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1   /*
2    * Copyright  2000-2004 The Apache Software Foundation
3    *
4    *  Licensed under the Apache License, Version 2.0 (the "License"); 
5    *  you may not use this file except in compliance with the License.
6    *  You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   *  Unless required by applicable law or agreed to in writing, software
11   *  distributed under the License is distributed on an "AS IS" BASIS,
12   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   *  See the License for the specific language governing permissions and
14   *  limitations under the License. 
15   *
16   */
17  package org.apache.bcel.generic;
18  
19  import org.apache.bcel.Constants;
20  import org.apache.bcel.ExceptionConstants;
21  
22  /*** 
23   * GETFIELD - Fetch field from object
24   * <PRE>Stack: ..., objectref -&gt; ..., value</PRE>
25   * OR
26   * <PRE>Stack: ..., objectref -&gt; ..., value.word1, value.word2</PRE>
27   *
28   * @version $Id: GETFIELD.java 386056 2006-03-15 11:31:56Z tcurdt $
29   * @author  <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
30   */
31  public class GETFIELD extends FieldInstruction implements ExceptionThrower, StackConsumer,
32          StackProducer {
33  
34      /***
35       * Empty constructor needed for the Class.newInstance() statement in
36       * Instruction.readInstruction(). Not to be used otherwise.
37       */
38      GETFIELD() {
39      }
40  
41  
42      public GETFIELD(int index) {
43          super(Constants.GETFIELD, index);
44      }
45  
46  
47      public int produceStack( ConstantPoolGen cpg ) {
48          return getFieldSize(cpg);
49      }
50  
51  
52      public Class[] getExceptions() {
53          Class[] cs = new Class[2 + ExceptionConstants.EXCS_FIELD_AND_METHOD_RESOLUTION.length];
54          System.arraycopy(ExceptionConstants.EXCS_FIELD_AND_METHOD_RESOLUTION, 0, cs, 0,
55                  ExceptionConstants.EXCS_FIELD_AND_METHOD_RESOLUTION.length);
56          cs[ExceptionConstants.EXCS_FIELD_AND_METHOD_RESOLUTION.length + 1] = ExceptionConstants.INCOMPATIBLE_CLASS_CHANGE_ERROR;
57          cs[ExceptionConstants.EXCS_FIELD_AND_METHOD_RESOLUTION.length] = ExceptionConstants.NULL_POINTER_EXCEPTION;
58          return cs;
59      }
60  
61  
62      /***
63       * Call corresponding visitor method(s). The order is:
64       * Call visitor methods of implemented interfaces first, then
65       * call methods according to the class hierarchy in descending order,
66       * i.e., the most specific visitXXX() call comes last.
67       *
68       * @param v Visitor object
69       */
70      public void accept( Visitor v ) {
71          v.visitExceptionThrower(this);
72          v.visitStackConsumer(this);
73          v.visitStackProducer(this);
74          v.visitTypedInstruction(this);
75          v.visitLoadClass(this);
76          v.visitCPInstruction(this);
77          v.visitFieldOrMethod(this);
78          v.visitFieldInstruction(this);
79          v.visitGETFIELD(this);
80      }
81  }