-
Notifications
You must be signed in to change notification settings - Fork 1.2k
/
DiscriminatedWrapperSerializer.cs
146 lines (133 loc) · 5.93 KB
/
DiscriminatedWrapperSerializer.cs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
/* Copyright 2010-present MongoDB Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
using MongoDB.Bson.IO;
using MongoDB.Bson.Serialization.Conventions;
namespace MongoDB.Bson.Serialization.Serializers
{
/// <summary>
/// Represents a serializer that serializes values as a discriminator/value pair.
/// </summary>
/// <typeparam name="TValue">The type of the value.</typeparam>
public class DiscriminatedWrapperSerializer<TValue> : SerializerBase<TValue>
{
// private constants
private static class Flags
{
public const long Discriminator = 1;
public const long Value = 2;
public const long Other = 4;
}
// private fields
private readonly IDiscriminatorConvention _discriminatorConvention;
private readonly SerializerHelper _helper;
private readonly SerializerHelper _isPositionedHelper;
private readonly IBsonSerializer<TValue> _wrappedSerializer;
// constructors
/// <summary>
/// Initializes a new instance of the <see cref="DiscriminatedWrapperSerializer{TValue}" /> class.
/// </summary>
/// <param name="discriminatorConvention">The discriminator convention.</param>
/// <param name="wrappedSerializer">The wrapped serializer.</param>
public DiscriminatedWrapperSerializer(IDiscriminatorConvention discriminatorConvention, IBsonSerializer<TValue> wrappedSerializer)
{
_discriminatorConvention = discriminatorConvention;
_wrappedSerializer = wrappedSerializer;
_helper = new SerializerHelper
(
new SerializerHelper.Member(discriminatorConvention.ElementName, Flags.Discriminator),
new SerializerHelper.Member("_v", Flags.Value)
);
_isPositionedHelper = new SerializerHelper
(
new SerializerHelper.Member(discriminatorConvention.ElementName, Flags.Discriminator, isOptional: true),
new SerializerHelper.Member("_v", Flags.Value, isOptional: true),
new SerializerHelper.Member("*", Flags.Other, isOptional: true)
);
}
// public methods
/// <summary>
/// Deserializes a value.
/// </summary>
/// <param name="context">The deserialization context.</param>
/// <param name="args">The deserialization args.</param>
/// <returns>A deserialized value.</returns>
public override TValue Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
{
var bsonReader = context.Reader;
var nominalType = args.NominalType;
var actualType = _discriminatorConvention.GetActualType(bsonReader, nominalType);
var serializer = BsonSerializer.LookupSerializer(actualType);
TValue value = default(TValue);
_helper.DeserializeMembers(context, (elementName, flag) =>
{
switch (flag)
{
case Flags.Discriminator:
bsonReader.SkipValue();
break;
case Flags.Value:
var valueDeserializationArgs = new BsonDeserializationArgs { NominalType = actualType };
value = (TValue)serializer.Deserialize(context, valueDeserializationArgs);
break;
}
});
return value;
}
/// <summary>
/// Determines whether the reader is positioned at a discriminated wrapper.
/// </summary>
/// <param name="context">The context.</param>
/// <returns>True if the reader is positioned at a discriminated wrapper.</returns>
public bool IsPositionedAtDiscriminatedWrapper(BsonDeserializationContext context)
{
var bsonReader = context.Reader;
var bookmark = bsonReader.GetBookmark();
try
{
if (bsonReader.GetCurrentBsonType() != BsonType.Document) { return false; }
var foundFields = _isPositionedHelper.DeserializeMembers(context, (elementName, flag) =>
{
context.Reader.SkipValue();
});
return foundFields == (Flags.Discriminator | Flags.Value);
}
finally
{
bsonReader.ReturnToBookmark(bookmark);
}
}
/// <summary>
/// Serializes a value.
/// </summary>
/// <param name="context">The serialization context.</param>
/// <param name="args">The serialization args.</param>
/// <param name="value">The value.</param>
public override void Serialize(BsonSerializationContext context, BsonSerializationArgs args, TValue value)
{
var bsonWriter = context.Writer;
var nominalType = args.NominalType;
var actualType = value.GetType();
var discriminator = _discriminatorConvention.GetDiscriminator(nominalType, actualType);
bsonWriter.WriteStartDocument();
bsonWriter.WriteName(_discriminatorConvention.ElementName);
BsonValueSerializer.Instance.Serialize(context, discriminator);
bsonWriter.WriteName("_v");
args.NominalType = actualType;
_wrappedSerializer.Serialize(context, args, value);
bsonWriter.WriteEndDocument();
}
}
}