001//////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code for adherence to a set of rules. 003// Copyright (C) 2001-2020 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.javadoc; 021 022import java.util.Locale; 023 024import com.puppycrawl.tools.checkstyle.StatelessCheck; 025import com.puppycrawl.tools.checkstyle.api.AbstractCheck; 026import com.puppycrawl.tools.checkstyle.api.DetailAST; 027import com.puppycrawl.tools.checkstyle.api.TokenTypes; 028import com.puppycrawl.tools.checkstyle.utils.JavadocUtil; 029 030/** 031 * <p> 032 * Checks that the Javadoc content begins from the same position 033 * for all Javadoc comments in the project. Any leading asterisks and spaces 034 * are not counted as the beginning of the content and are therefore ignored. 035 * </p> 036 * <p> 037 * It is possible to enforce two different styles: 038 * </p> 039 * <ul> 040 * <li> 041 * {@code first_line} - Javadoc content starts from the first line: 042 * <pre> 043 * /** Summary text. 044 * * More details. 045 * */ 046 * public void method(); 047 * </pre> 048 * </li> 049 * <li> 050 * {@code second_line} - Javadoc content starts from the second line: 051 * <pre> 052 * /** 053 * * Summary text. 054 * * More details. 055 * */ 056 * public void method(); 057 * </pre> 058 * </li> 059 * </ul> 060 * <p> 061 * This check does not validate the Javadoc summary itself nor its presence. 062 * The check will not report any violations for missing or malformed javadoc summary. 063 * To validate the Javadoc summary use 064 * <a href="https://checkstyle.org/config_javadoc.html#SummaryJavadoc">SummaryJavadoc</a> check. 065 * </p> 066 * <p> 067 * The <a href="https://docs.oracle.com/en/java/javase/11/docs/specs/doc-comment-spec.html"> 068 * Documentation Comment Specification</a> permits leading asterisks on the first line. 069 * For these Javadoc comments: 070 * </p> 071 * <pre> 072 * /*** 073 * * Some text. 074 * */ 075 * /************ 076 * * Some text. 077 * */ 078 * /** ** 079 * * Some text. 080 * */ 081 * </pre> 082 * <p> 083 * The documentation generated will be just "Some text." without any asterisks. 084 * Since these asterisks will not appear in the generated documentation, 085 * they should not be considered as the beginning of the Javadoc content. 086 * In such cases, the check assumes that the Javadoc content begins on the second line. 087 * </p> 088 * <ul> 089 * <li> 090 * Property {@code location} - Specify the policy on placement of the Javadoc content. 091 * Default value is {@code second_line}. 092 * </li> 093 * </ul> 094 * <p> 095 * By default Check validate that the Javadoc content starts from the second line: 096 * </p> 097 * <pre> 098 * <module name="JavadocContentLocationCheck"/> 099 * </pre> 100 * <p> 101 * This setting produces a violation for each multi-line comment starting 102 * on the same line as the initial asterisks: 103 * </p> 104 * <pre> 105 * /** This comment causes a violation because it starts from the first line 106 * * and spans several lines. 107 * */ 108 * /** 109 * * This comment is OK because it starts from the second line. 110 * */ 111 * /** This comment is OK because it is on the single line. */ 112 *</pre> 113 * <p> 114 * To ensure that Javadoc content starts from the first line: 115 * </p> 116 * <pre> 117 * <module name="JavadocContentLocationCheck"> 118 * <property name="location" value="first_line"/> 119 * </module> 120 * </pre> 121 * <p> 122 * This setting produces a violation for each comment not 123 * starting on the same line as the initial asterisks: 124 * </p> 125 * <pre> 126 * /** This comment is OK because it starts on the first line. 127 * * There may be additional text. 128 * */ 129 * /** 130 * * This comment causes a violation because it starts on the second line. 131 * */ 132 * /** This single-line comment also is OK. */ 133 * </pre> 134 * 135 * @since 8.27 136 */ 137@StatelessCheck 138public class JavadocContentLocationCheck extends AbstractCheck { 139 140 /** 141 * A key is pointing to the warning message text in "messages.properties" file. 142 */ 143 public static final String MSG_JAVADOC_CONTENT_FIRST_LINE = "javadoc.content.first.line"; 144 145 /** 146 * A key is pointing to the warning message text in "messages.properties" file. 147 */ 148 public static final String MSG_JAVADOC_CONTENT_SECOND_LINE = "javadoc.content.second.line"; 149 150 /** 151 * Specify the policy on placement of the Javadoc content. 152 */ 153 private JavadocContentLocationOption location = JavadocContentLocationOption.SECOND_LINE; 154 155 @Override 156 public int[] getRequiredTokens() { 157 return new int[] { 158 TokenTypes.BLOCK_COMMENT_BEGIN, 159 }; 160 } 161 162 @Override 163 public int[] getAcceptableTokens() { 164 return getRequiredTokens(); 165 } 166 167 @Override 168 public int[] getDefaultTokens() { 169 return getRequiredTokens(); 170 } 171 172 @Override 173 public boolean isCommentNodesRequired() { 174 return true; 175 } 176 177 /** 178 * Setter to specify the policy on placement of the Javadoc content. 179 * 180 * @param value string to decode location from 181 * @throws IllegalArgumentException if unable to decode 182 */ 183 public void setLocation(String value) { 184 location = JavadocContentLocationOption.valueOf(value.trim().toUpperCase(Locale.ENGLISH)); 185 } 186 187 @Override 188 public void visitToken(DetailAST ast) { 189 if (isMultilineComment(ast) && JavadocUtil.isJavadocComment(ast)) { 190 final String commentContent = JavadocUtil.getJavadocCommentContent(ast); 191 final int indexOfFirstNonBlankLine = findIndexOfFirstNonBlankLine(commentContent); 192 if (indexOfFirstNonBlankLine >= 0) { 193 if (location == JavadocContentLocationOption.FIRST_LINE) { 194 if (indexOfFirstNonBlankLine != 0) { 195 log(ast, MSG_JAVADOC_CONTENT_FIRST_LINE); 196 } 197 } 198 else if (indexOfFirstNonBlankLine != 1) { 199 log(ast, MSG_JAVADOC_CONTENT_SECOND_LINE); 200 } 201 } 202 } 203 } 204 205 /** 206 * Checks if a DetailAST of type {@code TokenTypes.BLOCK_COMMENT_BEGIN} span 207 * more than one line. The node always has at least one child of the type 208 * {@code TokenTypes.BLOCK_COMMENT_END}. 209 * 210 * @param node node to check 211 * @return {@code true} for multi-line comment nodes 212 */ 213 private static boolean isMultilineComment(DetailAST node) { 214 return node.getLineNo() != node.getLastChild().getLineNo(); 215 } 216 217 /** 218 * Returns the index of the first non-blank line. 219 * All lines consists only of asterisks and whitespaces are treated as blank. 220 * 221 * @param commentContent Javadoc content to process 222 * @return the index of the first non-blank line or {@code -1} if all lines are blank 223 */ 224 private static int findIndexOfFirstNonBlankLine(String commentContent) { 225 int lineNo = 0; 226 boolean noContent = true; 227 for (int i = 0; i < commentContent.length(); ++i) { 228 final char character = commentContent.charAt(i); 229 if (character == '\n') { 230 ++lineNo; 231 } 232 else if (character != '*' && !Character.isWhitespace(character)) { 233 noContent = false; 234 break; 235 } 236 } 237 if (noContent) { 238 lineNo = -1; 239 } 240 return lineNo; 241 } 242 243}