Implemented: Code Generation for Serialization

[nickrandolph]

Uno.Extensions.Serialization includes an implementation of json serialization that uses System.Text.Json which is reflection based.

Need a mechanism for using support for code generation to improve efficiency of json serialization

[nickrandolph]

Code Generation for serialization overview - https://devblogs.microsoft.com/dotnet/try-the-new-system-text-json-source-generator/

Developer needs to define PersonContext in order to serialize Person
eg

    [JsonSerializable(typeof(Person))]
    internal partial class PersonContext : JsonSerializerContext
    {
    }

Code generation creates various methods and properties, of which one is
public JsonTypeInfo<Person>Person
Which can be accessed by PersonContext.Default.Person when serializing an entity

Person person = new() { FirstName = "Jane", LastName = "Doe" };
byte[] utf8Json = JsonSerializer.SerializeToUtf8Bytes(person, PersonContext.Default.Person);
person = JsonSerializer.Deserialize(utf8Json, PersonContext.Default.Person):

Proposal

Developer has to create serializer context for each class they want to serialize eg PersonContext for Person class. Source generation will expose the JsonTypeInfo instance via the Default.Person property.

JsonTypeInfo is registered with the DI container eg:
services.AddSingleton<JsonTypeInfo<Person>>(PersonContext.Default.Person);
Implement ISerializer using the JsonTypeInfo which will be provide via constructor injection

public class SystemTextJsonGeneratedSerializer<T> : ISerializer<T>
{
    public SystemTextJsonGeneratedSerializer(ISerializer reflectionBasedSerializer, JsonTypeInfo<T>? typeInfo){....}
}

The typeInfo parameter would be marked as optional and if it's not available the implementation would fall back to the reflection based json serializer (a reflection based implementation would be provided via the ISerializer implementation).