    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 */
    030public class GETFIELD extends FieldInstruction implements ExceptionThrower, StackConsumer,
    031        StackProducer {
    032
    033    /**
    034     * Empty constructor needed for Instruction.readInstruction.
    035     * Not to be used otherwise.
    036     */
    037    GETFIELD() {
    038    }
    039
    040
    041    public GETFIELD(final int index) {
    042        super(Const.GETFIELD, index);
    043    }
    044
    045
    046    @Override
    047    public int produceStack( final ConstantPoolGen cpg ) {
    048        return getFieldSize(cpg);
    049    }
    050
    051
    052    @Override
    053    public Class<?>[] getExceptions() {
    054        return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_FIELD_AND_METHOD_RESOLUTION,
    055            ExceptionConst.NULL_POINTER_EXCEPTION,
    056            ExceptionConst.INCOMPATIBLE_CLASS_CHANGE_ERROR);
    057    }
    058
    059
    060    /**
    061     * Call corresponding visitor method(s). The order is:
    062     * Call visitor methods of implemented interfaces first, then
    063     * call methods according to the class hierarchy in descending order,
    064     * i.e., the most specific visitXXX() call comes last.
    065     *
    066     * @param v Visitor object
    067     */
    068    @Override
    069    public void accept( final Visitor v ) {
    070        v.visitExceptionThrower(this);
    071        v.visitStackConsumer(this);
    072        v.visitStackProducer(this);
    073        v.visitTypedInstruction(this);
    074        v.visitLoadClass(this);
    075        v.visitCPInstruction(this);
    076        v.visitFieldOrMethod(this);
    077        v.visitFieldInstruction(this);
    078        v.visitGETFIELD(this);
    079    }
    080}