1 /*
2 * Copyright (c) 2017, 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.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 package jdk.experimental.bytecode;
25
26 /**
27 * Base builder for attribute containing class file entities.
28 *
29 * @param <S> the type of the symbol representation
30 * @param <T> the type of type descriptors representation
31 * @param <E> the type of pool entries
32 * @param <D> the type of this builder
33 */
34 public class AttributeBuilder<S, T, E, D extends AttributeBuilder<S, T, E, D>>
35 extends AbstractBuilder<S, T, E, D> {
36
37 /**
38 * The number of attributes.
39 */
40 protected int nattrs;
41
42 /**
43 * The attributes represented as bytes.
44 */
45 protected GrowableByteBuffer attributes = new GrowableByteBuffer();
46
47 /**
48 * Create an attribute builder.
49 *
50 * @param poolHelper the helper to build the constant pool
51 * @param typeHelper the helper to use to manipulate type descriptors
52 */
53 public AttributeBuilder(PoolHelper<S, T, E> poolHelper, TypeHelper<S, T> typeHelper) {
54 super(poolHelper, typeHelper);
55 }
56
57 /**
58 * Add a class file Attribute. Defined as:
59 * <pre>
60 * {@code attribute_info {
61 * u2 attribute_name_index;
62 * u4 attribute_length;
63 * u1 info[attribute_length];
64 * }}
65 * </pre>
66 *
67 * @param name the attribute name
68 * @param bytes the bytes of the attribute info
69 * @return this builder, for chained calls
70 */
71 public D withAttribute(CharSequence name, byte[] bytes) {
72 attributes.writeChar(poolHelper.putUtf8(name));
73 attributes.writeInt(bytes.length);
74 attributes.writeBytes(bytes);
75 nattrs++;
76 return thisBuilder();
77 }
78
79 /**
80 * Add a class file Attribute, using a writer. Defined as:
81 * <pre>
82 * {@code attribute_info {
83 * u2 attribute_name_index;
84 * u4 attribute_length;
85 * u1 info[attribute_length];
86 * }}
87 * </pre>
88 *
89 * @param <Z> the type of the object representing the attribute
90 * @param name the attribute name
91 * @param attr the representation of the attribute
92 * @param attrWriter the writer which transform the attribute representation into bytes
93 * @return this builder, for chained calls
94 */
95 public <Z> D withAttribute(CharSequence name, Z attr, AttributeWriter<S, T, E, Z> attrWriter) {
96 attributes.writeChar(poolHelper.putUtf8(name));
97 int offset = attributes.offset;
98 attributes.writeInt(0);
99 attrWriter.write(attr, poolHelper, attributes);
100 int len = attributes.offset - offset - 4;
101 attributes.withOffset(offset, buf -> buf.writeInt(len));
102 nattrs++;
103 return thisBuilder();
104 }
105
106 /**
107 * Writer for transforming attribute representations to bytes
108 *
109 * @param <S> the type of symbol representation
110 * @param <T> the type of type descriptors representation
111 * @param <E> the type of pool entries
112 * @param <A> the type of the object representing the attribute
113 */
114 public interface AttributeWriter<S, T, E, A> {
115
116 /**
117 * Write an attribute representation into a byte buffer.
118 *
119 * @param attr the representation of the attribute
120 * @param poolHelper the constant pool helper
121 * @param buf the buffer to collect the bytes
122 */
123 void write(A attr, PoolHelper<S, T, E> poolHelper, GrowableByteBuffer buf);
124 }
125 }