1   package org.apache.bcel.generic;
2   
3   /* ====================================================================
4    * The Apache Software License, Version 1.1
5    *
6    * Copyright (c) 2001 The Apache Software Foundation.  All rights
7    * reserved.
8    *
9    * Redistribution and use in source and binary forms, with or without
10   * modification, are permitted provided that the following conditions
11   * are met:
12   *
13   * 1. Redistributions of source code must retain the above copyright
14   *    notice, this list of conditions and the following disclaimer.
15   *
16   * 2. Redistributions in binary form must reproduce the above copyright
17   *    notice, this list of conditions and the following disclaimer in
18   *    the documentation and/or other materials provided with the
19   *    distribution.
20   *
21   * 3. The end-user documentation included with the redistribution,
22   *    if any, must include the following acknowledgment:
23   *       "This product includes software developed by the
24   *        Apache Software Foundation (http://www.apache.org/)."
25   *    Alternately, this acknowledgment may appear in the software itself,
26   *    if and wherever such third-party acknowledgments normally appear.
27   *
28   * 4. The names "Apache" and "Apache Software Foundation" and
29   *    "Apache BCEL" must not be used to endorse or promote products
30   *    derived from this software without prior written permission. For
31   *    written permission, please contact apache@apache.org.
32   *
33   * 5. Products derived from this software may not be called "Apache",
34   *    "Apache BCEL", nor may "Apache" appear in their name, without
35   *    prior written permission of the Apache Software Foundation.
36   *
37   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48   * SUCH DAMAGE.
49   * ====================================================================
50   *
51   * This software consists of voluntary contributions made by many
52   * individuals on behalf of the Apache Software Foundation.  For more
53   * information on the Apache Software Foundation, please see
54   * <http://www.apache.org/>.
55   */
56  
57  import java.io.*;
58  import org.apache.bcel.util.ByteSequence;
59  import org.apache.bcel.Constants;
60  import org.apache.bcel.classfile.*;
61  
62  /*** 
63   * Abstract super class for instructions that use an index into the 
64   * constant pool such as LDC, INVOKEVIRTUAL, etc.
65   *
66   * @see ConstantPoolGen
67   * @see LDC
68   * @see INVOKEVIRTUAL
69   *
70   * @version $Id: CPInstruction.java,v 1.1.1.1 2001/10/29 20:00:07 jvanzyl Exp $
71   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
72   */
73  public abstract class CPInstruction extends Instruction
74    implements TypedInstruction, IndexedInstruction
75  {
76    protected int index; // index to constant pool
77  
78    /***
79     * Empty constructor needed for the Class.newInstance() statement in
80     * Instruction.readInstruction(). Not to be used otherwise.
81     */
82    CPInstruction() {}
83  
84    /***
85     * @param index to constant pool
86     */
87    protected CPInstruction(short opcode, int index) {
88      super(opcode, (short)3);
89      setIndex(index);
90    }
91  
92    /***
93     * Dump instruction as byte code to stream out.
94     * @param out Output stream
95     */
96    public void dump(DataOutputStream out) throws IOException {
97      out.writeByte(opcode);
98      out.writeShort(index);
99    }
100 
101   /***
102    * Long output format:
103    *
104    * <name of opcode> "["<opcode number>"]" 
105    * "("<length of instruction>")" "<"< constant pool index>">"
106    *
107    * @param verbose long/short format switch
108    * @return mnemonic for instruction
109    */
110   public String toString(boolean verbose) {
111     return super.toString(verbose) + " " + index;
112   }
113 
114   /***
115    * @return mnemonic for instruction with symbolic references resolved
116    */
117   public String toString(ConstantPool cp) {
118     Constant c   = cp.getConstant(index);
119     String   str = cp.constantToString(c);
120 
121     if(c instanceof ConstantClass)
122       str = str.replace('.', '/');
123 
124     return org.apache.bcel.Constants.OPCODE_NAMES[opcode] + " " + str;
125   }
126 
127   /***
128    * Read needed data (i.e., index) from file.
129    * @param bytes input stream
130    * @param wide wide prefix?
131    */
132   protected void initFromFile(ByteSequence bytes, boolean wide)
133        throws IOException
134   {
135     setIndex(bytes.readUnsignedShort());
136     length = 3;
137   }
138 
139   /***
140    * @return index in constant pool referred by this instruction.
141    */
142   public final int getIndex() { return index; }
143 
144   /***
145    * Set the index to constant pool.
146    * @param index in  constant pool.
147    */
148   public void setIndex(int index) { 
149     if(index < 0)
150       throw new ClassGenException("Negative index value: " + index);
151 
152     this.index = index;
153   }
154 
155   /*** @return type related with this instruction.
156    */
157   public Type getType(ConstantPoolGen cpg) {
158     ConstantPool cp   = cpg.getConstantPool();
159     String       name = cp.getConstantString(index, org.apache.bcel.Constants.CONSTANT_Class);
160 
161     if(!name.startsWith("["))
162       name = "L" + name + ";";
163 
164     return Type.getType(name);
165   }
166 }
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