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.Const;
023import org.apache.bcel.util.ByteSequence;
024
025/**
026 * IINC - Increment local variable by constant
027 */
028public class IINC extends LocalVariableInstruction {
029
030    private boolean wide;
031    private int c;
032
033    /**
034     * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
035     */
036    IINC() {
037    }
038
039    /**
040     * @param n index of local variable
041     * @param c increment factor
042     */
043    public IINC(final int n, final int c) {
044        // Default behavior of LocalVariableInstruction causes error
045        super.setOpcode(Const.IINC);
046        super.setLength((short) 3);
047        setIndex(n); // May set wide as side effect
048        setIncrement(c);
049    }
050
051    /**
052     * Calls corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
053     * methods according to the class hierarchy in descending order, i.e., the most specific visitXXX() call comes last.
054     *
055     * @param v Visitor object
056     */
057    @Override
058    public void accept(final Visitor v) {
059        v.visitLocalVariableInstruction(this);
060        v.visitIINC(this);
061    }
062
063    /**
064     * Dumps instruction as byte code to stream out.
065     *
066     * @param out Output stream
067     */
068    @Override
069    public void dump(final DataOutputStream out) throws IOException {
070        if (wide) {
071            out.writeByte(Const.WIDE);
072        }
073        out.writeByte(super.getOpcode());
074        if (wide) {
075            out.writeShort(super.getIndex());
076            out.writeShort(c);
077        } else {
078            out.writeByte(super.getIndex());
079            out.writeByte(c);
080        }
081    }
082
083    /**
084     * @return increment factor
085     */
086    public final int getIncrement() {
087        return c;
088    }
089
090    /**
091     * @return int type
092     */
093    @Override
094    public Type getType(final ConstantPoolGen cp) {
095        return Type.INT;
096    }
097
098    /**
099     * Reads needed data (e.g. index) from file.
100     */
101    @Override
102    protected void initFromFile(final ByteSequence bytes, final boolean wide) throws IOException {
103        this.wide = wide;
104        if (wide) {
105            super.setLength(6);
106            super.setIndexOnly(bytes.readUnsignedShort());
107            c = bytes.readShort();
108        } else {
109            super.setLength(3);
110            super.setIndexOnly(bytes.readUnsignedByte());
111            c = bytes.readByte();
112        }
113    }
114
115    /**
116     * Sets increment factor.
117     */
118    public final void setIncrement(final int c) {
119        this.c = c;
120        setWide();
121    }
122
123    /**
124     * Sets index of local variable.
125     */
126    @Override
127    public final void setIndex(final int n) {
128        if (n < 0) {
129            throw new ClassGenException("Negative index value: " + n);
130        }
131        super.setIndexOnly(n);
132        setWide();
133    }
134
135    private void setWide() {
136        wide = super.getIndex() > Const.MAX_BYTE;
137        if (c > 0) {
138            wide = wide || c > Byte.MAX_VALUE;
139        } else {
140            wide = wide || c < Byte.MIN_VALUE;
141        }
142        if (wide) {
143            super.setLength(6); // wide byte included
144        } else {
145            super.setLength(3);
146        }
147    }
148
149    /**
150     * Returns mnemonic for instruction.
151     *
152     * @return mnemonic for instruction.
153     */
154    @Override
155    public String toString(final boolean verbose) {
156        return super.toString(verbose) + " " + c;
157    }
158}