    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}