add experimentalDeserializationBackend switch

Author: k163377

src/main/kotlin/com/fasterxml/jackson/module/kotlin/KotlinFeature.kt

@@ -8,7 +8,8 @@ enum class KotlinFeature(val enabledByDefault: Boolean) {
     NullToEmptyMap(enabledByDefault = false),
     NullIsSameAsDefault(enabledByDefault = false),
     SingletonSupport(enabledByDefault = false),
-    StrictNullChecks(enabledByDefault = false);
+    StrictNullChecks(enabledByDefault = false),
+    ExperimentalDeserializationBackend(enabledByDefault = false);
 
     internal val bitSet: BitSet = 2.0.pow(ordinal).toInt().toBitSet()
 }

src/main/kotlin/com/fasterxml/jackson/module/kotlin/KotlinModule.kt

@@ -31,14 +31,18 @@ fun Class<*>.isKotlinClass(): Boolean {
  *                                      the default, collections which are typed to disallow null members
  *                                      (e.g. List<String>) may contain null values after deserialization.  Enabling it
  *                                      protects against this but has significant performance impact.
+ * @param   experimentalDeserializationBackend
+ *                                  Default: false.  Whether to enable experimental deserialization backend.  Enabling
+ *                                      it significantly improve performance in certain use cases.
  */
 class KotlinModule @Deprecated(level = DeprecationLevel.WARNING, message = "Use KotlinModule.Builder") constructor(
     val reflectionCacheSize: Int = 512,
     val nullToEmptyCollection: Boolean = false,
     val nullToEmptyMap: Boolean = false,
     val nullIsSameAsDefault: Boolean = false,
     val singletonSupport: SingletonSupport = DISABLED,
-    val strictNullChecks: Boolean = false
+    val strictNullChecks: Boolean = false,
+    val experimentalDeserializationBackend: Boolean = false
 ) : SimpleModule(PackageVersion.VERSION) {
     @Deprecated(level = DeprecationLevel.HIDDEN, message = "For ABI compatibility")
     constructor(
@@ -77,7 +81,8 @@ class KotlinModule @Deprecated(level = DeprecationLevel.WARNING, message = "Use
             builder.isEnabled(KotlinFeature.SingletonSupport) -> CANONICALIZE
             else -> DISABLED
         },
-        builder.isEnabled(StrictNullChecks)
+        builder.isEnabled(StrictNullChecks),
+        builder.isEnabled(KotlinFeature.ExperimentalDeserializationBackend)
     )
 
     companion object {
@@ -95,7 +100,14 @@ class KotlinModule @Deprecated(level = DeprecationLevel.WARNING, message = "Use
 
         val cache = ReflectionCache(reflectionCacheSize)
 
-        context.addValueInstantiators(KotlinInstantiators(cache, nullToEmptyCollection, nullToEmptyMap, nullIsSameAsDefault, strictNullChecks))
+        context.addValueInstantiators(KotlinInstantiators(
+            cache,
+            nullToEmptyCollection,
+            nullToEmptyMap,
+            nullIsSameAsDefault,
+            strictNullChecks,
+            experimentalDeserializationBackend
+        ))
 
         when (singletonSupport) {
             DISABLED -> Unit

src/main/kotlin/com/fasterxml/jackson/module/kotlin/KotlinValueInstantiator.kt

@@ -29,7 +29,8 @@ internal class KotlinValueInstantiator(
     private val nullToEmptyCollection: Boolean,
     private val nullToEmptyMap: Boolean,
     private val nullIsSameAsDefault: Boolean,
-    private val strictNullChecks: Boolean
+    private val strictNullChecks: Boolean,
+    private val experimentalDeserializationBackend: Boolean
 ) : StdValueInstantiator(src) {
     @Suppress("UNCHECKED_CAST")
     override fun createFromObjectWith(
@@ -188,7 +189,8 @@ internal class KotlinInstantiators(
     private val nullToEmptyCollection: Boolean,
     private val nullToEmptyMap: Boolean,
     private val nullIsSameAsDefault: Boolean,
-    private val strictNullChecks: Boolean
+    private val strictNullChecks: Boolean,
+    private val experimentalDeserializationBackend: Boolean
 ) : ValueInstantiators {
     override fun findValueInstantiator(
         deserConfig: DeserializationConfig,
@@ -197,7 +199,15 @@ internal class KotlinInstantiators(
     ): ValueInstantiator {
         return if (beanDescriptor.beanClass.isKotlinClass()) {
             if (defaultInstantiator is StdValueInstantiator) {
-                KotlinValueInstantiator(defaultInstantiator, cache, nullToEmptyCollection, nullToEmptyMap, nullIsSameAsDefault, strictNullChecks)
+                KotlinValueInstantiator(
+                    defaultInstantiator,
+                    cache,
+                    nullToEmptyCollection,
+                    nullToEmptyMap,
+                    nullIsSameAsDefault,
+                    strictNullChecks,
+                    experimentalDeserializationBackend
+                )
             } else {
                 // TODO: return defaultInstantiator and let default method parameters and nullability go unused?  or die with exception:
                 throw IllegalStateException("KotlinValueInstantiator requires that the default ValueInstantiator is StdValueInstantiator")