1 /*
 2  * Copyright (c) 2019, 2020, 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" (http://openjdk.java.net/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     public enum Feature {
63         SWITCH_PATTERN_MATCHING,
64         SCOPE_LOCALS,
65         VIRTUAL_THREADS,
66         /**
67          * A key for testing.
68          */
69         TEST,
70         ;
71     }
72 }