Add annotations array parameter for sealed, polymorphic, and object s…

…erialzers Enables support of @SerialInfo class-level annotation on such classes Fixes #708 Fixes #1240
Kotlin · Aug 24, 2021 · c4b7aff · c4b7aff
1 parent ff28e0f
commit c4b7aff
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Showing 6 changed files with 78 additions and 6 deletions.
diff --git a/core/commonMain/src/kotlinx/serialization/ContextualSerializer.kt b/core/commonMain/src/kotlinx/serialization/ContextualSerializer.kt
@@ -55,7 +55,9 @@ public class ContextualSerializer<T : Any>(
     public constructor(serializableClass: KClass<T>) : this(serializableClass, null, EMPTY_SERIALIZER_ARRAY)
 
     public override val descriptor: SerialDescriptor =
-        buildSerialDescriptor("kotlinx.serialization.ContextualSerializer", SerialKind.CONTEXTUAL).withContext(serializableClass)
+        buildSerialDescriptor("kotlinx.serialization.ContextualSerializer", SerialKind.CONTEXTUAL) {
+            annotations = fallbackSerializer?.descriptor?.annotations.orEmpty()
+        }.withContext(serializableClass)
 
     public override fun serialize(encoder: Encoder, value: T) {
         encoder.encodeSerializableValue(serializer(encoder.serializersModule), value)

diff --git a/core/commonMain/src/kotlinx/serialization/PolymorphicSerializer.kt b/core/commonMain/src/kotlinx/serialization/PolymorphicSerializer.kt
@@ -67,14 +67,28 @@ import kotlin.reflect.*
  */
 @OptIn(ExperimentalSerializationApi::class)
 public class PolymorphicSerializer<T : Any>(override val baseClass: KClass<T>) : AbstractPolymorphicSerializer<T>() {
-    public override val descriptor: SerialDescriptor =
+
+    @PublishedApi // should we allow user access to this constructor?
+    internal constructor(
+        baseClass: KClass<T>,
+        classAnnotations: Array<Annotation>
+    ) : this(baseClass) {
+        _descriptor.annotations = classAnnotations.asList()
+    }
+
+    private val _descriptor: SerialDescriptorImpl =
         buildSerialDescriptor("kotlinx.serialization.Polymorphic", PolymorphicKind.OPEN) {
             element("type", String.serializer().descriptor)
             element(
                 "value",
-                buildSerialDescriptor("kotlinx.serialization.Polymorphic<${baseClass.simpleName}>", SerialKind.CONTEXTUAL)
+                buildSerialDescriptor(
+                    "kotlinx.serialization.Polymorphic<${baseClass.simpleName}>",
+                    SerialKind.CONTEXTUAL
+                )
             )
-        }.withContext(baseClass)
+        } as SerialDescriptorImpl
+
+    public override val descriptor: SerialDescriptor = _descriptor.withContext(baseClass)
 
     override fun toString(): String {
         return "kotlinx.serialization.PolymorphicSerializer(baseClass: $baseClass)"

diff --git a/core/commonMain/src/kotlinx/serialization/SealedSerializer.kt b/core/commonMain/src/kotlinx/serialization/SealedSerializer.kt
@@ -77,6 +77,17 @@ public class SealedClassSerializer<T : Any>(
     subclassSerializers: Array<KSerializer<out T>>
 ) : AbstractPolymorphicSerializer<T>() {
 
+    @PublishedApi
+    internal constructor(
+        serialName: String,
+        baseClass: KClass<T>,
+        subclasses: Array<KClass<out T>>,
+        subclassSerializers: Array<KSerializer<out T>>,
+        classAnnotations: Array<Annotation>
+    ) : this(serialName, baseClass, subclasses, subclassSerializers) {
+        (this.descriptor as SerialDescriptorImpl).annotations = classAnnotations.asList()
+    }
+
     override val descriptor: SerialDescriptor = buildSerialDescriptor(serialName, PolymorphicKind.SEALED) {
         element("type", String.serializer().descriptor)
         val elementDescriptor =
@@ -87,7 +98,6 @@ public class SealedClassSerializer<T : Any>(
                 }
             }
         element("value", elementDescriptor)
-
     }
 
     private val class2Serializer: Map<KClass<out T>, KSerializer<out T>>

diff --git a/core/commonMain/src/kotlinx/serialization/descriptors/SerialDescriptors.kt b/core/commonMain/src/kotlinx/serialization/descriptors/SerialDescriptors.kt
@@ -308,7 +308,8 @@ internal class SerialDescriptorImpl(
     builder: ClassSerialDescriptorBuilder
 ) : SerialDescriptor, CachedNames {
 
-    override val annotations: List<Annotation> = builder.annotations
+    override var annotations: List<Annotation> = builder.annotations
+        internal set
     override val serialNames: Set<String> = builder.elementNames.toHashSet()
 
     private val elementNames: Array<String> = builder.elementNames.toTypedArray()

diff --git a/core/commonMain/src/kotlinx/serialization/internal/ObjectSerializer.kt b/core/commonMain/src/kotlinx/serialization/internal/ObjectSerializer.kt
@@ -17,6 +17,15 @@ import kotlinx.serialization.encoding.*
 @PublishedApi
 @OptIn(ExperimentalSerializationApi::class)
 internal class ObjectSerializer<T : Any>(serialName: String, private val objectInstance: T) : KSerializer<T> {
+    @PublishedApi
+    internal constructor(
+        serialName: String,
+        objectInstance: T,
+        classAnnotations: Array<Annotation>
+    ) : this(serialName, objectInstance) {
+        (this.descriptor as SerialDescriptorImpl).annotations = classAnnotations.asList()
+    }
+
     override val descriptor: SerialDescriptor = buildSerialDescriptor(serialName, StructureKind.OBJECT)
 
     override fun serialize(encoder: Encoder, value: T) {

diff --git a/core/commonTest/src/kotlinx/serialization/SerialDescriptorAnnotationsTest.kt b/core/commonTest/src/kotlinx/serialization/SerialDescriptorAnnotationsTest.kt
@@ -81,4 +81,40 @@ class SerialDescriptorAnnotationsTest {
     }
 
     private fun List<Annotation>.getCustom() = filterIsInstance<CustomAnnotation>().single().value
+
+    @Serializable
+    @CustomAnnotation("sealed")
+    sealed class Result {
+        @Serializable class OK(val s: String): Result()
+    }
+
+    @Serializable
+    @CustomAnnotation("abstract")
+    abstract class AbstractResult {
+        var result: String = ""
+    }
+
+    @Serializable
+    @CustomAnnotation("object")
+    object ObjectResult {}
+
+    @Serializable
+    class Holder(val r: Result, val a: AbstractResult, val o: ObjectResult, @Contextual val names: WithNames)
+
+    private fun doTest(position: Int, expected: String) {
+        val desc = Holder.serializer().descriptor.getElementDescriptor(position)
+        assertEquals(expected, desc.annotations.getCustom())
+    }
+
+    @Test
+    fun testCustomAnnotationOnSealedClass() = doTest(0, "sealed")
+
+    @Test
+    fun testCustomAnnotationOnPolymorphicClass() = doTest(1, "abstract")
+
+    @Test
+    fun testCustomAnnotationOnObject() = doTest(2, "object")
+
+    @Test
+    fun testCustomAnnotationTransparentForContextual() = doTest(3, "onClass")
 }