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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  package org.apache.bcel.generic;
18  
19  import org.apache.bcel.Const;
20  import org.apache.bcel.ExceptionConst;
21  
22  /**
23   * GETFIELD - Fetch field from object
24   *
25   * <PRE>
26   * Stack: ..., objectref -&gt; ..., value
27   * </PRE>
28   *
29   * OR
30   *
31   * <PRE>
32   * Stack: ..., objectref -&gt; ..., value.word1, value.word2
33   * </PRE>
34   */
35  public class GETFIELD extends FieldInstruction implements ExceptionThrower, StackConsumer, StackProducer {
36  
37      /**
38       * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
39       */
40      GETFIELD() {
41      }
42  
43      public GETFIELD(final int index) {
44          super(Const.GETFIELD, index);
45      }
46  
47      /**
48       * Call corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
49       * methods according to the class hierarchy in descending order, i.e., the most specific visitXXX() call comes last.
50       *
51       * @param v Visitor object
52       */
53      @Override
54      public void accept(final Visitor v) {
55          v.visitExceptionThrower(this);
56          v.visitStackConsumer(this);
57          v.visitStackProducer(this);
58          v.visitTypedInstruction(this);
59          v.visitLoadClass(this);
60          v.visitCPInstruction(this);
61          v.visitFieldOrMethod(this);
62          v.visitFieldInstruction(this);
63          v.visitGETFIELD(this);
64      }
65  
66      @Override
67      public Class<?>[] getExceptions() {
68          return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_FIELD_AND_METHOD_RESOLUTION, ExceptionConst.NULL_POINTER_EXCEPTION,
69              ExceptionConst.INCOMPATIBLE_CLASS_CHANGE_ERROR);
70      }
71  
72      @Override
73      public int produceStack(final ConstantPoolGen cpg) {
74          return getFieldSize(cpg);
75      }
76  }