Correctly implement TaggedDecoder's decodeNullableSerializableElement

Kotlin · Oct 18, 2023 · c64ba4a · c64ba4a
1 parent 9ac4c5f
commit c64ba4a
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Showing 3 changed files with 14 additions and 13 deletions.
diff --git a/core/commonMain/src/kotlinx/serialization/encoding/AbstractDecoder.kt b/core/commonMain/src/kotlinx/serialization/encoding/AbstractDecoder.kt
@@ -74,8 +74,7 @@ public abstract class AbstractDecoder : Decoder, CompositeDecoder {
  index: Int,
  deserializer: DeserializationStrategy<T?>,
  previousValue: T?
- ): T? {
- val isNullabilitySupported = deserializer.descriptor.isNullable
- return if (isNullabilitySupported || decodeNotNullMark()) decodeSerializableValue(deserializer, previousValue) else decodeNull()
+ ): T? = decodeIfNullable(deserializer) {
+ decodeSerializableValue(deserializer, previousValue)
  }
 }
diff --git a/core/commonMain/src/kotlinx/serialization/encoding/Decoding.kt b/core/commonMain/src/kotlinx/serialization/encoding/Decoding.kt
@@ -260,12 +260,17 @@ public interface Decoder {
  * Decodes the nullable value of type [T] by delegating the decoding process to the given [deserializer].
  */
  @ExperimentalSerializationApi
- public fun <T : Any> decodeNullableSerializableValue(deserializer: DeserializationStrategy<T?>): T? {
- val isNullabilitySupported = deserializer.descriptor.isNullable
- return if (isNullabilitySupported || decodeNotNullMark()) decodeSerializableValue(deserializer) else decodeNull()
+ public fun <T : Any> decodeNullableSerializableValue(deserializer: DeserializationStrategy<T?>): T? = decodeIfNullable(deserializer) {
+ decodeSerializableValue(deserializer)
  }
 }
 
+@OptIn(ExperimentalSerializationApi::class)
+internal inline fun <T : Any> Decoder.decodeIfNullable(deserializer: DeserializationStrategy<T?>, block: () -> T?): T? {
+ val isNullabilitySupported = deserializer.descriptor.isNullable
+ return if (isNullabilitySupported || decodeNotNullMark()) block() else decodeNull()
+}
+
 /**
  * [CompositeDecoder] is a part of decoding process that is bound to a particular structured part of
  * the serialized form, described by the serial descriptor passed to [Decoder.beginStructure].

diff --git a/core/commonMain/src/kotlinx/serialization/internal/Tagged.kt b/core/commonMain/src/kotlinx/serialization/internal/Tagged.kt
@@ -206,7 +206,6 @@ public abstract class TaggedDecoder<Tag : Any?> : Decoder, CompositeDecoder {
  protected open fun <T : Any?> decodeSerializableValue(deserializer: DeserializationStrategy<T>, previousValue: T?): T =
  decodeSerializableValue(deserializer)
 
-
  // ---- Implementation of low-level API ----
 
  override fun decodeInline(descriptor: SerialDescriptor): Decoder =
@@ -284,13 +283,11 @@ public abstract class TaggedDecoder<Tag : Any?> : Decoder, CompositeDecoder {
  index: Int,
  deserializer: DeserializationStrategy<T?>,
  previousValue: T?
- ): T? =
- tagBlock(descriptor.getTag(index)) {
- if (decodeNotNullMark() || deserializer.descriptor.isNullable) decodeSerializableValue(
- deserializer,
- previousValue
- ) else decodeNull()
+ ): T? = tagBlock(descriptor.getTag(index)) {
+ decodeIfNullable(deserializer) {
+ decodeSerializableValue(deserializer, previousValue)
  }
+ }
 
  private fun <E> tagBlock(tag: Tag, block: () -> E): E {
  pushTag(tag)