1 /*
2 * Copyright (c) 2019, 2024, 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
26 package jdk.internal.javac;
27
28 import java.lang.annotation.*;
29
30 /**
31 * Indicates the API declaration in question is associated with a
32 * <em>preview feature</em>. See JEP 12: "Preview Language and VM
33 * Features" (https://openjdk.org/jeps/12).
34 *
35 * Note this internal annotation is handled specially by the javac compiler.
36 * To work properly with {@code --release older-release}, it requires special
37 * handling in {@code make/langtools/src/classes/build/tools/symbolgenerator/CreateSymbols.java}
38 * and {@code src/jdk.compiler/share/classes/com/sun/tools/javac/jvm/ClassReader.java}.
39 *
40 * @since 14
41 */
42 // Match the meaningful targets of java.lang.Deprecated, omit local
43 // variables and parameter declarations
44 @Target({ElementType.METHOD,
45 ElementType.CONSTRUCTOR,
46 ElementType.FIELD,
47 ElementType.PACKAGE,
48 ElementType.MODULE,
49 ElementType.TYPE})
50 // CLASS retention will hopefully be sufficient for the purposes at hand
51 @Retention(RetentionPolicy.CLASS)
52 // *Not* @Documented
53 public @interface PreviewFeature {
54 /**
55 * Name of the preview feature the annotated API is associated
56 * with.
57 */
58 public Feature feature();
59
60 public boolean reflective() default false;
61
62 /**
63 * Enum of preview features in the current release.
64 * Values should be annotated with the feature's {@code JEP}.
65 */
66 public enum Feature {
67 // not used, but required for interim javac to not warn.
68 VIRTUAL_THREADS,
69 FOREIGN,
70 @JEP(number=459, title="String Templates", status="Second Preview")
71 STRING_TEMPLATES,
72 @JEP(number=477, title="Implicitly Declared Classes and Instance Main Methods", status="Third Preview")
73 IMPLICIT_CLASSES,
74 @JEP(number=481, title="Scoped Values", status="Third Preview")
75 SCOPED_VALUES,
76 @JEP(number=480, title="Structured Concurrency", status="Third Preview")
77 STRUCTURED_CONCURRENCY,
78 @JEP(number=466, title="ClassFile API", status="Second Preview")
79 CLASSFILE_API,
80 @JEP(number=473, title="Stream Gatherers", status="Second Preview")
81 STREAM_GATHERERS,
82 @JEP(number=476, title="Module Import Declarations", status="Preview")
83 MODULE_IMPORTS,
84 LANGUAGE_MODEL,
85 /**
86 * A key for testing.
87 */
88 @JEP(number=2_147_483_647, title="Test Feature")
89 TEST,
90 ;
91 }
92
93 /**
94 * Annotation identifying the JEP associated with a preview feature.
95 */
96 @Target(ElementType.FIELD)
97 @Retention(RetentionPolicy.CLASS)
98 @interface JEP {
99 /** JEP number */
100 int number() default 0;
101 /** JEP title in plain text */
102 String title();
103 /** JEP status such as "Preview", "Second Preview", etc */
104 String status() default "Preview";
105 }
106 }