1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.bcel.classfile;
19
20 import java.io.DataInput;
21 import java.io.DataOutputStream;
22 import java.io.IOException;
23
24 import org.apache.bcel.Const;
25 import org.apache.bcel.util.Args;
26
27 /**
28 * This class is derived from <em>Attribute</em> and records the nest host of the nest to which the current class or
29 * interface claims to belong. There may be at most one NestHost attribute in a ClassFile structure.
30 *
31 * @see Attribute
32 */
33 public final class NestHost extends Attribute {
34
35 private int hostClassIndex;
36
37 /**
38 * Constructs object from input stream.
39 *
40 * @param nameIndex Index in constant pool
41 * @param length Content length in bytes
42 * @param input Input stream
43 * @param constantPool Array of constants
44 * @throws IOException if an I/O error occurs.
45 */
46 NestHost(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
47 this(nameIndex, length, 0, constantPool);
48 hostClassIndex = input.readUnsignedShort();
49 }
50
51 /**
52 * @param nameIndex Index in constant pool
53 * @param length Content length in bytes
54 * @param hostClassIndex Host class index
55 * @param constantPool Array of constants
56 */
57 public NestHost(final int nameIndex, final int length, final int hostClassIndex, final ConstantPool constantPool) {
58 super(Const.ATTR_NEST_MEMBERS, nameIndex, length, constantPool);
59 this.hostClassIndex = Args.requireU2(hostClassIndex, "hostClassIndex");
60 }
61
62 /**
63 * Initializes from another object. Note that both objects use the same references (shallow copy). Use copy() for a
64 * physical copy.
65 *
66 * @param c Source to copy.
67 */
68 public NestHost(final NestHost c) {
69 this(c.getNameIndex(), c.getLength(), c.getHostClassIndex(), c.getConstantPool());
70 }
71
72 /**
73 * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
74 * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
75 *
76 * @param v Visitor object
77 */
78 @Override
79 public void accept(final Visitor v) {
80 v.visitNestHost(this);
81 }
82
83 /**
84 * @return deep copy of this attribute
85 */
86 @Override
87 public Attribute copy(final ConstantPool constantPool) {
88 final NestHost c = (NestHost) clone();
89 c.setConstantPool(constantPool);
90 return c;
91 }
92
93 /**
94 * Dumps NestHost attribute to file stream in binary format.
95 *
96 * @param file Output file stream
97 * @throws IOException if an I/O error occurs.
98 */
99 @Override
100 public void dump(final DataOutputStream file) throws IOException {
101 super.dump(file);
102 file.writeShort(hostClassIndex);
103 }
104
105 /**
106 * @return index into constant pool of host class name.
107 */
108 public int getHostClassIndex() {
109 return hostClassIndex;
110 }
111
112 /**
113 * @param hostClassIndex the host class index
114 */
115 public void setHostClassIndex(final int hostClassIndex) {
116 this.hostClassIndex = hostClassIndex;
117 }
118
119 /**
120 * @return String representation
121 */
122 @Override
123 public String toString() {
124 final StringBuilder buf = new StringBuilder();
125 buf.append("NestHost: ");
126 final String className = super.getConstantPool().getConstantString(hostClassIndex, Const.CONSTANT_Class);
127 buf.append(Utility.compactClassName(className, false));
128 return buf.toString();
129 }
130 }