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1   /*
2    * Copyright (c) 1999, 2012, Oracle and/or its affiliates. All rights reserved.
3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4    *
5    * This code is free software; you can redistribute it and/or modify it
6    * under the terms of the GNU General Public License version 2 only, as
7    * published by the Free Software Foundation.  Oracle designates this
8    * particular file as subject to the "Classpath" exception as provided
9    * by Oracle in the LICENSE file that accompanied this code.
10   *
11   * This code is distributed in the hope that it will be useful, but WITHOUT
12   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14   * version 2 for more details (a copy is included in the LICENSE file that
15   * accompanied this code).
16   *
17   * You should have received a copy of the GNU General Public License version
18   * 2 along with this work; if not, write to the Free Software Foundation,
19   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20   *
21   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22   * or visit www.oracle.com if you need additional information or have any
23   * questions.
24   */
25  
26  package com.sun.tools.javac.util;
27  
28  import java.io.IOException;
29  import java.lang.ref.SoftReference;
30  import java.nio.CharBuffer;
31  import javax.tools.JavaFileObject;
32  
33  import com.sun.tools.javac.file.JavacFileManager;
34  import com.sun.tools.javac.tree.EndPosTable;
35  
36  import static com.sun.tools.javac.util.LayoutCharacters.*;
37  
38  /**
39   * A simple abstraction of a source file, as needed for use in a diagnostic message.
40   * Provides access to the line and position in a line for any given character offset.
41   *
42   *  <p><b>This is NOT part of any supported API.
43   *  If you write code that depends on this, you do so at your own risk.
44   *  This code and its internal interfaces are subject to change or
45   *  deletion without notice.</b>
46   */
47  public class DiagnosticSource {
48  
49      /* constant DiagnosticSource to be used when sourcefile is missing */
50      public static final DiagnosticSource NO_SOURCE = new DiagnosticSource() {
51          @Override
52          protected boolean findLine(int pos) {
53              return false;
54          }
55      };
56  
57      public DiagnosticSource(JavaFileObject fo, AbstractLog log) {
58          this.fileObject = fo;
59          this.log = log;
60      }
61  
62      private DiagnosticSource() {}
63  
64      /** Return the underlying file object handled by this
65       *  DiagnosticSource object.
66       */
67      public JavaFileObject getFile() {
68          return fileObject;
69      }
70  
71      /** Return the one-based line number associated with a given pos
72       * for the current source file.  Zero is returned if no line exists
73       * for the given position.
74       */
75      public int getLineNumber(int pos) {
76          try {
77              if (findLine(pos)) {
78                  return line;
79              }
80              return 0;
81          } finally {
82              buf = null;
83          }
84      }
85  
86      /** Return the one-based column number associated with a given pos
87       * for the current source file.  Zero is returned if no column exists
88       * for the given position.
89       */
90      public int getColumnNumber(int pos, boolean expandTabs) {
91          try {
92              if (findLine(pos)) {
93                  int column = 0;
94                  for (int bp = lineStart; bp < pos; bp++) {
95                      if (bp >= bufLen) {
96                          return 0;
97                      }
98                      if (buf[bp] == '\t' && expandTabs) {
99                          column = (column / TabInc * TabInc) + TabInc;
100                     } else {
101                         column++;
102                     }
103                 }
104                 return column + 1; // positions are one-based
105             }
106             return 0;
107         } finally {
108             buf = null;
109         }
110     }
111 
112     /** Return the content of the line containing a given pos.
113      */
114     public String getLine(int pos) {
115         try {
116             if (!findLine(pos))
117                 return null;
118 
119             int lineEnd = lineStart;
120             while (lineEnd < bufLen && buf[lineEnd] != CR && buf[lineEnd] != LF)
121                 lineEnd++;
122             if (lineEnd - lineStart == 0)
123                 return null;
124             return new String(buf, lineStart, lineEnd - lineStart);
125         } finally {
126             buf = null;
127         }
128     }
129 
130     public EndPosTable getEndPosTable() {
131         return endPosTable;
132     }
133 
134     public void setEndPosTable(EndPosTable t) {
135         if (endPosTable != null && endPosTable != t)
136             throw new IllegalStateException("endPosTable already set");
137         endPosTable = t;
138     }
139 
140     /** Find the line in the buffer that contains the current position
141      * @param pos      Character offset into the buffer
142      */
143     protected boolean findLine(int pos) {
144         if (pos == Position.NOPOS)
145             return false;
146 
147         try {
148             // try and recover buffer from soft reference cache
149             if (buf == null && refBuf != null)
150                 buf = refBuf.get();
151 
152             if (buf == null) {
153                 buf = initBuf(fileObject);
154                 lineStart = 0;
155                 line = 1;
156             } else if (lineStart > pos) { // messages don't come in order
157                 lineStart = 0;
158                 line = 1;
159             }
160 
161             int bp = lineStart;
162             while (bp < bufLen && bp < pos) {
163                 switch (buf[bp++]) {
164                 case CR:
165                     if (bp < bufLen && buf[bp] == LF) bp++;
166                     line++;
167                     lineStart = bp;
168                     break;
169                 case LF:
170                     line++;
171                     lineStart = bp;
172                     break;
173                 }
174             }
175             return bp <= bufLen;
176         } catch (IOException e) {
177             log.directError("source.unavailable");
178             buf = new char[0];
179             return false;
180         }
181     }
182 
183     protected char[] initBuf(JavaFileObject fileObject) throws IOException {
184         char[] buf;
185         CharSequence cs = fileObject.getCharContent(true);
186         if (cs instanceof CharBuffer) {
187             CharBuffer cb = (CharBuffer) cs;
188             buf = JavacFileManager.toArray(cb);
189             bufLen = cb.limit();
190         } else {
191             buf = cs.toString().toCharArray();
192             bufLen = buf.length;
193         }
194         refBuf = new SoftReference<char[]>(buf);
195         return buf;
196     }
197 
198     /** The underlying file object. */
199     protected JavaFileObject fileObject;
200 
201     protected EndPosTable endPosTable;
202 
203     /** A soft reference to the content of the file object. */
204     protected SoftReference<char[]> refBuf;
205 
206     /** A temporary hard reference to the content of the file object. */
207     protected char[] buf;
208 
209     /** The length of the content. */
210     protected int bufLen;
211 
212     /** The start of a line found by findLine. */
213     protected int lineStart;
214 
215     /** The line number of a line found by findLine. */
216     protected int line;
217 
218     /** A log for reporting errors, such as errors accessing the content. */
219     protected AbstractLog log;
220 }