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 * This class is derived from <em>Attribute</em> and indicates the main class of a module. There may be at most one
31 * ModuleMainClass attribute in a ClassFile structure.
32 *
33 * @see Attribute
34 */
35 public final class ModuleMainClass extends Attribute {
36
37 private int mainClassIndex;
38
39 /**
40 * Constructs object from input stream.
41 *
42 * @param nameIndex Index in constant pool
43 * @param length Content length in bytes
44 * @param input Input stream
45 * @param constantPool Array of constants
46 * @throws IOException if an I/O error occurs.
47 */
48 ModuleMainClass(final int nameIndex, final int length, final DataInput input, final ConstantPool constantPool) throws IOException {
49 this(nameIndex, length, 0, constantPool);
50 mainClassIndex = input.readUnsignedShort();
51 }
52
53 /**
54 * @param nameIndex Index in constant pool
55 * @param length Content length in bytes
56 * @param mainClassIndex Host class index
57 * @param constantPool Array of constants
58 */
59 public ModuleMainClass(final int nameIndex, final int length, final int mainClassIndex, final ConstantPool constantPool) {
60 super(Const.ATTR_NEST_MEMBERS, nameIndex, length, constantPool);
61 this.mainClassIndex = Args.requireU2(mainClassIndex, "mainClassIndex");
62 }
63
64 /**
65 * Initialize from another object. Note that both objects use the same references (shallow copy). Use copy() for a
66 * physical copy.
67 *
68 * @param c Source to copy.
69 */
70 public ModuleMainClass(final ModuleMainClass c) {
71 this(c.getNameIndex(), c.getLength(), c.getHostClassIndex(), c.getConstantPool());
72 }
73
74 /**
75 * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class. I.e.,
76 * the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
77 *
78 * @param v Visitor object
79 */
80 @Override
81 public void accept(final Visitor v) {
82 v.visitModuleMainClass(this);
83 }
84
85 /**
86 * @return deep copy of this attribute
87 */
88 @Override
89 public Attribute copy(final ConstantPool constantPool) {
90 final ModuleMainClass c = (ModuleMainClass) clone();
91 c.setConstantPool(constantPool);
92 return c;
93 }
94
95 /**
96 * Dump ModuleMainClass attribute to file stream in binary format.
97 *
98 * @param file Output file stream
99 * @throws IOException if an I/O error occurs.
100 */
101 @Override
102 public void dump(final DataOutputStream file) throws IOException {
103 super.dump(file);
104 file.writeShort(mainClassIndex);
105 }
106
107 /**
108 * @return index into constant pool of host class name.
109 */
110 public int getHostClassIndex() {
111 return mainClassIndex;
112 }
113
114 /**
115 * @param mainClassIndex the host class index
116 */
117 public void setHostClassIndex(final int mainClassIndex) {
118 this.mainClassIndex = mainClassIndex;
119 }
120
121 /**
122 * @return String representation
123 */
124 @Override
125 public String toString() {
126 final StringBuilder buf = new StringBuilder();
127 buf.append("ModuleMainClass: ");
128 final String className = super.getConstantPool().getConstantString(mainClassIndex, Const.CONSTANT_Class);
129 buf.append(Utility.compactClassName(className, false));
130 return buf.toString();
131 }
132 }