001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2024 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.StatelessCheck;
023import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
024import com.puppycrawl.tools.checkstyle.api.DetailAST;
025import com.puppycrawl.tools.checkstyle.api.TokenTypes;
026import com.puppycrawl.tools.checkstyle.utils.CodePointUtil;
027import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
028
029/**
030 * <div>
031 * Checks that there is no whitespace before a token.
032 * More specifically, it checks that it is not preceded with whitespace,
033 * or (if linebreaks are allowed) all characters on the line before are
034 * whitespace. To allow linebreaks before a token, set property
035 * {@code allowLineBreaks} to {@code true}. No check occurs before semicolons in empty
036 * for loop initializers or conditions.
037 * </div>
038 * <ul>
039 * <li>
040 * Property {@code allowLineBreaks} - Control whether whitespace is allowed
041 * if the token is at a linebreak.
042 * Type is {@code boolean}.
043 * Default value is {@code false}.
044 * </li>
045 * <li>
046 * Property {@code tokens} - tokens to check
047 * Type is {@code java.lang.String[]}.
048 * Validation type is {@code tokenSet}.
049 * Default value is:
050 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#COMMA">
051 * COMMA</a>,
052 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#SEMI">
053 * SEMI</a>,
054 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#POST_INC">
055 * POST_INC</a>,
056 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#POST_DEC">
057 * POST_DEC</a>,
058 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ELLIPSIS">
059 * ELLIPSIS</a>,
060 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#LABELED_STAT">
061 * LABELED_STAT</a>.
062 * </li>
063 * </ul>
064 *
065 * <p>
066 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
067 * </p>
068 *
069 * <p>
070 * Violation Message Keys:
071 * </p>
072 * <ul>
073 * <li>
074 * {@code ws.preceded}
075 * </li>
076 * </ul>
077 *
078 * @since 3.0
079 */
080@StatelessCheck
081public class NoWhitespaceBeforeCheck
082    extends AbstractCheck {
083
084    /**
085     * A key is pointing to the warning message text in "messages.properties"
086     * file.
087     */
088    public static final String MSG_KEY = "ws.preceded";
089
090    /** Control whether whitespace is allowed if the token is at a linebreak. */
091    private boolean allowLineBreaks;
092
093    @Override
094    public int[] getDefaultTokens() {
095        return new int[] {
096            TokenTypes.COMMA,
097            TokenTypes.SEMI,
098            TokenTypes.POST_INC,
099            TokenTypes.POST_DEC,
100            TokenTypes.ELLIPSIS,
101            TokenTypes.LABELED_STAT,
102        };
103    }
104
105    @Override
106    public int[] getAcceptableTokens() {
107        return new int[] {
108            TokenTypes.COMMA,
109            TokenTypes.SEMI,
110            TokenTypes.POST_INC,
111            TokenTypes.POST_DEC,
112            TokenTypes.DOT,
113            TokenTypes.GENERIC_START,
114            TokenTypes.GENERIC_END,
115            TokenTypes.ELLIPSIS,
116            TokenTypes.LABELED_STAT,
117            TokenTypes.METHOD_REF,
118        };
119    }
120
121    @Override
122    public int[] getRequiredTokens() {
123        return CommonUtil.EMPTY_INT_ARRAY;
124    }
125
126    @Override
127    public void visitToken(DetailAST ast) {
128        final int[] line = getLineCodePoints(ast.getLineNo() - 1);
129        final int columnNoBeforeToken = ast.getColumnNo() - 1;
130        final boolean isFirstToken = columnNoBeforeToken == -1;
131
132        if ((isFirstToken || CommonUtil.isCodePointWhitespace(line, columnNoBeforeToken))
133                && !isInEmptyForInitializerOrCondition(ast)) {
134            final boolean isViolation = !allowLineBreaks
135                    || !isFirstToken
136                    && !CodePointUtil.hasWhitespaceBefore(columnNoBeforeToken, line);
137
138            if (isViolation) {
139                log(ast, MSG_KEY, ast.getText());
140            }
141        }
142    }
143
144    /**
145     * Checks that semicolon is in empty for initializer or condition.
146     *
147     * @param semicolonAst DetailAST of semicolon.
148     * @return true if semicolon is in empty for initializer or condition.
149     */
150    private static boolean isInEmptyForInitializerOrCondition(DetailAST semicolonAst) {
151        boolean result = false;
152        final DetailAST sibling = semicolonAst.getPreviousSibling();
153        if (sibling != null
154                && (sibling.getType() == TokenTypes.FOR_INIT
155                        || sibling.getType() == TokenTypes.FOR_CONDITION)
156                && !sibling.hasChildren()) {
157            result = true;
158        }
159        return result;
160    }
161
162    /**
163     * Setter to control whether whitespace is allowed if the token is at a linebreak.
164     *
165     * @param allowLineBreaks whether whitespace should be
166     *     flagged at line breaks.
167     * @since 3.0
168     */
169    public void setAllowLineBreaks(boolean allowLineBreaks) {
170        this.allowLineBreaks = allowLineBreaks;
171    }
172
173}