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