medium source code

GHObjectBuilder.kt

object GHObjectBuilder {
    // build function
    fun <T : Any> build(tClass: KClass<T>, json: JsonObject): T? {
        // check primary constructor
        if (tClass.primaryConstructor == null) return null
        // create parameter mapping
        val map: HashMap<KParameter, Any?> = HashMap<KParameter, Any?>()
        // for each paramete in constructor
        tClass.primaryConstructor!!.parameters.forEach {
            param ->
            // get annotation that is JsonKey class only!!
            val keyAnnotation: JsonKey? = params.annotations.filter {
                annotation ->
                return@filter annotation.annotationClass == JsonKey::class
            }.singleOrNull() as JsonKey
            // get value inside json object
            val value = json[keyAnnotation?.key]
            // mapping param with value
            map.put(param, value)
        }
        // create object with primary constructor
        return tClass.primaryConstructor!!.callBy(map)
    }
}