JSON.kt | Kotlin JSON Parsing that infers | JSON Processing library

I'm currently struggling with the experimental KXS-properties serialization backend, mainly because of two reasons:

1. I can't find any documentation for it (I think there is none)
2. KXS-properties only includes a serializer / deserializer, but no encoder / decoder

The endpoint provided by the framework is essentially Map, but the map is flat and the keys already have the usual dot-separated properties syntax. So the step that I have to take is to encode the map to a single string that is printable to a .properties file AND decode a single string from a .properties file into the map. I'm generally following the Properties Format Spec from https://docs.oracle.com/javase/10/docs/api/java/util/Properties.html#load(java.io.Reader), it's not as easy as one might think.

The problem is that I can't use java.util.Properties right away because KXS is multiplatform and it would kinda kill the purpose of it when I'd restrict it to JVM because I use java.util.Properties. If I were to use it, the solution would be pretty simple, like this: https://gist.github.com/RaphaelTarita/748e02c06574b20c25ab96c87235096d

So I'm trying to implement my own encoder / decoder, following the rough structure of kotlinx.serialization.json.Json.kt. Although it's pretty tedious, it went well so far, but now I've stumbled upon a new problem:

As far as I know (I am not sure because there is no documentation), the map only contains primitives (or primitive-equivalents, as Kotlin does not really have primitives). I suspect this because when you write your own KSerializers for the KXS frontend, you can specify to encode to any primitive by invoking the encodeXXX() functions of the Encoder interface. Now the problem is: When I try to decode to the map that should contain primitives, how do I even know which primitives are expected by the model class?

I've once written my own serializer / deserializer in Java to learn about the topic, but in that implementation, the backend was a lot more tightly coupled to the frontend, so that I could query the expected primitive type from the model class in the backend. But in my situation, I don't have access to the model class and I have no clue how to retrieve the expected types.

As you can see, I've tried multiple approaches, but none of them worked right away. If you can help me to get any of these to work, that would be very much appreciated

Thank you!

I'm very new to Kotlin and am curious what magic allows this code to work:

From https://github.com/Kotlin/kotlinx.serialization/blob/e2e764a132c8eebd31208120774baf9a71ec23c7/formats/json/commonTest/src/kotlinx/serialization/SerializerForNullableTypeTest.kt

I'm trying to create a custom deserializer using kotlinx.serialization but when I deerialize a JSON payload with null parameters, an exception kotlinx.serialization.json.JsonDecodingException: Unexpected JSON token at offset 31: Expected string or non-null literal. is threw. I apologize if there is any English error; if more information is missing, just let me know that I will edit the post.

Note: There is nothing wrong with the EventDecoder.

JSON:

I am trying kotlin for the first time.

I was able to run compile the hello world program in kotlin on command line but I am not able to compile program where I want to include external java library