Add KeyDeserializer for value class

Author: k163377

src/main/kotlin/io/github/projectmapk/jackson/module/kogera/KotlinModule.kt

@@ -79,7 +79,7 @@ public class KotlinModule private constructor(
         _deserializers = KotlinDeserializers(cache, useJavaDurationConversion)
 
         _keySerializers = KotlinKeySerializers(cache)
-        _keyDeserializers = KotlinKeyDeserializers
+        _keyDeserializers = KotlinKeyDeserializers(cache)
 
         _abstractTypes = ClosedRangeResolver
 

src/main/kotlin/io/github/projectmapk/jackson/module/kogera/deser/deserializers/KotlinKeyDeserializers.kt

@@ -4,9 +4,18 @@ import com.fasterxml.jackson.databind.BeanDescription
 import com.fasterxml.jackson.databind.DeserializationConfig
 import com.fasterxml.jackson.databind.DeserializationContext
 import com.fasterxml.jackson.databind.JavaType
+import com.fasterxml.jackson.databind.JsonMappingException
 import com.fasterxml.jackson.databind.KeyDeserializer
 import com.fasterxml.jackson.databind.deser.std.StdKeyDeserializer
+import com.fasterxml.jackson.databind.exc.InvalidDefinitionException
 import com.fasterxml.jackson.databind.module.SimpleKeyDeserializers
+import io.github.projectmapk.jackson.module.kogera.ReflectionCache
+import io.github.projectmapk.jackson.module.kogera.ValueClassBoxConverter
+import io.github.projectmapk.jackson.module.kogera.isUnboxableValueClass
+import io.github.projectmapk.jackson.module.kogera.toSignature
+import kotlinx.metadata.isSecondary
+import kotlinx.metadata.jvm.signature
+import java.lang.reflect.Method
 import java.math.BigInteger
 
 // The reason why key is treated as nullable is to match the tentative behavior of StdKeyDeserializer.
@@ -40,18 +49,74 @@ internal object ULongKeyDeserializer : StdKeyDeserializer(-1, ULong::class.java)
         key?.let { ULongChecker.readWithRangeCheck(null, BigInteger(it)) }
 }
 
-internal object KotlinKeyDeserializers : SimpleKeyDeserializers() {
-    private fun readResolve(): Any = KotlinKeyDeserializers
+// The implementation is designed to be compatible with various creators, just in case.
+internal class ValueClassKeyDeserializer<S, D : Any>(
+    private val creator: Method,
+    private val converter: ValueClassBoxConverter<S, D>
+) : KeyDeserializer() {
+    private val unboxedClass: Class<*> = creator.parameterTypes[0]
 
+    init {
+        creator.apply { if (!this.isAccessible) this.isAccessible = true }
+    }
+
+    // Based on databind error
+    // https://github.com/FasterXML/jackson-databind/blob/341f8d360a5f10b5e609d6ee0ea023bf597ce98a/src/main/java/com/fasterxml/jackson/databind/deser/DeserializerCache.java#L624
+    private fun errorMessage(boxedType: JavaType): String =
+        "Could not find (Map) Key deserializer for types wrapped in $boxedType"
+
+    override fun deserializeKey(key: String?, ctxt: DeserializationContext): Any {
+        val unboxedJavaType = ctxt.constructType(unboxedClass)
+
+        return try {
+            // findKeyDeserializer does not return null, and an exception will be thrown if not found.
+            val value = ctxt.findKeyDeserializer(unboxedJavaType, null).deserializeKey(key, ctxt)
+            @Suppress("UNCHECKED_CAST")
+            converter.convert(creator.invoke(null, value) as S)
+        } catch (e: InvalidDefinitionException) {
+            throw JsonMappingException.from(ctxt, errorMessage(ctxt.constructType(converter.boxedClass)), e)
+        }
+    }
+
+    companion object {
+        fun createOrNull(
+            valueClass: Class<*>,
+            cache: ReflectionCache
+        ): ValueClassKeyDeserializer<*, *>? {
+            val jmClass = cache.getJmClass(valueClass) ?: return null
+            val primaryKmConstructorSignature =
+                jmClass.constructors.first { !it.isSecondary }.signature
+
+            // Only primary constructor is allowed as creator, regardless of visibility.
+            // This is because it is based on the WrapsNullableValueClassBoxDeserializer.
+            // Also, as far as I could research, there was no such functionality as JsonKeyCreator,
+            // so it was not taken into account.
+            return valueClass.declaredMethods.find { it.toSignature() == primaryKmConstructorSignature }?.let {
+                val unboxedClass = it.returnType
+
+                val converter = cache.getValueClassBoxConverter(unboxedClass, valueClass)
+
+                ValueClassKeyDeserializer(it, converter)
+            }
+        }
+    }
+}
+
+internal class KotlinKeyDeserializers(private val cache: ReflectionCache) : SimpleKeyDeserializers() {
     override fun findKeyDeserializer(
         type: JavaType,
         config: DeserializationConfig?,
         beanDesc: BeanDescription?
-    ): KeyDeserializer? = when (type.rawClass) {
-        UByte::class.java -> UByteKeyDeserializer
-        UShort::class.java -> UShortKeyDeserializer
-        UInt::class.java -> UIntKeyDeserializer
-        ULong::class.java -> ULongKeyDeserializer
-        else -> null
+    ): KeyDeserializer? {
+        val rawClass = type.rawClass
+
+        return when {
+            rawClass == UByte::class.java -> UByteKeyDeserializer
+            rawClass == UShort::class.java -> UShortKeyDeserializer
+            rawClass == UInt::class.java -> UIntKeyDeserializer
+            rawClass == ULong::class.java -> ULongKeyDeserializer
+            rawClass.isUnboxableValueClass() -> ValueClassKeyDeserializer.createOrNull(rawClass, cache)
+            else -> null
+        }
     }
 }