Use source generator instead of in-memory collection

[Marvin-Brouwer]

Discussed in #69

^{Originally posted by Marvin-Brouwer February 9, 2022}
We'd like to research the possibility of generating the JSON/XML/whatever mappings on build instead of reflecting this on startup.
For example, change this:

    public sealed class ProjectProfile : OpenAirSerializerProfile
    {
        public override void Configure()
        {
            For<Project>(
                attributeNamingStrategy: Names.Use.SnakeCase,
                tagNamingStrategy: Names.Use.PascalCase
            )
                .Child(project => project.Name)
                .Child(project => project.LastUpdate,
                    namingStrategy: Names.Equal("updated"),
                    converter: Converters.Use.OpenAirDate)
                .Child(project => project.Active,
                    converter: Converters.Use.StringBitBoolean)
                .Child(project => project.CustomDate,
                    namingStrategy: Names.Use.CustomFieldNames,
                    converter: Converters.Use.SimpleDate)
                .Child(project => project.RateCardId);
        }
    }

Into this:

public sealed class GeneratedSerializer {
    
    public string? Serialize(object? objectToSerialize) {
         if(object is null) return null)

         if(objectToSerialize is FullNamespace.Project)) return ProjectSerializer.Serialize(objectToSerialize);
         // ...
         
         throw new ClassMapNotFoundException(objectToSerialize.GetType());
    }
}

public static class ProjectSerializer {

    public static string? Serialize(Project objectToSerialize, ISerializerContext context) {
   
         const projectName = Names.Use.PascalCase(objectToSerialize.GetType(), context);
         var dataConatiner = new XObject(projectName,
                new XmlBuilder.Element(
                       Names.Use.SnakeCase(objectToSerialize.GetType().GetProperty(nameof(objectToSerialize.Name)), context),
                       Converters.Use.Convertible(objectToSerialize.Name, context)),
                new XmlBuilder.Element(
                       Names.Equal("updated")(nameof(objectToSerialize.LastUpdate), context),
                       Converters.Use.OpenAirDate(objectToSerialize.LastUpdate)),
                new XmlBuilder.Element(
                       Names.Use.SnakeCase(objectToSerialize.GetType().GetProperty(nameof(objectToSerialize.Active)), context),
                       Converters.Use.StringBitBoolean(objectToSerialize.Active, context)),
                new XmlBuilder.Element(
                       Names.Use.CustomFieldNames(objectToSerialize.GetType().GetProperty(nameof(objectToSerialize.CustomDate)), context),
                       Converters.Use.SimpleDate(objectToSerialize.CustomDate, context)),
                new XmlBuilder.Element(
                       Names.Use.SnakeCase(objectToSerialize.GetType().GetProperty(nameof(objectToSerialize.RateCardId)), context),
                       Converters.Use.Convertible(objectToSerialize.RateCardId.ToString(), context))
         );

        return dataContainer.ToString();
    }

}

Or something similar to that.

The question is, do we even want this?
Do we want to support this as an option or is it always on?

---

Additional notes:

These might be interesting libraries:

• https://andrewlock.net/netescapades-enumgenerators-a-source-generator-for-enum-performance/

[Marvin-Brouwer]

andrewlock/StronglyTypedId#102 (comment)

[Marvin-Brouwer]

https://lemire.me/blog/2024/07/05/scan-html-faster-with-simd-instructions-net-c-edition/?utm_source=newsletter.csharpdigest.net&utm_medium=newsletter&utm_campaign=why-and-how-to-execute-graphql-queries-in-net