1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2026 the original author or authors.
4 //
5 // This library is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU Lesser General Public
7 // License as published by the Free Software Foundation; either
8 // version 2.1 of the License, or (at your option) any later version.
9 //
10 // This library is distributed in the hope that it will be useful,
11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 // Lesser General Public License for more details.
14 //
15 // You should have received a copy of the GNU Lesser General Public
16 // License along with this library; if not, write to the Free Software
17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 ///////////////////////////////////////////////////////////////////////////////////////////////
19
20 package com.puppycrawl.tools.checkstyle.checks.javadoc;
21
22 import java.util.ArrayList;
23 import java.util.List;
24
25 import com.puppycrawl.tools.checkstyle.StatelessCheck;
26 import com.puppycrawl.tools.checkstyle.api.DetailNode;
27 import com.puppycrawl.tools.checkstyle.api.JavadocCommentsTokenTypes;
28 import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
29 import com.puppycrawl.tools.checkstyle.utils.JavadocUtil;
30
31 /**
32 * <div>
33 * Checks the indentation of the continuation lines in block tags. That is whether the continued
34 * description of at clauses should be indented or not. If the text is not properly indented it
35 * throws a violation. A continuation line is when the description starts/spans past the line with
36 * the tag. Default indentation required is at least 4, but this can be changed with the help of
37 * properties below.
38 * </div>
39 * <ul>
40 * <li>
41 * Notes:
42 * This check does not validate the indentation of lines inside {@code pre} tags.
43 * </li>
44 * </ul>
45 *
46 * @since 6.0
47 */
48 @StatelessCheck
49 public class JavadocTagContinuationIndentationCheck extends AbstractJavadocCheck {
50
51 /**
52 * A key is pointing to the warning message text in "messages.properties"
53 * file.
54 */
55 public static final String MSG_KEY = "tag.continuation.indent";
56
57 /** Default tag continuation indentation. */
58 private static final int DEFAULT_INDENTATION = 4;
59
60 /**
61 * Constant for the pre tag name.
62 */
63 private static final String PRE_TAG = "pre";
64
65 /**
66 * Specify how many spaces to use for new indentation level.
67 */
68 private int offset = DEFAULT_INDENTATION;
69
70 /**
71 * Creates a new {@code JavadocTagContinuationIndentationCheck} instance.
72 */
73 public JavadocTagContinuationIndentationCheck() {
74 // no code by default
75 }
76
77 /**
78 * Setter to specify how many spaces to use for new indentation level.
79 *
80 * @param offset custom value.
81 * @since 6.0
82 */
83 public void setOffset(int offset) {
84 this.offset = offset;
85 }
86
87 @Override
88 public int[] getDefaultJavadocTokens() {
89 return new int[] {
90 JavadocCommentsTokenTypes.HTML_ELEMENT,
91 JavadocCommentsTokenTypes.DESCRIPTION,
92 };
93 }
94
95 @Override
96 public int[] getRequiredJavadocTokens() {
97 return getAcceptableJavadocTokens();
98 }
99
100 @Override
101 public void visitJavadocToken(DetailNode ast) {
102 if (isBlockDescription(ast) && !isInlineDescription(ast)) {
103 final List<DetailNode> textNodes = getTargetedTextNodes(ast);
104 for (DetailNode textNode : textNodes) {
105 if (isViolation(textNode)) {
106 log(textNode.getLineNumber(), MSG_KEY, offset);
107 }
108 }
109 }
110 }
111
112 /**
113 * Returns all targeted text nodes from the given AST node.
114 * This method decides whether to process the node as a description node
115 * or as an HTML element node and delegates to the appropriate helper method.
116 *
117 * @param ast the AST node to process
118 * @return list of targeted text nodes
119 */
120 private static List<DetailNode> getTargetedTextNodes(DetailNode ast) {
121 final List<DetailNode> textNodes;
122 if (ast.getType() == JavadocCommentsTokenTypes.DESCRIPTION) {
123 textNodes = getTargetedTextNodesInsideDescription(ast);
124 }
125 else {
126 textNodes = getTargetedTextNodesInsideHtmlElement(ast);
127 }
128 return textNodes;
129 }
130
131 /**
132 * Returns all targeted text nodes within an HTML element subtree.
133 *
134 * @param ast the HTML element AST node
135 * @return list of targeted text nodes inside the HTML element
136 */
137 private static List<DetailNode> getTargetedTextNodesInsideHtmlElement(DetailNode ast) {
138 final List<DetailNode> textNodes = new ArrayList<>();
139 if (!JavadocUtil.isTag(ast, PRE_TAG) && !isInsidePreTag(ast)) {
140 final DetailNode prevSibling = ast.getPreviousSibling();
141 if (prevSibling != null && isTargetTextNode(prevSibling)) {
142 textNodes.add(prevSibling);
143 }
144 DetailNode node = ast.getFirstChild();
145 while (node != null) {
146 if (node.getType() == JavadocCommentsTokenTypes.HTML_CONTENT) {
147 // HTML_CONTENT contain text nodes only, so it can be treated as
148 // DESCRIPTION node
149 textNodes.addAll(getTargetedTextNodesInsideDescription(node));
150 }
151 else if (subtreeContainsAttributeValue(node)) {
152 textNodes.addAll(getTargetedTextNodesInsideHtmlElement(node));
153 }
154 else if (isTargetTextNode(node)) {
155 textNodes.add(node);
156 }
157 node = node.getNextSibling();
158 }
159 }
160 return textNodes;
161 }
162
163 /**
164 * Checks whether the given subtree node represents part of an HTML tag
165 * structure that may contain attribute values.
166 *
167 * @param node the AST node to check
168 * @return true if the subtree may contain attribute values, false otherwise
169 */
170 private static boolean subtreeContainsAttributeValue(DetailNode node) {
171 return node.getType() == JavadocCommentsTokenTypes.HTML_TAG_START
172 || node.getType() == JavadocCommentsTokenTypes.HTML_ATTRIBUTES
173 || node.getType() == JavadocCommentsTokenTypes.HTML_ATTRIBUTE;
174 }
175
176 /**
177 * Returns all targeted text nodes inside a description node.
178 *
179 * @param descriptionNode the DESCRIPTION node to process
180 * @return list of targeted text nodes inside the description node
181 */
182 private static List<DetailNode> getTargetedTextNodesInsideDescription(
183 DetailNode descriptionNode) {
184 final List<DetailNode> textNodes = new ArrayList<>();
185 DetailNode node = descriptionNode.getFirstChild();
186 final DetailNode previousSibling = descriptionNode.getPreviousSibling();
187
188 // special case if the text node is previous sibling of the description node
189 if (isTargetTextNode(previousSibling)) {
190 textNodes.add(previousSibling);
191 }
192
193 // special case for the first child, because leading asterisk
194 // will be previous sibling of the parent (description node) not the node itself
195 if (isLeadingAsterisk(descriptionNode.getPreviousSibling())) {
196 textNodes.add(node);
197 }
198
199 while (node != null) {
200 if (isTargetTextNode(node)) {
201 textNodes.add(node);
202 }
203 node = node.getNextSibling();
204 }
205
206 return textNodes;
207 }
208
209 /**
210 * Determines whether the given node is a targeted node.
211 *
212 * @param node the AST node to check
213 * @return true if the node is a targeted node, false otherwise
214 */
215 private static boolean isTargetTextNode(DetailNode node) {
216 final DetailNode previousSibling = node.getPreviousSibling();
217
218 return previousSibling != null
219 && isTextOrAttributeValueNode(node)
220 && !isBeforePreTag(node)
221 && isLeadingAsterisk(previousSibling);
222 }
223
224 /**
225 * Checks whether the given node is a leading asterisk.
226 *
227 * @param node the AST node to check
228 * @return true if the node is a leading asterisk, false otherwise
229 */
230 private static boolean isLeadingAsterisk(DetailNode node) {
231 return node.getType() == JavadocCommentsTokenTypes.LEADING_ASTERISK
232 || node.getType() == JavadocCommentsTokenTypes.LEADING_ASTERISKS;
233 }
234
235 /**
236 * Checks if a node is located before a {@code pre} tag.
237 *
238 * @param node the node to check
239 * @return true if the node is before a pre tag, false otherwise
240 */
241 private static boolean isBeforePreTag(DetailNode node) {
242 final DetailNode nextSibling = node.getNextSibling();
243 final boolean isBeforePreTag;
244 if (nextSibling != null
245 && nextSibling.getType() == JavadocCommentsTokenTypes.DESCRIPTION) {
246 isBeforePreTag = JavadocUtil.isTag(nextSibling.getFirstChild(), PRE_TAG);
247 }
248 else if (nextSibling != null) {
249 isBeforePreTag = JavadocUtil.isTag(nextSibling, PRE_TAG);
250 }
251 else {
252 isBeforePreTag = false;
253 }
254 return isBeforePreTag;
255 }
256
257 /**
258 * Checks if a node is inside a {@code pre} tag.
259 *
260 * @param node the node to check
261 * @return true if the node is inside a pre tag, false otherwise
262 */
263 private static boolean isInsidePreTag(DetailNode node) {
264 final DetailNode htmlElementParent = node.getParent().getParent();
265 return JavadocUtil.isTag(htmlElementParent, PRE_TAG);
266 }
267
268 /**
269 * Checks whether the given node is either a TEXT node or an ATTRIBUTE_VALUE node.
270 *
271 * @param node the AST node to check
272 * @return true if the node is a TEXT or ATTRIBUTE_VALUE node, false otherwise
273 */
274 private static boolean isTextOrAttributeValueNode(DetailNode node) {
275 return node.getType() == JavadocCommentsTokenTypes.TEXT
276 || node.getType() == JavadocCommentsTokenTypes.ATTRIBUTE_VALUE;
277 }
278
279 /**
280 * Checks if a text node meets the criteria for a violation.
281 * If the text is shorter than {@code offset} characters, then a violation is
282 * detected if the text is not blank or the next node is not a newline.
283 * If the text is longer than {@code offset} characters, then a violation is
284 * detected if any of the first {@code offset} characters are not blank.
285 *
286 * @param textNode the node to check.
287 * @return true if the node has a violation.
288 */
289 private boolean isViolation(DetailNode textNode) {
290 boolean result = false;
291 final String text = textNode.getText();
292 if (text.length() <= offset) {
293 if (CommonUtil.isBlank(text)) {
294 final DetailNode nextNode = textNode.getNextSibling();
295 if (nextNode.getType() != JavadocCommentsTokenTypes.NEWLINE) {
296 // text is blank but line hasn't ended yet
297 result = true;
298 }
299 }
300 else {
301 // text is not blank
302 result = true;
303 }
304 }
305 else if (!CommonUtil.isBlank(text.substring(1, offset + 1))) {
306 // first offset number of characters are not blank
307 result = true;
308 }
309 return result;
310 }
311
312 /**
313 * Checks if the given description node is part of a block Javadoc tag.
314 *
315 * @param description the node to check
316 * @return {@code true} if the node is inside a block tag, {@code false} otherwise
317 */
318 private static boolean isBlockDescription(DetailNode description) {
319 boolean isBlock = false;
320 DetailNode currentNode = description;
321 while (currentNode != null) {
322 if (currentNode.getType() == JavadocCommentsTokenTypes.JAVADOC_BLOCK_TAG) {
323 isBlock = true;
324 break;
325 }
326 currentNode = currentNode.getParent();
327 }
328 return isBlock;
329 }
330
331 /**
332 * Checks, if description node is a description of in-line tag.
333 *
334 * @param description DESCRIPTION node.
335 * @return true, if description node is a description of in-line tag.
336 */
337 private static boolean isInlineDescription(DetailNode description) {
338 boolean isInline = false;
339 DetailNode currentNode = description;
340 while (currentNode != null) {
341 if (currentNode.getType() == JavadocCommentsTokenTypes.JAVADOC_INLINE_TAG) {
342 isInline = true;
343 break;
344 }
345 currentNode = currentNode.getParent();
346 }
347 return isInline;
348 }
349
350 }