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 package org.apache.commons.compress.harmony.unpack200.bytecode;
20
21 import java.io.DataOutputStream;
22 import java.io.IOException;
23
24 /**
25 * The abstract superclass for all types of class file entries.
26 */
27 public abstract class ClassFileEntry {
28
29 /**
30 * An empty ClassFileEntry array.
31 */
32 protected static final ClassFileEntry[] NONE = {};
33 private boolean resolved;
34
35 /**
36 * Writes this instance to the output stream.
37 *
38 * @param dos the output stream.
39 * @throws IOException if an I/O error occurs.
40 */
41 protected abstract void doWrite(DataOutputStream dos) throws IOException;
42
43 @Override
44 public abstract boolean equals(Object arg0);
45
46 /**
47 * Returns an empty array.
48 *
49 * @return an empty array.
50 */
51 protected ClassFileEntry[] getNestedClassFileEntries() {
52 return NONE;
53 }
54
55 @Override
56 public abstract int hashCode();
57
58 /**
59 * Delegates to super {@link #hashCode}.
60 *
61 * @return super {@link #hashCode}.
62 */
63 protected int objectHashCode() {
64 return super.hashCode();
65 }
66
67 /**
68 * Allows the constant pool entries to resolve their nested entries.
69 *
70 * @param pool The class constant pool.
71 */
72 protected void resolve(final ClassConstantPool pool) {
73 resolved = true;
74 }
75
76 @Override
77 public abstract String toString();
78
79 /**
80 * Writes this instance to the output stream.
81 *
82 * @param dos the output stream.
83 * @throws IOException if an I/O error occurs.
84 */
85 public final void write(final DataOutputStream dos) throws IOException {
86 if (!resolved) {
87 throw new IllegalStateException("Entry has not been resolved");
88 }
89 doWrite(dos);
90 }
91
92 }