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
33using System;
34using System.Reflection;
35using Google.Protobuf.Compatibility;
36
37namespace 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
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
71        public override void Clear(IMessage message)
72        {
73            clearDelegate(message);
74        }
75
76        public override void SetValue(IMessage message, object value)
77        {
78            setValueDelegate(message, value);
79        }
80    }
81}
82