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Merge pull request #117 from arkivanov/polymorphic-serializer
Added polymorphicSerializer API
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92 changes: 92 additions & 0 deletions
92
...e-keeper/src/commonMain/kotlin/com/arkivanov/essenty/statekeeper/PolymorphicSerializer.kt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,92 @@ | ||
| package com.arkivanov.essenty.statekeeper | ||
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| import com.arkivanov.essenty.utils.internal.ExperimentalEssentyApi | ||
| import kotlinx.serialization.ExperimentalSerializationApi | ||
| import kotlinx.serialization.KSerializer | ||
| import kotlinx.serialization.descriptors.SerialDescriptor | ||
| import kotlinx.serialization.descriptors.SerialKind | ||
| import kotlinx.serialization.descriptors.buildClassSerialDescriptor | ||
| import kotlinx.serialization.descriptors.element | ||
| import kotlinx.serialization.encoding.CompositeDecoder | ||
| import kotlinx.serialization.encoding.Decoder | ||
| import kotlinx.serialization.encoding.Encoder | ||
| import kotlinx.serialization.encoding.decodeStructure | ||
| import kotlinx.serialization.encoding.encodeStructure | ||
| import kotlinx.serialization.modules.SerializersModule | ||
| import kotlin.reflect.KClass | ||
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| /** | ||
| * Creates a polymorphic [KSerializer] for the specified class of type [T] using the specified [module]. | ||
| */ | ||
| @ExperimentalEssentyApi | ||
| @ExperimentalSerializationApi | ||
| inline fun <reified T : Any> polymorphicSerializer(module: SerializersModule) : KSerializer<T> = | ||
| polymorphicSerializer(baseClass = T::class, module = module) | ||
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| /** | ||
| * Creates a polymorphic [KSerializer] for the specified [baseClass] class using the specified [module]. | ||
| */ | ||
| @ExperimentalEssentyApi | ||
| @ExperimentalSerializationApi | ||
| fun <T : Any> polymorphicSerializer(baseClass: KClass<T>, module: SerializersModule) : KSerializer<T> = | ||
| PolymorphicSerializer(baseClass = baseClass, module = module) | ||
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| @ExperimentalSerializationApi | ||
| private class PolymorphicSerializer<T : Any>( | ||
| private val baseClass: KClass<T>, | ||
| private val module: SerializersModule, | ||
| ) : KSerializer<T> { | ||
| override val descriptor: SerialDescriptor = | ||
| buildClassSerialDescriptor("PolymorphicSerializer") { | ||
| element<String>("type") | ||
| element("value", ContextualSerialDescriptor) | ||
| } | ||
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| override fun serialize(encoder: Encoder, value: T) { | ||
| val serializer = requireNotNull(module.getPolymorphic(baseClass, value)) | ||
| encoder.encodeStructure(descriptor) { | ||
| encodeStringElement(descriptor, 0, serializer.descriptor.serialName) | ||
| encodeSerializableElement(descriptor, 1, serializer, value) | ||
| } | ||
| } | ||
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| override fun deserialize(decoder: Decoder): T = | ||
| decoder.decodeStructure(descriptor) { | ||
| var className: String? = null | ||
| var value: T? = null | ||
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| while (true) { | ||
| when (val index = decodeElementIndex(descriptor)) { | ||
| 0 -> className = decodeStringElement(descriptor, index) | ||
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| 1 -> { | ||
| val actualClassName = requireNotNull(className) | ||
| val serializer = requireNotNull(module.getPolymorphic(baseClass, actualClassName)) | ||
| value = decodeSerializableElement(descriptor, 1, serializer) | ||
| } | ||
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| CompositeDecoder.DECODE_DONE -> break | ||
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| else -> error("Unsupported index: $index") | ||
| } | ||
| } | ||
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| requireNotNull(value) | ||
| } | ||
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| private object ContextualSerialDescriptor : SerialDescriptor { | ||
| override val elementsCount: Int = 0 | ||
| override val kind: SerialKind = SerialKind.CONTEXTUAL | ||
| override val serialName: String = "Value" | ||
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| override fun getElementAnnotations(index: Int): List<Annotation> = elementNotFoundError(index) | ||
| override fun getElementDescriptor(index: Int): SerialDescriptor = elementNotFoundError(index) | ||
| override fun getElementIndex(name: String): Int = CompositeDecoder.UNKNOWN_NAME | ||
| override fun getElementName(index: Int): String = elementNotFoundError(index) | ||
| override fun isElementOptional(index: Int): Boolean = elementNotFoundError(index) | ||
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| private fun elementNotFoundError(index: Int): Nothing { | ||
| throw IndexOutOfBoundsException("Element at index $index not found") | ||
| } | ||
| } | ||
| } |
42 changes: 42 additions & 0 deletions
42
...eper/src/commonTest/kotlin/com/arkivanov/essenty/statekeeper/PolymorphicSerializerTest.kt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,42 @@ | ||
| package com.arkivanov.essenty.statekeeper | ||
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| import com.arkivanov.essenty.utils.internal.ExperimentalEssentyApi | ||
| import kotlinx.serialization.ExperimentalSerializationApi | ||
| import kotlinx.serialization.KSerializer | ||
| import kotlinx.serialization.Serializable | ||
| import kotlinx.serialization.builtins.ListSerializer | ||
| import kotlinx.serialization.modules.SerializersModule | ||
| import kotlinx.serialization.modules.polymorphic | ||
| import kotlin.test.Test | ||
| import kotlin.test.assertEquals | ||
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| class PolymorphicSerializerTest { | ||
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| @Test | ||
| fun serialize_and_deserialize() { | ||
| val someListSerializer = ListSerializer(SomeSerializer) | ||
| val originalSome = listOf(Some1(1), Some2("2")) | ||
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| val newSome = originalSome.serialize(someListSerializer).deserialize(someListSerializer) | ||
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| assertEquals(originalSome, newSome) | ||
| } | ||
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| private interface Some | ||
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| @Serializable | ||
| private data class Some1(val value: Int) : Some | ||
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| @Serializable | ||
| private data class Some2(val value: String) : Some | ||
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| @OptIn(ExperimentalEssentyApi::class, ExperimentalSerializationApi::class) | ||
| private object SomeSerializer : KSerializer<Some> by polymorphicSerializer( | ||
| SerializersModule { | ||
| polymorphic(Some::class) { | ||
| subclass(Some1::class, Some1.serializer()) | ||
| subclass(Some2::class, Some2.serializer()) | ||
| } | ||
| } | ||
| ) | ||
| } |