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