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="http://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}