commonMain.dk.cachet.carp.common.infrastructure.serialization.NotSerializable.kt Maven / Gradle / Ivy

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Helper classes and base types relied upon by all subsystems. This library does not contain any domain logic.

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package dk.cachet.carp.common.infrastructure.serialization

import kotlinx.serialization.*
import kotlinx.serialization.descriptors.*
import kotlinx.serialization.encoding.*
import kotlin.reflect.KFunction1


/**
 * A dummy serializer which can be applied to types that are never expected to be serialized,
 * but for which the compiler is trying to generate/retrieve a serializer. E.g., types used as generic type parameters.
 * Applying `@Serializable( with = NotSerializable::class )` to those types ensures compilation succeeds,
 * without having to actually make them serializable.
 */
object NotSerializable : KSerializer
{
    private val exception = SerializationException(
        "Types annotated as `@Serializable( with = NotSerializable::class )` are never expected to be serialized. " +
        "The serializer is only defined since the compiler does not know this, causing a compilation error."
    )

    override val descriptor: SerialDescriptor = buildClassSerialDescriptor( "This should never be serialized." )
    override fun deserialize( decoder: Decoder ): Nothing = throw exception
    override fun serialize( encoder: Encoder, value: Nothing ) = throw exception
}


/**
 * Creates a serializer for a class with one type parameter which can safely be ignored during serialization.
 * This requires that the type parameter is not used during serialization.
 */
@Suppress( "UNCHECKED_CAST" )
fun  ignoreTypeParameters( createSerializer: KFunction1, KSerializer> ): KSerializer =
    object : KSerializer
    {
        val innerSerializer = createSerializer.invoke( NotSerializable as KSerializer )
        override val descriptor: SerialDescriptor = innerSerializer.descriptor

        override fun serialize( encoder: Encoder, value: T ) =
            encoder.encodeSerializableValue( innerSerializer, value )

        override fun deserialize( decoder: Decoder ): T =
            decoder.decodeSerializableValue( innerSerializer )
    }