Improve Kotlin collections support when producing framework

* Represent MutableList, Set, Map as standard Objective-C collections
* Represent MutableSet and MutableMap as Obj-C collection subclasses
* Use Objective-C generics to represent collection element type
* Make type mapping more correct

Interop/Runtime/src/native/kotlin/kotlinx/cinterop/ObjectiveCExportImpl.kt

@@ -1,41 +0,0 @@
-/*
- * Copyright 2010-2017 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package kotlinx.cinterop
-
-import konan.internal.ExportForCppRuntime
-
-// TODO: it it actually not related to cinterop.
-
-@ExportTypeInfo("theNSArrayListTypeInfo")
-internal class NSArrayList : AbstractList<Any?> {
-
-    // FIXME: override methods of Any.
-
-    @konan.internal.ExportForCppRuntime("Kotlin_NSArrayList_constructor")
-    constructor() : super()
-
-    override val size: Int get() = getSize()
-
-    @SymbolName("Kotlin_NSArrayList_getSize")
-    private external fun getSize(): Int
-
-    @SymbolName("Kotlin_NSArrayList_getElement")
-    external override fun get(index: Int): Any?
-}
-
-@ExportForCppRuntime private fun Kotlin_List_get(list: List<*>, index: Int): Any? = list.get(index)
-@ExportForCppRuntime private fun Kotlin_List_getSize(list: List<*>): Int = list.size

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/ContextUtils.kt

@@ -398,6 +398,11 @@ internal class Llvm(val context: Context, val llvmModule: LLVMModuleRef) {
     val Kotlin_ObjCExport_refFromObjC by lazyRtFunction
     val Kotlin_Interop_CreateNSStringFromKString by lazyRtFunction
     val Kotlin_Interop_CreateNSArrayFromKList by lazyRtFunction
+    val Kotlin_Interop_CreateNSMutableArrayFromKList by lazyRtFunction
+    val Kotlin_Interop_CreateNSSetFromKSet by lazyRtFunction
+    val Kotlin_Interop_CreateKotlinMutableSetFromKSet by lazyRtFunction
+    val Kotlin_Interop_CreateNSDictionaryFromKMap by lazyRtFunction
+    val Kotlin_Interop_CreateKotlinMutableDictonaryFromKMap by lazyRtFunction
     val Kotlin_ObjCExport_convertUnit by lazyRtFunction
     val Kotlin_ObjCExport_GetAssociatedObject by lazyRtFunction
     val Kotlin_ObjCExport_AbstractMethodCalled by lazyRtFunction

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/objc/ObjCDataGenerator.kt

@@ -70,6 +70,11 @@ internal class ObjCDataGenerator(val codegen: CodeGenerator) {
 
     val classObjectType = codegen.runtime.getStructType("_class_t")
 
+    fun exportClass(name: String) {
+        context.llvm.usedGlobals += getClassGlobal(name, isMetaclass = false).llvm
+        context.llvm.usedGlobals += getClassGlobal(name, isMetaclass = true).llvm
+    }
+
     private fun getClassGlobal(name: String, isMetaclass: Boolean): ConstPointer {
         val prefix = if (isMetaclass) {
             "OBJC_METACLASS_\$_"

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/objcexport/ObjCExportCodeGenerator.kt

@@ -178,6 +178,9 @@ internal class ObjCExportCodeGenerator(
             dataGenerator.emitEmptyClass(namer.getPackageName(fqName), namer.kotlinAnyName)
         }
 
+        dataGenerator.exportClass("KotlinMutableSet")
+        dataGenerator.exportClass("KotlinMutableDictionary")
+
         emitSpecialClassesConvertions()
 
         objCTypeAdapters += createTypeAdapter(context.builtIns.any)
@@ -375,7 +378,7 @@ private fun ObjCExportCodeGenerator.emitBoxConverter(objCValueType: ObjCValueTyp
 private fun ObjCExportCodeGenerator.emitFunctionConverters() {
     val generator = BlockAdapterToFunctionGenerator(this)
 
-    (0 .. 22).forEach { numberOfParameters ->
+    (0 .. mapper.maxFunctionTypeParameterCount).forEach { numberOfParameters ->
         val converter = generator.run { generateConvertFunctionToBlock(numberOfParameters) }
         setObjCExportTypeInfo(context.builtIns.getFunction(numberOfParameters), constPointer(converter))
     }
@@ -399,7 +402,7 @@ private fun ObjCExportCodeGenerator.emitKotlinFunctionAdaptersToBlock() {
     val ptr = staticData.placeGlobalArray(
             "",
             pointerType(runtime.typeInfoType),
-            (0 .. 22).map {
+            (0 .. mapper.maxFunctionTypeParameterCount).map {
                 generateKotlinFunctionAdapterToBlock(it)
             }
     ).pointer.getElementPtr(0)
@@ -419,6 +422,31 @@ private fun ObjCExportCodeGenerator.emitSpecialClassesConvertions() {
             constPointer(context.llvm.Kotlin_Interop_CreateNSArrayFromKList)
     )
 
+    setObjCExportTypeInfo(
+            context.builtIns.mutableList,
+            constPointer(context.llvm.Kotlin_Interop_CreateNSMutableArrayFromKList)
+    )
+
+    setObjCExportTypeInfo(
+            context.builtIns.set,
+            constPointer(context.llvm.Kotlin_Interop_CreateNSSetFromKSet)
+    )
+
+    setObjCExportTypeInfo(
+            context.builtIns.mutableSet,
+            constPointer(context.llvm.Kotlin_Interop_CreateKotlinMutableSetFromKSet)
+    )
+
+    setObjCExportTypeInfo(
+            context.builtIns.map,
+            constPointer(context.llvm.Kotlin_Interop_CreateNSDictionaryFromKMap)
+    )
+
+    setObjCExportTypeInfo(
+            context.builtIns.mutableMap,
+            constPointer(context.llvm.Kotlin_Interop_CreateKotlinMutableDictonaryFromKMap)
+    )
+
     ObjCValueType.values().forEach {
         emitBoxConverter(it)
     }

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/objcexport/ObjCExportHeaderGenerator.kt

@@ -23,10 +23,10 @@ import org.jetbrains.kotlin.backend.konan.descriptors.getPackageFragments
 import org.jetbrains.kotlin.backend.konan.descriptors.isArray
 import org.jetbrains.kotlin.backend.konan.descriptors.isInterface
 import org.jetbrains.kotlin.backend.konan.reportCompilationError
+import org.jetbrains.kotlin.backend.konan.reportCompilationWarning
 import org.jetbrains.kotlin.builtins.getReceiverTypeFromFunctionType
 import org.jetbrains.kotlin.builtins.getReturnTypeFromFunctionType
 import org.jetbrains.kotlin.builtins.getValueParameterTypesFromFunctionType
-import org.jetbrains.kotlin.builtins.isFunctionType
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.resolve.descriptorUtil.*
@@ -38,13 +38,10 @@ import org.jetbrains.kotlin.utils.addIfNotNull
 
 internal class ObjCExportHeaderGenerator(val context: Context) {
     val mapper: ObjCExportMapper = object : ObjCExportMapper {
-        override fun isRepresentedAsObjCInterface(descriptor: ClassDescriptor): Boolean {
-            val objCType = mapReferenceType(descriptor.defaultType)
-            return objCType is ObjCClassType && objCType.className == translateClassName(descriptor)
-        }
-
         override fun getCategoryMembersFor(descriptor: ClassDescriptor) =
                 extensions[descriptor].orEmpty()
+
+        override val specialMappedTypes get() = customTypeMappers.keys
     }
 
     val namer = ObjCExportNamer(context, mapper)
@@ -52,6 +49,43 @@ internal class ObjCExportHeaderGenerator(val context: Context) {
     val generatedClasses = mutableSetOf<ClassDescriptor>()
     val topLevel = mutableMapOf<FqName, MutableList<CallableMemberDescriptor>>()
 
+    val customTypeMappers: Map<ClassDescriptor, CustomTypeMapper> = with (context.builtIns) {
+        val result = mutableListOf<CustomTypeMapper>()
+
+        val generator = this@ObjCExportHeaderGenerator
+
+        result += CustomTypeMapper.Collection(generator, list, "NSArray")
+        result += CustomTypeMapper.Collection(generator, mutableList, "NSMutableArray")
+        result += CustomTypeMapper.Collection(generator, set, "NSSet")
+        result += CustomTypeMapper.Collection(generator, mutableSet, namer.mutableSetName)
+        result += CustomTypeMapper.Collection(generator, map, "NSDictionary")
+        result += CustomTypeMapper.Collection(generator, mutableMap, namer.mutableMapName)
+
+        for (descriptor in listOf(boolean, char, byte, short, int, long, float, double)) {
+            // TODO: Kotlin code doesn't have any checkcasts on unboxing,
+            // so it is possible that it expects boxed number of other type and unboxes it incorrectly.
+            // TODO: NSNumber seem to have different equality semantics.
+            result += CustomTypeMapper.Simple(descriptor, "NSNumber")
+        }
+
+        result += CustomTypeMapper.Simple(string, "NSString")
+
+        (0 .. mapper.maxFunctionTypeParameterCount).forEach {
+            result += CustomTypeMapper.Function(generator, it)
+        }
+
+        result.associateBy { it.mappedClassDescriptor }
+    }
+
+    val hiddenTypes: Set<ClassDescriptor> = run {
+        val customMappedTypes = customTypeMappers.keys
+
+        customMappedTypes
+                .flatMap { it.getAllSuperClassifiers().toList() }
+                .map { it as ClassDescriptor }
+                .toSet() - customMappedTypes
+    }
+
     private val kotlinAnyName = namer.kotlinAnyName
 
     private val stubs = mutableListOf<Stub>()
@@ -175,7 +209,7 @@ internal class ObjCExportHeaderGenerator(val context: Context) {
         val name = namer.getPackageName(packageFqName)
         stubs.addBuiltBy {
             +"__attribute__((objc_subclassing_restricted))"
-            +"@interface $name : KotlinBase" // TODO: stop inheriting KotlinBase.
+            +"@interface $name : ${namer.kotlinAnyName}" // TODO: stop inheriting KotlinBase.
 
             translateMembers(declarations)
 
@@ -443,6 +477,21 @@ internal class ObjCExportHeaderGenerator(val context: Context) {
         add("@end;")
         add("")
 
+        // TODO: add comment to the header.
+        add("@interface $kotlinAnyName (${kotlinAnyName}Copying) <NSCopying>")
+        add("@end;")
+        add("")
+
+        add("__attribute__((objc_runtime_name(\"KotlinMutableSet\")))")
+        add("@interface ${namer.mutableSetName}<ObjectType> : NSMutableSet<ObjectType>") // TODO: only if appears
+        add("@end;")
+        add("")
+
+        add("__attribute__((objc_runtime_name(\"KotlinMutableDictionary\")))")
+        add("@interface ${namer.mutableMapName}<KeyType, ObjectType> : NSMutableDictionary<KeyType, ObjectType>") // TODO: only if appears
+        add("@end;")
+        add("")
+
         stubs.forEach {
             addAll(it.lines)
             add("")
@@ -452,19 +501,34 @@ internal class ObjCExportHeaderGenerator(val context: Context) {
     }
 }
 
-private sealed class ObjCType {
+internal sealed class ObjCType {
     final override fun toString(): String = this.render()
 
     open fun render(varName: String): String = "${this.render()} $varName"
     abstract fun render(): String
 }
 
-private sealed class ObjCReferenceType(kotlinType: KotlinType) : ObjCType() {
+internal sealed class ObjCReferenceType(kotlinType: KotlinType) : ObjCType() {
     val attributes = if (TypeUtils.isNullableType(kotlinType)) " _Nullable" else ""
 }
 
-private class ObjCClassType(kotlinType: KotlinType, val className: String) : ObjCReferenceType(kotlinType) {
-    override fun render() = "$className*$attributes"
+private class ObjCClassType(
+        kotlinType: KotlinType,
+        val className: String,
+        val typeArguments: List<ObjCReferenceType> = emptyList()
+) : ObjCReferenceType(kotlinType) {
+
+    override fun render() = buildString {
+        append(className)
+        if (typeArguments.isNotEmpty()) {
+            append("<")
+            typeArguments.joinTo(this) { it.render() }
+            append(">")
+        }
+        append('*')
+
+        append(attributes)
+    }
 }
 
 private class ObjCProtocolType(kotlinType: KotlinType, val protocolName: String) : ObjCReferenceType(kotlinType) {
@@ -502,43 +566,101 @@ private object ObjCVoidType : ObjCType() {
     override fun render(varName: String) = error("variables can't have `void` type")
 }
 
+internal interface CustomTypeMapper {
+    val mappedClassDescriptor: ClassDescriptor
+    fun mapType(type: KotlinType, mappedSuperType: KotlinType): ObjCReferenceType
+
+    class Simple(
+            override val mappedClassDescriptor: ClassDescriptor,
+            private val objCClassName: String
+    ) : CustomTypeMapper {
+
+        override fun mapType(type: KotlinType, mappedSuperType: KotlinType): ObjCReferenceType =
+                ObjCClassType(type, objCClassName)
+    }
+
+    class Collection(
+            private val generator: ObjCExportHeaderGenerator,
+            override val mappedClassDescriptor: ClassDescriptor,
+            private val objCClassName: String
+    ) : CustomTypeMapper {
+        override fun mapType(type: KotlinType, mappedSuperType: KotlinType): ObjCReferenceType {
+            val typeArguments = mappedSuperType.arguments.map {
+                val argument = it.type
+                if (TypeUtils.isNullableType(argument)) {
+                    // Kotlin `null` keys and values are represented as `NSNull` singleton.
+                    ObjCIdType(generator.context.builtIns.anyType)
+                } else {
+                    generator.mapReferenceType(argument)
+                }
+            }
+
+            return ObjCClassType(type, objCClassName, typeArguments)
+        }
+    }
+
+    class Function(
+            private val generator: ObjCExportHeaderGenerator,
+            parameterCount: Int
+    ) : CustomTypeMapper {
+        override val mappedClassDescriptor = generator.context.builtIns.getFunction(parameterCount)
+
+        override fun mapType(type: KotlinType, mappedSuperType: KotlinType): ObjCReferenceType {
+            val functionType = mappedSuperType
+
+            val returnType = functionType.getReturnTypeFromFunctionType()
+            val parameterTypes = listOfNotNull(functionType.getReceiverTypeFromFunctionType()) +
+                    functionType.getValueParameterTypesFromFunctionType().map { it.type }
+
+            return ObjCBlockPointerType(
+                    type,
+                    generator.mapReferenceType(returnType),
+                    parameterTypes.map { generator.mapReferenceType(it) }
+            )
+        }
+    }
+}
+
 private fun ObjCExportHeaderGenerator.mapReferenceType(kotlinType: KotlinType): ObjCReferenceType {
-    // TODO: translate `where T : BaseClass, T : SomeInterface` to `BaseClass* <SomeInterface>`
+
+    val typeToMapper = (listOf(kotlinType) + kotlinType.supertypes()).mapNotNull { type ->
+        val mapper = customTypeMappers[type.constructor.declarationDescriptor]
+        if (mapper != null) {
+            type to mapper
+        } else {
+            null
+        }
+    }.toMap()
+
+    val mostSpecificTypeToMapper = typeToMapper.filter { (_, mapper) ->
+        typeToMapper.values.all { it.mappedClassDescriptor == mapper.mappedClassDescriptor ||
+                !it.mappedClassDescriptor.isSubclassOf(mapper.mappedClassDescriptor) }
+
+        // E.g. if both List and MutableList are present, then retain only MutableList.
+    }
+
+    if (mostSpecificTypeToMapper.size > 1) {
+        val types = mostSpecificTypeToMapper.keys.toList()
+        val firstType = types[0]
+        val secondType = types[1]
+
+        context.reportCompilationWarning(
+                "Exposed type '$kotlinType' is '$firstType' and '$secondType' at the same time. " +
+                        "This most likely wouldn't work as expected.")
+
+        // TODO: the same warning for such classes.
+    }
+
+    mostSpecificTypeToMapper.entries.firstOrNull()?.let { (type, mapper) ->
+        return mapper.mapType(kotlinType, type)
+    }
+
     val classDescriptor = kotlinType.getErasedTypeClass()
 
-    if (classDescriptor.isSubclassOf(context.builtIns.list)) {
-        return ObjCClassType(kotlinType, "NSArray")
-    }
+    // TODO: translate `where T : BaseClass, T : SomeInterface` to `BaseClass* <SomeInterface>`
 
-
-    // TODO: Kotlin code doesn't have any checkcasts on unboxing,
-    // so it is possible that it expects boxed number of other type and unboxes it incorrectly.
-
-    if (classDescriptor.isSubclassOf(context.builtIns.number) ||
-            classDescriptor == context.builtIns.boolean ||
-            classDescriptor == context.builtIns.char) return ObjCClassType(kotlinType, "NSNumber")
-
-    when (classDescriptor) {
-        context.builtIns.any -> return ObjCIdType(kotlinType)
-        context.builtIns.string -> return ObjCClassType(kotlinType, "NSString")
-    }
-
-    val functionType = if (kotlinType.isFunctionType) {
-        kotlinType
-    } else {
-        kotlinType.supertypes().firstOrNull { it.isFunctionType }
-        // TODO: may be incorrect if type has more then one function supertype.
-    }
-    if (functionType != null) {
-        val returnType = functionType.getReturnTypeFromFunctionType()
-        val parameterTypes = listOfNotNull(functionType.getReceiverTypeFromFunctionType()) +
-                functionType.getValueParameterTypesFromFunctionType().map { it.type }
-
-        return ObjCBlockPointerType(
-                kotlinType,
-                mapReferenceType(returnType),
-                parameterTypes.map { mapReferenceType(it) }
-        )
+    if (classDescriptor == context.builtIns.any || classDescriptor in hiddenTypes) {
+        return ObjCIdType(kotlinType)
     }
 
     if (classDescriptor !in generatedClasses) {

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/objcexport/ObjCExportMapper.kt

@@ -21,19 +21,28 @@ import org.jetbrains.kotlin.backend.common.descriptors.isSuspend
 import org.jetbrains.kotlin.backend.konan.ValueType
 import org.jetbrains.kotlin.backend.konan.correspondingValueType
 import org.jetbrains.kotlin.backend.konan.descriptors.isArray
+import org.jetbrains.kotlin.backend.konan.descriptors.isInterface
 import org.jetbrains.kotlin.backend.konan.isObjCObjectType
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.resolve.descriptorUtil.builtIns
+import org.jetbrains.kotlin.resolve.descriptorUtil.getAllSuperClassifiers
 import org.jetbrains.kotlin.resolve.descriptorUtil.isEffectivelyPublicApi
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.TypeUtils
 import org.jetbrains.kotlin.types.typeUtil.isUnit
 
 internal interface ObjCExportMapper {
-    fun isRepresentedAsObjCInterface(descriptor: ClassDescriptor): Boolean
     fun getCategoryMembersFor(descriptor: ClassDescriptor): List<CallableMemberDescriptor>
+    val maxFunctionTypeParameterCount get() = 22
+    val specialMappedTypes: Set<ClassDescriptor>
 }
 
+private fun ObjCExportMapper.isRepresentedAsObjCInterface(descriptor: ClassDescriptor): Boolean =
+        !descriptor.isInterface && !isSpecialMapped(descriptor)
+
+private fun ObjCExportMapper.isSpecialMapped(descriptor: ClassDescriptor): Boolean =
+        descriptor.getAllSuperClassifiers().any { it in specialMappedTypes }
+
 internal fun ObjCExportMapper.getClassIfCategory(descriptor: CallableMemberDescriptor): ClassDescriptor? {
     if (descriptor.dispatchReceiverParameter != null) return null
 
@@ -55,7 +64,7 @@ internal fun ObjCExportMapper.shouldBeExposed(descriptor: ClassDescriptor): Bool
         descriptor.isEffectivelyPublicApi && !descriptor.defaultType.isObjCObjectType() && when (descriptor.kind) {
             ClassKind.CLASS, ClassKind.INTERFACE, ClassKind.ENUM_CLASS, ClassKind.OBJECT -> true
             ClassKind.ENUM_ENTRY, ClassKind.ANNOTATION_CLASS -> false
-        }
+        } && !isSpecialMapped(descriptor)
 
 private fun ObjCExportMapper.isBase(descriptor: CallableMemberDescriptor): Boolean =
         descriptor.overriddenDescriptors.all { !shouldBeExposed(it) }

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/objcexport/ObjCExportNamer.kt

@@ -34,6 +34,9 @@ internal class ObjCExportNamer(val context: Context, val mapper: ObjCExportMappe
     private val commonPackageSegments = context.moduleDescriptor.guessMainPackage().pathSegments()
     private val topLevelNamePrefix = context.moduleDescriptor.namePrefix
 
+    val mutableSetName = "${topLevelNamePrefix}MutableSet"
+    val mutableMapName = "${topLevelNamePrefix}MutableDictionary"
+
     private val methodSelectors = object : Mapping<FunctionDescriptor, String>() {
 
         // Try to avoid clashing with critical NSObject instance methods:
@@ -231,6 +234,8 @@ internal class ObjCExportNamer(val context: Context, val mapper: ObjCExportMappe
         val any = context.builtIns.any
 
         classNames.forceAssign(any, kotlinAnyName)
+        classNames.forceAssign(context.builtIns.mutableSet, mutableSetName)
+        classNames.forceAssign(context.builtIns.mutableMap, mutableMapName)
 
         fun ClassDescriptor.method(name: String) =
                 this.unsubstitutedMemberScope.getContributedFunctions(

runtime/src/main/cpp/ObjCExport.h

@@ -0,0 +1,36 @@
+#ifndef RUNTIME_OBJCEXPORT_H
+#define RUNTIME_OBJCEXPORT_H
+
+#if KONAN_OBJC_INTEROP
+
+#import <objc/runtime.h>
+
+#import "Types.h"
+#import "Memory.h"
+
+extern "C" id objc_retain(id self);
+extern "C" void objc_release(id self);
+
+inline static bool HasAssociatedObjectField(ObjHeader* obj) {
+  return HasReservedObjectTail(obj);
+}
+
+inline static id GetAssociatedObject(ObjHeader* obj) {
+  return *reinterpret_cast<id*>(GetReservedObjectTail(obj));
+}
+
+inline static void SetAssociatedObject(ObjHeader* obj, id value) {
+  *reinterpret_cast<id*>(GetReservedObjectTail(obj)) = value;
+}
+
+extern "C" id Kotlin_ObjCExport_refToObjC(ObjHeader* obj);
+extern "C" OBJ_GETTER(Kotlin_ObjCExport_refFromObjC, id obj);
+
+@protocol ConvertibleToKotlin
+@required
+-(KRef)toKotlin:(KRef*)OBJ_RESULT;
+@end;
+
+#endif // KONAN_OBJC_INTEROP
+
+#endif // RUNTIME_OBJCEXPORT_H

runtime/src/main/cpp/ObjCExport.mm

@@ -20,14 +20,14 @@
 #if KONAN_OBJC_INTEROP
 
 #import <Foundation/NSObject.h>
-#import <Foundation/NSArray.h>
 #import <Foundation/NSValue.h>
 #import <Foundation/NSString.h>
-#import <Foundation/NSNull.h>
 #import <Foundation/NSMethodSignature.h>
 #import <Foundation/NSException.h>
 #import <objc/runtime.h>
 #import <dispatch/dispatch.h>
+
+#import "ObjCExport.h"
 #import "MemoryPrivate.hpp"
 #import "Runtime.h"
 #import "Utils.h"
@@ -92,18 +92,6 @@ static void setAssociatedTypeInfo(Class clazz, const TypeInfo* typeInfo) {
   objc_setAssociatedObject(clazz, &associatedTypeInfoKey, [NSValue valueWithPointer:typeInfo], OBJC_ASSOCIATION_RETAIN);
 }
 
-inline static bool HasAssociatedObjectField(ObjHeader* obj) {
-  return HasReservedObjectTail(obj);
-}
-
-inline static void SetAssociatedObject(ObjHeader* obj, id value) {
-  *reinterpret_cast<id*>(GetReservedObjectTail(obj)) = value;
-}
-
-static inline id GetAssociatedObject(ObjHeader* obj) {
-  return *reinterpret_cast<id*>(GetReservedObjectTail(obj));
-}
-
 extern "C" id Kotlin_ObjCExport_GetAssociatedObject(ObjHeader* obj) {
   return GetAssociatedObject(obj);
 }
@@ -118,12 +106,7 @@ inline static OBJ_GETTER(AllocInstanceWithAssociatedObject, const TypeInfo* type
 static Class getOrCreateClass(const TypeInfo* typeInfo);
 static void initializeClass(Class clazz);
 
-@protocol ConvertibleToKotlin
-@required
--(KRef)toKotlin:(KRef*)OBJ_RESULT;
-@end;
-
-@interface KotlinBase : NSObject <ConvertibleToKotlin>
+@interface KotlinBase : NSObject <ConvertibleToKotlin, NSCopying>
 @end;
 
 @implementation KotlinBase {
@@ -199,6 +182,11 @@ static void initializeClass(Class clazz);
   [super release];
 }
 
+- (instancetype)copyWithZone:(NSZone *)zone {
+  // TODO: write documentation.
+  return [self retain];
+}
+
 @end;
 
 extern "C" void Kotlin_ObjCExport_releaseReservedObjectTail(ObjHeader* obj) {
@@ -324,9 +312,7 @@ static void initializeClass(Class clazz) {
 @interface NSObject (NSObjectToKotlin) <ConvertibleToKotlin>
 @end;
 
-extern "C" id objc_retain(id self);
 extern "C" id objc_retainBlock(id self);
-extern "C" void objc_release(id self);
 extern "C" id objc_retainAutoreleaseReturnValue(id self);
 
 @implementation NSObject (NSObjectToKotlin)
@@ -351,27 +337,6 @@ extern "C" OBJ_GETTER(Kotlin_Interop_CreateKStringFromNSString, NSString* str);
 }
 @end;
 
-@interface NSArray (NSArrayToKotlin) <ConvertibleToKotlin>
-@end;
-
-extern "C" void Kotlin_NSArrayList_constructor(ObjHeader* obj);
-
-extern const TypeInfo *theNSArrayListTypeInfo;
-
-@implementation NSArray (NSArrayToKotlin)
--(ObjHeader*)toKotlin:(ObjHeader**)OBJ_RESULT {
-  ObjHeader* result = AllocInstanceWithAssociatedObject(theNSArrayListTypeInfo, objc_retain(self), OBJ_RESULT);
-
-  Kotlin_NSArrayList_constructor(result);
-
-  return result;
-}
-
--(void)releaseAsAssociatedObject {
-  objc_release(self);
-}
-@end;
-
 extern "C" {
 
 OBJ_GETTER(Kotlin_boxBoolean, KBoolean value);
@@ -425,47 +390,6 @@ static Class __NSCFBooleanClass = nullptr;
 }
 @end;
 
-@interface KListNSArray : NSArray <ConvertibleToKotlin>
-@end;
-
-extern "C" OBJ_GETTER(Kotlin_List_get, ObjHeader* list, KInt index);
-extern "C" KInt Kotlin_List_getSize(ObjHeader* list);
-
-extern "C" id Kotlin_ObjCExport_refToObjC(ObjHeader* obj);
-
-@implementation KListNSArray {
-  ObjHeader* list;
-}
-
--(void)dealloc {
-  UpdateRef(&list, nullptr);
-  [super dealloc];
-}
-
-+(id)createWithKList:(ObjHeader*)list {
-  KListNSArray* result = [[[KListNSArray alloc] init] autorelease];
-  UpdateRef(&result->list, list);
-  return result;
-}
-
--(ObjHeader*)toKotlin:(ObjHeader**)OBJ_RESULT {
-  RETURN_OBJ(list);
-}
-
--(id)objectAtIndex:(NSUInteger)index {
-  ObjHolder kotlinValueHolder;
-  ObjHeader* kotlinValue = Kotlin_List_get(list, index, kotlinValueHolder.slot());
-  if (kotlinValue == nullptr) return [NSNull null];
-
-  return Kotlin_ObjCExport_refToObjC(kotlinValue);
-}
-
--(NSUInteger)count {
-  return Kotlin_List_getSize(list);
-}
-
-@end;
-
 @interface NSBlock <NSObject>
 @end;
 
@@ -567,10 +491,6 @@ static const TypeInfo* getFunctionTypeInfoForBlock(id block) {
 
 @end;
 
-extern "C" id Kotlin_Interop_CreateNSArrayFromKList(ObjHeader* obj) {
-  return [KListNSArray createWithKList:obj];
-}
-
 static id Kotlin_ObjCExport_refToObjC_slowpath(ObjHeader* obj);
 
 extern "C" id Kotlin_ObjCExport_refToObjC(ObjHeader* obj) {
@@ -603,14 +523,35 @@ static id convertKotlinObject(ObjHeader* obj) {
   return [clazz createWrapper:obj];
 }
 
+extern "C" id Kotlin_Interop_CreateNSStringFromKString(KRef str);
+
+static convertReferenceToObjC findConverterFromInterfaces(const TypeInfo* typeInfo) {
+  const TypeInfo* foundTypeInfo = nullptr;
+
+  for (int i = 0; i < typeInfo->implementedInterfacesCount_; ++i) {
+    const TypeInfo* interfaceTypeInfo = typeInfo->implementedInterfaces_[i];
+    if (interfaceTypeInfo->writableInfo_->objCExport.convert != nullptr) {
+      if (foundTypeInfo == nullptr || IsSubInterface(interfaceTypeInfo, foundTypeInfo)) {
+        foundTypeInfo = interfaceTypeInfo;
+      } else if (!IsSubInterface(foundTypeInfo, interfaceTypeInfo)) {
+        [NSException raise:NSGenericException
+            format:@"Can't convert to Objective-C Kotlin object that is '%@' and '%@' and the same time",
+            Kotlin_Interop_CreateNSStringFromKString(foundTypeInfo->relativeName_),
+            Kotlin_Interop_CreateNSStringFromKString(interfaceTypeInfo->relativeName_)];
+      }
+    }
+  }
+
+  return foundTypeInfo == nullptr ?
+    nullptr :
+    (convertReferenceToObjC)foundTypeInfo->writableInfo_->objCExport.convert;
+}
+
 static id Kotlin_ObjCExport_refToObjC_slowpath(ObjHeader* obj) {
   const TypeInfo* typeInfo = obj->type_info();
   convertReferenceToObjC converter = nullptr;
 
-  for (int i = 0; i < typeInfo->implementedInterfacesCount_; ++i) {
-    converter = (convertReferenceToObjC)typeInfo->implementedInterfaces_[i]->writableInfo_->objCExport.convert;
-    if (converter != nullptr) break;
-  }
+  converter = findConverterFromInterfaces(typeInfo);
 
   if (converter == nullptr) {
     getOrCreateClass(typeInfo);
@@ -622,18 +563,6 @@ static id Kotlin_ObjCExport_refToObjC_slowpath(ObjHeader* obj) {
   return converter(obj);
 }
 
-extern "C" KInt Kotlin_NSArrayList_getSize(ObjHeader* obj) {
-  NSArray* array = (NSArray*) GetAssociatedObject(obj);
-  return [array count];
-}
-
-extern "C" OBJ_GETTER(Kotlin_NSArrayList_getElement, ObjHeader* obj, KInt index) {
-  NSArray* array = (NSArray*) GetAssociatedObject(obj);
-  id element = [array objectAtIndex:index];
-  if (element == NSNull.null) RETURN_OBJ(nullptr);
-  RETURN_RESULT_OF(Kotlin_ObjCExport_refFromObjC, element);
-}
-
 static const TypeInfo* createTypeInfo(
   const TypeInfo* superType,
   const KStdVector<const TypeInfo*>& superInterfaces,
@@ -968,16 +897,4 @@ extern "C" void Kotlin_ObjCExport_AbstractMethodCalled(id self, SEL selector) {
         class_getName(object_getClass(self)), sel_getName(selector)];
 }
 
-#else  // KONAN_OBJC_INTEROP
-
-extern "C" KInt Kotlin_NSArrayList_getSize(ObjHeader* obj) {
-  RuntimeAssert(false, "Objective-C interop is disabled");
-  return -1;
-}
-
-extern "C" OBJ_GETTER(Kotlin_NSArrayList_getElement, ObjHeader* obj, KInt index) {
-  RuntimeAssert(false, "Objective-C interop is disabled");
-  RETURN_OBJ(nullptr);
-}
-
 #endif // KONAN_OBJC_INTEROP

runtime/src/main/cpp/ObjCExportCollections.mm

@@ -0,0 +1,806 @@
+#import "Memory.h"
+#import "Types.h"
+
+#if KONAN_OBJC_INTEROP
+
+#import <objc/runtime.h>
+
+#import <Foundation/NSObject.h>
+#import <Foundation/NSArray.h>
+#import <Foundation/NSDictionary.h>
+#import <Foundation/NSSet.h>
+#import <Foundation/NSNull.h>
+
+#import "Exceptions.h"
+#import "Runtime.h"
+#import "ObjCExport.h"
+
+extern "C" {
+
+// Imports from ObjCExportUtils.kt:
+
+OBJ_GETTER0(Kotlin_NSArrayAsKList_create);
+OBJ_GETTER0(Kotlin_NSMutableArrayAsKMutableList_create);
+OBJ_GETTER0(Kotlin_NSEnumeratorAsKIterator_create);
+OBJ_GETTER0(Kotlin_NSSetAsKSet_create);
+OBJ_GETTER0(Kotlin_NSDictionaryAsKMap_create);
+
+KBoolean Kotlin_Iterator_hasNext(KRef iterator);
+OBJ_GETTER(Kotlin_Iterator_next, KRef iterator);
+KInt Kotlin_Collection_getSize(KRef collection);
+KBoolean Kotlin_Set_contains(KRef set, KRef element);
+OBJ_GETTER(Kotlin_Set_getElement, KRef set, KRef element);
+OBJ_GETTER(Kotlin_Set_iterator, KRef set);
+void Kotlin_MutableCollection_removeObject(KRef collection, KRef element);
+void Kotlin_MutableCollection_addObject(KRef list, KRef obj);
+OBJ_GETTER(Kotlin_MutableSet_createWithCapacity, KInt capacity);
+
+KInt Kotlin_Map_getSize(KRef map);
+KBoolean Kotlin_Map_containsKey(KRef map, KRef key);
+OBJ_GETTER(Kotlin_Map_get, KRef map, KRef key);
+OBJ_GETTER(Kotlin_Map_keyIterator, KRef map);
+OBJ_GETTER(Kotlin_List_get, KRef list, KInt index);
+
+OBJ_GETTER(Kotlin_MutableMap_createWithCapacity, KInt capacity);
+void Kotlin_MutableMap_set(KRef map, KRef key, KRef value);
+void Kotlin_MutableMap_remove(KRef map, KRef key);
+void Kotlin_MutableList_addObjectAtIndex(KRef list, KInt index, KRef obj);
+void Kotlin_MutableList_removeObjectAtIndex(KRef list, KInt index);
+void Kotlin_MutableList_removeLastObject(KRef list);
+void Kotlin_MutableList_setObject(KRef list, KInt index, KRef obj);
+
+void Kotlin_NSEnumeratorAsKIterator_done(KRef thiz);
+void Kotlin_NSEnumeratorAsKIterator_setNext(KRef thiz, KRef value);
+
+void Kotlin_ObjCExport_ThrowCollectionTooLarge();
+void Kotlin_ObjCExport_ThrowCollectionConcurrentModification();
+
+} // extern "C"
+
+// Objective-C collections can't store `nil`, and the common convention is to use `NSNull.null` instead.
+// Follow the convention when converting Kotlin `null`:
+
+static inline id refToObjCOrNSNull(KRef obj) {
+  if (obj == nullptr) {
+    return NSNull.null;
+  } else {
+    return Kotlin_ObjCExport_refToObjC(obj);
+  }
+}
+
+static inline OBJ_GETTER(refFromObjCOrNSNull, id obj) {
+  if (obj == NSNull.null) {
+    RETURN_OBJ(nullptr);
+  } else {
+    RETURN_RESULT_OF(Kotlin_ObjCExport_refFromObjC, obj);
+  }
+}
+
+static inline KInt objCCapacityToKotlin(NSUInteger capacity) {
+  KInt max = std::numeric_limits<KInt>::max();
+  return capacity > max ? max : capacity;
+}
+
+static inline KInt objCSizeToKotlinOrThrow(NSUInteger size) {
+  if (size > std::numeric_limits<KInt>::max()) {
+    Kotlin_ObjCExport_ThrowCollectionTooLarge();
+  }
+
+  return size;
+}
+
+static inline KInt objCIndexToKotlinOrThrow(NSUInteger index) {
+  if (index > std::numeric_limits<KInt>::max()) {
+    ThrowArrayIndexOutOfBoundsException();
+  }
+
+  return index;
+}
+
+static inline OBJ_GETTER(invokeAndAssociate, KRef (*func)(KRef* result), id obj) {
+  Kotlin_initRuntimeIfNeeded();
+
+  KRef kotlinObj = func(OBJ_RESULT);
+
+  RuntimeAssert(HasAssociatedObjectField(kotlinObj), "");
+  SetAssociatedObject(kotlinObj, obj);
+
+  return kotlinObj;
+}
+
+@interface NSArray (NSArrayToKotlin) <ConvertibleToKotlin>
+@end;
+
+@implementation NSArray (NSArrayToKotlin)
+-(KRef)toKotlin:(KRef*)OBJ_RESULT {
+  RETURN_RESULT_OF(invokeAndAssociate, Kotlin_NSArrayAsKList_create, objc_retain(self));
+}
+
+-(void)releaseAsAssociatedObject {
+  objc_release(self);
+}
+@end;
+
+@interface NSMutableArray (NSMutableArrayToKotlin) <ConvertibleToKotlin>
+@end;
+
+@implementation NSMutableArray (NSArrayToKotlin)
+-(KRef)toKotlin:(KRef*)OBJ_RESULT {
+  RETURN_RESULT_OF(invokeAndAssociate, Kotlin_NSMutableArrayAsKMutableList_create, objc_retain(self));
+}
+
+-(void)releaseAsAssociatedObject {
+  objc_release(self);
+}
+@end;
+
+
+@interface NSSet (NSSetToKotlin) <ConvertibleToKotlin>
+@end;
+
+@implementation NSSet (NSSetToKotlin)
+-(KRef)toKotlin:(KRef*)OBJ_RESULT {
+  RETURN_RESULT_OF(invokeAndAssociate, Kotlin_NSSetAsKSet_create, objc_retain(self));
+}
+
+-(void)releaseAsAssociatedObject {
+  objc_release(self);
+}
+
+@end;
+
+@interface NSDictionary (NSDictionaryToKotlin) <ConvertibleToKotlin>
+@end;
+
+@implementation NSDictionary (NSDictionaryToKotlin)
+-(KRef)toKotlin:(KRef*)OBJ_RESULT {
+  RETURN_RESULT_OF(invokeAndAssociate, Kotlin_NSDictionaryAsKMap_create, objc_retain(self));
+}
+
+-(void)releaseAsAssociatedObject {
+  objc_release(self);
+}
+
+@end;
+
+@interface KIteratorAsNSEnumerator : NSEnumerator
+@end;
+
+@implementation KIteratorAsNSEnumerator {
+  KRef iterator;
+}
+
+-(void)dealloc {
+  UpdateRef(&iterator, nullptr);
+  [super dealloc];
+}
+
++(id)createWithKIterator:(KRef)iterator {
+  KIteratorAsNSEnumerator* result = [[[KIteratorAsNSEnumerator alloc] init] autorelease];
+  UpdateRef(&result->iterator, iterator);
+  return result;
+}
+
+- (id)nextObject {
+  if (Kotlin_Iterator_hasNext(iterator)) {
+    ObjHolder holder;
+    return refToObjCOrNSNull(Kotlin_Iterator_next(iterator, holder.slot()));
+  } else {
+    return nullptr;
+  }
+}
+@end;
+
+@interface KListAsNSArray : NSArray <ConvertibleToKotlin>
+@end;
+
+@implementation KListAsNSArray {
+  KRef list;
+}
+
+-(void)dealloc {
+  UpdateRef(&list, nullptr);
+  [super dealloc];
+}
+
++(id)createWithKList:(KRef)list {
+  KListAsNSArray* result = [[[KListAsNSArray alloc] init] autorelease];
+  UpdateRef(&result->list, list);
+  return result;
+}
+
+-(KRef)toKotlin:(KRef*)OBJ_RESULT {
+  RETURN_OBJ(list);
+}
+
+-(id)objectAtIndex:(NSUInteger)index {
+  ObjHolder kotlinValueHolder;
+  KRef kotlinValue = Kotlin_List_get(list, index, kotlinValueHolder.slot());
+  return refToObjCOrNSNull(kotlinValue);
+}
+
+-(NSUInteger)count {
+  return Kotlin_Collection_getSize(list);
+}
+
+@end;
+
+@interface KMutableListAsNSMutableArray : NSMutableArray <ConvertibleToKotlin>
+@end;
+
+@implementation KMutableListAsNSMutableArray {
+  KRef list;
+}
+
+-(void)dealloc {
+  UpdateRef(&list, nullptr);
+  [super dealloc];
+}
+
++(id)createWithKList:(KRef)list {
+  KMutableListAsNSMutableArray* result = [[[KMutableListAsNSMutableArray alloc] init] autorelease];
+  UpdateRef(&result->list, list);
+  return result;
+}
+
+-(KRef)toKotlin:(KRef*)OBJ_RESULT {
+  RETURN_OBJ(list);
+}
+
+-(id)objectAtIndex:(NSUInteger)index {
+  ObjHolder kotlinValueHolder;
+  KRef kotlinValue = Kotlin_List_get(list, index, kotlinValueHolder.slot());
+  return refToObjCOrNSNull(kotlinValue);
+}
+
+-(NSUInteger)count {
+  return Kotlin_Collection_getSize(list);
+}
+
+- (void)insertObject:(id)anObject atIndex:(NSUInteger)index {
+  ObjHolder holder;
+  KRef kotlinObject = refFromObjCOrNSNull(anObject, holder.slot());
+  Kotlin_MutableList_addObjectAtIndex(list, objCIndexToKotlinOrThrow(index), kotlinObject);
+}
+
+- (void)removeObjectAtIndex:(NSUInteger)index {
+  Kotlin_MutableList_removeObjectAtIndex(list, objCIndexToKotlinOrThrow(index));
+}
+
+- (void)addObject:(id)anObject {
+  ObjHolder holder;
+  Kotlin_MutableCollection_addObject(list, refFromObjCOrNSNull(anObject, holder.slot()));
+}
+
+- (void)removeLastObject {
+  Kotlin_MutableList_removeLastObject(list);
+}
+
+- (void)replaceObjectAtIndex:(NSUInteger)index withObject:(id)anObject {
+  ObjHolder holder;
+  KRef kotlinObject = refFromObjCOrNSNull(anObject, holder.slot());
+  Kotlin_MutableList_setObject(list, objCIndexToKotlinOrThrow(index), kotlinObject);
+}
+
+@end;
+
+@interface KSetAsNSSet : NSSet <ConvertibleToKotlin>
+@end;
+
+static inline id KSet_getElement(KRef set, id object) {
+  if (object == NSNull.null) {
+    return Kotlin_Set_contains(set, nullptr) ? object : nullptr;
+  } else {
+    ObjHolder requestHolder, resultHolder;
+    KRef request = Kotlin_ObjCExport_refFromObjC(object, requestHolder.slot());
+    KRef result = Kotlin_Set_getElement(set, request, resultHolder.slot());
+    return refToObjCOrNSNull(result);
+  }
+}
+
+@implementation KSetAsNSSet {
+  KRef set;
+}
+
+-(void)dealloc {
+  UpdateRef(&set, nullptr);
+  [super dealloc];
+}
+
++(id)createWithKSet:(KRef)set {
+  KSetAsNSSet* result = [[[KSetAsNSSet alloc] init] autorelease];
+  UpdateRef(&result->set, set);
+  return result;
+}
+
+-(KRef)toKotlin:(KRef*)OBJ_RESULT {
+  RETURN_OBJ(set);
+}
+
+-(NSUInteger) count {
+  return Kotlin_Collection_getSize(set);
+}
+
+- (id)member:(id)object {
+  return KSet_getElement(set, object);
+}
+
+// Not mandatory, just an optimization:
+- (BOOL)containsObject:(id)anObject {
+  ObjHolder holder;
+  return Kotlin_Set_contains(set, refFromObjCOrNSNull(anObject, holder.slot()));
+}
+
+- (NSEnumerator*)objectEnumerator {
+  ObjHolder holder;
+  return [KIteratorAsNSEnumerator createWithKIterator:Kotlin_Set_iterator(set, holder.slot())];
+}
+@end;
+
+@interface KotlinMutableSet : NSMutableSet <ConvertibleToKotlin>
+@end;
+
+@implementation KotlinMutableSet {
+  KRef set;
+}
+
+-(instancetype)init {
+  if (self = [super init]) {
+    Kotlin_initRuntimeIfNeeded();
+    Kotlin_MutableSet_createWithCapacity(8, &self->set);
+  }
+
+  return self;
+}
+
+- (instancetype)initWithCapacity:(NSUInteger)numItems {
+  if (self = [super init]) {
+    Kotlin_initRuntimeIfNeeded();
+    Kotlin_MutableSet_createWithCapacity(objCCapacityToKotlin(numItems), &self->set);
+  }
+
+  return self;
+}
+
+- (instancetype)initWithObjects:(const id _Nonnull [_Nullable])objects count:(NSUInteger)cnt {
+  if (self = [self initWithCapacity:cnt]) {
+    for (NSUInteger i = 0; i < cnt; ++i) {
+      [self addObject:objects[i]];
+    }
+  }
+
+  return self;
+}
+
+// TODO: what about
+// - (nullable instancetype)initWithCoder:(NSCoder *)aDecoder
+// ?
+
+-(void)dealloc {
+  UpdateRef(&set, nullptr);
+  [super dealloc];
+}
+
++(id)createWithKSet:(KRef)set {
+  KotlinMutableSet* result = [[[super allocWithZone:nullptr] init] autorelease];
+  UpdateRef(&result->set, set);
+  return result;
+}
+
+-(KRef)toKotlin:(KRef*)OBJ_RESULT {
+  RETURN_OBJ(set);
+}
+
+-(NSUInteger) count {
+  return Kotlin_Collection_getSize(set);
+}
+
+- (id)member:(id)object {
+  return KSet_getElement(set, object);
+}
+
+// Not mandatory, just an optimization:
+- (BOOL)containsObject:(id)anObject {
+  ObjHolder holder;
+  return Kotlin_Set_contains(set, refFromObjCOrNSNull(anObject, holder.slot()));
+}
+
+- (NSEnumerator*)objectEnumerator {
+  ObjHolder holder;
+  return [KIteratorAsNSEnumerator createWithKIterator:Kotlin_Set_iterator(set, holder.slot())];
+}
+
+- (void)addObject:(id)object {
+  ObjHolder holder;
+  Kotlin_MutableCollection_addObject(set, refFromObjCOrNSNull(object, holder.slot()));
+}
+
+- (void)removeObject:(id)object {
+  ObjHolder holder;
+  Kotlin_MutableCollection_removeObject(set, refFromObjCOrNSNull(object, holder.slot()));
+}
+@end;
+
+@interface KMapAsNSDictionary : NSDictionary <ConvertibleToKotlin>
+@end;
+
+static inline id KMap_get(KRef map, id aKey) {
+  ObjHolder keyHolder, valueHolder;
+
+  KRef kotlinKey = refFromObjCOrNSNull(aKey, keyHolder.slot());
+  KRef kotlinValue = Kotlin_Map_get(map, kotlinKey, valueHolder.slot());
+
+  if (kotlinValue == nullptr) {
+    // Either null or not found.
+    return Kotlin_Map_containsKey(map, kotlinKey) ? NSNull.null : nullptr;
+  } else {
+    return refToObjCOrNSNull(kotlinValue);
+  }
+}
+
+@implementation KMapAsNSDictionary {
+  KRef map;
+}
+
+-(void)dealloc {
+  UpdateRef(&map, nullptr);
+  [super dealloc];
+}
+
++(id)createWithKMap:(KRef)map {
+  KMapAsNSDictionary* result = [[[KMapAsNSDictionary alloc] init] autorelease];
+  UpdateRef(&result->map, map);
+  return result;
+}
+
+-(KRef)toKotlin:(KRef*)OBJ_RESULT {
+  RETURN_OBJ(map);
+}
+
+// According to documentation, initWithObjects:forKeys:count: is required to be overridden when subclassing.
+// But that doesn't make any sense, since this class can't be arbitrary initialized.
+
+-(NSUInteger) count {
+  return Kotlin_Map_getSize(map);
+}
+
+- (id)objectForKey:(id)aKey {
+  return KMap_get(map, aKey);
+}
+
+- (NSEnumerator *)keyEnumerator {
+  ObjHolder holder;
+  return [KIteratorAsNSEnumerator createWithKIterator:Kotlin_Map_keyIterator(map, holder.slot())];
+}
+
+@end;
+
+@interface KotlinMutableDictionary : NSMutableDictionary <ConvertibleToKotlin>
+@end;
+
+@implementation KotlinMutableDictionary {
+  KRef map;
+}
+
+-(void)dealloc {
+  UpdateRef(&map, nullptr);
+  [super dealloc];
+}
+
+-(instancetype)init {
+  if (self = [super init]) {
+    Kotlin_initRuntimeIfNeeded();
+    Kotlin_MutableMap_createWithCapacity(8, &self->map);
+  }
+  return self;
+}
+
+// 'initWithObjects:forKeys:count:' seems to be implemented in base class.
+
+// TODO: what about
+//  - (nullable instancetype)initWithCoder:(NSCoder *)aDecoder
+// ?
+
+- (instancetype)initWithCapacity:(NSUInteger)numItems {
+  if (self = [super init]) {
+    Kotlin_initRuntimeIfNeeded();
+    Kotlin_MutableMap_createWithCapacity(objCCapacityToKotlin(numItems), &self->map);
+  }
+  return self;
+}
+
++(id)createWithKMap:(KRef)map {
+  KotlinMutableDictionary* result = [[[KotlinMutableDictionary alloc] init] autorelease];
+  UpdateRef(&result->map, map);
+  return result;
+}
+
+-(KRef)toKotlin:(KRef*)OBJ_RESULT {
+  RETURN_OBJ(map);
+}
+
+-(NSUInteger) count {
+  return Kotlin_Map_getSize(map);
+}
+
+- (id)objectForKey:(id)aKey {
+  return KMap_get(map, aKey);
+}
+
+- (NSEnumerator *)keyEnumerator {
+  ObjHolder holder;
+  return [KIteratorAsNSEnumerator createWithKIterator:Kotlin_Map_keyIterator(map, holder.slot())];
+}
+
+- (void)setObject:(id)anObject forKey:(id<NSCopying>)aKey {
+  ObjHolder keyHolder, valueHolder;
+
+  id keyCopy = [aKey copyWithZone:nullptr]; // Correspond to the expected NSMutableDictionary behaviour.
+  KRef kotlinKey = refFromObjCOrNSNull(keyCopy, keyHolder.slot());
+  objc_release(keyCopy);
+
+  KRef kotlinValue = refFromObjCOrNSNull(anObject, valueHolder.slot());
+
+  Kotlin_MutableMap_set(map, kotlinKey, kotlinValue);
+}
+
+- (void)removeObjectForKey:(id)aKey {
+  ObjHolder holder;
+  KRef kotlinKey = refFromObjCOrNSNull(aKey, holder.slot());
+
+  Kotlin_MutableMap_remove(map, kotlinKey);
+}
+
+@end;
+
+@interface NSEnumerator (NSEnumeratorAsAssociatedObject)
+@end;
+
+@implementation NSEnumerator (NSEnumeratorAsAssociatedObject)
+-(void)releaseAsAssociatedObject {
+  objc_release(self);
+}
+@end;
+
+// Referenced from the generated code:
+
+extern "C" id Kotlin_Interop_CreateNSArrayFromKList(KRef obj) {
+  return [KListAsNSArray createWithKList:obj];
+}
+
+extern "C" id Kotlin_Interop_CreateNSMutableArrayFromKList(KRef obj) {
+  return [KMutableListAsNSMutableArray createWithKList:obj];
+}
+
+extern "C" id Kotlin_Interop_CreateNSSetFromKSet(KRef obj) {
+  return [KSetAsNSSet createWithKSet:obj];
+}
+
+extern "C" id Kotlin_Interop_CreateKotlinMutableSetFromKSet(KRef obj) {
+  return [KotlinMutableSet createWithKSet:obj];
+}
+
+extern "C" id Kotlin_Interop_CreateNSDictionaryFromKMap(KRef obj) {
+  return [KMapAsNSDictionary createWithKMap:obj];
+}
+
+extern "C" id Kotlin_Interop_CreateKotlinMutableDictonaryFromKMap(KRef obj) {
+  return [KotlinMutableDictionary createWithKMap:obj];
+}
+
+// Imported to ObjCExportUtils.kt:
+
+extern "C" KInt Kotlin_NSArrayAsKList_getSize(KRef obj) {
+  NSArray* array = (NSArray*) GetAssociatedObject(obj);
+  return objCSizeToKotlinOrThrow([array count]);
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSArrayAsKList_get, KRef obj, KInt index) {
+  NSArray* array = (NSArray*) GetAssociatedObject(obj);
+  id element = [array objectAtIndex:index];
+  RETURN_RESULT_OF(refFromObjCOrNSNull, element);
+}
+
+extern "C" void Kotlin_NSMutableArrayAsKMutableList_add(KRef thiz, KInt index, KRef element) {
+  NSMutableArray* mutableArray = (NSMutableArray*) GetAssociatedObject(thiz);
+  [mutableArray insertObject:refToObjCOrNSNull(element) atIndex:index];
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSMutableArrayAsKMutableList_removeAt, KRef thiz, KInt index) {
+  NSMutableArray* mutableArray = (NSMutableArray*) GetAssociatedObject(thiz);
+
+  KRef res = refFromObjCOrNSNull([mutableArray objectAtIndex:index], OBJ_RESULT);
+  [mutableArray removeObjectAtIndex:index];
+
+  return res;
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSMutableArrayAsKMutableList_set, KRef thiz, KInt index, KRef element) {
+  NSMutableArray* mutableArray = (NSMutableArray*) GetAssociatedObject(thiz);
+
+  KRef res = refFromObjCOrNSNull([mutableArray objectAtIndex:index], OBJ_RESULT);
+  [mutableArray replaceObjectAtIndex:index withObject:refToObjCOrNSNull(element)];
+
+  return res;
+}
+
+extern "C" void Kotlin_NSEnumeratorAsKIterator_computeNext(KRef thiz) {
+  NSEnumerator* enumerator = (NSEnumerator*) GetAssociatedObject(thiz);
+  id next = [enumerator nextObject];
+  if (next == nullptr) {
+    Kotlin_NSEnumeratorAsKIterator_done(thiz);
+  } else {
+    ObjHolder holder;
+    Kotlin_NSEnumeratorAsKIterator_setNext(thiz, refFromObjCOrNSNull(next, holder.slot()));
+  }
+}
+
+extern "C" KInt Kotlin_NSSetAsKSet_getSize(KRef thiz) {
+  NSSet* set = (NSSet*) GetAssociatedObject(thiz);
+  return objCSizeToKotlinOrThrow(set.count);
+}
+
+extern "C" KBoolean Kotlin_NSSetAsKSet_contains(KRef thiz, KRef element) {
+  NSSet* set = (NSSet*) GetAssociatedObject(thiz);
+  return [set containsObject:refToObjCOrNSNull(element)];
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSSetAsKSet_getElement, KRef thiz, KRef element) {
+  NSSet* set = (NSSet*) GetAssociatedObject(thiz);
+  id res = [set member:refToObjCOrNSNull(element)];
+  RETURN_RESULT_OF(refFromObjCOrNSNull, res);
+}
+
+static inline OBJ_GETTER(CreateKIteratorFromNSEnumerator, NSEnumerator* enumerator) {
+  RETURN_RESULT_OF(invokeAndAssociate, Kotlin_NSEnumeratorAsKIterator_create, objc_retain(enumerator));
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSSetAsKSet_iterator, KRef thiz) {
+  NSSet* set = (NSSet*) GetAssociatedObject(thiz);
+  RETURN_RESULT_OF(CreateKIteratorFromNSEnumerator, [set objectEnumerator]);
+}
+
+extern "C" KInt Kotlin_NSDictionaryAsKMap_getSize(KRef thiz) {
+  NSDictionary* dict = (NSDictionary*) GetAssociatedObject(thiz);
+  return objCSizeToKotlinOrThrow(dict.count);
+}
+
+extern "C" KBoolean Kotlin_NSDictionaryAsKMap_containsKey(KRef thiz, KRef key) {
+  NSDictionary* dict = (NSDictionary*) GetAssociatedObject(thiz);
+  return [dict objectForKey:refToObjCOrNSNull(key)] != nullptr;
+}
+
+extern "C" KBoolean Kotlin_NSDictionaryAsKMap_containsValue(KRef thiz, KRef value) {
+  NSDictionary* dict = (NSDictionary*) GetAssociatedObject(thiz);
+  id objCValue = refToObjCOrNSNull(value);
+  for (id key in dict) {
+    if ([[dict objectForKey:key] isEqual:objCValue]) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSDictionaryAsKMap_get, KRef thiz, KRef key) {
+  NSDictionary* dict = (NSDictionary*) GetAssociatedObject(thiz);
+  id value = [dict objectForKey:refToObjCOrNSNull(key)];
+  RETURN_RESULT_OF(refFromObjCOrNSNull, value);
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSDictionaryAsKMap_getOrThrowConcurrentModification, KRef thiz, KRef key) {
+  NSDictionary* dict = (NSDictionary*) GetAssociatedObject(thiz);
+  id value = [dict objectForKey:refToObjCOrNSNull(key)];
+  if (value == nullptr) {
+    Kotlin_ObjCExport_ThrowCollectionConcurrentModification();
+  }
+
+  RETURN_RESULT_OF(refFromObjCOrNSNull, value);
+}
+
+extern "C" KBoolean Kotlin_NSDictionaryAsKMap_containsEntry(KRef thiz, KRef key, KRef value) {
+  NSDictionary* dict = (NSDictionary*) GetAssociatedObject(thiz);
+  return [refToObjCOrNSNull(value) isEqual:[dict objectForKey:refToObjCOrNSNull(key)]];
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSDictionaryAsKMap_keyIterator, KRef thiz) {
+  NSDictionary* dict = (NSDictionary*) GetAssociatedObject(thiz);
+  RETURN_RESULT_OF(CreateKIteratorFromNSEnumerator, [dict keyEnumerator]);
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSDictionaryAsKMap_valueIterator, KRef thiz) {
+  NSDictionary* dict = (NSDictionary*) GetAssociatedObject(thiz);
+  RETURN_RESULT_OF(CreateKIteratorFromNSEnumerator, [dict objectEnumerator]);
+}
+
+#else  // KONAN_OBJC_INTEROP
+
+extern "C" KInt Kotlin_NSArrayAsKList_getSize(KRef obj) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  return -1;
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSArrayAsKList_get, KRef obj, KInt index) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  RETURN_OBJ(nullptr);
+}
+
+extern "C" void Kotlin_NSMutableArrayAsKMutableList_add(KRef thiz, KInt index, KRef element) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSMutableArrayAsKMutableList_removeAt, KRef thiz, KInt index) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  RETURN_OBJ(nullptr);
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSMutableArrayAsKMutableList_set, KRef thiz, KInt index, KRef element) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  RETURN_OBJ(nullptr);
+}
+
+extern "C" void Kotlin_NSEnumeratorAsKIterator_computeNext(KRef thiz) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+}
+
+extern "C" KInt Kotlin_NSSetAsKSet_getSize(KRef thiz) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  return -1;
+}
+
+extern "C" KBoolean Kotlin_NSSetAsKSet_contains(KRef thiz, KRef element) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  return false;
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSSetAsKSet_getElement, KRef thiz, KRef element) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  RETURN_OBJ(nullptr);
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSSetAsKSet_iterator, KRef thiz) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  RETURN_OBJ(nullptr);
+}
+
+extern "C" KInt Kotlin_NSDictionaryAsKMap_getSize(KRef thiz) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  return -1;
+}
+
+extern "C" KBoolean Kotlin_NSDictionaryAsKMap_containsKey(KRef thiz, KRef key) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  return false;
+}
+
+extern "C" KBoolean Kotlin_NSDictionaryAsKMap_containsValue(KRef thiz, KRef value) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  return false;
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSDictionaryAsKMap_get, KRef thiz, KRef key) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  RETURN_OBJ(nullptr);
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSDictionaryAsKMap_getOrThrowConcurrentModification, KRef thiz, KRef key) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  RETURN_OBJ(nullptr);
+}
+
+extern "C" KBoolean Kotlin_NSDictionaryAsKMap_containsEntry(KRef thiz, KRef key, KRef value) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  return false;
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSDictionaryAsKMap_keyIterator, KRef thiz) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  RETURN_OBJ(nullptr);
+}
+
+extern "C" OBJ_GETTER(Kotlin_NSDictionaryAsKMap_valueIterator, KRef thiz) {
+  RuntimeAssert(false, "Objective-C interop is disabled");
+  RETURN_OBJ(nullptr);
+}
+
+#endif // KONAN_OBJC_INTEROP

runtime/src/main/cpp/Types.cpp

@@ -62,4 +62,14 @@ OBJ_GETTER(Kotlin_TypeInfo_getRelativeName, KNativePtr typeInfo) {
   RETURN_OBJ(reinterpret_cast<const TypeInfo*>(typeInfo)->relativeName_);
 }
 
+bool IsSubInterface(const TypeInfo* thiz, const TypeInfo* other) {
+  for (int i = 0; i < thiz->implementedInterfacesCount_; ++i) {
+    if (thiz->implementedInterfaces_[i] == other) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
 }  // extern "C"

runtime/src/main/cpp/Types.h

@@ -88,6 +88,7 @@ extern const TypeInfo* theObjCPointerHolderTypeInfo;
 KBoolean IsInstance(const ObjHeader* obj, const TypeInfo* type_info) RUNTIME_PURE;
 void CheckCast(const ObjHeader* obj, const TypeInfo* type_info);
 KBoolean IsArray(KConstRef obj) RUNTIME_PURE;
+bool IsSubInterface(const TypeInfo* thiz, const TypeInfo* other) RUNTIME_PURE;
 
 #ifdef __cplusplus
 }

runtime/src/main/kotlin/konan/internal/KonanCollections.kt

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package konan.internal
+
+internal interface KonanSet<out E> : Set<E> {
+    /**
+     * Searches for the specified element in this set.
+     *
+     * @return the element from the set equal to [element], or `null` if no such element found.
+     */
+    fun getElement(element: @UnsafeVariance E): E?
+}

runtime/src/main/kotlin/konan/internal/ObjCExportUtils.kt

@@ -0,0 +1,270 @@
+/*
+ * Copyright 2010-2017 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package konan.internal
+
+import konan.internal.ExportForCppRuntime
+
+internal class NSArrayAsKList : AbstractList<Any?>() {
+
+    override val size: Int get() = getSize()
+
+    @SymbolName("Kotlin_NSArrayAsKList_getSize")
+    private external fun getSize(): Int
+
+    @SymbolName("Kotlin_NSArrayAsKList_get")
+    external override fun get(index: Int): Any?
+}
+
+internal class NSMutableArrayAsKMutableList : AbstractMutableList<Any?>() {
+
+    override val size: Int get() = getSize()
+
+    @SymbolName("Kotlin_NSArrayAsKList_getSize")
+    private external fun getSize(): Int
+
+    @SymbolName("Kotlin_NSArrayAsKList_get")
+    external override fun get(index: Int): Any?
+
+    @SymbolName("Kotlin_NSMutableArrayAsKMutableList_add")
+    external override fun add(index: Int, element: Any?): Unit
+
+    @SymbolName("Kotlin_NSMutableArrayAsKMutableList_removeAt")
+    external override fun removeAt(index: Int): Any?
+
+    @SymbolName("Kotlin_NSMutableArrayAsKMutableList_set")
+    external override fun set(index: Int, element: Any?): Any?
+}
+
+internal class NSSetAsKSet : AbstractSet<Any?>(), konan.internal.KonanSet<Any?> {
+
+    override val size: Int get() = getSize()
+
+    @SymbolName("Kotlin_NSSetAsKSet_getSize")
+    private external fun getSize(): Int
+
+    @SymbolName("Kotlin_NSSetAsKSet_contains")
+    external override fun contains(element: Any?): Boolean
+
+    @SymbolName("Kotlin_NSSetAsKSet_getElement")
+    external override fun getElement(element: Any?): Any?
+
+    @SymbolName("Kotlin_NSSetAsKSet_iterator")
+    external override fun iterator(): Iterator<Any?>
+}
+
+internal class NSDictionaryAsKMap : Map<Any?, Any?> {
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other !is Map<*, *>) return false
+        if (this.size != other.size) return false
+
+        return other.entries.all { this.containsEntry(it.key, it.value) }
+    }
+
+    override fun hashCode(): Int {
+        var result = 0
+        keyIterator().forEach { key ->
+            result += key.hashCode() xor this.getOrThrowConcurrentModification(key).hashCode()
+        }
+        return result
+    }
+
+    override fun toString(): String = entries.joinToString(", ", "{", "}") { toString(it.key) + "=" + toString(it.value) }
+
+    private fun toString(o: Any?): String = if (o === this) "(this Map)" else o.toString()
+
+    override val size: Int get() = getSize()
+
+    @SymbolName("Kotlin_NSDictionaryAsKMap_getSize")
+    private external fun getSize(): Int
+
+    override fun isEmpty(): Boolean = (size == 0)
+
+    @SymbolName("Kotlin_NSDictionaryAsKMap_containsKey")
+    override external fun containsKey(key: Any?): Boolean
+
+    @SymbolName("Kotlin_NSDictionaryAsKMap_containsValue")
+    override external fun containsValue(value: Any?): Boolean
+
+    @SymbolName("Kotlin_NSDictionaryAsKMap_get")
+    external override operator fun get(key: Any?): Any?
+
+    @SymbolName("Kotlin_NSDictionaryAsKMap_getOrThrowConcurrentModification")
+    private external fun getOrThrowConcurrentModification(key: Any?): Any?
+
+    @SymbolName("Kotlin_NSDictionaryAsKMap_containsEntry")
+    private external fun containsEntry(key: Any?, value: Any?): Boolean
+
+    // Views
+    override val keys: Set<Any?> get() = this.Keys()
+
+    override val values: Collection<Any?> get() = this.Values()
+
+    override val entries: Set<Map.Entry<Any?, Any?>> get() = this.Entries()
+
+    @SymbolName("Kotlin_NSDictionaryAsKMap_keyIterator")
+    private external fun keyIterator(): Iterator<Any?>
+
+    private inner class Keys : AbstractSet<Any?>() {
+
+        override val size: Int get() = this@NSDictionaryAsKMap.size
+
+        override fun iterator(): Iterator<Any?> = this@NSDictionaryAsKMap.keyIterator()
+
+        override fun contains(element: Any?): Boolean = this@NSDictionaryAsKMap.containsKey(element)
+    }
+
+    @SymbolName("Kotlin_NSDictionaryAsKMap_valueIterator")
+    private external fun valueIterator(): Iterator<Any?>
+
+    private inner class Values : AbstractCollection<Any?>() {
+        // TODO: what about equals and hashCode?
+
+        override val size: Int get() = this@NSDictionaryAsKMap.size
+
+        override fun iterator(): Iterator<Any?> = this@NSDictionaryAsKMap.valueIterator()
+
+        override fun contains(element: Any?): Boolean = this@NSDictionaryAsKMap.containsValue(element)
+    }
+
+    private inner class Entries : AbstractSet<Map.Entry<Any?, Any?>>() {
+
+        override val size: Int get() = this@NSDictionaryAsKMap.size
+
+        @SymbolName("Kotlin_NSSetAsKSet_iterator")
+        override fun iterator(): Iterator<Map.Entry<Any?, Any?>> = this@NSDictionaryAsKMap.EntryIterator()
+
+        override fun contains(element: Map.Entry<Any?, Any?>): Boolean {
+            return this@NSDictionaryAsKMap.containsEntry(element.key, element.value)
+        }
+    }
+
+    private class Entry(override val key: Any?, override val value: Any?) : Map.Entry<Any?, Any?> {
+        override fun equals(other: Any?): Boolean =
+                other is Map.Entry<*, *> &&
+                        other.key == key &&
+                        other.value == value
+
+        override fun hashCode(): Int = key.hashCode() xor value.hashCode()
+
+        override fun toString(): String = "$key=$value"
+    }
+
+    private inner class EntryIterator : Iterator<Map.Entry<Any?, Any?>> {
+        val keyIterator = this@NSDictionaryAsKMap.keyIterator()
+
+        override fun hasNext(): Boolean = keyIterator.hasNext()
+
+        override fun next(): Map.Entry<Any?, Any?> {
+            val nextKey = keyIterator.next()
+            val nextValue = this@NSDictionaryAsKMap.getOrThrowConcurrentModification(nextKey)
+
+            return Entry(nextKey, nextValue)
+        }
+    }
+
+}
+
+internal class NSEnumeratorAsKIterator : AbstractIterator<Any?>() {
+
+    @SymbolName("Kotlin_NSEnumeratorAsKIterator_computeNext")
+    override external fun computeNext()
+
+    @ExportForCppRuntime
+    private fun Kotlin_NSEnumeratorAsKIterator_done() = this.done()
+
+    @ExportForCppRuntime
+    private fun Kotlin_NSEnumeratorAsKIterator_setNext(value: Any?) = this.setNext(value)
+}
+
+@ExportForCppRuntime private fun Kotlin_Collection_getSize(collection: Collection<*>): Int = collection.size
+
+@ExportForCppRuntime private fun Kotlin_List_get(list: List<*>, index: Int): Any? = list.get(index)
+
+@ExportForCppRuntime private fun Kotlin_MutableList_addObjectAtIndex(list: MutableList<Any?>, index: Int, obj: Any?) {
+    list.add(index, obj)
+}
+
+@ExportForCppRuntime private fun Kotlin_MutableList_removeObjectAtIndex(list: MutableList<Any?>, index: Int) {
+    list.removeAt(index)
+}
+
+@ExportForCppRuntime private fun Kotlin_MutableCollection_addObject(list: MutableCollection<Any?>, obj: Any?) {
+    list.add(obj)
+}
+
+@ExportForCppRuntime private fun Kotlin_MutableList_removeLastObject(list: MutableList<Any?>) {
+    list.removeAt(list.lastIndex)
+}
+
+@ExportForCppRuntime private fun Kotlin_MutableList_setObject(list: MutableList<Any?>, index: Int, obj: Any?) {
+    list.set(index, obj)
+}
+
+@ExportForCppRuntime private fun Kotlin_MutableCollection_removeObject(
+        collection: MutableCollection<Any?>, element: Any?
+) {
+    collection.remove(element)
+}
+
+@ExportForCppRuntime private fun Kotlin_Iterator_hasNext(iterator: Iterator<Any?>): Boolean = iterator.hasNext()
+@ExportForCppRuntime private fun Kotlin_Iterator_next(iterator: Iterator<Any?>): Any? = iterator.next()
+
+@ExportForCppRuntime private fun Kotlin_Set_contains(set: Set<Any?>, element: Any?): Boolean = set.contains(element)
+
+@ExportForCppRuntime private fun Kotlin_Set_getElement(set: Set<Any?>, element: Any?): Any? =
+        if (set is konan.internal.KonanSet<Any?>) {
+            set.getElement(element)
+        } else if (set.contains(element)) {
+            set.first { it == element }
+        } else {
+            null
+        }
+
+@ExportForCppRuntime private fun Kotlin_Set_iterator(set: Set<Any?>): Iterator<Any?> = set.iterator()
+@ExportForCppRuntime private fun Kotlin_MutableSet_createWithCapacity(capacity: Int): MutableSet<Any?> =
+        HashSet<Any?>(capacity)
+
+@ExportForCppRuntime private fun Kotlin_Map_getSize(map: Map<Any?, Any?>): Int = map.size
+@ExportForCppRuntime private fun Kotlin_Map_containsKey(map: Map<Any?, Any?>, key: Any?): Boolean = map.containsKey(key)
+@ExportForCppRuntime private fun Kotlin_Map_get(map: Map<Any?, Any?>, key: Any?): Any? = map.get(key)
+@ExportForCppRuntime private fun Kotlin_Map_keyIterator(map: Map<Any?, Any?>): Iterator<Any?> = map.keys.iterator()
+
+@ExportForCppRuntime private fun Kotlin_MutableMap_createWithCapacity(capacity: Int): MutableMap<Any?, Any?> =
+        HashMap<Any?, Any?>(capacity)
+
+@ExportForCppRuntime private fun Kotlin_MutableMap_set(map: MutableMap<Any?, Any?>, key: Any?, value: Any?) {
+    map.set(key, value)
+}
+@ExportForCppRuntime private fun Kotlin_MutableMap_remove(map: MutableMap<Any?, Any?>, key: Any?) {
+    map.remove(key)
+}
+
+@ExportForCppRuntime private fun Kotlin_ObjCExport_ThrowCollectionTooLarge() {
+    throw Error("an Objective-C collection is too large")
+}
+
+@ExportForCppRuntime private fun Kotlin_ObjCExport_ThrowCollectionConcurrentModification() {
+    throw Error("an Objective-C collection was modified while iterating")
+}
+
+@ExportForCppRuntime private fun Kotlin_NSArrayAsKList_create() = NSArrayAsKList()
+@ExportForCppRuntime private fun Kotlin_NSMutableArrayAsKMutableList_create() = NSMutableArrayAsKMutableList()
+@ExportForCppRuntime private fun Kotlin_NSEnumeratorAsKIterator_create() = NSEnumeratorAsKIterator()
+@ExportForCppRuntime private fun Kotlin_NSSetAsKSet_create() = NSSetAsKSet()
+@ExportForCppRuntime private fun Kotlin_NSDictionaryAsKMap_create() = NSDictionaryAsKMap()

runtime/src/main/kotlin/kotlin/collections/HashMap.kt

@@ -368,6 +368,24 @@ class HashMap<K, V> private constructor(
         return valuesArray!![index] == entry.value
     }
 
+    internal fun getEntry(entry: Map.Entry<K, V>): MutableMap.MutableEntry<K, V>? {
+        val index = findKey(entry.key)
+        return if (index < 0 || valuesArray!![index] != entry.value) {
+            null
+        } else {
+            EntryRef(this, index)
+        }
+    }
+
+    internal fun getKey(key: K): K? {
+        val index = findKey(key)
+        return if (index >= 0) {
+            keysArray[index]!!
+        } else {
+            null
+        }
+    }
+
     private fun contentEquals(other: Map<*, *>): Boolean = size == other.size && containsAllEntries(other.entries)
 
     internal fun containsAllEntries(m: Collection<Map.Entry<*, *>>): Boolean {
@@ -644,11 +662,12 @@ internal class HashMapValues<V> internal constructor(
 
 internal class HashMapEntrySet<K, V> internal constructor(
         val backing: HashMap<K, V>
-) : MutableSet<MutableMap.MutableEntry<K, V>> {
+) : MutableSet<MutableMap.MutableEntry<K, V>>, konan.internal.KonanSet<MutableMap.MutableEntry<K, V>> {
 
     override val size: Int get() = backing.size
     override fun isEmpty(): Boolean = backing.isEmpty()
     override fun contains(element: MutableMap.MutableEntry<K, V>): Boolean = backing.containsEntry(element)
+    override fun getElement(element: MutableMap.MutableEntry<K, V>): MutableMap.MutableEntry<K, V>? = backing.getEntry(element)
     override fun clear() = backing.clear()
     override fun add(element: MutableMap.MutableEntry<K, V>): Boolean = backing.putEntry(element)
     override fun remove(element: MutableMap.MutableEntry<K, V>): Boolean = backing.removeEntry(element)

runtime/src/main/kotlin/kotlin/collections/HashSet.kt

@@ -18,7 +18,7 @@ package kotlin.collections
 
 class HashSet<K> internal constructor(
         val backing: HashMap<K, *>
-) : MutableSet<K>, AbstractMutableCollection<K>() {
+) : MutableSet<K>, AbstractMutableCollection<K>(), konan.internal.KonanSet<K> {
 
     constructor() : this(HashMap<K, Nothing>())
 
@@ -31,6 +31,7 @@ class HashSet<K> internal constructor(
     override val size: Int get() = backing.size
     override fun isEmpty(): Boolean = backing.isEmpty()
     override fun contains(element: K): Boolean = backing.containsKey(element)
+    override fun getElement(element: K): K? = backing.getKey(element)
     override fun clear() = backing.clear()
     override fun add(element: K): Boolean = backing.addKey(element) >= 0
     override fun remove(element: K): Boolean = backing.removeKey(element) >= 0

runtime/src/main/kotlin/kotlin/collections/Sets.kt

@@ -17,7 +17,7 @@
 package kotlin.collections
 
 
-internal object EmptySet : Set<Nothing> {
+internal object EmptySet : Set<Nothing>, konan.internal.KonanSet<Nothing> {
     override fun equals(other: Any?): Boolean = other is Set<*> && other.isEmpty()
     override fun hashCode(): Int = 0
     override fun toString(): String = "[]"
@@ -25,6 +25,7 @@ internal object EmptySet : Set<Nothing> {
     override val size: Int get() = 0
     override fun isEmpty(): Boolean = true
     override fun contains(element: Nothing): Boolean = false
+    override fun getElement(element: Nothing): Nothing? = null
     override fun containsAll(elements: Collection<Nothing>): Boolean = elements.isEmpty()
 
     override fun iterator(): Iterator<Nothing> = EmptyIterator