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 * Extends {@link Attribute} and records the classes and
29 * interfaces that are authorized to claim membership in the nest hosted by the
30 * current class or interface. There may be at most one Record attribute in a
31 * ClassFile structure.
32 *
33 * @see Attribute
34 * @since 6.9.0
35 */
36 public final class Record extends Attribute {
37
38 private static final RecordComponentInfo[] EMPTY_RCI_ARRAY = {};
39
40 private static RecordComponentInfo[] readComponents(final DataInput input, final ConstantPool constantPool)
41 throws IOException {
42 final int classCount = input.readUnsignedShort();
43 final RecordComponentInfo[] components = new RecordComponentInfo[classCount];
44 for (int i = 0; i < classCount; i++) {
45 components[i] = new RecordComponentInfo(input, constantPool);
46 }
47 return components;
48 }
49
50 private RecordComponentInfo[] components;
51
52 /**
53 * Constructs object from input stream.
54 *
55 * @param nameIndex Index in constant pool
56 * @param length Content length in bytes
57 * @param input Input stream
58 * @param constantPool Array of constants
59 * @throws IOException if an I/O error occurs.
60 */
61 Record(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool)
62 throws IOException {
63 this(nameIndex, length, readComponents(input, constantPool), constantPool);
64 }
65
66 /**
67 * Constructs a new instance using components.
68 *
69 * @param nameIndex Index in constant pool
70 * @param length Content length in bytes
71 * @param classes Array of Record Component Info elements
72 * @param constantPool Array of constants
73 */
74 public Record(final int nameIndex, final int length, final RecordComponentInfo[] classes,
75 final ConstantPool constantPool) {
76 super(Const.ATTR_RECORD, nameIndex, length, constantPool);
77 this.components = classes != null ? classes : EMPTY_RCI_ARRAY;
78 Args.requireU2(this.components.length, "attributes.length");
79 }
80
81 /**
82 * Called by objects that are traversing the nodes of the tree implicitly
83 * defined by the contents of a Java class. For example, the hierarchy of methods,
84 * fields, attributes, etc. spawns a tree of objects.
85 *
86 * @param v Visitor object
87 */
88 @Override
89 public void accept(final Visitor v) {
90 v.visitRecord(this);
91 }
92
93 /**
94 * Copies this instance and its components.
95 *
96 * @return a deep copy of this instance and its components.
97 */
98 @Override
99 public Attribute copy(final ConstantPool constantPool) {
100 final Record c = (Record) clone();
101 if (components.length > 0) {
102 c.components = components.clone();
103 }
104 c.setConstantPool(constantPool);
105 return c;
106 }
107
108 /**
109 * Dumps this instance into a file stream in binary format.
110 *
111 * @param file output stream.
112 * @throws IOException if an I/O error occurs.
113 */
114 @Override
115 public void dump(final DataOutputStream file) throws IOException {
116 super.dump(file);
117 file.writeShort(components.length);
118 for (final RecordComponentInfo component : components) {
119 component.dump(file);
120 }
121 }
122
123 /**
124 * Gets all the record components.
125 *
126 * @return array of Record Component Info elements.
127 */
128 public RecordComponentInfo[] getComponents() {
129 return components;
130 }
131
132 /**
133 * Converts this instance to a String suitable for debugging.
134 *
135 * @return String a String suitable for debugging.
136 */
137 @Override
138 public String toString() {
139 final StringBuilder buf = new StringBuilder();
140 buf.append("Record(");
141 buf.append(components.length);
142 buf.append("):\n");
143 for (final RecordComponentInfo component : components) {
144 buf.append(" ").append(component.toString()).append("\n");
145 }
146 return buf.substring(0, buf.length() - 1); // remove the last newline
147 }
148
149 }