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 */
017package org.apache.bcel.generic;
018
019import java.io.DataOutputStream;
020import java.io.IOException;
021
022import org.apache.bcel.util.ByteSequence;
023
024/**
025 * RET - Return from subroutine
026 *
027 * <PRE>
028 * Stack: ... -&gt; ...
029 * </PRE>
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     * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
038     */
039    RET() {
040    }
041
042    public RET(final int index) {
043        super(org.apache.bcel.Const.RET, (short) 2);
044        setIndex(index); // May set wide as side effect
045    }
046
047    /**
048     * Call corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
049     * methods according to the class hierarchy in descending order, i.e., the most specific visitXXX() call comes last.
050     *
051     * @param v Visitor object
052     */
053    @Override
054    public void accept(final Visitor v) {
055        v.visitRET(this);
056    }
057
058    /**
059     * Dump instruction as byte code to stream out.
060     *
061     * @param out Output stream
062     */
063    @Override
064    public void dump(final DataOutputStream out) throws IOException {
065        if (wide) {
066            out.writeByte(org.apache.bcel.Const.WIDE);
067        }
068        out.writeByte(super.getOpcode());
069        if (wide) {
070            out.writeShort(index);
071        } else {
072            out.writeByte(index);
073        }
074    }
075
076    /**
077     * @return index of local variable containg the return address
078     */
079    @Override
080    public final int getIndex() {
081        return index;
082    }
083
084    /**
085     * @return return address type
086     */
087    @Override
088    public Type getType(final ConstantPoolGen cp) {
089        return ReturnaddressType.NO_TARGET;
090    }
091
092    /**
093     * Read needed data (e.g. index) from file.
094     */
095    @Override
096    protected void initFromFile(final ByteSequence bytes, final boolean wide) throws IOException {
097        this.wide = wide;
098        if (wide) {
099            index = bytes.readUnsignedShort();
100            super.setLength(4);
101        } else {
102            index = bytes.readUnsignedByte();
103            super.setLength(2);
104        }
105    }
106
107    /**
108     * Sets index of local variable containg the return address
109     */
110    @Override
111    public final void setIndex(final int n) {
112        if (n < 0) {
113            throw new ClassGenException("Negative index value: " + n);
114        }
115        index = n;
116        setWide();
117    }
118
119    private void setWide() {
120        wide = index > org.apache.bcel.Const.MAX_BYTE;
121        if (wide) {
122            super.setLength(4); // Including the wide byte
123        } else {
124            super.setLength(2);
125        }
126    }
127
128    /**
129     * @return mnemonic for instruction
130     */
131    @Override
132    public String toString(final boolean verbose) {
133        return super.toString(verbose) + " " + index;
134    }
135}