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1   /*
2    * reserved comment block
3    * DO NOT REMOVE OR ALTER!
4    */
5   package com.sun.org.apache.bcel.internal.generic;
6   
7   /* ====================================================================
8    * The Apache Software License, Version 1.1
9    *
10   * Copyright (c) 2001 The Apache Software Foundation.  All rights
11   * reserved.
12   *
13   * Redistribution and use in source and binary forms, with or without
14   * modification, are permitted provided that the following conditions
15   * are met:
16   *
17   * 1. Redistributions of source code must retain the above copyright
18   *    notice, this list of conditions and the following disclaimer.
19   *
20   * 2. Redistributions in binary form must reproduce the above copyright
21   *    notice, this list of conditions and the following disclaimer in
22   *    the documentation and/or other materials provided with the
23   *    distribution.
24   *
25   * 3. The end-user documentation included with the redistribution,
26   *    if any, must include the following acknowledgment:
27   *       "This product includes software developed by the
28   *        Apache Software Foundation (http://www.apache.org/)."
29   *    Alternately, this acknowledgment may appear in the software itself,
30   *    if and wherever such third-party acknowledgments normally appear.
31   *
32   * 4. The names "Apache" and "Apache Software Foundation" and
33   *    "Apache BCEL" must not be used to endorse or promote products
34   *    derived from this software without prior written permission. For
35   *    written permission, please contact apache@apache.org.
36   *
37   * 5. Products derived from this software may not be called "Apache",
38   *    "Apache BCEL", nor may "Apache" appear in their name, without
39   *    prior written permission of the Apache Software Foundation.
40   *
41   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
42   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
43   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
44   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
45   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
46   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
47   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
48   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
49   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
50   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
51   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52   * SUCH DAMAGE.
53   * ====================================================================
54   *
55   * This software consists of voluntary contributions made by many
56   * individuals on behalf of the Apache Software Foundation.  For more
57   * information on the Apache Software Foundation, please see
58   * <http://www.apache.org/>.
59   */
60  import java.io.*;
61  import com.sun.org.apache.bcel.internal.util.ByteSequence;
62  
63  /**
64   * LDC - Push item from constant pool.
65   *
66   * <PRE>Stack: ... -&gt; ..., item</PRE>
67   *
68   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
69   */
70  public class LDC extends CPInstruction
71    implements PushInstruction, ExceptionThrower, TypedInstruction {
72    /**
73     * Empty constructor needed for the Class.newInstance() statement in
74     * Instruction.readInstruction(). Not to be used otherwise.
75     */
76    LDC() {}
77  
78    public LDC(int index) {
79      super(com.sun.org.apache.bcel.internal.Constants.LDC_W, index);
80      setSize();
81    }
82  
83    // Adjust to proper size
84    protected final void setSize() {
85      if(index <= com.sun.org.apache.bcel.internal.Constants.MAX_BYTE) { // Fits in one byte?
86        opcode = com.sun.org.apache.bcel.internal.Constants.LDC;
87        length = 2;
88      } else {
89        opcode = com.sun.org.apache.bcel.internal.Constants.LDC_W;
90        length = 3;
91      }
92    }
93  
94    /**
95     * Dump instruction as byte code to stream out.
96     * @param out Output stream
97     */
98    public void dump(DataOutputStream out) throws IOException {
99      out.writeByte(opcode);
100 
101     if(length == 2)
102       out.writeByte(index);
103     else // Applies for LDC_W
104       out.writeShort(index);
105   }
106 
107   /**
108    * Set the index to constant pool and adjust size.
109    */
110   public final void setIndex(int index) {
111     super.setIndex(index);
112     setSize();
113   }
114 
115   /**
116    * Read needed data (e.g. index) from file.
117    */
118   protected void initFromFile(ByteSequence bytes, boolean wide)
119        throws IOException
120   {
121     length = 2;
122     index  = bytes.readUnsignedByte();
123   }
124 
125   public Object getValue(ConstantPoolGen cpg) {
126     com.sun.org.apache.bcel.internal.classfile.Constant c = cpg.getConstantPool().getConstant(index);
127 
128     switch(c.getTag()) {
129       case com.sun.org.apache.bcel.internal.Constants.CONSTANT_String:
130         int i = ((com.sun.org.apache.bcel.internal.classfile.ConstantString)c).getStringIndex();
131         c = cpg.getConstantPool().getConstant(i);
132         return ((com.sun.org.apache.bcel.internal.classfile.ConstantUtf8)c).getBytes();
133 
134     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Float:
135         return new Float(((com.sun.org.apache.bcel.internal.classfile.ConstantFloat)c).getBytes());
136 
137     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Integer:
138         return new Integer(((com.sun.org.apache.bcel.internal.classfile.ConstantInteger)c).getBytes());
139 
140     default: // Never reached
141       throw new RuntimeException("Unknown or invalid constant type at " + index);
142       }
143   }
144 
145   public Type getType(ConstantPoolGen cpg) {
146     switch(cpg.getConstantPool().getConstant(index).getTag()) {
147     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_String:  return Type.STRING;
148     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Float:   return Type.FLOAT;
149     case com.sun.org.apache.bcel.internal.Constants.CONSTANT_Integer: return Type.INT;
150     default: // Never reached
151       throw new RuntimeException("Unknown or invalid constant type at " + index);
152     }
153   }
154 
155   public Class[] getExceptions() {
156     return com.sun.org.apache.bcel.internal.ExceptionConstants.EXCS_STRING_RESOLUTION;
157   }
158 
159   /**
160    * Call corresponding visitor method(s). The order is:
161    * Call visitor methods of implemented interfaces first, then
162    * call methods according to the class hierarchy in descending order,
163    * i.e., the most specific visitXXX() call comes last.
164    *
165    * @param v Visitor object
166    */
167   public void accept(Visitor v) {
168     v.visitStackProducer(this);
169     v.visitPushInstruction(this);
170     v.visitExceptionThrower(this);
171     v.visitTypedInstruction(this);
172     v.visitCPInstruction(this);
173     v.visitLDC(this);
174   }
175 }