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src/java.base/share/classes/jdk/internal/reflect/DelegatingMethodAccessorImpl.java

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 1 /*
 2  * Copyright (c) 2001, 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.reflect;
27 
28 import jdk.internal.vm.annotation.Stable;
29 
30 import java.lang.reflect.InvocationTargetException;
31 import java.util.Objects;
32 
33 /** Delegates its invocation to another MethodAccessorImpl and can
34     change its delegate at run time. */
35 
36 class DelegatingMethodAccessorImpl extends MethodAccessorImpl {
37     // initial non-null delegate
38     @Stable private final MethodAccessorImpl initialDelegate;
39     // alternative delegate: starts as null;
40     // only single change from null -> non-null is guaranteed
41     @Stable private  MethodAccessorImpl altDelegate;

42 
43     DelegatingMethodAccessorImpl(MethodAccessorImpl delegate) {
44         initialDelegate = Objects.requireNonNull(delegate);
45     }
46 
47     @Override
48     public Object invoke(Object obj, Object[] args)
49         throws IllegalArgumentException, InvocationTargetException
50     {
51         return delegate().invoke(obj, args);
52     }
53 







54     private MethodAccessorImpl delegate() {
55         var d = altDelegate;
56         return  d != null ? d : initialDelegate;
57     }
58 
59     void setDelegate(MethodAccessorImpl delegate) {
60         altDelegate = Objects.requireNonNull(delegate);
61     }
62 }

 1 /*
 2  * Copyright (c) 2001, 2021, 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.reflect;
27 
28 import jdk.internal.vm.annotation.Stable;
29 
30 import java.lang.reflect.InvocationTargetException;
31 import java.util.Objects;
32 
33 /** Delegates its invocation to another MethodAccessorImpl and can
34     change its delegate at run time. */
35 
36 class DelegatingMethodAccessorImpl extends MethodAccessorImpl {
37     // initial non-null delegate
38     private final MethodAccessorImpl initialDelegate;
39     // alternative delegate: starts as null;
40     // only single change from null -> non-null is guaranteed
41     @Stable
42     private MethodAccessorImpl altDelegate;
43 
44     DelegatingMethodAccessorImpl(MethodAccessorImpl delegate) {
45         initialDelegate = Objects.requireNonNull(delegate);
46     }
47 
48     @Override
49     public Object invoke(Object obj, Object[] args)
50         throws IllegalArgumentException, InvocationTargetException
51     {
52         return delegate().invoke(obj, args);
53     }
54 
55     @Override
56     public Object invoke(Object obj, Object[] args, Class<?> caller)
57             throws IllegalArgumentException, InvocationTargetException
58     {
59         return delegate().invoke(obj, args, caller);
60     }
61 
62     private MethodAccessorImpl delegate() {
63         var d = altDelegate;
64         return  d != null ? d : initialDelegate;
65     }
66 
67     void setDelegate(MethodAccessorImpl delegate) {
68         altDelegate = Objects.requireNonNull(delegate);
69     }
70 }
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