001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2025 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 * <div class="wrapper"><pre class="prettyprint"><code class="language-java">
057 * import java.util.regex.Pattern; // The length of this comment will be taken into consideration
058 * </code></pre></div>
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 * <ul>
064 * <li>
065 * Property {@code fileExtensions} - Specify the file extensions of the files to process.
066 * Type is {@code java.lang.String[]}.
067 * Default value is {@code ""}.
068 * Since version 8.24
069 * </li>
070 * <li>
071 * Property {@code ignorePattern} - Specify pattern for lines to ignore.
072 * Type is {@code java.util.regex.Pattern}.
073 * Default value is {@code "^(package|import) .*"}.
074 * </li>
075 * <li>
076 * Property {@code max} - Specify the maximum line length allowed.
077 * Type is {@code int}.
078 * Default value is {@code 80}.
079 * </li>
080 * </ul>
081 *
082 * <p>
083 * Parent is {@code com.puppycrawl.tools.checkstyle.Checker}
084 * </p>
085 *
086 * <p>
087 * Violation Message Keys:
088 * </p>
089 * <ul>
090 * <li>
091 * {@code maxLineLen}
092 * </li>
093 * </ul>
094 *
095 * @since 3.0
096 */
097@StatelessCheck
098public class LineLengthCheck extends AbstractFileSetCheck {
099
100    /**
101     * A key is pointing to the warning message text in "messages.properties"
102     * file.
103     */
104    public static final String MSG_KEY = "maxLineLen";
105
106    /** Default maximum number of columns in a line. */
107    private static final int DEFAULT_MAX_COLUMNS = 80;
108
109    /** Specify the maximum line length allowed. */
110    private int max = DEFAULT_MAX_COLUMNS;
111
112    /** Specify pattern for lines to ignore. */
113    private Pattern ignorePattern = Pattern.compile("^(package|import) .*");
114
115    @Override
116    protected void processFiltered(File file, FileText fileText) {
117        for (int i = 0; i < fileText.size(); i++) {
118            final String line = fileText.get(i);
119            final int realLength = CommonUtil.lengthExpandedTabs(
120                line, line.codePointCount(0, line.length()), getTabWidth());
121
122            if (realLength > max && !ignorePattern.matcher(line).find()) {
123                log(i + 1, MSG_KEY, max, realLength);
124            }
125        }
126    }
127
128    /**
129     * Setter to specify the maximum line length allowed.
130     *
131     * @param length the maximum length of a line
132     * @since 3.0
133     */
134    public void setMax(int length) {
135        max = length;
136    }
137
138    /**
139     * Setter to specify pattern for lines to ignore.
140     *
141     * @param pattern a pattern.
142     * @since 3.0
143     */
144    public final void setIgnorePattern(Pattern pattern) {
145        ignorePattern = pattern;
146    }
147
148}