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1   ///////////////////////////////////////////////////////////////////////////////////////////////
2   // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3   // Copyright (C) 2001-2025 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.site;
21  
22  import java.io.IOException;
23  import java.nio.file.Files;
24  import java.nio.file.Path;
25  import java.util.ArrayList;
26  import java.util.Collection;
27  import java.util.List;
28  import java.util.Locale;
29  import java.util.regex.Pattern;
30  import java.util.stream.Collectors;
31  
32  import org.apache.maven.doxia.macro.AbstractMacro;
33  import org.apache.maven.doxia.macro.Macro;
34  import org.apache.maven.doxia.macro.MacroExecutionException;
35  import org.apache.maven.doxia.macro.MacroRequest;
36  import org.apache.maven.doxia.sink.Sink;
37  import org.codehaus.plexus.component.annotations.Component;
38  
39  /**
40   * A macro that inserts a snippet of code or configuration from a file.
41   */
42  @Component(role = Macro.class, hint = "example")
43  public class ExampleMacro extends AbstractMacro {
44  
45      /** Starting delimiter for config snippets. */
46      private static final String XML_CONFIG_START = "/*xml";
47  
48      /** Ending delimiter for config snippets. */
49      private static final String XML_CONFIG_END = "*/";
50  
51      /** Starting delimiter for code snippets. */
52      private static final String CODE_SNIPPET_START = "// xdoc section -- start";
53  
54      /** Ending delimiter for code snippets. */
55      private static final String CODE_SNIPPET_END = "// xdoc section -- end";
56  
57      /** Newline character. */
58      private static final String NEWLINE = System.lineSeparator();
59  
60      /** Eight whitespace characters. All example source tags are indented 8 spaces. */
61      private static final String INDENTATION = "        ";
62  
63      /** The pattern of xml code blocks. */
64      private static final Pattern XML_PATTERN = Pattern.compile(
65              "^\\s*(<!DOCTYPE\\s+.*?>|<\\?xml\\s+.*?>|<module\\s+.*?>)\\s*",
66              Pattern.DOTALL
67      );
68  
69      /** The path of the last file. */
70      private String lastPath = "";
71  
72      /** The line contents of the last file. */
73      private List<String> lastLines = new ArrayList<>();
74  
75      @Override
76      public void execute(Sink sink, MacroRequest request) throws MacroExecutionException {
77          final String path = (String) request.getParameter("path");
78          final String type = (String) request.getParameter("type");
79  
80          List<String> lines = lastLines;
81          if (!path.equals(lastPath)) {
82              lines = readFile("src/xdocs-examples/" + path);
83              lastPath = path;
84              lastLines = lines;
85          }
86  
87          if ("config".equals(type)) {
88              final String config = getConfigSnippet(lines);
89  
90              if (config.isBlank()) {
91                  final String message = String.format(Locale.ROOT,
92                          "Empty config snippet from %s, check"
93                                  + " for xml config snippet delimiters in input file.", path
94                  );
95                  throw new MacroExecutionException(message);
96              }
97  
98              writeSnippet(sink, config);
99          }
100         else if ("code".equals(type)) {
101             String code = getCodeSnippet(lines);
102             // Replace tabs with spaces for FileTabCharacterCheck examples
103             if (path.contains("filetabcharacter")) {
104                 code = code.replace("\t", "  ");
105             }
106 
107             if (code.isBlank()) {
108                 final String message = String.format(Locale.ROOT,
109                         "Empty code snippet from %s, check"
110                                 + " for code snippet delimiters in input file.", path
111                 );
112                 throw new MacroExecutionException(message);
113             }
114 
115             writeSnippet(sink, code);
116         }
117         else if ("raw".equals(type)) {
118             final String content = String.join(NEWLINE, lines);
119             writeSnippet(sink, content);
120         }
121         else {
122             final String message = String.format(Locale.ROOT, "Unknown example type: %s", type);
123             throw new MacroExecutionException(message);
124         }
125     }
126 
127     /**
128      * Read the file at the given path and returns its contents as a list of lines.
129      *
130      * @param path the path to the file to read.
131      * @return the contents of the file as a list of lines.
132      * @throws MacroExecutionException if the file could not be read.
133      */
134     private static List<String> readFile(String path) throws MacroExecutionException {
135         try {
136             final Path exampleFilePath = Path.of(path);
137             return Files.readAllLines(exampleFilePath);
138         }
139         catch (IOException ioException) {
140             final String message = String.format(Locale.ROOT, "Failed to read %s", path);
141             throw new MacroExecutionException(message, ioException);
142         }
143     }
144 
145     /**
146      * Extract a configuration snippet from the given lines. Config delimiters use the whole
147      * line for themselves and have no indentation. We use equals() instead of contains()
148      * to be more strict because some examples contain those delimiters.
149      *
150      * @param lines the lines to extract the snippet from.
151      * @return the configuration snippet.
152      */
153     private static String getConfigSnippet(Collection<String> lines) {
154         return lines.stream()
155                 .dropWhile(line -> !XML_CONFIG_START.equals(line))
156                 .skip(1)
157                 .takeWhile(line -> !XML_CONFIG_END.equals(line))
158                 .collect(Collectors.joining(NEWLINE));
159     }
160 
161     /**
162      * Extract a code snippet from the given lines. Code delimiters can be indented, so
163      * we use contains() instead of equals().
164      *
165      * @param lines the lines to extract the snippet from.
166      * @return the code snippet.
167      */
168     private static String getCodeSnippet(Collection<String> lines) {
169         return lines.stream()
170                 .dropWhile(line -> !line.contains(CODE_SNIPPET_START))
171                 .skip(1)
172                 .takeWhile(line -> !line.contains(CODE_SNIPPET_END))
173                 .collect(Collectors.joining(NEWLINE));
174     }
175 
176     /**
177      * Writes the given snippet inside a formatted source block.
178      *
179      * @param sink the sink to write to.
180      * @param snippet the snippet to write.
181      */
182     private static void writeSnippet(Sink sink, String snippet) {
183         sink.rawText("<div class=\"wrapper\">");
184         final boolean isXml = isXml(snippet);
185 
186         final String languageClass;
187         if (isXml) {
188             languageClass = "language-xml";
189         }
190         else {
191             languageClass = "language-java";
192         }
193         sink.rawText("<pre class=\"prettyprint\"><code class=\"" + languageClass + "\">" + NEWLINE);
194         sink.rawText(escapeHtml(snippet).trim() + NEWLINE);
195         sink.rawText("</code></pre>");
196         sink.rawText("</div>");
197     }
198 
199     /**
200      * Escapes HTML special characters in the snippet.
201      *
202      * @param snippet the snippet to escape.
203      * @return the escaped snippet.
204      */
205     private static String escapeHtml(String snippet) {
206         return snippet.replace("&", "&amp;")
207                 .replace("<", "&lt;")
208                 .replace(">", "&gt;");
209     }
210 
211     /**
212      * Determines if the given snippet is likely an XML fragment.
213      *
214      * @param snippet the code snippet to analyze.
215      * @return {@code true} if the snippet appears to be XML, otherwise {@code false}.
216      */
217     private static boolean isXml(String snippet) {
218         return XML_PATTERN.matcher(snippet.trim()).matches();
219     }
220 }