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 import java.util.Arrays;
26
27 import org.apache.bcel.Const;
28 import org.apache.bcel.util.Args;
29 import org.apache.commons.lang3.ArrayUtils;
30
31 /**
32 * This class is derived from <em>Attribute</em> and records the classes and interfaces that are authorized to claim
33 * membership in the nest hosted by the current class or interface. There may be at most one NestMembers attribute in a
34 * ClassFile structure.
35 *
36 * @see Attribute
37 */
38 public final class NestMembers extends Attribute {
39
40 private int[] classes;
41
42 /**
43 * Constructs object from input stream.
44 *
45 * @param nameIndex Index in constant pool
46 * @param length Content length in bytes
47 * @param input Input stream
48 * @param constantPool Array of constants
49 * @throws IOException if an I/O error occurs.
50 */
51 NestMembers(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
52 this(nameIndex, length, (int[]) null, constantPool);
53 final int classCount = input.readUnsignedShort();
54 classes = new int[classCount];
55 for (int i = 0; i < classCount; i++) {
56 classes[i] = input.readUnsignedShort();
57 }
58 }
59
60 /**
61 * @param nameIndex Index in constant pool
62 * @param length Content length in bytes
63 * @param classes Table of indices in constant pool
64 * @param constantPool Array of constants
65 */
66 public NestMembers(final int nameIndex, final int length, final int[] classes, final ConstantPool constantPool) {
67 super(Const.ATTR_NEST_MEMBERS, nameIndex, length, constantPool);
68 this.classes = ArrayUtils.nullToEmpty(classes);
69 Args.requireU2(this.classes.length, "classes.length");
70 }
71
72 /**
73 * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
74 * physical copy.
75 *
76 * @param c Source to copy.
77 */
78 public NestMembers(final NestMembers c) {
79 this(c.getNameIndex(), c.getLength(), c.getClasses(), c.getConstantPool());
80 }
81
82 /**
83 * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
84 * I.e., the hierarchy of methods, 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.visitNestMembers(this);
91 }
92
93 /**
94 * @return deep copy of this attribute
95 */
96 @Override
97 public Attribute copy(final ConstantPool constantPool) {
98 final NestMembers c = (NestMembers) clone();
99 if (classes.length > 0) {
100 c.classes = classes.clone();
101 }
102 c.setConstantPool(constantPool);
103 return c;
104 }
105
106 /**
107 * Dump NestMembers attribute to file stream in binary format.
108 *
109 * @param file Output file stream
110 * @throws IOException if an I/O error occurs.
111 */
112 @Override
113 public void dump(final DataOutputStream file) throws IOException {
114 super.dump(file);
115 file.writeShort(classes.length);
116 for (final int index : classes) {
117 file.writeShort(index);
118 }
119 }
120
121 /**
122 * @return array of indices into constant pool of class names.
123 */
124 public int[] getClasses() {
125 return classes;
126 }
127
128 /**
129 * @return string array of class names
130 */
131 public String[] getClassNames() {
132 final String[] names = new String[classes.length];
133 Arrays.setAll(names, i -> Utility.pathToPackage(super.getConstantPool().getConstantString(classes[i], Const.CONSTANT_Class)));
134 return names;
135 }
136
137 /**
138 * @return Length of classes table.
139 */
140 public int getNumberClasses() {
141 return classes.length;
142 }
143
144 /**
145 * @param classes the list of class indexes Also redefines number_of_classes according to table length.
146 */
147 public void setClasses(final int[] classes) {
148 this.classes = ArrayUtils.nullToEmpty(classes);
149 }
150
151 /**
152 * @return String representation, i.e., a list of classes.
153 */
154 @Override
155 public String toString() {
156 final StringBuilder buf = new StringBuilder();
157 buf.append("NestMembers(");
158 buf.append(classes.length);
159 buf.append("):\n");
160 for (final int index : classes) {
161 final String className = super.getConstantPool().getConstantString(index, Const.CONSTANT_Class);
162 buf.append(" ").append(Utility.compactClassName(className, false)).append("\n");
163 }
164 return buf.substring(0, buf.length() - 1); // remove the last newline
165 }
166 }