1   package org.apache.bcel.classfile;
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  org.apache.bcel.Constants;
58  import  java.io.*;
59  
60  /***
61   * This class represents the type of a local variable or item on stack
62   * used in the StackMap entries.
63   *
64   * @version $Id: StackMapType.java,v 1.2 2002/03/11 16:16:35 mdahm Exp $
65   * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
66   * @see     StackMapEntry
67   * @see     StackMap
68   * @see     Constants
69   */
70  public final class StackMapType implements Cloneable {
71    private byte         type;
72    private int          index = -1; // Index to CONSTANT_Class or offset
73    private ConstantPool constant_pool;
74  
75    /***
76     * Construct object from file stream.
77     * @param file Input stream
78     * @throws IOException
79     */
80    StackMapType(DataInputStream file, ConstantPool constant_pool) throws IOException
81    {
82      this(file.readByte(), -1, constant_pool);
83  
84      if(hasIndex())
85        setIndex(file.readShort());
86  
87      setConstantPool(constant_pool);
88    }
89  
90    /***
91     * @param type type tag as defined in the Constants interface
92     * @param index index to constant pool, or byte code offset
93     */
94    public StackMapType(byte type, int index, ConstantPool constant_pool) {
95      setType(type);
96      setIndex(index);
97      setConstantPool(constant_pool);
98    }
99  
100   public void setType(byte t) {
101     if((t < Constants.ITEM_Bogus) || (t > Constants.ITEM_NewObject))
102       throw new RuntimeException("Illegal type for StackMapType: " + t);
103     type = t;
104   }
105 
106   public byte getType()       { return type; }
107   public void setIndex(int t) { index = t; }
108 
109   /*** @return index to constant pool if type == ITEM_Object, or offset
110    * in byte code, if type == ITEM_NewObject, and -1 otherwise
111    */
112   public int  getIndex()      { return index; }
113   
114   /***
115    * Dump type entries to file.
116    *
117    * @param file Output file stream
118    * @throws IOException
119    */ 
120   public final void dump(DataOutputStream file) throws IOException
121   {
122     file.writeByte(type);
123     if(hasIndex())
124       file.writeShort(getIndex());
125   }    
126 
127   /*** @return true, if type is either ITEM_Object or ITEM_NewObject
128    */
129   public final boolean hasIndex() {
130     return ((type == Constants.ITEM_Object) ||
131 	    (type == Constants.ITEM_NewObject));
132   }
133 
134   private String printIndex() {
135     if(type == Constants.ITEM_Object)
136       return ", class=" + constant_pool.constantToString(index, Constants.CONSTANT_Class);
137     else if(type == Constants.ITEM_NewObject)
138       return ", offset=" + index;
139     else
140       return "";
141   }
142 
143   /***
144    * @return String representation
145    */ 
146   public final String toString() {
147     return "(type=" + Constants.ITEM_NAMES[type] + printIndex() + ")";
148   }    
149 
150   /***
151    * @return deep copy of this object
152    */
153   public StackMapType copy() {
154     try {
155       return (StackMapType)clone();
156     } catch(CloneNotSupportedException e) {}
157 
158     return null;
159   }
160 
161   /***
162    * @return Constant pool used by this object.
163    */   
164   public final ConstantPool getConstantPool() { return constant_pool; }
165 
166   /***
167    * @param constant_pool Constant pool to be used for this object.
168    */   
169   public final void setConstantPool(ConstantPool constant_pool) {
170     this.constant_pool = constant_pool;
171   }
172 }
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