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
29 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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     /// Accessor for single fields.
41     /// </summary>
42     internal sealed class SingleFieldAccessor : FieldAccessorBase
43     {
44         // All the work here is actually done in the constructor - it creates the appropriate delegates.
45         // There are various cases to consider, based on the property type (message, string/bytes, or "genuine" primitive)
46         // and proto2 vs proto3 for non-message types, as proto3 doesn't support "full" presence detection or default
47         // values.
48 
49         private readonly Action<IMessage, object> setValueDelegate;
50         private readonly Action<IMessage> clearDelegate;
51 
SingleFieldAccessor(PropertyInfo property, FieldDescriptor descriptor)52         internal SingleFieldAccessor(PropertyInfo property, FieldDescriptor descriptor) : base(property, descriptor)
53         {
54             if (!property.CanWrite)
55             {
56                 throw new ArgumentException("Not all required properties/methods available");
57             }
58             setValueDelegate = ReflectionUtil.CreateActionIMessageObject(property.GetSetMethod());
59 
60             var clrType = property.PropertyType;
61 
62             // TODO: Validate that this is a reasonable single field? (Should be a value type, a message type, or string/ByteString.)
63             object defaultValue =
64                 descriptor.FieldType == FieldType.Message ? null
65                 : clrType == typeof(string) ? ""
66                 : clrType == typeof(ByteString) ? ByteString.Empty
67                 : Activator.CreateInstance(clrType);
68             clearDelegate = message => SetValue(message, defaultValue);
69         }
70 
Clear(IMessage message)71         public override void Clear(IMessage message)
72         {
73             clearDelegate(message);
74         }
75 
SetValue(IMessage message, object value)76         public override void SetValue(IMessage message, object value)
77         {
78             setValueDelegate(message, value);
79         }
80     }
81 }
82