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.whitespace;
021
022import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
023import com.puppycrawl.tools.checkstyle.api.DetailAST;
024import com.puppycrawl.tools.checkstyle.api.TokenTypes;
025import com.puppycrawl.tools.checkstyle.utils.CommonUtils;
026
027/**
028 * <p>
029 * Checks that there is no whitespace before a token.
030 * More specifically, it checks that it is not preceded with whitespace,
031 * or (if line breaks are allowed) all characters on the line before are
032 * whitespace. To allow line breaks before a token, set property
033 * allowLineBreaks to true.
034 * </p>
035 * <p> By default the check will check the following operators:
036 *  {@link TokenTypes#SEMI SEMI},
037 *  {@link TokenTypes#POST_DEC POST_DEC},
038 *  {@link TokenTypes#POST_INC POST_INC}.
039 * {@link TokenTypes#DOT DOT} is also an acceptable token in a configuration
040 * of this check.
041 * </p>
042 *
043 * <p>
044 * An example of how to configure the check is:
045 * </p>
046 * <pre>
047 * &lt;module name="NoWhitespaceBefore"/&gt;
048 * </pre>
049 * <p> An example of how to configure the check to allow line breaks before
050 * a {@link TokenTypes#DOT DOT} token is:
051 * </p>
052 * <pre>
053 * &lt;module name="NoWhitespaceBefore"&gt;
054 *     &lt;property name="tokens" value="DOT"/&gt;
055 *     &lt;property name="allowLineBreaks" value="true"/&gt;
056 * &lt;/module&gt;
057 * </pre>
058 * @author Rick Giles
059 * @author lkuehne
060 */
061public class NoWhitespaceBeforeCheck
062    extends AbstractCheck {
063
064    /**
065     * A key is pointing to the warning message text in "messages.properties"
066     * file.
067     */
068    public static final String MSG_KEY = "ws.preceded";
069
070    /** Whether whitespace is allowed if the AST is at a linebreak. */
071    private boolean allowLineBreaks;
072
073    @Override
074    public int[] getDefaultTokens() {
075        return new int[] {
076            TokenTypes.COMMA,
077            TokenTypes.SEMI,
078            TokenTypes.POST_INC,
079            TokenTypes.POST_DEC,
080        };
081    }
082
083    @Override
084    public int[] getAcceptableTokens() {
085        return new int[] {
086            TokenTypes.COMMA,
087            TokenTypes.SEMI,
088            TokenTypes.POST_INC,
089            TokenTypes.POST_DEC,
090            TokenTypes.DOT,
091            TokenTypes.GENERIC_START,
092            TokenTypes.GENERIC_END,
093        };
094    }
095
096    @Override
097    public int[] getRequiredTokens() {
098        return CommonUtils.EMPTY_INT_ARRAY;
099    }
100
101    @Override
102    public void visitToken(DetailAST ast) {
103        final String line = getLine(ast.getLineNo() - 1);
104        final int before = ast.getColumnNo() - 1;
105
106        if ((before < 0 || Character.isWhitespace(line.charAt(before)))
107                && !isInEmptyForInitializer(ast)) {
108
109            boolean flag = !allowLineBreaks;
110            // verify all characters before '.' are whitespace
111            for (int i = 0; !flag && i < before; i++) {
112                if (!Character.isWhitespace(line.charAt(i))) {
113                    flag = true;
114                }
115            }
116            if (flag) {
117                log(ast.getLineNo(), before, MSG_KEY, ast.getText());
118            }
119        }
120    }
121
122    /**
123     * Checks that semicolon is in empty for initializer.
124     * @param semicolonAst DetailAST of semicolon.
125     * @return true if semicolon is in empty for initializer.
126     */
127    private static boolean isInEmptyForInitializer(DetailAST semicolonAst) {
128        boolean result = false;
129        if (semicolonAst.getType() == TokenTypes.SEMI) {
130            final DetailAST sibling = semicolonAst.getPreviousSibling();
131            if (sibling != null
132                    && sibling.getType() == TokenTypes.FOR_INIT
133                    && sibling.getChildCount() == 0) {
134                result = true;
135            }
136        }
137        return result;
138    }
139
140    /**
141     * Control whether whitespace is flagged at line breaks.
142     * @param allowLineBreaks whether whitespace should be
143     *     flagged at line breaks.
144     */
145    public void setAllowLineBreaks(boolean allowLineBreaks) {
146        this.allowLineBreaks = allowLineBreaks;
147    }
148}