| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.iapi.services.classfile.ConstantPoolEntry |
| 4 | |
| 5 | Copyright 2000, 2004 The Apache Software Foundation or its licensors, as applicable. |
| 6 | |
| 7 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | you may not use this file except in compliance with the License. |
| 9 | You may obtain a copy of the License at |
| 10 | |
| 11 | http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | |
| 13 | Unless required by applicable law or agreed to in writing, software |
| 14 | distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | See the License for the specific language governing permissions and |
| 17 | limitations under the License. |
| 18 | |
| 19 | */ |
| 20 | |
| 21 | package org.apache.derby.iapi.services.classfile; |
| 22 | |
| 23 | import org.apache.derby.iapi.services.classfile.VMDescriptor; |
| 24 | |
| 25 | import org.apache.derby.iapi.services.sanity.SanityManager; |
| 26 | |
| 27 | import java.io.IOException; |
| 28 | |
| 29 | /** Constant Pool class - pages 92-99 */ |
| 30 | public abstract class ConstantPoolEntry /*implements PoolEntry*/ |
| 31 | { |
| 32 | |
| 33 | protected int tag; // u1 (page 83) |
| 34 | protected boolean doubleSlot; // Some entries take up two slots! (see footnote page 98) |
| 35 | |
| 36 | /* Index within Vector */ |
| 37 | protected int index; |
| 38 | |
| 39 | protected ConstantPoolEntry(int tag) { |
| 40 | this.tag = tag; |
| 41 | } |
| 42 | |
| 43 | int getIndex() { |
| 44 | if (SanityManager.DEBUG) { |
| 45 | if (index <= 0) |
| 46 | { |
| 47 | SanityManager.THROWASSERT("index is expected to be > 0, is " + index); |
| 48 | } |
| 49 | } |
| 50 | return index; |
| 51 | } |
| 52 | |
| 53 | void setIndex(int index) { |
| 54 | this.index = index; |
| 55 | } |
| 56 | |
| 57 | boolean doubleSlot() { |
| 58 | return doubleSlot; |
| 59 | } |
| 60 | |
| 61 | /** |
| 62 | Return the key used to key this object in a hashtable |
| 63 | */ |
| 64 | Object getKey() { |
| 65 | return this; |
| 66 | } |
| 67 | |
| 68 | /** |
| 69 | Return an estimate of the size of the constant pool entry. |
| 70 | */ |
| 71 | abstract int classFileSize(); |
| 72 | |
| 73 | void put(ClassFormatOutput out) throws IOException { |
| 74 | out.putU1(tag); |
| 75 | } |
| 76 | |
| 77 | /* |
| 78 | ** Public API methods |
| 79 | */ |
| 80 | |
| 81 | /** |
| 82 | Return the tag or type of the entry. Will be equal to one of the |
| 83 | constants above, e.g. CONSTANT_Class. |
| 84 | */ |
| 85 | final int getTag() { |
| 86 | return tag; |
| 87 | } |
| 88 | |
| 89 | /** |
| 90 | Get the first index in a index type pool entry. |
| 91 | This call is valid when getTag() returns one of |
| 92 | <UL> |
| 93 | <LI> CONSTANT_Class |
| 94 | <LI> CONSTANT_Fieldref |
| 95 | <LI> CONSTANT_Methodref |
| 96 | <LI> CONSTANT_InterfaceMethodref |
| 97 | <LI> CONSTANT_String |
| 98 | <LI> CONSTANT_NameAndType |
| 99 | </UL> |
| 100 | */ |
| 101 | int getI1() { return 0; } |
| 102 | |
| 103 | /** |
| 104 | Get the second index in a index type pool entry. |
| 105 | This call is valid when getTag() returns one of |
| 106 | <UL> |
| 107 | <LI> CONSTANT_Fieldref |
| 108 | <LI> CONSTANT_Methodref |
| 109 | <LI> CONSTANT_InterfaceMethodref |
| 110 | <LI> CONSTANT_NameAndType |
| 111 | </UL> |
| 112 | */ |
| 113 | int getI2() { return 0; }; |
| 114 | } |
| 115 | |