1 /*
 2  * Copyright (c) 2023, 2025, 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.value;
27 
28 import jdk.internal.access.JavaLangReflectAccess;
29 import jdk.internal.access.SharedSecrets;
30 import jdk.internal.vm.annotation.IntrinsicCandidate;
31 
32 import java.lang.reflect.Array;
33 import java.lang.reflect.Field;
34 
35 /**
36  * Utilities to access package private methods of java.lang.Class and related reflection classes.
37  */
38 public class ValueClass {
39     private static final JavaLangReflectAccess JLRA = SharedSecrets.getJavaLangReflectAccess();
40 
41     /**
42      * {@return {@code true} if the field is NullRestricted}
43      */
44     public static boolean isNullRestrictedField(Field f) {
45         return JLRA.isNullRestrictedField(f);
46     }
47 
48     /**
49      * Allocate an array of a value class type with components that behave in
50      * the same way as a {@link jdk.internal.vm.annotation.NullRestricted}
51      * field.
52      * <p>
53      * Because these behaviors are not specified by Java SE, arrays created with
54      * this method should only be used by internal JDK code for experimental
55      * purposes and should not affect user-observable outcomes.
56      *
57      * @throws IllegalArgumentException if {@code componentType} is not a
58      *                                  value class type.
59      */
60     @IntrinsicCandidate
61     public static native Object[] newNullRestrictedAtomicArray(Class<?> componentType,
62                                                                int length, Object initVal);
63 
64     @IntrinsicCandidate
65     public static native Object[] newNullRestrictedNonAtomicArray(Class<?> componentType,
66                                                                   int length, Object initVal);
67 
68     @IntrinsicCandidate
69     public static native Object[] newNullableAtomicArray(Class<?> componentType,
70                                                          int length);
71 
72     public static native boolean isFlatArray(Object array);
73 
74     public static Object[] copyOfSpecialArray(Object[] array, int from, int to) {
75         return copyOfSpecialArray0(array, from, to);
76     }
77 
78     private static native Object[] copyOfSpecialArray0(Object[] array, int from, int to);
79 
80     /**
81      * {@return true if the given array is a null-restricted array}
82      */
83     public static native boolean isNullRestrictedArray(Object array);
84 
85     /**
86      * {@return true if the given array uses a layout designed for atomic accesses }
87      */
88     public static native boolean isAtomicArray(Object array);
89 }