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