1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2024 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.coding;
21
22 import java.util.List;
23 import java.util.stream.Collectors;
24
25 import com.puppycrawl.tools.checkstyle.StatelessCheck;
26 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
27 import com.puppycrawl.tools.checkstyle.api.DetailAST;
28 import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
29 import com.puppycrawl.tools.checkstyle.xpath.AbstractNode;
30 import com.puppycrawl.tools.checkstyle.xpath.RootNode;
31 import net.sf.saxon.Configuration;
32 import net.sf.saxon.om.Item;
33 import net.sf.saxon.sxpath.XPathDynamicContext;
34 import net.sf.saxon.sxpath.XPathEvaluator;
35 import net.sf.saxon.sxpath.XPathExpression;
36 import net.sf.saxon.trans.XPathException;
37
38 /**
39 * <p>
40 * Evaluates Xpath query and report violation on all matching AST nodes. This check allows
41 * user to implement custom checks using Xpath. If Xpath query is not specified explicitly,
42 * then the check does nothing.
43 * </p>
44 * <p>
45 * It is recommended to define custom message for violation to explain what is not allowed and what
46 * to use instead, default message might be too abstract. To customize a message you need to
47 * add {@code message} element with <b>matchxpath.match</b> as {@code key} attribute and
48 * desired message as {@code value} attribute.
49 * </p>
50 * <p>
51 * Please read more about Xpath syntax at
52 * <a href="https://www.saxonica.com/html/documentation10/expressions/index.html">Xpath Syntax</a>.
53 * Information regarding Xpath functions can be found at
54 * <a href="https://www.saxonica.com/html/documentation10/functions/fn/index.html">
55 * XSLT/XPath Reference</a>.
56 * Note, that <b>@text</b> attribute can be used only with token types that are listed in
57 * <a href="https://github.com/checkstyle/checkstyle/search?q=%22TOKEN_TYPES_WITH_TEXT_ATTRIBUTE+%3D+Arrays.asList%22">
58 * XpathUtil</a>.
59 * </p>
60 * <ul>
61 * <li>
62 * Property {@code query} - Specify Xpath query.
63 * Type is {@code java.lang.String}.
64 * Default value is {@code ""}.
65 * </li>
66 * </ul>
67 * <p>
68 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
69 * </p>
70 * <p>
71 * Violation Message Keys:
72 * </p>
73 * <ul>
74 * <li>
75 * {@code matchxpath.match}
76 * </li>
77 * </ul>
78 *
79 * @since 8.39
80 */
81 @StatelessCheck
82 public class MatchXpathCheck extends AbstractCheck {
83
84 /**
85 * A key is pointing to the warning message text provided by user.
86 */
87 public static final String MSG_KEY = "matchxpath.match";
88
89 /** Specify Xpath query. */
90 private String query = "";
91
92 /** Xpath expression. */
93 private XPathExpression xpathExpression;
94
95 /**
96 * Setter to specify Xpath query.
97 *
98 * @param query Xpath query.
99 * @throws IllegalStateException if creation of xpath expression fails
100 * @since 8.39
101 */
102 public void setQuery(String query) {
103 this.query = query;
104 if (!query.isEmpty()) {
105 try {
106 final XPathEvaluator xpathEvaluator =
107 new XPathEvaluator(Configuration.newConfiguration());
108 xpathExpression = xpathEvaluator.createExpression(query);
109 }
110 catch (XPathException ex) {
111 throw new IllegalStateException("Creating Xpath expression failed: " + query, ex);
112 }
113 }
114 }
115
116 @Override
117 public int[] getDefaultTokens() {
118 return getRequiredTokens();
119 }
120
121 @Override
122 public int[] getAcceptableTokens() {
123 return getRequiredTokens();
124 }
125
126 @Override
127 public int[] getRequiredTokens() {
128 return CommonUtil.EMPTY_INT_ARRAY;
129 }
130
131 @Override
132 public boolean isCommentNodesRequired() {
133 return true;
134 }
135
136 @Override
137 public void beginTree(DetailAST rootAST) {
138 if (!query.isEmpty()) {
139 final List<DetailAST> matchingNodes = findMatchingNodesByXpathQuery(rootAST);
140 matchingNodes.forEach(node -> log(node, MSG_KEY));
141 }
142 }
143
144 /**
145 * Find nodes that match query.
146 *
147 * @param rootAST root node
148 * @return list of matching nodes
149 * @throws IllegalStateException if evaluation of xpath query fails
150 */
151 private List<DetailAST> findMatchingNodesByXpathQuery(DetailAST rootAST) {
152 try {
153 final RootNode rootNode = new RootNode(rootAST);
154 final XPathDynamicContext xpathDynamicContext =
155 xpathExpression.createDynamicContext(rootNode);
156 final List<Item> matchingItems = xpathExpression.evaluate(xpathDynamicContext);
157 return matchingItems.stream()
158 .map(item -> (DetailAST) ((AbstractNode) item).getUnderlyingNode())
159 .collect(Collectors.toUnmodifiableList());
160 }
161 catch (XPathException ex) {
162 throw new IllegalStateException("Evaluation of Xpath query failed: " + query, ex);
163 }
164 }
165 }