    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 java.io.DataOutputStream;
    021import java.io.IOException;
    022
    023import org.apache.bcel.Const;
    024import org.apache.bcel.ExceptionConst;
    025import org.apache.bcel.classfile.ConstantPool;
    026import org.apache.bcel.util.ByteSequence;
    027
    028/**
    029 * INVOKEINTERFACE - Invoke interface method
    030 * <PRE>Stack: ..., objectref, [arg1, [arg2 ...]] -&gt; ...</PRE>
    031 *
    032 * @see
    033 * <a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-6.html#jvms-6.5.invokeinterface">
    034 * The invokeinterface instruction in The Java Virtual Machine Specification</a>
    035 */
    036public final class INVOKEINTERFACE extends InvokeInstruction {
    037
    038    private int nargs; // Number of arguments on stack (number of stack slots), called "count" in vmspec2
    039
    040
    041    /**
    042     * Empty constructor needed for Instruction.readInstruction.
    043     * Not to be used otherwise.
    044     */
    045    INVOKEINTERFACE() {
    046    }
    047
    048
    049    public INVOKEINTERFACE(final int index, final int nargs) {
    050        super(Const.INVOKEINTERFACE, index);
    051        super.setLength(5);
    052        if (nargs < 1) {
    053            throw new ClassGenException("Number of arguments must be > 0 " + nargs);
    054        }
    055        this.nargs = nargs;
    056    }
    057
    058
    059    /**
    060     * Dump instruction as byte code to stream out.
    061     * @param out Output stream
    062     */
    063    @Override
    064    public void dump( final DataOutputStream out ) throws IOException {
    065        out.writeByte(super.getOpcode());
    066        out.writeShort(super.getIndex());
    067        out.writeByte(nargs);
    068        out.writeByte(0);
    069    }
    070
    071
    072    /**
    073     * The <B>count</B> argument according to the Java Language Specification,
    074     * Second Edition.
    075     */
    076    public int getCount() {
    077        return nargs;
    078    }
    079
    080
    081    /**
    082     * Read needed data (i.e., index) from file.
    083     */
    084    @Override
    085    protected void initFromFile( final ByteSequence bytes, final boolean wide ) throws IOException {
    086        super.initFromFile(bytes, wide);
    087        super.setLength(5);
    088        nargs = bytes.readUnsignedByte();
    089        bytes.readByte(); // Skip 0 byte
    090    }
    091
    092
    093    /**
    094     * @return mnemonic for instruction with symbolic references resolved
    095     */
    096    @Override
    097    public String toString( final ConstantPool cp ) {
    098        return super.toString(cp) + " " + nargs;
    099    }
    100
    101
    102    @Override
    103    public int consumeStack( final ConstantPoolGen cpg ) { // nargs is given in byte-code
    104        return nargs; // nargs includes this reference
    105    }
    106
    107
    108    @Override
    109    public Class<?>[] getExceptions() {
    110        return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_INTERFACE_METHOD_RESOLUTION,
    111            ExceptionConst.UNSATISFIED_LINK_ERROR,
    112            ExceptionConst.ABSTRACT_METHOD_ERROR,
    113            ExceptionConst.ILLEGAL_ACCESS_ERROR,
    114            ExceptionConst.INCOMPATIBLE_CLASS_CHANGE_ERROR);
    115    }
    116
    117
    118    /**
    119     * Call corresponding visitor method(s). The order is:
    120     * Call visitor methods of implemented interfaces first, then
    121     * call methods according to the class hierarchy in descending order,
    122     * i.e., the most specific visitXXX() call comes last.
    123     *
    124     * @param v Visitor object
    125     */
    126    @Override
    127    public void accept( final Visitor v ) {
    128        v.visitExceptionThrower(this);
    129        v.visitTypedInstruction(this);
    130        v.visitStackConsumer(this);
    131        v.visitStackProducer(this);
    132        v.visitLoadClass(this);
    133        v.visitCPInstruction(this);
    134        v.visitFieldOrMethod(this);
    135        v.visitInvokeInstruction(this);
    136        v.visitINVOKEINTERFACE(this);
    137    }
    138}