001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   https://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.bcel.generic;
020
021import java.io.DataOutputStream;
022import java.io.IOException;
023
024import org.apache.bcel.classfile.Constant;
025import org.apache.bcel.classfile.ConstantClass;
026import org.apache.bcel.classfile.ConstantPool;
027import org.apache.bcel.classfile.Utility;
028import org.apache.bcel.util.ByteSequence;
029
030/**
031 * Abstract super class for instructions that use an index into the constant pool such as LDC, INVOKEVIRTUAL, etc.
032 *
033 * @see ConstantPoolGen
034 * @see LDC
035 * @see INVOKEVIRTUAL
036 */
037public abstract class CPInstruction extends Instruction implements TypedInstruction, IndexedInstruction {
038
039    /**
040     * @deprecated (since 6.0) will be made private; do not access directly, use getter/setter
041     */
042    @Deprecated
043    protected int index; // index to constant pool
044
045    /**
046     * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
047     */
048    CPInstruction() {
049    }
050
051    /**
052     * Constructs a CPInstruction.
053     *
054     * @param opcode the opcode.
055     * @param index to constant pool.
056     */
057    protected CPInstruction(final short opcode, final int index) {
058        super(opcode, (short) 3);
059        setIndex(index);
060    }
061
062    /**
063     * Dumps instruction as byte code to stream out.
064     *
065     * @param out Output stream.
066     */
067    @Override
068    public void dump(final DataOutputStream out) throws IOException {
069        out.writeByte(super.getOpcode());
070        out.writeShort(index);
071    }
072
073    /**
074     * @return index in constant pool referred by this instruction.
075     */
076    @Override
077    public final int getIndex() {
078        return index;
079    }
080
081    /**
082     * @return type related with this instruction.
083     */
084    @Override
085    public Type getType(final ConstantPoolGen cpg) {
086        final ConstantPool cp = cpg.getConstantPool();
087        String name = cp.getConstantString(index, org.apache.bcel.Const.CONSTANT_Class);
088        if (!name.startsWith("[")) {
089            name = "L" + name + ";";
090        }
091        return Type.getType(name);
092    }
093
094    /**
095     * Reads needed data (that is, index) from file.
096     *
097     * @param bytes input stream.
098     * @param wide wide prefix?.
099     */
100    @Override
101    protected void initFromFile(final ByteSequence bytes, final boolean wide) throws IOException {
102        setIndex(bytes.readUnsignedShort());
103        super.setLength(3);
104    }
105
106    /**
107     * Sets the index to constant pool.
108     *
109     * @param index in constant pool.
110     */
111    @Override
112    public void setIndex(final int index) { // TODO could be package-protected?
113        if (index < 0) {
114            throw new ClassGenException("Negative index value: " + index);
115        }
116        this.index = index;
117    }
118
119    /**
120     * Long output format:
121     *
122     * &lt;name of opcode&gt; "["&lt;opcode number&gt;"]" "("&lt;length of instruction&gt;")" "&lt;"&lt; constant pool
123     * index&gt;"&gt;"
124     *
125     * @param verbose long/short format switch.
126     * @return mnemonic for instruction.
127     */
128    @Override
129    public String toString(final boolean verbose) {
130        return super.toString(verbose) + " " + index;
131    }
132
133    /**
134     * @return mnemonic for instruction with symbolic references resolved.
135     */
136    @Override
137    public String toString(final ConstantPool cp) {
138        final Constant c = cp.getConstant(index);
139        String str = cp.constantToString(c);
140        if (c instanceof ConstantClass) {
141            str = Utility.packageToPath(str);
142        }
143        return org.apache.bcel.Const.getOpcodeName(super.getOpcode()) + " " + str;
144    }
145}