001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 *  Unless required by applicable law or agreed to in writing, software
012 *  distributed under the License is distributed on an "AS IS" BASIS,
013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 *  See the License for the specific language governing permissions and
015 *  limitations under the License.
016 *
017 */
018package org.apache.bcel.generic;
019
020import org.apache.bcel.Const;
021import org.apache.bcel.ExceptionConst;
022
023/**
024 * GETFIELD - Fetch field from object
025 * <PRE>Stack: ..., objectref -&gt; ..., value</PRE>
026 * OR
027 * <PRE>Stack: ..., objectref -&gt; ..., value.word1, value.word2</PRE>
028 *
029 * @version $Id: GETFIELD.java 1812166 2017-10-13 23:48:11Z ggregory $
030 */
031public class GETFIELD extends FieldInstruction implements ExceptionThrower, StackConsumer,
032        StackProducer {
033
034    /**
035     * Empty constructor needed for Instruction.readInstruction.
036     * Not to be used otherwise.
037     */
038    GETFIELD() {
039    }
040
041
042    public GETFIELD(final int index) {
043        super(Const.GETFIELD, index);
044    }
045
046
047    @Override
048    public int produceStack( final ConstantPoolGen cpg ) {
049        return getFieldSize(cpg);
050    }
051
052
053    @Override
054    public Class<?>[] getExceptions() {
055        return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_FIELD_AND_METHOD_RESOLUTION,
056            ExceptionConst.NULL_POINTER_EXCEPTION,
057            ExceptionConst.INCOMPATIBLE_CLASS_CHANGE_ERROR);
058    }
059
060
061    /**
062     * Call corresponding visitor method(s). The order is:
063     * Call visitor methods of implemented interfaces first, then
064     * call methods according to the class hierarchy in descending order,
065     * i.e., the most specific visitXXX() call comes last.
066     *
067     * @param v Visitor object
068     */
069    @Override
070    public void accept( final Visitor v ) {
071        v.visitExceptionThrower(this);
072        v.visitStackConsumer(this);
073        v.visitStackProducer(this);
074        v.visitTypedInstruction(this);
075        v.visitLoadClass(this);
076        v.visitCPInstruction(this);
077        v.visitFieldOrMethod(this);
078        v.visitFieldInstruction(this);
079        v.visitGETFIELD(this);
080    }
081}