001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2026 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.sizes;
021
022import java.io.File;
023import java.util.regex.Pattern;
024
025import com.puppycrawl.tools.checkstyle.StatelessCheck;
026import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck;
027import com.puppycrawl.tools.checkstyle.api.FileText;
028import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
029
030/**
031 * <div>
032 * Checks for long lines.
033 * </div>
034 *
035 * <p>
036 * Rationale: Long lines are hard to read in printouts or if developers
037 * have limited screen space for the source code, e.g. if the IDE displays
038 * additional information like project tree, class hierarchy, etc.
039 * </p>
040 * <ul>
041 * <li>
042 * Notes:
043 * The calculation of the length of a line takes into account the number of
044 * expanded spaces for a tab character ({@code '\t'}). The default number of spaces is {@code 8}.
045 * To specify a different number of spaces, the user can set
046 * <a href="https://checkstyle.org/config.html#Checker">{@code Checker}</a>
047 * property {@code tabWidth} which applies to all Checks, including {@code LineLength};
048 * or can set property {@code tabWidth} for {@code LineLength} alone.
049 * </li>
050 * <li>
051 * By default, package and import statements (lines matching pattern {@code ^(package|import) .*})
052 * are not verified by this check.
053 * </li>
054 * <li>
055 * Trailing comments are taken into consideration while calculating the line length.
056 * {@snippet :
057 * import java.util.regex.Pattern; // The length of this comment will be taken into consideration
058 * }
059 * In the example above the length of the import statement is just 31 characters but total length
060 * will be 94 characters.
061 * </li>
062 * </ul>
063 *
064 * @since 3.0
065 * @noinspection EmptyClass
066 * @noinspectionreason EmptyClass - until IDEA-394242
067 */
068@StatelessCheck
069public class LineLengthCheck extends AbstractFileSetCheck {
070
071    /**
072     * A key is pointing to the warning message text in "messages.properties" file.
073     */
074    public static final String MSG_KEY = "maxLineLen";
075
076    /** Default maximum number of columns in a line. */
077    private static final int DEFAULT_MAX_COLUMNS = 80;
078
079    /** Specify the maximum line length allowed. */
080    private int max = DEFAULT_MAX_COLUMNS;
081
082    /** Specify pattern for lines to ignore. */
083    private Pattern ignorePattern = Pattern.compile("^(package|import) .*");
084
085    /**
086     * Creates a new {@code LineLengthCheck} instance.
087     */
088    public LineLengthCheck() {
089        // no code by default
090    }
091
092    @Override
093    protected void processFiltered(File file, FileText fileText) {
094        for (int index = 0; index < fileText.size(); index++) {
095            final String line = fileText.get(index);
096            final int realLength = CommonUtil.lengthExpandedTabs(
097                line, line.codePointCount(0, line.length()), getTabWidth());
098
099            if (realLength > max && !ignorePattern.matcher(line).find()) {
100                log(index + 1, MSG_KEY, max, realLength);
101            }
102        }
103    }
104
105    /**
106     * Setter to specify the maximum line length allowed.
107     *
108     * @param length the maximum length of a line
109     * @since 3.0
110     */
111    public void setMax(int length) {
112        max = length;
113    }
114
115    /**
116     * Setter to specify pattern for lines to ignore.
117     *
118     * @param pattern a pattern.
119     * @since 3.0
120     */
121    public final void setIgnorePattern(Pattern pattern) {
122        ignorePattern = pattern;
123    }
124
125    /**
126     * Setter to specify the file extensions of the files to process.
127     *
128     * @param extensions the set of file extensions. A missing
129     *         initial '.' character of an extension is automatically added.
130     * @throws IllegalArgumentException is argument is null
131     * @propertySince 8.24
132     */
133    @Override
134    public final void setFileExtensions(String... extensions) {
135        super.setFileExtensions(extensions);
136    }
137
138}