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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) 2001-2024 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.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.stream.Collectors;
30  
31  import org.apache.maven.doxia.macro.AbstractMacro;
32  import org.apache.maven.doxia.macro.Macro;
33  import org.apache.maven.doxia.macro.MacroExecutionException;
34  import org.apache.maven.doxia.macro.MacroRequest;
35  import org.apache.maven.doxia.sink.Sink;
36  import org.apache.maven.doxia.sink.impl.SinkEventAttributeSet;
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 path of the last file. */
64      private String lastPath = "";
65  
66      /** The line contents of the last file. */
67      private List<String> lastLines = new ArrayList<>();
68  
69      @Override
70      public void execute(Sink sink, MacroRequest request) throws MacroExecutionException {
71          final String path = (String) request.getParameter("path");
72          final String type = (String) request.getParameter("type");
73  
74          List<String> lines = lastLines;
75          if (!path.equals(lastPath)) {
76              lines = readFile("src/xdocs-examples/" + path);
77              lastPath = path;
78              lastLines = lines;
79          }
80  
81          if ("config".equals(type)) {
82              final String config = getConfigSnippet(lines);
83  
84              if (config.isBlank()) {
85                  final String message = String.format(Locale.ROOT,
86                          "Empty config snippet from %s, check"
87                                  + " for xml config snippet delimiters in input file.", path
88                  );
89                  throw new MacroExecutionException(message);
90              }
91  
92              writeSnippet(sink, config);
93          }
94          else if ("code".equals(type)) {
95              String code = getCodeSnippet(lines);
96              // Replace tabs with spaces for FileTabCharacterCheck examples
97              if (path.contains("filetabcharacter")) {
98                  code = code.replace("\t", "  ");
99              }
100 
101             if (code.isBlank()) {
102                 final String message = String.format(Locale.ROOT,
103                         "Empty code snippet from %s, check"
104                                 + " for code snippet delimiters in input file.", path
105                 );
106                 throw new MacroExecutionException(message);
107             }
108 
109             writeSnippet(sink, code);
110         }
111         else {
112             final String message = String.format(Locale.ROOT, "Unknown example type: %s", type);
113             throw new MacroExecutionException(message);
114         }
115     }
116 
117     /**
118      * Read the file at the given path and returns its contents as a list of lines.
119      *
120      * @param path the path to the file to read.
121      * @return the contents of the file as a list of lines.
122      * @throws MacroExecutionException if the file could not be read.
123      */
124     private static List<String> readFile(String path) throws MacroExecutionException {
125         try {
126             final Path exampleFilePath = Path.of(path);
127             return Files.readAllLines(exampleFilePath);
128         }
129         catch (IOException ioException) {
130             final String message = String.format(Locale.ROOT, "Failed to read %s", path);
131             throw new MacroExecutionException(message, ioException);
132         }
133     }
134 
135     /**
136      * Extract a configuration snippet from the given lines. Config delimiters use the whole
137      * line for themselves and have no indentation. We use equals() instead of contains()
138      * to be more strict because some examples contain those delimiters.
139      *
140      * @param lines the lines to extract the snippet from.
141      * @return the configuration snippet.
142      */
143     private static String getConfigSnippet(Collection<String> lines) {
144         return lines.stream()
145                 .dropWhile(line -> !XML_CONFIG_START.equals(line))
146                 .skip(1)
147                 .takeWhile(line -> !XML_CONFIG_END.equals(line))
148                 .collect(Collectors.joining(NEWLINE));
149     }
150 
151     /**
152      * Extract a code snippet from the given lines. Code delimiters can be indented, so
153      * we use contains() instead of equals().
154      *
155      * @param lines the lines to extract the snippet from.
156      * @return the code snippet.
157      */
158     private static String getCodeSnippet(Collection<String> lines) {
159         return lines.stream()
160                 .dropWhile(line -> !line.contains(CODE_SNIPPET_START))
161                 .skip(1)
162                 .takeWhile(line -> !line.contains(CODE_SNIPPET_END))
163                 .collect(Collectors.joining(NEWLINE));
164     }
165 
166     /**
167      * Write the given snippet to the file inside a source block.
168      *
169      * @param sink the sink to write to.
170      * @param snippet the snippet to write.
171      */
172     private static void writeSnippet(Sink sink, String snippet) {
173         sink.verbatim(SinkEventAttributeSet.BOXED);
174         final String text = NEWLINE
175                 + String.join(NEWLINE, snippet.stripTrailing(), INDENTATION);
176         sink.text(text);
177         sink.verbatim_();
178     }
179 }