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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  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.apache.bcel.generic;
19  
20  import org.apache.bcel.Const;
21  import org.apache.bcel.ExceptionConst;
22  
23  /**
24   * GETFIELD - Fetch field from object
25   * <PRE>Stack: ..., objectref -&gt; ..., value</PRE>
26   * OR
27   * <PRE>Stack: ..., objectref -&gt; ..., value.word1, value.word2</PRE>
28   *
29   * @version $Id: GETFIELD.html 1021978 2017-12-09 17:38:21Z ggregory $
30   */
31  public class GETFIELD extends FieldInstruction implements ExceptionThrower, StackConsumer,
32          StackProducer {
33  
34      /**
35       * Empty constructor needed for Instruction.readInstruction.
36       * Not to be used otherwise.
37       */
38      GETFIELD() {
39      }
40  
41  
42      public GETFIELD(final int index) {
43          super(Const.GETFIELD, index);
44      }
45  
46  
47      @Override
48      public int produceStack( final ConstantPoolGen cpg ) {
49          return getFieldSize(cpg);
50      }
51  
52  
53      @Override
54      public Class<?>[] getExceptions() {
55          return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_FIELD_AND_METHOD_RESOLUTION,
56              ExceptionConst.NULL_POINTER_EXCEPTION,
57              ExceptionConst.INCOMPATIBLE_CLASS_CHANGE_ERROR);
58      }
59  
60  
61      /**
62       * Call corresponding visitor method(s). The order is:
63       * Call visitor methods of implemented interfaces first, then
64       * call methods according to the class hierarchy in descending order,
65       * i.e., the most specific visitXXX() call comes last.
66       *
67       * @param v Visitor object
68       */
69      @Override
70      public void accept( final 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  }