Add serializer for kotlin.uuid.Uuid (#2744)

in a simple .toString()/.parse() form.

It is expected to be added as a standard serializer to the Kotlin 2.1 serialization plugin.

Fixes #2730

Author: sandwwraith

buildSrc/src/main/kotlin/source-sets-conventions.gradle.kts

@@ -66,7 +66,6 @@ kotlin {
             progressiveMode = true
 
             optIn("kotlin.ExperimentalMultiplatform")
-            optIn("kotlin.ExperimentalStdlibApi")
             optIn("kotlinx.serialization.InternalSerializationApi")
         }
     }

core/api/kotlinx-serialization-core.api

@@ -199,6 +199,7 @@ public final class kotlinx/serialization/builtins/BuiltinSerializersKt {
 	public static final fun serializer (Lkotlin/jvm/internal/ShortCompanionObject;)Lkotlinx/serialization/KSerializer;
 	public static final fun serializer (Lkotlin/jvm/internal/StringCompanionObject;)Lkotlinx/serialization/KSerializer;
 	public static final fun serializer (Lkotlin/time/Duration$Companion;)Lkotlinx/serialization/KSerializer;
+	public static final fun serializer (Lkotlin/uuid/Uuid$Companion;)Lkotlinx/serialization/KSerializer;
 }
 
 public final class kotlinx/serialization/builtins/LongAsStringSerializer : kotlinx/serialization/KSerializer {
@@ -1293,6 +1294,15 @@ public final class kotlinx/serialization/internal/UnitSerializer : kotlinx/seria
 	public fun serialize (Lkotlinx/serialization/encoding/Encoder;Lkotlin/Unit;)V
 }
 
+public final class kotlinx/serialization/internal/UuidSerializer : kotlinx/serialization/KSerializer {
+	public static final field INSTANCE Lkotlinx/serialization/internal/UuidSerializer;
+	public synthetic fun deserialize (Lkotlinx/serialization/encoding/Decoder;)Ljava/lang/Object;
+	public fun deserialize (Lkotlinx/serialization/encoding/Decoder;)Lkotlin/uuid/Uuid;
+	public fun getDescriptor ()Lkotlinx/serialization/descriptors/SerialDescriptor;
+	public synthetic fun serialize (Lkotlinx/serialization/encoding/Encoder;Ljava/lang/Object;)V
+	public fun serialize (Lkotlinx/serialization/encoding/Encoder;Lkotlin/uuid/Uuid;)V
+}
+
 public final class kotlinx/serialization/modules/PolymorphicModuleBuilder {
 	public fun <init> (Lkotlin/reflect/KClass;Lkotlinx/serialization/KSerializer;)V
 	public synthetic fun <init> (Lkotlin/reflect/KClass;Lkotlinx/serialization/KSerializer;ILkotlin/jvm/internal/DefaultConstructorMarker;)V

core/api/kotlinx-serialization-core.klib.api

@@ -1046,6 +1046,14 @@ final object kotlinx.serialization.internal/UnitSerializer : kotlinx.serializati
     final fun serialize(kotlinx.serialization.encoding/Encoder, kotlin/Unit) // kotlinx.serialization.internal/UnitSerializer.serialize|serialize(kotlinx.serialization.encoding.Encoder;kotlin.Unit){}[0]
 }
 
+final object kotlinx.serialization.internal/UuidSerializer : kotlinx.serialization/KSerializer<kotlin.uuid/Uuid> { // kotlinx.serialization.internal/UuidSerializer|null[0]
+    final val descriptor // kotlinx.serialization.internal/UuidSerializer.descriptor|{}descriptor[0]
+        final fun <get-descriptor>(): kotlinx.serialization.descriptors/SerialDescriptor // kotlinx.serialization.internal/UuidSerializer.descriptor.<get-descriptor>|<get-descriptor>(){}[0]
+
+    final fun deserialize(kotlinx.serialization.encoding/Decoder): kotlin.uuid/Uuid // kotlinx.serialization.internal/UuidSerializer.deserialize|deserialize(kotlinx.serialization.encoding.Decoder){}[0]
+    final fun serialize(kotlinx.serialization.encoding/Encoder, kotlin.uuid/Uuid) // kotlinx.serialization.internal/UuidSerializer.serialize|serialize(kotlinx.serialization.encoding.Encoder;kotlin.uuid.Uuid){}[0]
+}
+
 final val kotlinx.serialization.builtins/nullable // kotlinx.serialization.builtins/nullable|@kotlinx.serialization.KSerializer<0:0>{0§<kotlin.Any>}nullable[0]
     final fun <#A1: kotlin/Any> (kotlinx.serialization/KSerializer<#A1>).<get-nullable>(): kotlinx.serialization/KSerializer<#A1?> // kotlinx.serialization.builtins/nullable.<get-nullable>|<get-nullable>@kotlinx.serialization.KSerializer<0:0>(){0§<kotlin.Any>}[0]
 final val kotlinx.serialization.descriptors/capturedKClass // kotlinx.serialization.descriptors/capturedKClass|@kotlinx.serialization.descriptors.SerialDescriptor{}capturedKClass[0]
@@ -1062,6 +1070,7 @@ final val kotlinx.serialization.modules/EmptySerializersModule // kotlinx.serial
     final fun <get-EmptySerializersModule>(): kotlinx.serialization.modules/SerializersModule // kotlinx.serialization.modules/EmptySerializersModule.<get-EmptySerializersModule>|<get-EmptySerializersModule>(){}[0]
 
 final fun (kotlin.time/Duration.Companion).kotlinx.serialization.builtins/serializer(): kotlinx.serialization/KSerializer<kotlin.time/Duration> // kotlinx.serialization.builtins/serializer|[email protected](){}[0]
+final fun (kotlin.uuid/Uuid.Companion).kotlinx.serialization.builtins/serializer(): kotlinx.serialization/KSerializer<kotlin.uuid/Uuid> // kotlinx.serialization.builtins/serializer|[email protected](){}[0]
 final fun (kotlin/Boolean.Companion).kotlinx.serialization.builtins/serializer(): kotlinx.serialization/KSerializer<kotlin/Boolean> // kotlinx.serialization.builtins/serializer|[email protected](){}[0]
 final fun (kotlin/Byte.Companion).kotlinx.serialization.builtins/serializer(): kotlinx.serialization/KSerializer<kotlin/Byte> // kotlinx.serialization.builtins/serializer|[email protected](){}[0]
 final fun (kotlin/Char.Companion).kotlinx.serialization.builtins/serializer(): kotlinx.serialization/KSerializer<kotlin/Char> // kotlinx.serialization.builtins/serializer|[email protected](){}[0]

core/commonMain/src/kotlinx/serialization/builtins/BuiltinSerializers.kt

@@ -10,6 +10,7 @@ import kotlinx.serialization.internal.*
 import kotlin.reflect.*
 import kotlinx.serialization.descriptors.*
 import kotlin.time.Duration
+import kotlin.uuid.*
 
 /**
  * Returns a nullable serializer for the given serializer of non-null type.
@@ -251,6 +252,20 @@ public fun UShort.Companion.serializer(): KSerializer<UShort> = UShortSerializer
  */
 public fun Duration.Companion.serializer(): KSerializer<Duration> = DurationSerializer
 
+/**
+ * Returns serializer for [Uuid].
+ * Serializer operates with a standard UUID string representation, also known as "hex-and-dash" format —
+ * [RFC 9562 section 4](https://www.rfc-editor.org/rfc/rfc9562.html#section-4).
+ *
+ * Serialization always produces lowercase string, deserialization is case-insensitive.
+ * More details can be found in the documentation of [Uuid.toString] and [Uuid.parse] functions.
+ *
+ * @see Uuid.toString
+ * @see Uuid.parse
+ */
+@ExperimentalUuidApi
+public fun Uuid.Companion.serializer(): KSerializer<Uuid> = UuidSerializer
+
 /**
  * Returns serializer for [Nothing].
  * Throws an exception when trying to encode or decode.

core/commonMain/src/kotlinx/serialization/internal/BuiltInSerializers.kt

@@ -10,6 +10,7 @@ import kotlinx.serialization.descriptors.SerialDescriptor
 import kotlinx.serialization.encoding.Decoder
 import kotlinx.serialization.encoding.Encoder
 import kotlin.time.Duration
+import kotlin.uuid.*
 
 
 @PublishedApi
@@ -37,3 +38,17 @@ internal object NothingSerializer : KSerializer<Nothing> {
         throw SerializationException("'kotlin.Nothing' does not have instances")
     }
 }
+
+@PublishedApi
+@ExperimentalUuidApi
+internal object UuidSerializer: KSerializer<Uuid> {
+    override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor("kotlin.uuid.Uuid", PrimitiveKind.STRING)
+
+    override fun serialize(encoder: Encoder, value: Uuid) {
+        encoder.encodeString(value.toString())
+    }
+
+    override fun deserialize(decoder: Decoder): Uuid {
+        return Uuid.parse(decoder.decodeString())
+    }
+}

core/commonMain/src/kotlinx/serialization/internal/Primitives.kt

@@ -11,11 +11,11 @@ import kotlinx.serialization.*
 import kotlinx.serialization.builtins.*
 import kotlinx.serialization.descriptors.*
 import kotlinx.serialization.encoding.*
-import kotlin.native.concurrent.*
 import kotlin.reflect.*
 import kotlin.time.Duration
+import kotlin.uuid.*
 
-@OptIn(ExperimentalUnsignedTypes::class)
+@OptIn(ExperimentalUnsignedTypes::class, ExperimentalUuidApi::class)
 private val BUILTIN_SERIALIZERS = mapOf(
     String::class to String.serializer(),
     Char::class to Char.serializer(),
@@ -44,7 +44,8 @@ private val BUILTIN_SERIALIZERS = mapOf(
     BooleanArray::class to BooleanArraySerializer(),
     Unit::class to Unit.serializer(),
     Nothing::class to NothingSerializer(),
-    Duration::class to Duration.serializer()
+    Duration::class to Duration.serializer(),
+    Uuid::class to Uuid.serializer()
 )
 
 internal class PrimitiveSerialDescriptor(

formats/json-tests/build.gradle.kts

@@ -26,6 +26,7 @@ kotlin {
     sourceSets {
         configureEach {
             languageSettings {
+                optIn("kotlin.uuid.ExperimentalUuidApi")
                 optIn("kotlinx.serialization.internal.CoreFriendModuleApi")
                 optIn("kotlinx.serialization.json.internal.JsonFriendModuleApi")
             }

formats/json-tests/commonTest/src/kotlinx/serialization/SerializersLookupTest.kt

@@ -15,6 +15,7 @@ import kotlinx.serialization.test.*
 import kotlin.reflect.*
 import kotlin.test.*
 import kotlin.time.Duration
+import kotlin.uuid.*
 
 @Suppress("RemoveExplicitTypeArguments") // This is exactly what's being tested
 class SerializersLookupTest : JsonTestBase() {
@@ -141,6 +142,14 @@ class SerializersLookupTest : JsonTestBase() {
         assertSame(Duration.serializer(), serializer<Duration>())
     }
 
+    @Test
+    @OptIn(ExperimentalUuidApi::class)
+    fun testLookupUuid() {
+        assertSame<KSerializer<*>?>(Uuid.serializer(), serializerOrNull(typeOf<Uuid>()))
+        // TODO: uncomment in 2.1 release
+//        assertSame<KSerializer<*>?>(Uuid.serializer(), serializer<Uuid>())
+    }
+
     @Test
     fun testCustomGeneric() {
         val intBox = Box(42)

formats/json-tests/commonTest/src/kotlinx/serialization/features/UuidTest.kt

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2017-2024 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package kotlinx.serialization.features
+
+import kotlinx.serialization.*
+import kotlinx.serialization.builtins.*
+import kotlinx.serialization.json.*
+import kotlinx.serialization.modules.*
+import kotlin.test.*
+import kotlin.uuid.*
+
+class UuidTest : JsonTestBase() {
+    @Test
+    fun testPlainUuid() {
+        val uuid = Uuid.random()
+        assertJsonFormAndRestored(Uuid.serializer(), uuid, "\"$uuid\"")
+    }
+
+    // TODO: write a test without @Contextual after 2.1.0 release
+    @Serializable
+    data class Holder(@Contextual val uuid: Uuid)
+
+    val json = Json { serializersModule = serializersModuleOf(Uuid.serializer()) }
+
+    @Test
+    fun testNested() {
+        val fixed = Uuid.parse("bc501c76-d806-4578-b45e-97a264e280f1")
+        assertJsonFormAndRestored(
+            Holder.serializer(),
+            Holder(fixed),
+            """{"uuid":"bc501c76-d806-4578-b45e-97a264e280f1"}""",
+            json
+        )
+    }
+}