrawl.tools.checkstyle.api.DetailAST;
025import com.puppycrawl.tools.checkstyle.api.TokenTypes;
026
027/**
028 * <p>
029 * Checks for braces around code blocks.
030 * </p>
031 * <p> By default the check will check the following blocks:
032 *  {@link TokenTypes#LITERAL_DO LITERAL_DO},
033 *  {@link TokenTypes#LITERAL_ELSE LITERAL_ELSE},
034 *  {@link TokenTypes#LITERAL_FOR LITERAL_FOR},
035 *  {@link TokenTypes#LITERAL_IF LITERAL_IF},
036 *  {@link TokenTypes#LITERAL_WHILE LITERAL_WHILE}.
037 * </p>
038 * <p>
039 * An example of how to configure the check is:
040 * </p>
041 * <pre>
042 * &lt;module name="NeedBraces"/&gt;
043 * </pre>
044 * <p> An example of how to configure the check for <code>if</code> and
045 * <code>else</code> blocks is:
046 * </p>
047 * <pre>
048 * &lt;module name="NeedBraces"&gt;
049 *     &lt;property name="tokens" value="LITERAL_IF, LITERAL_ELSE"/&gt;
050 * &lt;/module&gt;
051 * </pre>
052 * Check has an option <b>allowSingleLineIf</b> which allows one line
053 * if-statements without braces, e.g.:
054 * <p>
055 * <code>
056 * if (obj.isValid()) return true;
057 * </code>
058 * </p>
059 * <br>
060 *
061 * @author Rick Giles
062 * @author <a href="mailto:nesterenko-aleksey@list.ru">Aleksey Nesterenko</a>
063 * @version 1.0
064 */
065public class NeedBracesCheck extends Check
066{
067    /**
068     * Check's option for skipping single-line if-statements.
069     */
070    private boolean allowSingleLineIf;
071
072    /**
073     * A key is pointing to the warning message text in "messages.properties"
074     * file.
075     */
076    public static final String MSG_KEY_NEED_BRACES = "needBraces";
077
078    /**
079     * Setter.
080     * @param allowSingleLineIf Check's option for skipping single-line if-statements
081     */
082    public void setAllowSingleLineIf(boolean allowSingleLineIf)
083    {
084        this.allowSingleLineIf = allowSingleLineIf;
085    }
086
087    @Override
088    public int[] getDefaultTokens()
089    {
090        return new int[] {
091            TokenTypes.LITERAL_DO,
092            TokenTypes.LITERAL_ELSE,
093            TokenTypes.LITERAL_FOR,
094            TokenTypes.LITERAL_IF,
095            TokenTypes.LITERAL_WHILE,
096        };
097    }
098
099    @Override
100    public void visitToken(DetailAST ast)
101    {
102        final DetailAST slistAST = ast.findFirstToken(TokenTypes.SLIST);
103        boolean isElseIf = false;
104        if ((ast.getType() == TokenTypes.LITERAL_ELSE)
105            && (ast.findFirstToken(TokenTypes.LITERAL_IF) != null))
106        {
107            isElseIf = true;
108        }
109        boolean skipStatement = false;
110        if (ast.getType() == TokenTypes.LITERAL_IF) {
111            skipStatement = isSkipIfBlock(ast);
112        }
113        if ((slistAST == null) && !isElseIf && !skipStatement) {
114            log(ast.getLineNo(), MSG_KEY_NEED_BRACES, ast.getText());
115        }
116    }
117
118    /**
119     * Checks if current if-block can be skipped by "need braces" warning.
120     * @param literalIf {@link TokenTypes#LITERAL_IF LITERAL_IF}
121     * @return true if current if block can be skipped by Check
122     */
123    private boolean isSkipIfBlock(DetailAST literalIf)
124    {
125        return allowSingleLineIf && isSingleLineIf(literalIf);
126    }
127
128    /**
129     * Checks if current if-statement is single-line statement, e.g.:
130     * <p>
131     * <code>
132     * if (obj.isValid()) return true;
133     * </code>
134     * </p>
135     * @param literalIf {@link TokenTypes#LITERAL_IF LITERAL_IF}
136     * @return true if current if-statement is single-line statement
137     */
138    private static boolean isSingleLineIf(DetailAST literalIf)
139    {
140        boolean result = false;
141        final DetailAST ifBlock = literalIf.getLastChild();
142        final DetailAST lastElementInIfBlock = ifBlock.getLastChild();
143        if (lastElementInIfBlock != null
144            && lastElementInIfBlock.getFirstChild() == null
145            && literalIf.getLineNo() == lastElementInIfBlock.getLineNo())
146        {
147            result = true;
148        }
149        return result;
150    }
151}