1/*
2 * Copyright (c) 2007, 2008, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package com.sun.tools.classfile;
27
28import java.io.BufferedInputStream;
29import java.io.ByteArrayInputStream;
30import java.io.DataInputStream;
31import java.io.IOException;
32import java.io.InputStream;
33import java.util.Objects;
34
35/**
36 *  <p><b>This is NOT part of any supported API.
37 *  If you write code that depends on this, you do so at your own risk.
38 *  This code and its internal interfaces are subject to change or
39 *  deletion without notice.</b>
40 */
41public class ClassReader {
42    ClassReader(ClassFile classFile, InputStream in, Attribute.Factory attributeFactory) throws IOException {
43        this.classFile = Objects.requireNonNull(classFile);
44        this.attributeFactory = Objects.requireNonNull(attributeFactory);
45        this.in = new DataInputStream(new BufferedInputStream(in));
46    }
47
48    ClassFile getClassFile() {
49        return classFile;
50    }
51
52    ConstantPool getConstantPool() {
53        return classFile.constant_pool;
54    }
55
56    public Attribute readAttribute() throws IOException {
57        int name_index = readUnsignedShort();
58        int length = readInt();
59        byte[] data = new byte[length];
60        readFully(data);
61
62        DataInputStream prev = in;
63        in = new DataInputStream(new ByteArrayInputStream(data));
64        try {
65            return attributeFactory.createAttribute(this, name_index, data);
66        } finally {
67            in = prev;
68        }
69    }
70
71    public void readFully(byte[] b) throws IOException {
72        in.readFully(b);
73    }
74
75    public int readUnsignedByte() throws IOException {
76        return in.readUnsignedByte();
77    }
78
79    public int readUnsignedShort() throws IOException {
80        return in.readUnsignedShort();
81    }
82
83    public int readInt() throws IOException {
84        return in.readInt();
85    }
86
87    public long readLong() throws IOException {
88        return in.readLong();
89    }
90
91    public float readFloat() throws IOException {
92        return in.readFloat();
93    }
94
95    public double readDouble() throws IOException {
96        return in.readDouble();
97    }
98
99    public String readUTF() throws IOException {
100        return in.readUTF();
101    }
102
103    private DataInputStream in;
104    private ClassFile classFile;
105    private Attribute.Factory attributeFactory;
106}
107