    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.util.ByteSequence;
    024
    025/**
    026 * RET - Return from subroutine
    027 *
    028 * <PRE>Stack: ... -&gt; ...</PRE>
    029 *
    030 * @version $Id$
    031 */
    032public class RET extends Instruction implements IndexedInstruction, TypedInstruction {
    033
    034    private boolean wide;
    035    private int index; // index to local variable containg the return address
    036
    037
    038    /**
    039     * Empty constructor needed for Instruction.readInstruction.
    040     * Not to be used otherwise.
    041     */
    042    RET() {
    043    }
    044
    045
    046    public RET(final int index) {
    047        super(org.apache.bcel.Const.RET, (short) 2);
    048        setIndex(index); // May set wide as side effect
    049    }
    050
    051
    052    /**
    053     * Dump instruction as byte code to stream out.
    054     * @param out Output stream
    055     */
    056    @Override
    057    public void dump( final DataOutputStream out ) throws IOException {
    058        if (wide) {
    059            out.writeByte(org.apache.bcel.Const.WIDE);
    060        }
    061        out.writeByte(super.getOpcode());
    062        if (wide) {
    063            out.writeShort(index);
    064        } else {
    065            out.writeByte(index);
    066        }
    067    }
    068
    069
    070    private void setWide() {
    071        wide = index > org.apache.bcel.Const.MAX_BYTE;
    072        if (wide) {
    073            super.setLength(4); // Including the wide byte
    074        } else {
    075            super.setLength(2);
    076        }
    077    }
    078
    079
    080    /**
    081     * Read needed data (e.g. index) from file.
    082     */
    083    @Override
    084    protected void initFromFile( final ByteSequence bytes, final boolean wide ) throws IOException {
    085        this.wide = wide;
    086        if (wide) {
    087            index = bytes.readUnsignedShort();
    088            super.setLength(4);
    089        } else {
    090            index = bytes.readUnsignedByte();
    091            super.setLength(2);
    092        }
    093    }
    094
    095
    096    /**
    097     * @return index of local variable containg the return address
    098     */
    099    @Override
    100    public final int getIndex() {
    101        return index;
    102    }
    103
    104
    105    /**
    106     * Set index of local variable containg the return address
    107     */
    108    @Override
    109    public final void setIndex( final int n ) {
    110        if (n < 0) {
    111            throw new ClassGenException("Negative index value: " + n);
    112        }
    113        index = n;
    114        setWide();
    115    }
    116
    117
    118    /**
    119     * @return mnemonic for instruction
    120     */
    121    @Override
    122    public String toString( final boolean verbose ) {
    123        return super.toString(verbose) + " " + index;
    124    }
    125
    126
    127    /** @return return address type
    128     */
    129    @Override
    130    public Type getType( final ConstantPoolGen cp ) {
    131        return ReturnaddressType.NO_TARGET;
    132    }
    133
    134
    135    /**
    136     * Call corresponding visitor method(s). The order is:
    137     * Call visitor methods of implemented interfaces first, then
    138     * call methods according to the class hierarchy in descending order,
    139     * i.e., the most specific visitXXX() call comes last.
    140     *
    141     * @param v Visitor object
    142     */
    143    @Override
    144    public void accept( final Visitor v ) {
    145        v.visitRET(this);
    146    }
    147}