/
ObjectSerializer.kt
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/
ObjectSerializer.kt
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/*
* Copyright 2017-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
*/
package kotlinx.serialization.internal
import kotlinx.serialization.*
import kotlinx.serialization.descriptors.*
import kotlinx.serialization.encoding.*
/**
* Serializer for Kotlin's singletons (denoted by `object` keyword).
* To preserve singleton identity after serialization and deserialization, object serializer
* uses an [object instance][objectInstance].
* By default, a singleton is serialized as an empty structure, e.g. `{}` in JSON.
*/
@PublishedApi
@OptIn(ExperimentalSerializationApi::class)
internal class ObjectSerializer<T : Any>(serialName: String, private val objectInstance: T) : KSerializer<T> {
@PublishedApi // See comment in SealedClassSerializer
internal constructor(
serialName: String,
objectInstance: T,
classAnnotations: Array<Annotation>
) : this(serialName, objectInstance) {
_annotations = classAnnotations.asList()
}
private var _annotations: List<Annotation> = emptyList()
override val descriptor: SerialDescriptor by lazy(LazyThreadSafetyMode.PUBLICATION) {
buildSerialDescriptor(serialName, StructureKind.OBJECT) {
annotations = _annotations
}
}
override fun serialize(encoder: Encoder, value: T) {
encoder.beginStructure(descriptor).endStructure(descriptor)
}
override fun deserialize(decoder: Decoder): T {
decoder.decodeStructure(descriptor) {
when (val index = decodeElementIndex(descriptor)) {
CompositeDecoder.DECODE_DONE -> {
return@decodeStructure
}
else -> throw SerializationException("Unexpected index $index")
}
}
return objectInstance
}
}