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 * The calculation of the length of a line takes into account the number of
043 * expanded spaces for a tab character ({@code '\t'}). The default number of spaces is {@code 8}.
044 * To specify a different number of spaces, the user can set
045 * <a href="https://checkstyle.org/config.html#Checker">{@code Checker}</a>
046 * property {@code tabWidth} which applies to all Checks, including {@code LineLength};
047 * or can set property {@code tabWidth} for {@code LineLength} alone.
048 * </li>
049 * <li>
050 * By default, package and import statements (lines matching pattern {@code ^(package|import) .*})
051 * are not verified by this check.
052 * </li>
053 * <li>
054 * Trailing comments are taken into consideration while calculating the line length.
055 * <pre>
056 * import java.util.regex.Pattern; // The length of this comment will be taken into consideration
057 * </pre>
058 * In the example above the length of the import statement is just 31 characters but total length
059 * will be 94 characters.
060 * </li>
061 * </ul>
062 * <ul>
063 * <li>
064 * Property {@code fileExtensions} - Specify the file extensions of the files to process.
065 * Type is {@code java.lang.String[]}.
066 * Default value is {@code ""}.
067 * Since version 8.24
068 * </li>
069 * <li>
070 * Property {@code ignorePattern} - Specify pattern for lines to ignore.
071 * Type is {@code java.util.regex.Pattern}.
072 * Default value is {@code "^(package|import) .*"}.
073 * </li>
074 * <li>
075 * Property {@code max} - Specify the maximum line length allowed.
076 * Type is {@code int}.
077 * Default value is {@code 80}.
078 * </li>
079 * </ul>
080 *
081 * <p>
082 * Parent is {@code com.puppycrawl.tools.checkstyle.Checker}
083 * </p>
084 *
085 * <p>
086 * Violation Message Keys:
087 * </p>
088 * <ul>
089 * <li>
090 * {@code maxLineLen}
091 * </li>
092 * </ul>
093 *
094 * @since 3.0
095 */
096@StatelessCheck
097public class LineLengthCheck extends AbstractFileSetCheck {
098
099    /**
100     * A key is pointing to the warning message text in "messages.properties"
101     * file.
102     */
103    public static final String MSG_KEY = "maxLineLen";
104
105    /** Default maximum number of columns in a line. */
106    private static final int DEFAULT_MAX_COLUMNS = 80;
107
108    /** Specify the maximum line length allowed. */
109    private int max = DEFAULT_MAX_COLUMNS;
110
111    /** Specify pattern for lines to ignore. */
112    private Pattern ignorePattern = Pattern.compile("^(package|import) .*");
113
114    @Override
115    protected void processFiltered(File file, FileText fileText) {
116        for (int i = 0; i < fileText.size(); i++) {
117            final String line = fileText.get(i);
118            final int realLength = CommonUtil.lengthExpandedTabs(
119                line, line.codePointCount(0, line.length()), getTabWidth());
120
121            if (realLength > max && !ignorePattern.matcher(line).find()) {
122                log(i + 1, MSG_KEY, max, realLength);
123            }
124        }
125    }
126
127    /**
128     * Setter to specify the maximum line length allowed.
129     *
130     * @param length the maximum length of a line
131     * @since 3.0
132     */
133    public void setMax(int length) {
134        max = length;
135    }
136
137    /**
138     * Setter to specify pattern for lines to ignore.
139     *
140     * @param pattern a pattern.
141     * @since 3.0
142     */
143    public final void setIgnorePattern(Pattern pattern) {
144        ignorePattern = pattern;
145    }
146
147}