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 * Dump 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 * @param constantPool Array of constants usually obtained from the ClassFile object
91 * @return module name
92 * @since 6.10.0
93 */
94 public String getModuleName(final ConstantPool constantPool) {
95 return constantPool.constantToString(requiresIndex, Const.CONSTANT_Module);
96 }
97
98 /**
99 * Gets the flags for this ModuleRequires.
100 * @return the requiresFlags
101 * @since 6.10.0
102 */
103 public int getRequiresFlags() {
104 return requiresFlags;
105 }
106
107 /**
108 * Gets the required version from the constant pool.
109 * @param constantPool Array of constants usually obtained from the ClassFile object
110 * @return required version, "0" if version index is 0.
111 * @since 6.10.0
112 */
113 public String getVersion(final ConstantPool constantPool) {
114 return requiresVersionIndex == 0 ? "0" : constantPool.getConstantString(requiresVersionIndex, Const.CONSTANT_Utf8);
115 }
116
117 /**
118 * @return String representation
119 */
120 @Override
121 public String toString() {
122 return "requires(" + requiresIndex + ", " + String.format("%04x", requiresFlags) + ", " + requiresVersionIndex + ")";
123 }
124
125 /**
126 * @return Resolved string representation
127 */
128 public String toString(final ConstantPool constantPool) {
129 final StringBuilder buf = new StringBuilder();
130 final String moduleName = getModuleName(constantPool);
131 buf.append(moduleName);
132 buf.append(", ").append(String.format("%04x", requiresFlags));
133 final String version = getVersion(constantPool);
134 buf.append(", ").append(version);
135 return buf.toString();
136 }
137 }