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1   /*
2    * @(#) CHECKCAST.java Jan 8, 2004
3    * 
4    * Copyright (c) 2003 Delft University of Technology Jaffalaan 5, 2628 BX Delft,
5    * the Netherlands All rights reserved.
6    * 
7    * This software is proprietary information of Delft University of Technology
8    * The code is published under the General Public License
9    */
10  package nl.tudelft.simulation.dsol.interpreter.operations;
11  
12  import java.io.DataInput;
13  import java.io.IOException;
14  
15  import nl.tudelft.simulation.dsol.interpreter.InterpreterException;
16  import nl.tudelft.simulation.dsol.interpreter.LocalVariable;
17  import nl.tudelft.simulation.dsol.interpreter.OperandStack;
18  import nl.tudelft.simulation.dsol.interpreter.classfile.Constant;
19  import nl.tudelft.simulation.dsol.interpreter.classfile.ConstantClass;
20  
21  /***
22   * The CHECKCAST operation as defined in <a
23   * href="http://java.sun.com/docs/books/vmspec/2nd-edition/html/Instructions2.doc2.html">
24   * http://java.sun.com/docs/books/vmspec/2nd-edition/html/Instructions2.doc2.html
25   * </a>.
26   * <p>
27   * (c) copyright 2003 <a href="http://www.simulation.tudelft.nl">Delft
28   * University of Technology </a>, the Netherlands. <br>
29   * See for project information <a
30   * href="http://www.simulation.tudelft.nl">www.simulation.tudelft.nl </a> <br>
31   * License of use: <a href="http://www.gnu.org/copyleft/gpl.html">General Public
32   * License (GPL) </a>, no warranty <br>
33   * 
34   * @author <a href="http://www.tbm.tudelft.nl/webstaf/peterja/index.htm">Peter
35   *         Jacobs </a><a
36   *         href="http://www.tbm.tudelft.nl/webstaf/alexandv/index.htm">Alexander
37   *         Verbraeck </a>
38   * @version 1.3 Apr 6, 2004
39   * @since 1.4
40   */
41  public class CHECKCAST extends VoidOperation
42  {
43  	/*** OP refers to the operand code */
44  	public static final int OP = 192;
45  
46  	/*** the index to load */
47  	private int index = -1;
48  
49  	/***
50  	 * constructs a new ALOAD
51  	 * 
52  	 * @param dataInput the dataInput
53  	 * @throws IOException on IOfailure
54  	 */
55  	public CHECKCAST(final DataInput dataInput) throws IOException
56  	{
57  		super();
58  		this.index = dataInput.readUnsignedShort();
59  	}
60  
61  	/***
62  	 * @see nl.tudelft.simulation.dsol.interpreter.operations.VoidOperation
63  	 *      #execute(nl.tudelft.simulation.dsol.interpreter.OperandStack,
64  	 *      nl.tudelft.simulation.dsol.interpreter.classfile.Constant[],
65  	 *      nl.tudelft.simulation.dsol.interpreter.LocalVariable[])
66  	 */
67  	public void execute(final OperandStack stack,
68  			final Constant[] constantPool, final LocalVariable[] localVariables)
69  	{
70  		Object objectReference = stack.peek();
71  		if (objectReference == null)
72  		{
73  			return;
74  		}
75  		Class clazz = null;
76  		try
77  		{
78  			clazz = ((ConstantClass) constantPool[this.index]).getValue()
79  					.getClassValue();
80  		} catch (ClassNotFoundException exception)
81  		{
82  			throw new InterpreterException(exception);
83  		}
84  		if (!clazz.isAssignableFrom(objectReference.getClass()))
85  		{
86  			throw new ClassCastException("CHECKCAST operation failed");
87  		}
88  	}
89  
90  	/***
91  	 * @see nl.tudelft.simulation.dsol.interpreter.Operation#getByteLength()
92  	 */
93  	public int getByteLength()
94  	{
95  		return OPCODE_BYTE_LENGTH + 2;
96  	}
97  
98  	/***
99  	 * @see nl.tudelft.simulation.dsol.interpreter.Operation#getOpcode()
100 	 */
101 	public int getOpcode()
102 	{
103 		return CHECKCAST.OP;
104 	}
105 }