1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * https://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19
20 package org.apache.bcel.classfile;
21
22 import java.io.DataInput;
23 import java.io.DataOutputStream;
24 import java.io.IOException;
25
26 import org.apache.bcel.Const;
27 import org.apache.bcel.util.Args;
28
29 /**
30 * Extends {@link Attribute} and records the classes and
31 * interfaces that are authorized to claim membership in the nest hosted by the
32 * current class or interface. There may be at most one Record attribute in a
33 * ClassFile structure.
34 *
35 * @see Attribute
36 * @since 6.9.0
37 */
38 public final class Record extends Attribute {
39
40 private static final RecordComponentInfo[] EMPTY_RCI_ARRAY = {};
41
42 private static RecordComponentInfo[] readComponents(final DataInput input, final ConstantPool constantPool)
43 throws IOException {
44 final int classCount = input.readUnsignedShort();
45 final RecordComponentInfo[] components = new RecordComponentInfo[classCount];
46 for (int i = 0; i < classCount; i++) {
47 components[i] = new RecordComponentInfo(input, constantPool);
48 }
49 return components;
50 }
51
52 private RecordComponentInfo[] components;
53
54 /**
55 * Constructs object from input stream.
56 *
57 * @param nameIndex Index in constant pool
58 * @param length Content length in bytes
59 * @param input Input stream
60 * @param constantPool Array of constants
61 * @throws IOException if an I/O error occurs.
62 */
63 Record(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool)
64 throws IOException {
65 this(nameIndex, length, readComponents(input, constantPool), constantPool);
66 }
67
68 /**
69 * Constructs a new instance using components.
70 *
71 * @param nameIndex Index in constant pool
72 * @param length Content length in bytes
73 * @param classes Array of Record Component Info elements
74 * @param constantPool Array of constants
75 */
76 public Record(final int nameIndex, final int length, final RecordComponentInfo[] classes,
77 final ConstantPool constantPool) {
78 super(Const.ATTR_RECORD, nameIndex, length, constantPool);
79 this.components = classes != null ? classes : EMPTY_RCI_ARRAY;
80 Args.requireU2(this.components.length, "attributes.length");
81 }
82
83 /**
84 * Called by objects that are traversing the nodes of the tree implicitly
85 * defined by the contents of a Java class. For example, the hierarchy of methods,
86 * fields, attributes, etc. spawns a tree of objects.
87 *
88 * @param v Visitor object
89 */
90 @Override
91 public void accept(final Visitor v) {
92 v.visitRecord(this);
93 }
94
95 /**
96 * Copies this instance and its components.
97 *
98 * @return a deep copy of this instance and its components.
99 */
100 @Override
101 public Attribute copy(final ConstantPool constantPool) {
102 final Record c = (Record) clone();
103 if (components.length > 0) {
104 c.components = components.clone();
105 }
106 c.setConstantPool(constantPool);
107 return c;
108 }
109
110 /**
111 * Dumps this instance into a file stream in binary format.
112 *
113 * @param file output stream.
114 * @throws IOException if an I/O error occurs.
115 */
116 @Override
117 public void dump(final DataOutputStream file) throws IOException {
118 super.dump(file);
119 file.writeShort(components.length);
120 for (final RecordComponentInfo component : components) {
121 component.dump(file);
122 }
123 }
124
125 /**
126 * Gets all the record components.
127 *
128 * @return array of Record Component Info elements.
129 */
130 public RecordComponentInfo[] getComponents() {
131 return components;
132 }
133
134 /**
135 * Converts this instance to a String suitable for debugging.
136 *
137 * @return String a String suitable for debugging.
138 */
139 @Override
140 public String toString() {
141 final StringBuilder buf = new StringBuilder();
142 buf.append("Record(");
143 buf.append(components.length);
144 buf.append("):\n");
145 for (final RecordComponentInfo component : components) {
146 buf.append(" ").append(component.toString()).append("\n");
147 }
148 return buf.substring(0, buf.length() - 1); // remove the last newline
149 }
150
151 }