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1   /***
2    *
3    * Copyright 2005 Jeremy Rayner
4    *
5    * Licensed under the Apache License, Version 2.0 (the "License");
6    * you may not use this file except in compliance with the License.
7    * You may obtain a copy of the License at
8    *
9    * http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   *
17   **/
18  package org.codehaus.groovy.antlr;
19  
20  import java.util.List;
21  import java.util.ArrayList;
22  
23  /***
24   * A simple buffer that provides line/col access to chunks of source code
25   * held within itself.
26   *
27   * @author <a href="mailto:groovy@ross-rayner.com">Jeremy Rayner</a>
28   * @version $Revision: 1.4 $
29   */
30  public class SourceBuffer {
31      private List lines;
32      private StringBuffer current;
33  
34      public SourceBuffer() {
35          lines = new ArrayList();
36          //lines.add(new StringBuffer()); // dummy row for position [0] in the List
37  
38          current = new StringBuffer();
39          lines.add(current);
40      }
41  
42      /***
43       * Obtains a snippet of the source code within the bounds specified
44       * @param start (inclusive line/ inclusive column)
45       * @param end (inclusive line / exclusive column)
46       * @return specified snippet of source code as a String, or null if no source available
47       */
48      public String getSnippet(LineColumn start, LineColumn end) {
49          // preconditions
50          if (start == null || end == null) { return null; } // no text to return
51          if (start.equals(end)) { return null; } // no text to return
52          if (lines.size() == 1 && current.length() == 0) { return null; } // buffer hasn't been filled yet
53  
54          // working variables
55          int startLine = start.getLine();
56          int startColumn = start.getColumn();
57          int endLine = end.getLine();
58          int endColumn = end.getColumn();
59  
60          // reset any out of bounds requests
61          if (startLine < 1) { startLine = 1;}
62          if (endLine < 1) { endLine = 1;}
63          if (startColumn < 1) { startColumn = 1;}
64          if (endColumn < 1) { endColumn = 1;}
65          if (startLine > lines.size()) { startLine = lines.size(); }
66          if (endLine > lines.size()) { endLine = lines.size(); }
67  
68          // obtain the snippet from the buffer within specified bounds
69          StringBuffer snippet = new StringBuffer();
70          for (int i = startLine - 1; i < endLine;i++) {
71              String line = ((StringBuffer)lines.get(i)).toString();
72              if (startLine == endLine) {
73                  // reset any out of bounds requests (again)
74                  if (startColumn > line.length()) { startColumn = line.length();}
75                  if (startColumn < 1) { startColumn = 1;}
76                  if (endColumn > line.length()) { endColumn = line.length() + 1;}
77                  if (endColumn < 1) { endColumn = 1;}
78  
79                  line = line.substring(startColumn - 1, endColumn - 1);
80              } else {
81                  if (i == startLine - 1) {
82                      if (startColumn - 1 < line.length()) {
83                          line = line.substring(startColumn - 1);
84                      }
85                  }
86                  if (i == endLine - 1) {
87                      if (endColumn - 1 < line.length()) {
88                          line = line.substring(0,endColumn - 1);
89                      }
90                  }
91              }
92              snippet.append(line);
93          }
94          return snippet.toString();
95      }
96  
97      /***
98       * Writes the specified character into the buffer
99       * @param c
100      */
101     public void write(int c) {
102         if (c != -1) {
103             current.append((char)c);
104         }
105         if (c == '\n') {
106             current = new StringBuffer();
107             lines.add(current);
108         }
109     }
110 }