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1   ////////////////////////////////////////////////////////////////////////////////
2   // checkstyle: Checks Java source code for adherence to a set of rules.
3   // Copyright (C) 2001-2018 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;
21  
22  import java.io.File;
23  import java.io.IOException;
24  import java.io.Reader;
25  import java.io.StringReader;
26  import java.nio.charset.StandardCharsets;
27  import java.util.Locale;
28  
29  import antlr.CommonHiddenStreamToken;
30  import antlr.RecognitionException;
31  import antlr.Token;
32  import antlr.TokenStreamException;
33  import antlr.TokenStreamHiddenTokenFilter;
34  import com.puppycrawl.tools.checkstyle.api.CheckstyleException;
35  import com.puppycrawl.tools.checkstyle.api.DetailAST;
36  import com.puppycrawl.tools.checkstyle.api.FileContents;
37  import com.puppycrawl.tools.checkstyle.api.FileText;
38  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
39  import com.puppycrawl.tools.checkstyle.grammars.GeneratedJavaLexer;
40  import com.puppycrawl.tools.checkstyle.grammars.GeneratedJavaRecognizer;
41  import com.puppycrawl.tools.checkstyle.utils.CommonUtils;
42  
43  /**
44   * Helper methods to parse java source files.
45   *
46   */
47  public final class JavaParser {
48  
49      /**
50       * Enum to be used for test if comments should be used.
51       */
52      public enum Options {
53  
54          /**
55           * Comments nodes should be processed.
56           */
57          WITH_COMMENTS,
58  
59          /**
60           * Comments nodes should be ignored.
61           */
62          WITHOUT_COMMENTS
63  
64      }
65  
66      /** Stop instances being created. **/
67      private JavaParser() {
68      }
69  
70      /**
71       * Static helper method to parses a Java source file.
72       * @param contents contains the contents of the file
73       * @return the root of the AST
74       * @throws CheckstyleException if the contents is not a valid Java source
75       */
76      public static DetailAST parse(FileContents contents)
77              throws CheckstyleException {
78          final String fullText = contents.getText().getFullText().toString();
79          final Reader reader = new StringReader(fullText);
80          final GeneratedJavaLexer lexer = new GeneratedJavaLexer(reader);
81          lexer.setCommentListener(contents);
82          lexer.setTokenObjectClass("antlr.CommonHiddenStreamToken");
83  
84          final TokenStreamHiddenTokenFilter filter = new TokenStreamHiddenTokenFilter(lexer);
85          filter.hide(TokenTypes.SINGLE_LINE_COMMENT);
86          filter.hide(TokenTypes.BLOCK_COMMENT_BEGIN);
87  
88          final GeneratedJavaRecognizer parser = new GeneratedJavaRecognizer(filter);
89          parser.setFilename(contents.getFileName());
90          parser.setASTNodeClass(DetailAST.class.getName());
91          try {
92              parser.compilationUnit();
93          }
94          catch (RecognitionException | TokenStreamException ex) {
95              final String exceptionMsg = String.format(Locale.ROOT,
96                  "%s occurred while parsing file %s.",
97                  ex.getClass().getSimpleName(), contents.getFileName());
98              throw new CheckstyleException(exceptionMsg, ex);
99          }
100 
101         return (DetailAST) parser.getAST();
102     }
103 
104     /**
105      * Parse a text and return the parse tree.
106      * @param text the text to parse
107      * @param options {@link Options} to control inclusion of comment nodes
108      * @return the root node of the parse tree
109      * @throws CheckstyleException if the text is not a valid Java source
110      */
111     public static DetailAST parseFileText(FileText text, Options options)
112             throws CheckstyleException {
113         final FileContents contents = new FileContents(text);
114         DetailAST ast = parse(contents);
115         if (options == Options.WITH_COMMENTS) {
116             ast = appendHiddenCommentNodes(ast);
117         }
118         return ast;
119     }
120 
121     /**
122      * Parses Java source file.
123      * @param file the file to parse
124      * @param options {@link Options} to control inclusion of comment nodes
125      * @return DetailAST tree
126      * @throws IOException if the file could not be read
127      * @throws CheckstyleException if the file is not a valid Java source file
128      */
129     public static DetailAST parseFile(File file, Options options)
130             throws IOException, CheckstyleException {
131         final FileText text = new FileText(file.getAbsoluteFile(),
132             System.getProperty("file.encoding", StandardCharsets.UTF_8.name()));
133         return parseFileText(text, options);
134     }
135 
136     /**
137      * Appends comment nodes to existing AST.
138      * It traverses each node in AST, looks for hidden comment tokens
139      * and appends found comment tokens as nodes in AST.
140      * @param root of AST
141      * @return root of AST with comment nodes
142      */
143     public static DetailAST appendHiddenCommentNodes(DetailAST root) {
144         DetailAST result = root;
145         DetailAST curNode = root;
146         DetailAST lastNode = root;
147 
148         while (curNode != null) {
149             if (isPositionGreater(curNode, lastNode)) {
150                 lastNode = curNode;
151             }
152 
153             CommonHiddenStreamToken tokenBefore = curNode.getHiddenBefore();
154             DetailAST currentSibling = curNode;
155             while (tokenBefore != null) {
156                 final DetailAST newCommentNode =
157                          createCommentAstFromToken(tokenBefore);
158 
159                 currentSibling.addPreviousSibling(newCommentNode);
160 
161                 if (currentSibling == result) {
162                     result = newCommentNode;
163                 }
164 
165                 currentSibling = newCommentNode;
166                 tokenBefore = tokenBefore.getHiddenBefore();
167             }
168 
169             DetailAST toVisit = curNode.getFirstChild();
170             while (curNode != null && toVisit == null) {
171                 toVisit = curNode.getNextSibling();
172                 if (toVisit == null) {
173                     curNode = curNode.getParent();
174                 }
175             }
176             curNode = toVisit;
177         }
178         if (lastNode != null) {
179             CommonHiddenStreamToken tokenAfter = lastNode.getHiddenAfter();
180             DetailAST currentSibling = lastNode;
181             while (tokenAfter != null) {
182                 final DetailAST newCommentNode =
183                         createCommentAstFromToken(tokenAfter);
184 
185                 currentSibling.addNextSibling(newCommentNode);
186 
187                 currentSibling = newCommentNode;
188                 tokenAfter = tokenAfter.getHiddenAfter();
189             }
190         }
191         return result;
192     }
193 
194     /**
195      * Checks if position of first DetailAST is greater than position of
196      * second DetailAST. Position is line number and column number in source file.
197      * @param ast1 first DetailAST node
198      * @param ast2 second DetailAST node
199      * @return true if position of ast1 is greater than position of ast2
200      */
201     private static boolean isPositionGreater(DetailAST ast1, DetailAST ast2) {
202         boolean isGreater = ast1.getLineNo() > ast2.getLineNo();
203         if (!isGreater && ast1.getLineNo() == ast2.getLineNo()) {
204             isGreater = ast1.getColumnNo() > ast2.getColumnNo();
205         }
206         return isGreater;
207     }
208 
209     /**
210      * Create comment AST from token. Depending on token type
211      * SINGLE_LINE_COMMENT or BLOCK_COMMENT_BEGIN is created.
212      * @param token to create the AST
213      * @return DetailAST of comment node
214      */
215     private static DetailAST createCommentAstFromToken(Token token) {
216         final DetailAST commentAst;
217         if (token.getType() == TokenTypes.SINGLE_LINE_COMMENT) {
218             commentAst = createSlCommentNode(token);
219         }
220         else {
221             commentAst = CommonUtils.createBlockCommentNode(token);
222         }
223         return commentAst;
224     }
225 
226     /**
227      * Create single-line comment from token.
228      * @param token to create the AST
229      * @return DetailAST with SINGLE_LINE_COMMENT type
230      */
231     private static DetailAST createSlCommentNode(Token token) {
232         final DetailAST slComment = new DetailAST();
233         slComment.setType(TokenTypes.SINGLE_LINE_COMMENT);
234         slComment.setText("//");
235 
236         // column counting begins from 0
237         slComment.setColumnNo(token.getColumn() - 1);
238         slComment.setLineNo(token.getLine());
239 
240         final DetailAST slCommentContent = new DetailAST();
241         slCommentContent.setType(TokenTypes.COMMENT_CONTENT);
242 
243         // column counting begins from 0
244         // plus length of '//'
245         slCommentContent.setColumnNo(token.getColumn() - 1 + 2);
246         slCommentContent.setLineNo(token.getLine());
247         slCommentContent.setText(token.getText());
248 
249         slComment.addChild(slCommentContent);
250         return slComment;
251     }
252 
253 }