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
28 /**
29 * This class represents an entry in the requires table of the Module attribute. Each entry describes a module on which
30 * the parent module depends.
31 *
32 * @see Module
33 * @since 6.4.0
34 */
35 public final class ModuleRequires implements Cloneable, Node {
36
37 private final int requiresIndex; // points to CONSTANT_Module_info
38 private final int requiresFlags;
39 private final int requiresVersionIndex; // either 0 or points to CONSTANT_Utf8_info
40
41 /**
42 * Constructs object from file stream.
43 *
44 * @param file Input stream.
45 * @throws IOException if an I/O Exception occurs in readUnsignedShort.
46 */
47 ModuleRequires(final DataInput file) throws IOException {
48 requiresIndex = file.readUnsignedShort();
49 requiresFlags = file.readUnsignedShort();
50 requiresVersionIndex = file.readUnsignedShort();
51 }
52
53 /**
54 * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
55 * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
56 *
57 * @param v Visitor object.
58 */
59 @Override
60 public void accept(final Visitor v) {
61 v.visitModuleRequires(this);
62 }
63
64 /**
65 * @return deep copy of this object.
66 */
67 public ModuleRequires copy() {
68 try {
69 return (ModuleRequires) clone();
70 } catch (final CloneNotSupportedException e) {
71 // TODO should this throw?
72 }
73 return null;
74 }
75
76 /**
77 * Dumps table entry to file stream in binary format.
78 *
79 * @param file Output file stream.
80 * @throws IOException if an I/O Exception occurs in writeShort.
81 */
82 public void dump(final DataOutputStream file) throws IOException {
83 file.writeShort(requiresIndex);
84 file.writeShort(requiresFlags);
85 file.writeShort(requiresVersionIndex);
86 }
87
88 /**
89 * Gets the module name from the constant pool.
90 *
91 * @param constantPool Array of constants usually obtained from the ClassFile object.
92 * @return module name.
93 * @since 6.10.0
94 */
95 public String getModuleName(final ConstantPool constantPool) {
96 return constantPool.constantToString(requiresIndex, Const.CONSTANT_Module);
97 }
98
99 /**
100 * Gets the flags for this ModuleRequires.
101 *
102 * @return the requiresFlags.
103 * @since 6.10.0
104 */
105 public int getRequiresFlags() {
106 return requiresFlags;
107 }
108
109 /**
110 * Gets the required version from the constant pool.
111 *
112 * @param constantPool Array of constants usually obtained from the ClassFile object.
113 * @return required version, "0" if version index is 0.
114 * @since 6.10.0
115 */
116 public String getVersion(final ConstantPool constantPool) {
117 return requiresVersionIndex == 0 ? "0" : constantPool.getConstantString(requiresVersionIndex, Const.CONSTANT_Utf8);
118 }
119
120 /**
121 * @return String representation.
122 */
123 @Override
124 public String toString() {
125 return "requires(" + requiresIndex + ", " + String.format("%04x", requiresFlags) + ", " + requiresVersionIndex + ")";
126 }
127
128 /**
129 * @return Resolved string representation.
130 */
131 public String toString(final ConstantPool constantPool) {
132 final StringBuilder buf = new StringBuilder();
133 final String moduleName = getModuleName(constantPool);
134 buf.append(moduleName);
135 buf.append(", ").append(String.format("%04x", requiresFlags));
136 final String version = getVersion(constantPool);
137 buf.append(", ").append(version);
138 return buf.toString();
139 }
140 }