    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 * @version $Id: INVOKEINTERFACE.java 1812166 2017-10-13 23:48:11Z ggregory $
    033 * @see
    034 * <a href="http://docs.oracle.com/javase/specs/jvms/se8/html/jvms-6.html#jvms-6.5.invokeinterface">
    035 * The invokeinterface instruction in The Java Virtual Machine Specification</a>
    036 */
    037public final class INVOKEINTERFACE extends InvokeInstruction {
    038
    039    private int nargs; // Number of arguments on stack (number of stack slots), called "count" in vmspec2
    040
    041
    042    /**
    043     * Empty constructor needed for Instruction.readInstruction.
    044     * Not to be used otherwise.
    045     */
    046    INVOKEINTERFACE() {
    047    }
    048
    049
    050    public INVOKEINTERFACE(final int index, final int nargs) {
    051        super(Const.INVOKEINTERFACE, index);
    052        super.setLength(5);
    053        if (nargs < 1) {
    054            throw new ClassGenException("Number of arguments must be > 0 " + nargs);
    055        }
    056        this.nargs = nargs;
    057    }
    058
    059
    060    /**
    061     * Dump instruction as byte code to stream out.
    062     * @param out Output stream
    063     */
    064    @Override
    065    public void dump( final DataOutputStream out ) throws IOException {
    066        out.writeByte(super.getOpcode());
    067        out.writeShort(super.getIndex());
    068        out.writeByte(nargs);
    069        out.writeByte(0);
    070    }
    071
    072
    073    /**
    074     * The <B>count</B> argument according to the Java Language Specification,
    075     * Second Edition.
    076     */
    077    public int getCount() {
    078        return nargs;
    079    }
    080
    081
    082    /**
    083     * Read needed data (i.e., index) from file.
    084     */
    085    @Override
    086    protected void initFromFile( final ByteSequence bytes, final boolean wide ) throws IOException {
    087        super.initFromFile(bytes, wide);
    088        super.setLength(5);
    089        nargs = bytes.readUnsignedByte();
    090        bytes.readByte(); // Skip 0 byte
    091    }
    092
    093
    094    /**
    095     * @return mnemonic for instruction with symbolic references resolved
    096     */
    097    @Override
    098    public String toString( final ConstantPool cp ) {
    099        return super.toString(cp) + " " + nargs;
    100    }
    101
    102
    103    @Override
    104    public int consumeStack( final ConstantPoolGen cpg ) { // nargs is given in byte-code
    105        return nargs; // nargs includes this reference
    106    }
    107
    108
    109    @Override
    110    public Class<?>[] getExceptions() {
    111        return ExceptionConst.createExceptions(ExceptionConst.EXCS.EXCS_INTERFACE_METHOD_RESOLUTION,
    112            ExceptionConst.UNSATISFIED_LINK_ERROR,
    113            ExceptionConst.ABSTRACT_METHOD_ERROR,
    114            ExceptionConst.ILLEGAL_ACCESS_ERROR,
    115            ExceptionConst.INCOMPATIBLE_CLASS_CHANGE_ERROR);
    116    }
    117
    118
    119    /**
    120     * Call corresponding visitor method(s). The order is:
    121     * Call visitor methods of implemented interfaces first, then
    122     * call methods according to the class hierarchy in descending order,
    123     * i.e., the most specific visitXXX() call comes last.
    124     *
    125     * @param v Visitor object
    126     */
    127    @Override
    128    public void accept( final Visitor v ) {
    129        v.visitExceptionThrower(this);
    130        v.visitTypedInstruction(this);
    131        v.visitStackConsumer(this);
    132        v.visitStackProducer(this);
    133        v.visitLoadClass(this);
    134        v.visitCPInstruction(this);
    135        v.visitFieldOrMethod(this);
    136        v.visitInvokeInstruction(this);
    137        v.visitINVOKEINTERFACE(this);
    138    }
    139}