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  import java.io.*;
57  import org.apache.bcel.util.ByteSequence;
58  
59  /*** 
60   * LDC - Push item from constant pool.
61   *
62   * <PRE>Stack: ... -> ..., item</PRE>
63   *
64   * @version $Id: LDC.java,v 1.1.1.1 2001/10/29 20:00:21 jvanzyl Exp $
65   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
66   */
67  public class LDC extends CPInstruction
68    implements PushInstruction, ExceptionThrower, TypedInstruction {
69    /***
70     * Empty constructor needed for the Class.newInstance() statement in
71     * Instruction.readInstruction(). Not to be used otherwise.
72     */
73    LDC() {}
74  
75    public LDC(int index) {
76      super(org.apache.bcel.Constants.LDC_W, index);
77      setSize();
78    }
79    
80    // Adjust to proper size
81    protected final void setSize() {
82      if(index <= org.apache.bcel.Constants.MAX_BYTE) { // Fits in one byte?
83        opcode = org.apache.bcel.Constants.LDC;
84        length = 2;
85      } else {
86        opcode = org.apache.bcel.Constants.LDC_W;
87        length = 3;
88      }
89    }
90  
91    /***
92     * Dump instruction as byte code to stream out.
93     * @param out Output stream
94     */
95    public void dump(DataOutputStream out) throws IOException {
96      out.writeByte(opcode);
97  
98      if(length == 2)
99        out.writeByte(index);
100     else // Applies for LDC_W
101       out.writeShort(index);
102   }
103 
104   /***
105    * Set the index to constant pool and adjust size.
106    */
107   public final void setIndex(int index) { 
108     super.setIndex(index);
109     setSize();
110   }
111 
112   /***
113    * Read needed data (e.g. index) from file.
114    */
115   protected void initFromFile(ByteSequence bytes, boolean wide)
116        throws IOException
117   {
118     length = 2;
119     index  = bytes.readUnsignedByte();
120   }
121 
122   public Object getValue(ConstantPoolGen cpg) {
123     org.apache.bcel.classfile.Constant c = cpg.getConstantPool().getConstant(index);
124 
125     switch(c.getTag()) {
126       case org.apache.bcel.Constants.CONSTANT_String:
127 	int i = ((org.apache.bcel.classfile.ConstantString)c).getStringIndex();
128 	c = cpg.getConstantPool().getConstant(i);
129 	return ((org.apache.bcel.classfile.ConstantUtf8)c).getBytes();
130 
131     case org.apache.bcel.Constants.CONSTANT_Float:
132 	return new Float(((org.apache.bcel.classfile.ConstantFloat)c).getBytes());
133 
134     case org.apache.bcel.Constants.CONSTANT_Integer:
135 	return new Integer(((org.apache.bcel.classfile.ConstantInteger)c).getBytes());
136 
137     default: // Never reached
138       throw new RuntimeException("Unknown or invalid constant type at " + index);
139       }
140   }
141 
142   public Type getType(ConstantPoolGen cpg) {
143     switch(cpg.getConstantPool().getConstant(index).getTag()) {
144     case org.apache.bcel.Constants.CONSTANT_String:  return Type.STRING;
145     case org.apache.bcel.Constants.CONSTANT_Float:   return Type.FLOAT;
146     case org.apache.bcel.Constants.CONSTANT_Integer: return Type.INT;
147     default: // Never reached
148       throw new RuntimeException("Unknown or invalid constant type at " + index);
149     }
150   }
151 
152   public Class[] getExceptions() {
153     return org.apache.bcel.ExceptionConstants.EXCS_STRING_RESOLUTION;
154   }
155 
156   /***
157    * Call corresponding visitor method(s). The order is:
158    * Call visitor methods of implemented interfaces first, then
159    * call methods according to the class hierarchy in descending order,
160    * i.e., the most specific visitXXX() call comes last.
161    *
162    * @param v Visitor object
163    */
164   public void accept(Visitor v) {
165     v.visitStackProducer(this);
166     v.visitPushInstruction(this);
167     v.visitExceptionThrower(this);
168     v.visitTypedInstruction(this);
169     v.visitCPInstruction(this);
170     v.visitLDC(this);
171   }
172 }
This page was automatically generated by Maven