commonMain.pro.felixo.protobuf.serialization.encoding.PolymorphicDecoder.kt Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of protobuf-kotlin-serialization Show documentation
Protocol Buffers 3 support for Kotlin Multiplatform
The newest version!
package pro.felixo.protobuf.serialization.encoding

import kotlinx.serialization.DeserializationStrategy
import kotlinx.serialization.ExperimentalSerializationApi
import kotlinx.serialization.descriptors.SerialDescriptor
import kotlinx.serialization.encoding.CompositeDecoder
import kotlinx.serialization.encoding.Decoder
import kotlinx.serialization.modules.SerializersModule
import pro.felixo.protobuf.FieldNumber
import pro.felixo.protobuf.serialization.Field
import pro.felixo.protobuf.wire.WireValue
import pro.felixo.protobuf.wire.decodeMessage

class PolymorphicDecoder(
    override val serializersModule: SerializersModule,
    fieldByDescriptor: Map>,
    wireValues: List
) : HybridDecoder() {
    private val values = mutableListOf()
    private val descriptor: SerialDescriptor
    private val field: Field

    init {
        var fieldNumber: FieldNumber? = null
        wireValues.forEach {
            (it as WireValue.Len).value.decodeMessage { number, wireValue ->
                if (number != fieldNumber) {
                    values.clear()
                    fieldNumber = number
                }
                values.add(wireValue)
            }
        }
        if (fieldNumber == null)
            error("No values found in message for PolymorphicDecoder")

        val descriptorFieldPair =
            fieldByDescriptor[fieldNumber] ?: error("Invalid field number for polymorphic type: $fieldNumber")
        descriptor = descriptorFieldPair.first
        field = descriptorFieldPair.second
    }

    override fun decodeBooleanElement(descriptor: SerialDescriptor, index: Int): Boolean =
        error("PolymorphicDecoder does not support Boolean elements")

    override fun decodeByteElement(descriptor: SerialDescriptor, index: Int): Byte =
        error("PolymorphicDecoder does not support Byte elements")

    override fun decodeCharElement(descriptor: SerialDescriptor, index: Int): Char =
        error("PolymorphicDecoder does not support Char elements")

    override fun decodeDoubleElement(descriptor: SerialDescriptor, index: Int): Double =
        error("PolymorphicDecoder does not support Double elements")

    private var currentElementIndex = -1
    override fun decodeElementIndex(descriptor: SerialDescriptor): Int {
        currentElementIndex++
        return if (currentElementIndex >= 2)
            CompositeDecoder.DECODE_DONE
        else
            currentElementIndex
    }

    override fun decodeFloatElement(descriptor: SerialDescriptor, index: Int): Float =
        error("PolymorphicDecoder does not support Float elements")

    override fun decodeInlineElement(descriptor: SerialDescriptor, index: Int): Decoder =
        error("PolymorphicDecoder does not support Inline elements")

    override fun decodeIntElement(descriptor: SerialDescriptor, index: Int): Int =
        error("PolymorphicDecoder does not support Int elements")

    override fun decodeLongElement(descriptor: SerialDescriptor, index: Int): Long =
        error("PolymorphicDecoder does not support Long elements")

    @ExperimentalSerializationApi
    override fun  decodeNullableSerializableElement(
        descriptor: SerialDescriptor,
        index: Int,
        deserializer: DeserializationStrategy,
        previousValue: T?
    ): T = error("PolymorphicDecoder does not support nullable elements")

    override fun  decodeSerializableElement(
        descriptor: SerialDescriptor,
        index: Int,
        deserializer: DeserializationStrategy,
        previousValue: T?
    ): T = deserializer.deserialize(field.decoder(values))

    override fun decodeShortElement(descriptor: SerialDescriptor, index: Int): Short =
        error("PolymorphicDecoder does not support Short elements")


    /**
     * This may be called by the Serializer to find out what the subtype is.
     */
    @OptIn(ExperimentalSerializationApi::class)
    override fun decodeStringElement(descriptor: SerialDescriptor, index: Int): String = this.descriptor.serialName

    override fun endStructure(descriptor: SerialDescriptor) {
        // Nothing for us to do here.
    }
}