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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 $Id$
     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 }
     82