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