1 #region Copyright notice and license
2 // Protocol Buffers - Google's data interchange format
3 // Copyright 2015 Google Inc.  All rights reserved.
4 // https://developers.google.com/protocol-buffers/
5 //
6 // Redistribution and use in source and binary forms, with or without
7 // modification, are permitted provided that the following conditions are
8 // met:
9 //
10 //     * Redistributions of source code must retain the above copyright
11 // notice, this list of conditions and the following disclaimer.
12 //     * Redistributions in binary form must reproduce the above
13 // copyright notice, this list of conditions and the following disclaimer
14 // in the documentation and/or other materials provided with the
15 // distribution.
16 //     * Neither the name of Google Inc. nor the names of its
17 // contributors may be used to endorse or promote products derived from
18 // this software without specific prior written permission.
19 //
20 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
24 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
25 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
26 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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30 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 #endregion
32 
33 using System;
34 using System.Reflection;
35 using Google.Protobuf.Compatibility;
36 
37 namespace Google.Protobuf.Reflection
38 {
39     /// <summary>
40     /// Reflection access for a oneof, allowing clear and "get case" actions.
41     /// </summary>
42     public sealed class OneofAccessor
43     {
44         private readonly Func<IMessage, int> caseDelegate;
45         private readonly Action<IMessage> clearDelegate;
46         private OneofDescriptor descriptor;
47 
OneofAccessor(PropertyInfo caseProperty, MethodInfo clearMethod, OneofDescriptor descriptor)48         internal OneofAccessor(PropertyInfo caseProperty, MethodInfo clearMethod, OneofDescriptor descriptor)
49         {
50             if (!caseProperty.CanRead)
51             {
52                 throw new ArgumentException("Cannot read from property");
53             }
54             this.descriptor = descriptor;
55             caseDelegate = ReflectionUtil.CreateFuncIMessageT<int>(caseProperty.GetGetMethod());
56 
57             this.descriptor = descriptor;
58             clearDelegate = ReflectionUtil.CreateActionIMessage(clearMethod);
59         }
60 
61         /// <summary>
62         /// Gets the descriptor for this oneof.
63         /// </summary>
64         /// <value>
65         /// The descriptor of the oneof.
66         /// </value>
67         public OneofDescriptor Descriptor { get { return descriptor; } }
68 
69         /// <summary>
70         /// Clears the oneof in the specified message.
71         /// </summary>
Clear(IMessage message)72         public void Clear(IMessage message)
73         {
74             clearDelegate(message);
75         }
76 
77         /// <summary>
78         /// Indicates which field in the oneof is set for specified message
79         /// </summary>
GetCaseFieldDescriptor(IMessage message)80         public FieldDescriptor GetCaseFieldDescriptor(IMessage message)
81         {
82             int fieldNumber = caseDelegate(message);
83             if (fieldNumber > 0)
84             {
85                 return descriptor.ContainingType.FindFieldByNumber(fieldNumber);
86             }
87             return null;
88         }
89     }
90 }
91