Item


1   /***
2    * ASM: a very small and fast Java bytecode manipulation framework
3    * Copyright (c) 2000-2005 INRIA, France Telecom
4    * All rights reserved.
5    *
6    * Redistribution and use in source and binary forms, with or without
7    * modification, are permitted provided that the following conditions
8    * are met:
9    * 1. Redistributions of source code must retain the above copyright
10   *    notice, this list of conditions and the following disclaimer.
11   * 2. Redistributions in binary form must reproduce the above copyright
12   *    notice, this list of conditions and the following disclaimer in the
13   *    documentation and/or other materials provided with the distribution.
14   * 3. Neither the name of the copyright holders nor the names of its
15   *    contributors may be used to endorse or promote products derived from
16   *    this software without specific prior written permission.
17   *
18   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
22   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
28   * THE POSSIBILITY OF SUCH DAMAGE.
29   */
30  package org.objectweb.asm;
31  
32  /**
33   * A constant pool item. Constant pool items can be created with the 'newXXX'
34   * methods in the {@link ClassWriter} class.
35   * 
36   * @author Eric Bruneton
37   */
38  final class Item {
39  
40      /**
41       * Index of this item in the constant pool.
42       */
43      short index;
44  
45      /**
46       * Type of this constant pool item. A single class is used to represent all
47       * constant pool item types, in order to minimize the bytecode size of this
48       * package. The value of this field is I, J, F, D, S, s, C, T, G, M, or N
49       * (for Constant Integer, Long, Float, Double, STR, UTF8, Class, NameType,
50       * Fieldref, Methodref, or InterfaceMethodref constant pool items
51       * respectively).
52       */
53      char type;
54  
55      /**
56       * Value of this item, for an integer item.
57       */
58      int intVal;
59  
60      /**
61       * Value of this item, for a long item.
62       */
63      long longVal;
64  
65      /**
66       * Value of this item, for a float item.
67       */
68      float floatVal;
69  
70      /**
71       * Value of this item, for a double item.
72       */
73      double doubleVal;
74  
75      /**
76       * First part of the value of this item, for items that do not hold a
77       * primitive value.
78       */
79      String   strVal1;
80  
81      /**
82       * Second part of the value of this item, for items that do not hold a
83       * primitive value.
84       */
85      String   strVal2;
86  
87      /**
88       * Third part of the value of this item, for items that do not hold a
89       * primitive value.
90       */
91      String   strVal3;
92  
93      /**
94       * The hash code value of this constant pool item.
95       */
96      int hashCode;
97  
98      /**
99       * Link to another constant pool item, used for collision lists in the
100      * constant pool's hash table.
101      */
102     Item next;
103 
104     /**
105      * Constructs an uninitialized {@link Item}.
106      */
107     Item() {
108     }
109 
110     /**
111      * Constructs a copy of the given item.
112      * 
113      * @param index index of the item to be constructed.
114      * @param i the item that must be copied into the item to be constructed.
115      */
116     Item(final short index, final Item i) {
117         this.index = index;
118         type = i.type;
119         intVal = i.intVal;
120         longVal = i.longVal;
121         floatVal = i.floatVal;
122         doubleVal = i.doubleVal;
123         strVal1 = i.strVal1;
124         strVal2 = i.strVal2;
125         strVal3 = i.strVal3;
126         hashCode = i.hashCode;
127     }
128 
129     /**
130      * Sets this item to an integer item.
131      * 
132      * @param intVal the value of this item.
133      */
134     void set(final int intVal) {
135         this.type = 'I';
136         this.intVal = intVal;
137         this.hashCode = 0x7FFFFFFF & (type + intVal);
138     }
139 
140     /**
141      * Sets this item to a long item.
142      * 
143      * @param longVal the value of this item.
144      */
145     void set(final long longVal) {
146         this.type = 'J';
147         this.longVal = longVal;
148         this.hashCode = 0x7FFFFFFF & (type + (int) longVal);
149     }
150 
151     /**
152      * Sets this item to a float item.
153      * 
154      * @param floatVal the value of this item.
155      */
156     void set(final float floatVal) {
157         this.type = 'F';
158         this.floatVal = floatVal;
159         this.hashCode = 0x7FFFFFFF & (type + (int) floatVal);
160     }
161 
162     /**
163      * Sets this item to a double item.
164      * 
165      * @param doubleVal the value of this item.
166      */
167     void set(final double doubleVal) {
168         this.type = 'D';
169         this.doubleVal = doubleVal;
170         this.hashCode = 0x7FFFFFFF & (type + (int) doubleVal);
171     }
172 
173     /**
174      * Sets this item to an item that do not hold a primitive value.
175      * 
176      * @param type the type of this item.
177      * @param strVal1 first part of the value of this item.
178      * @param strVal2 second part of the value of this item.
179      * @param strVal3 third part of the value of this item.
180      */
181     void set(
182         final char type,
183         final String   strVal1,
184         final String   strVal2,
185         final String   strVal3)
186     {
187         this.type = type;
188         this.strVal1 = strVal1;
189         this.strVal2 = strVal2;
190         this.strVal3 = strVal3;
191         switch (type) {
192             case 's':
193             case 'S':
194             case 'C':
195                 hashCode = 0x7FFFFFFF & (type + strVal1.hashCode());
196                 return;
197             case 'T':
198                 hashCode = 0x7FFFFFFF & (type + strVal1.hashCode()
199                         * strVal2.hashCode());
200                 return;
201             // case 'G':
202             // case 'M':
203             // case 'N':
204             default:
205                 hashCode = 0x7FFFFFFF & (type + strVal1.hashCode()
206                         * strVal2.hashCode() * strVal3.hashCode());
207         }
208     }
209 
210     /**
211      * Indicates if the given item is equal to this one.
212      * 
213      * @param i the item to be compared to this one.
214      * @return <tt>true</tt> if the given item if equal to this one,
215      *         <tt>false</tt> otherwise.
216      */
217     boolean isEqualTo(final Item i) {
218         if (i.type == type) {
219             switch (type) {
220                 case 'I':
221                     return i.intVal == intVal;
222                 case 'J':
223                     return i.longVal == longVal;
224                 case 'F':
225                     return i.floatVal == floatVal;
226                 case 'D':
227                     return i.doubleVal == doubleVal;
228                 case 's':
229                 case 'S':
230                 case 'C':
231                     return i.strVal1.equals(strVal1);
232                 case 'T':
233                     return i.strVal1.equals(strVal1)
234                             && i.strVal2.equals(strVal2);
235                 // case 'G':
236                 // case 'M':
237                 // case 'N':
238                 default:
239                     return i.strVal1.equals(strVal1)
240                             && i.strVal2.equals(strVal2)
241                             && i.strVal3.equals(strVal3);
242             }
243         }
244         return false;
245     }
246 }
247
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