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