runtime/commonMain/src/kotlinx/serialization/json/internal/Polymorphic.kt


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/*
 * Copyright 2017-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
 */

package kotlinx.serialization.json.internal

import kotlinx.serialization.*
import kotlinx.serialization.json.*

internal inline fun <T> JsonOutput.encodePolymorphically(serializer: SerializationStrategy<T>, value: T, ifPolymorphic: () -> Unit) {
    if (serializer !is PolymorphicSerializer<*> || json.configuration.useArrayPolymorphism) {
        serializer.serialize(this, value)
        return
    }

    @Suppress("UNCHECKED_CAST")
    val actualSerializer = serializer.findPolymorphicSerializer(this, value as Any) as KSerializer<Any>
    val kind = actualSerializer.descriptor.kind
    checkKind(kind)

    ifPolymorphic()
    actualSerializer.serialize(this, value)
}

fun checkKind(kind: SerialKind) {
    if (kind is UnionKind.ENUM_KIND) error("Enums cannot be serialized polymorphically with 'type' parameter. You can use 'JsonConfiguration.useArrayPolymorphism' instead")
    if (kind is PrimitiveKind) error("Primitives cannot be serialized polymorphically with 'type' parameter. You can use 'JsonConfiguration.useArrayPolymorphism' instead")
    if (kind is UnionKind.POLYMORPHIC) error("Actual serializer for polymorphic cannot be polymorphic itself")
}

internal fun <T> JsonInput.decodeSerializableValuePolymorphic(deserializer: DeserializationStrategy<T>): T {
    if (deserializer !is PolymorphicSerializer<*> || json.configuration.useArrayPolymorphism) {
        return deserializer.deserialize(this)
    }

    val jsonTree = cast<JsonObject>(decodeJson())
    val type = jsonTree.getValue(json.configuration.classDiscriminator).content
    (jsonTree.content as MutableMap).remove(json.configuration.classDiscriminator)
    @Suppress("UNCHECKED_CAST")
    val actualSerializer = deserializer.findPolymorphicSerializer(this, type) as KSerializer<T>
    return json.readJson(jsonTree, actualSerializer)
}