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
26 /**
27 * This class represents an entry in the requires table of the Module attribute. Each entry describes a module on which
28 * the parent module depends.
29 *
30 * @see Module
31 * @since 6.4.0
32 */
33 public final class ModuleRequires implements Cloneable, Node {
34
35 private final int requiresIndex; // points to CONSTANT_Module_info
36 private final int requiresFlags;
37 private final int requiresVersionIndex; // either 0 or points to CONSTANT_Utf8_info
38
39 /**
40 * Constructs object from file stream.
41 *
42 * @param file Input stream
43 * @throws IOException if an I/O Exception occurs in readUnsignedShort
44 */
45 ModuleRequires(final DataInput file) throws IOException {
46 requiresIndex = file.readUnsignedShort();
47 requiresFlags = file.readUnsignedShort();
48 requiresVersionIndex = file.readUnsignedShort();
49 }
50
51 /**
52 * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
53 * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
54 *
55 * @param v Visitor object
56 */
57 @Override
58 public void accept(final Visitor v) {
59 v.visitModuleRequires(this);
60 }
61
62 /**
63 * @return deep copy of this object
64 */
65 public ModuleRequires copy() {
66 try {
67 return (ModuleRequires) clone();
68 } catch (final CloneNotSupportedException e) {
69 // TODO should this throw?
70 }
71 return null;
72 }
73
74 /**
75 * Dump table entry to file stream in binary format.
76 *
77 * @param file Output file stream
78 * @throws IOException if an I/O Exception occurs in writeShort
79 */
80 public void dump(final DataOutputStream file) throws IOException {
81 file.writeShort(requiresIndex);
82 file.writeShort(requiresFlags);
83 file.writeShort(requiresVersionIndex);
84 }
85
86 /**
87 * Gets the module name from the constant pool.
88 * @param constantPool Array of constants usually obtained from the ClassFile object
89 * @return module name
90 * @since 6.10.0
91 */
92 public String getModuleName(final ConstantPool constantPool) {
93 return constantPool.constantToString(requiresIndex, Const.CONSTANT_Module);
94 }
95
96 /**
97 * Gets the flags for this ModuleRequires.
98 * @return the requiresFlags
99 * @since 6.10.0
100 */
101 public int getRequiresFlags() {
102 return requiresFlags;
103 }
104
105 /**
106 * Gets the required version from the constant pool.
107 * @param constantPool Array of constants usually obtained from the ClassFile object
108 * @return required version, "0" if version index is 0.
109 * @since 6.10.0
110 */
111 public String getVersion(final ConstantPool constantPool) {
112 return requiresVersionIndex == 0 ? "0" : constantPool.getConstantString(requiresVersionIndex, Const.CONSTANT_Utf8);
113 }
114
115 /**
116 * @return String representation
117 */
118 @Override
119 public String toString() {
120 return "requires(" + requiresIndex + ", " + String.format("%04x", requiresFlags) + ", " + requiresVersionIndex + ")";
121 }
122
123 /**
124 * @return Resolved string representation
125 */
126 public String toString(final ConstantPool constantPool) {
127 final StringBuilder buf = new StringBuilder();
128 final String moduleName = getModuleName(constantPool);
129 buf.append(moduleName);
130 buf.append(", ").append(String.format("%04x", requiresFlags));
131 final String version = getVersion(constantPool);
132 buf.append(", ").append(version);
133 return buf.toString();
134 }
135 }