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 */
017package org.apache.bcel.generic;
018
019import org.apache.bcel.Const;
020import org.apache.bcel.ExceptionConst;
021
022/**
023 * GETFIELD - Fetch field from object
024 *
025 * <PRE>
026 * Stack: ..., objectref -&gt; ..., value
027 * </PRE>
028 *
029 * OR
030 *
031 * <PRE>
032 * Stack: ..., objectref -&gt; ..., value.word1, value.word2
033 * </PRE>
034 */
035public class GETFIELD extends FieldInstruction implements ExceptionThrower, StackConsumer, StackProducer {
036
037    /**
038     * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
039     */
040    GETFIELD() {
041    }
042
043    public GETFIELD(final int index) {
044        super(Const.GETFIELD, index);
045    }
046
047    /**
048     * Call corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
049     * methods according to the class hierarchy in descending order, i.e., the most specific visitXXX() call comes last.
050     *
051     * @param v Visitor object
052     */
053    @Override
054    public void accept(final Visitor v) {
055        v.visitExceptionThrower(this);
056        v.visitStackConsumer(this);
057        v.visitStackProducer(this);
058        v.visitTypedInstruction(this);
059        v.visitLoadClass(this);
060        v.visitCPInstruction(this);
061        v.visitFieldOrMethod(this);
062        v.visitFieldInstruction(this);
063        v.visitGETFIELD(this);
064    }
065
066    @Override
067    public Class<?>[] getExceptions() {
068        return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_FIELD_AND_METHOD_RESOLUTION, ExceptionConst.NULL_POINTER_EXCEPTION,
069            ExceptionConst.INCOMPATIBLE_CLASS_CHANGE_ERROR);
070    }
071
072    @Override
073    public int produceStack(final ConstantPoolGen cpg) {
074        return getFieldSize(cpg);
075    }
076}