Rework Objective-C header generation (#1618)

Provide simple tree representation for generated header
to be used in IDE for cross-resolve.

Also do some cleanup.

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

@@ -0,0 +1,62 @@
+package org.jetbrains.kotlin.backend.konan.objcexport
+
+import org.jetbrains.kotlin.builtins.getReceiverTypeFromFunctionType
+import org.jetbrains.kotlin.builtins.getReturnTypeFromFunctionType
+import org.jetbrains.kotlin.builtins.getValueParameterTypesFromFunctionType
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.types.KotlinType
+import org.jetbrains.kotlin.types.TypeUtils
+
+internal interface CustomTypeMapper {
+    val mappedClassDescriptor: ClassDescriptor
+    fun mapType(mappedSuperType: KotlinType): ObjCNonNullReferenceType
+
+    class Simple(
+            override val mappedClassDescriptor: ClassDescriptor,
+            private val objCClassName: String
+    ) : CustomTypeMapper {
+
+        override fun mapType(mappedSuperType: KotlinType): ObjCNonNullReferenceType =
+                ObjCClassType(objCClassName)
+    }
+
+    class Collection(
+            private val generator: ObjCExportHeaderGenerator,
+            override val mappedClassDescriptor: ClassDescriptor,
+            private val objCClassName: String
+    ) : CustomTypeMapper {
+        override fun mapType(mappedSuperType: KotlinType): ObjCNonNullReferenceType {
+            val typeArguments = mappedSuperType.arguments.map {
+                val argument = it.type
+                if (TypeUtils.isNullableType(argument)) {
+                    // Kotlin `null` keys and values are represented as `NSNull` singleton.
+                    ObjCIdType
+                } else {
+                    generator.mapReferenceTypeIgnoringNullability(argument)
+                }
+            }
+
+            return ObjCClassType(objCClassName, typeArguments)
+        }
+    }
+
+    class Function(
+            private val generator: ObjCExportHeaderGenerator,
+            parameterCount: Int
+    ) : CustomTypeMapper {
+        override val mappedClassDescriptor = generator.builtIns.getFunction(parameterCount)
+
+        override fun mapType(mappedSuperType: KotlinType): ObjCNonNullReferenceType {
+            val functionType = mappedSuperType
+
+            val returnType = functionType.getReturnTypeFromFunctionType()
+            val parameterTypes = listOfNotNull(functionType.getReceiverTypeFromFunctionType()) +
+                    functionType.getValueParameterTypesFromFunctionType().map { it.type }
+
+            return ObjCBlockPointerType(
+                    generator.mapReferenceType(returnType),
+                    parameterTypes.map { generator.mapReferenceType(it) }
+            )
+        }
+    }
+}

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

@@ -0,0 +1,102 @@
+package org.jetbrains.kotlin.backend.konan.objcexport
+
+import org.jetbrains.kotlin.backend.common.descriptors.allParameters
+import org.jetbrains.kotlin.descriptors.FunctionDescriptor
+import org.jetbrains.kotlin.descriptors.ParameterDescriptor
+
+internal sealed class TypeBridge
+internal object ReferenceBridge : TypeBridge()
+internal data class ValueTypeBridge(val objCValueType: ObjCValueType) : TypeBridge()
+
+internal sealed class MethodBridgeParameter
+
+internal sealed class MethodBridgeReceiver : MethodBridgeParameter() {
+    object Static : MethodBridgeReceiver()
+    object Factory : MethodBridgeReceiver()
+    object Instance : MethodBridgeReceiver()
+}
+
+internal object MethodBridgeSelector : MethodBridgeParameter()
+
+internal sealed class MethodBridgeValueParameter : MethodBridgeParameter() {
+    data class Mapped(val bridge: TypeBridge) : MethodBridgeValueParameter()
+    object ErrorOutParameter : MethodBridgeValueParameter()
+    data class KotlinResultOutParameter(val bridge: TypeBridge) : MethodBridgeValueParameter()
+}
+
+internal data class MethodBridge(
+        val returnBridge: ReturnValue,
+        val receiver: MethodBridgeReceiver,
+        val valueParameters: List<MethodBridgeValueParameter>
+) {
+
+    sealed class ReturnValue {
+        object Void : ReturnValue()
+        object HashCode : ReturnValue()
+        data class Mapped(val bridge: TypeBridge) : ReturnValue()
+        sealed class Instance : ReturnValue() {
+            object InitResult : Instance()
+            object FactoryResult : Instance()
+        }
+
+        sealed class WithError : ReturnValue() {
+            object Success : WithError()
+            data class RefOrNull(val successBridge: ReturnValue) : WithError()
+        }
+    }
+
+    val paramBridges: List<MethodBridgeParameter> =
+            listOf(receiver) + MethodBridgeSelector + valueParameters
+
+    // TODO: it is not exactly true in potential future cases.
+    val isInstance: Boolean get() = when (receiver) {
+        MethodBridgeReceiver.Static,
+        MethodBridgeReceiver.Factory -> false
+
+        MethodBridgeReceiver.Instance -> true
+    }
+}
+
+internal fun MethodBridge.valueParametersAssociated(
+        descriptor: FunctionDescriptor
+): List<Pair<MethodBridgeValueParameter, ParameterDescriptor?>> {
+    val kotlinParameters = descriptor.allParameters.iterator()
+    val skipFirstKotlinParameter = when (this.receiver) {
+        MethodBridgeReceiver.Static -> false
+        MethodBridgeReceiver.Factory, MethodBridgeReceiver.Instance -> true
+    }
+    if (skipFirstKotlinParameter) {
+        kotlinParameters.next()
+    }
+
+    return this.valueParameters.map {
+        when (it) {
+            is MethodBridgeValueParameter.Mapped -> it to kotlinParameters.next()
+
+            is MethodBridgeValueParameter.ErrorOutParameter,
+            is MethodBridgeValueParameter.KotlinResultOutParameter -> it to null
+        }
+    }.also { assert(!kotlinParameters.hasNext()) }
+}
+
+internal fun MethodBridge.parametersAssociated(
+        descriptor: FunctionDescriptor
+): List<Pair<MethodBridgeParameter, ParameterDescriptor?>> {
+    val kotlinParameters = descriptor.allParameters.iterator()
+
+    return this.paramBridges.map {
+        when (it) {
+            is MethodBridgeValueParameter.Mapped, MethodBridgeReceiver.Instance ->
+                it to kotlinParameters.next()
+
+            MethodBridgeReceiver.Static, MethodBridgeSelector, MethodBridgeValueParameter.ErrorOutParameter,
+            is MethodBridgeValueParameter.KotlinResultOutParameter ->
+                it to null
+
+            MethodBridgeReceiver.Factory -> {
+                kotlinParameters.next()
+                it to null
+            }
+        }
+    }.also { assert(!kotlinParameters.hasNext()) }
+}

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

@@ -46,7 +46,7 @@ internal class ObjCExport(val codegen: CodeGenerator) {
         val topLevelDeclarations: Map<FqName, List<CallableMemberDescriptor>>
 
         if (context.config.produce == CompilerOutputKind.FRAMEWORK) {
-            val headerGenerator = ObjCExportHeaderGenerator(context)
+            val headerGenerator = ObjCExportHeaderGeneratorImpl(context)
             produceFrameworkSpecific(headerGenerator)
 
             generatedClasses = headerGenerator.generatedClasses
@@ -63,7 +63,7 @@ internal class ObjCExport(val codegen: CodeGenerator) {
 
             }
 
-            val namer = ObjCExportNamer(context, mapper)
+            val namer = ObjCExportNamer(context.moduleDescriptor, context.builtIns, mapper)
             objCCodeGenerator = ObjCExportCodeGenerator(codegen, namer, mapper)
 
             generatedClasses = emptySet()

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

@@ -0,0 +1,22 @@
+package org.jetbrains.kotlin.backend.konan.objcexport
+
+import org.jetbrains.kotlin.backend.konan.Context
+import org.jetbrains.kotlin.backend.konan.reportCompilationWarning
+import org.jetbrains.kotlin.descriptors.FunctionDescriptor
+import org.jetbrains.kotlin.ir.util.report
+
+internal class ObjCExportHeaderGeneratorImpl(val context: Context)
+    : ObjCExportHeaderGenerator(context.moduleDescriptor, context.builtIns) {
+
+    override fun reportWarning(text: String) {
+        context.reportCompilationWarning(text)
+    }
+
+    override fun reportWarning(method: FunctionDescriptor, text: String) {
+        context.report(
+                context.ir.get(method),
+                text,
+                isError = false
+        )
+    }
+}

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

@@ -36,7 +36,7 @@ internal abstract class ObjCExportMapper {
 
     private val methodBridgeCache = mutableMapOf<FunctionDescriptor, MethodBridge>()
 
-    fun bridgeMethod(descriptor: FunctionDescriptor) = methodBridgeCache.getOrPut(descriptor) {
+    fun bridgeMethod(descriptor: FunctionDescriptor): MethodBridge = methodBridgeCache.getOrPut(descriptor) {
         bridgeMethodImpl(descriptor)
     }
 }
@@ -110,105 +110,6 @@ internal fun ObjCExportMapper.doesThrow(method: FunctionDescriptor): Boolean = m
     it.overriddenDescriptors.isEmpty() && it.annotations.hasAnnotation(KonanBuiltIns.FqNames.throws)
 }
 
-// TODO: generalize type bridges to support such things as selectors, ignored class method receivers etc.
-
-internal sealed class TypeBridge
-internal object ReferenceBridge : TypeBridge()
-internal data class ValueTypeBridge(val objCValueType: ObjCValueType) : TypeBridge()
-
-internal sealed class MethodBridgeParameter
-
-internal sealed class MethodBridgeReceiver : MethodBridgeParameter() {
-    object Static : MethodBridgeReceiver()
-    object Factory : MethodBridgeReceiver()
-    object Instance : MethodBridgeReceiver()
-}
-
-internal object MethodBridgeSelector : MethodBridgeParameter()
-
-internal sealed class MethodBridgeValueParameter : MethodBridgeParameter() {
-    data class Mapped(val bridge: TypeBridge) : MethodBridgeValueParameter()
-    object ErrorOutParameter : MethodBridgeValueParameter()
-    data class KotlinResultOutParameter(val bridge: TypeBridge) : MethodBridgeValueParameter()
-}
-
-internal data class MethodBridge(
-        val returnBridge: ReturnValue,
-        val receiver: MethodBridgeReceiver,
-        val valueParameters: List<MethodBridgeValueParameter>
-) {
-
-    sealed class ReturnValue {
-        object Void : ReturnValue()
-        object HashCode : ReturnValue()
-        data class Mapped(val bridge: TypeBridge) : ReturnValue()
-        sealed class Instance : ReturnValue() {
-            object InitResult : Instance()
-            object FactoryResult : Instance()
-        }
-
-        sealed class WithError : ReturnValue() {
-            object Success : WithError()
-            data class RefOrNull(val successBridge: ReturnValue) : WithError()
-        }
-    }
-
-    val paramBridges: List<MethodBridgeParameter> =
-            listOf(receiver) + MethodBridgeSelector + valueParameters
-
-    // TODO: it is not exactly true in potential future cases.
-    val isInstance: Boolean get() = when (receiver) {
-        MethodBridgeReceiver.Static,
-        MethodBridgeReceiver.Factory -> false
-
-        MethodBridgeReceiver.Instance -> true
-    }
-}
-
-internal fun MethodBridge.valueParametersAssociated(
-        descriptor: FunctionDescriptor
-): List<Pair<MethodBridgeValueParameter, ParameterDescriptor?>> {
-    val kotlinParameters = descriptor.allParameters.iterator()
-    val skipFirstKotlinParameter = when (this.receiver) {
-        MethodBridgeReceiver.Static -> false
-        MethodBridgeReceiver.Factory, MethodBridgeReceiver.Instance -> true
-    }
-    if (skipFirstKotlinParameter) {
-        kotlinParameters.next()
-    }
-
-    return this.valueParameters.map {
-        when (it) {
-            is MethodBridgeValueParameter.Mapped -> it to kotlinParameters.next()
-
-            is MethodBridgeValueParameter.ErrorOutParameter,
-            is MethodBridgeValueParameter.KotlinResultOutParameter -> it to null
-        }
-    }.also { assert(!kotlinParameters.hasNext()) }
-}
-
-internal fun MethodBridge.parametersAssociated(
-        descriptor: FunctionDescriptor
-): List<Pair<MethodBridgeParameter, ParameterDescriptor?>> {
-    val kotlinParameters = descriptor.allParameters.iterator()
-
-    return this.paramBridges.map {
-        when (it) {
-            is MethodBridgeValueParameter.Mapped, MethodBridgeReceiver.Instance ->
-                it to kotlinParameters.next()
-
-            MethodBridgeReceiver.Static, MethodBridgeSelector, MethodBridgeValueParameter.ErrorOutParameter,
-            is MethodBridgeValueParameter.KotlinResultOutParameter ->
-                it to null
-
-            MethodBridgeReceiver.Factory -> {
-                kotlinParameters.next()
-                it to null
-            }
-        }
-    }.also { assert(!kotlinParameters.hasNext()) }
-}
-
 private fun ObjCExportMapper.bridgeType(kotlinType: KotlinType): TypeBridge {
     val valueType = kotlinType.correspondingValueType
             ?: return ReferenceBridge
@@ -305,30 +206,4 @@ internal fun ObjCExportMapper.bridgePropertyType(descriptor: PropertyDescriptor)
     assert(isBaseProperty(descriptor))
 
     return bridgeType(descriptor.type)
-}
+}
-
-internal enum class ObjCValueType(
-        val kotlinValueType: ValueType, // It is here for simplicity.
-        val encoding: String
-) {
-
-    BOOL(ValueType.BOOLEAN, "c"),
-    CHAR(ValueType.BYTE, "c"),
-    UNSIGNED_SHORT(ValueType.CHAR, "S"),
-    SHORT(ValueType.SHORT, "s"),
-    INT(ValueType.INT, "i"),
-    LONG_LONG(ValueType.LONG, "q"),
-    FLOAT(ValueType.FLOAT, "f"),
-    DOUBLE(ValueType.DOUBLE, "d")
-
-    ;
-
-    // UNSIGNED_SHORT -> unsignedShort
-    val nsNumberName = this.name.split('_').mapIndexed { index, s ->
-        val lower = s.toLowerCase()
-        if (index > 0) lower.capitalize() else lower
-    }.joinToString("")
-
-    val nsNumberValueSelector get() = "${nsNumberName}Value"
-    val nsNumberFactorySelector get() = "numberWith${nsNumberName.capitalize()}:"
-}

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

@@ -16,9 +16,9 @@
 
 package org.jetbrains.kotlin.backend.konan.objcexport
 
-import org.jetbrains.kotlin.backend.konan.Context
 import org.jetbrains.kotlin.backend.konan.descriptors.isArray
 import org.jetbrains.kotlin.backend.konan.descriptors.isInterface
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.incremental.components.NoLookupLocation
 import org.jetbrains.kotlin.name.FqName
@@ -28,11 +28,14 @@ import org.jetbrains.kotlin.resolve.descriptorUtil.isSubclassOf
 import org.jetbrains.kotlin.resolve.descriptorUtil.module
 import org.jetbrains.kotlin.resolve.descriptorUtil.parentsWithSelf
 
-internal class ObjCExportNamer(val context: Context, val mapper: ObjCExportMapper) {
+internal class ObjCExportNamer(val moduleDescriptor: ModuleDescriptor,
+        val builtIns: KotlinBuiltIns,
+        val mapper: ObjCExportMapper,
+        private val topLevelNamePrefix: String = moduleDescriptor.namePrefix
+    ) {
     val kotlinAnyName = "KotlinBase"
 
-    private val commonPackageSegments = context.moduleDescriptor.guessMainPackage().pathSegments()
+    private val commonPackageSegments = moduleDescriptor.guessMainPackage().pathSegments()
-    private val topLevelNamePrefix = context.moduleDescriptor.namePrefix
 
     val mutableSetName = "${topLevelNamePrefix}MutableSet"
     val mutableMapName = "${topLevelNamePrefix}MutableDictionary"
@@ -116,7 +119,7 @@ internal class ObjCExportNamer(val context: Context, val mapper: ObjCExportMappe
             StringBuilder().apply {
                 append(topLevelNamePrefix)
 
-                if (descriptor.module != context.moduleDescriptor) {
+                if (descriptor.module != moduleDescriptor) {
                     append(descriptor.module.namePrefix)
                 }
 
@@ -246,11 +249,11 @@ internal class ObjCExportNamer(val context: Context, val mapper: ObjCExportMappe
     }
 
     init {
-        val any = context.builtIns.any
+        val any = builtIns.any
 
         classNames.forceAssign(any, kotlinAnyName)
-        classNames.forceAssign(context.builtIns.mutableSet, mutableSetName)
+        classNames.forceAssign(builtIns.mutableSet, mutableSetName)
-        classNames.forceAssign(context.builtIns.mutableMap, mutableMapName)
+        classNames.forceAssign(builtIns.mutableMap, mutableMapName)
 
         fun ClassDescriptor.method(name: String) =
                 this.unsubstitutedMemberScope.getContributedFunctions(
@@ -439,7 +442,7 @@ private fun ObjCExportMapper.canHaveSameName(first: PropertyDescriptor, second:
     return bridgePropertyType(first) == bridgePropertyType(second)
 }
 
-private val ModuleDescriptor.namePrefix: String get() {
+internal val ModuleDescriptor.namePrefix: String get() {
     // <fooBar> -> FooBar
     val moduleName = this.name.asString().let { it.substring(1, it.lastIndex) }.capitalize()
 

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

@@ -0,0 +1,20 @@
+package org.jetbrains.kotlin.backend.konan.objcexport
+
+internal class StubBuilder {
+    private val children = mutableListOf<Stub<*>>()
+
+    operator fun Stub<*>.unaryPlus() {
+        children.add(this)
+    }
+
+    operator fun plusAssign(set: Collection<Stub<*>>) {
+        children += set
+    }
+
+    fun build() = children
+}
+
+internal inline fun buildMembers(block: StubBuilder.() -> Unit): List<Stub<*>> = StubBuilder().let {
+    it.block()
+    it.build()
+}

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

@@ -0,0 +1,179 @@
+package org.jetbrains.kotlin.backend.konan.objcexport
+
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+
+object StubRenderer {
+    fun render(stub: Stub<*>): List<String> = collect {
+        stub.run {
+            when (this) {
+                is ObjCProtocol -> {
+                    +renderProtocolHeader()
+                    +"@required"
+                    renderMembers(this)
+                    +"@end;"
+                }
+                is ObjCInterface -> {
+                    attributes.forEach {
+                        +renderAttribute(it)
+                    }
+                    +renderInterfaceHeader()
+                    renderMembers(this)
+                    +"@end;"
+                }
+                is ObjCMethod -> {
+                    +renderMethod(this)
+                }
+                is ObjCProperty -> {
+                    +renderProperty(this)
+                }
+                else -> throw IllegalArgumentException("unsupported stub: " + stub::class)
+            }
+        }
+    }
+
+    private fun renderProperty(property: ObjCProperty): String = buildString {
+        fun StringBuilder.appendTypeAndName() {
+            append(' ')
+            append(property.type.render(property.name))
+        }
+
+        fun ObjCProperty.getAllAttributes(): List<String> {
+            if (getterName == null && setterName == null) return attributes
+
+            val allAttributes = attributes.toMutableList()
+            getterName?.let { allAttributes += "getter=$it" }
+            setterName?.let { allAttributes += "setter=$it" }
+            return allAttributes
+        }
+
+        fun StringBuilder.appendAttributes() {
+            val attributes = property.getAllAttributes()
+            if (attributes.isNotEmpty()) {
+                append(' ')
+                attributes.joinTo(this, prefix = "(", postfix = ")")
+            }
+        }
+
+        append("@property")
+        appendAttributes()
+        appendTypeAndName()
+        append(';')
+    }
+
+    private fun renderMethod(method: ObjCMethod): String = buildString {
+        fun appendStaticness() {
+            if (method.isInstanceMethod) {
+                append('-')
+            } else {
+                append('+')
+            }
+        }
+
+        fun appendReturnType() {
+            append(" (")
+            append(method.returnType.render())
+            append(')')
+        }
+
+        fun appendParameters() {
+            assert(method.selectors.size == method.parameters.size ||
+                   method.selectors.size == 1 && method.parameters.size == 0)
+
+            if (method.selectors.size == 1 && method.parameters.size == 0) {
+                append(method.selectors[0])
+            } else {
+                for (i in 0 until method.selectors.size) {
+                    if (i > 0) append(' ')
+
+                    val parameter = method.parameters[i]
+                    val selector = method.selectors[i]
+                    append(selector)
+                    append("(")
+                    append(parameter.type.render())
+                    append(")")
+                    append(parameter.name)
+                }
+            }
+        }
+
+        fun appendAttributes() {
+            if (method.attributes.isNotEmpty()) append(' ')
+            method.attributes.joinTo(this, separator = " ", transform = ::renderAttribute)
+        }
+
+        appendStaticness()
+        appendReturnType()
+        appendParameters()
+        appendAttributes()
+        append(';')
+    }
+
+    private fun ObjCProtocol.renderProtocolHeader() = buildString {
+        append("@protocol ")
+        append(name)
+        appendSuperProtocols(this@renderProtocolHeader)
+    }
+
+    private fun StringBuilder.appendSuperProtocols(clazz: ObjCClass<ClassDescriptor>) {
+        val protocols = clazz.superProtocols
+        if (protocols.isNotEmpty()) {
+            protocols.joinTo(this, separator = ", ", prefix = " <", postfix = ">")
+        }
+    }
+
+    private fun ObjCInterface.renderInterfaceHeader() = buildString {
+        fun appendSuperClass() {
+            if (superClass != null) append(" : $superClass")
+        }
+
+        fun appendGenerics() {
+            val generics = generics
+            if (generics.isNotEmpty()) {
+                generics.joinTo(this, separator = ", ", prefix = "<", postfix = ">")
+            }
+        }
+
+        fun appendCategoryName() {
+            if (categoryName != null) {
+                append(" (")
+                append(categoryName)
+                append(')')
+            }
+        }
+
+        append("@interface ")
+        append(name)
+        appendGenerics()
+        appendCategoryName()
+        appendSuperClass()
+        appendSuperProtocols(this@renderInterfaceHeader)
+    }
+
+    private fun Collector.renderMembers(clazz: ObjCClass<*>) {
+        clazz.members.forEach {
+            +render(it)
+        }
+    }
+
+    private fun renderAttribute(attribute: String) = "__attribute__(($attribute))"
+
+    private fun collect(p: Collector.() -> Unit): List<String> {
+        val collector = Collector()
+        collector.p()
+        return collector.build()
+    }
+
+    private class Collector {
+        private val collection: MutableList<String> = mutableListOf()
+        fun build(): List<String> = collection
+
+        operator fun String.unaryPlus() {
+            collection += this
+        }
+
+        operator fun List<String>.unaryPlus() {
+            collection += this
+        }
+    }
+}
+

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

@@ -0,0 +1,129 @@
+/*
+ * 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 org.jetbrains.kotlin.backend.konan.objcexport
+
+import org.jetbrains.kotlin.backend.konan.ValueType
+
+sealed class ObjCType {
+    final override fun toString(): String = this.render()
+
+    abstract fun render(attrsAndName: String): String
+
+    fun render() = render("")
+
+    protected fun String.withAttrsAndName(attrsAndName: String) =
+            if (attrsAndName.isEmpty()) this else "$this ${attrsAndName.trimStart()}"
+}
+
+internal class ObjCRawType(private val rawText: String) : ObjCType() {
+    override fun render(attrsAndName: String): String = rawText.withAttrsAndName(attrsAndName)
+}
+
+internal sealed class ObjCReferenceType : ObjCType()
+
+internal sealed class ObjCNonNullReferenceType : ObjCReferenceType()
+
+internal data class ObjCNullableReferenceType(val nonNullType: ObjCNonNullReferenceType) : ObjCReferenceType() {
+    override fun render(attrsAndName: String) = nonNullType.render(" _Nullable".withAttrsAndName(attrsAndName))
+}
+
+internal class ObjCClassType(
+        val className: String,
+        val typeArguments: List<ObjCNonNullReferenceType> = emptyList()
+) : ObjCNonNullReferenceType() {
+
+    override fun render(attrsAndName: String) = buildString {
+        append(className)
+        if (typeArguments.isNotEmpty()) {
+            append("<")
+            typeArguments.joinTo(this) { it.render() }
+            append(">")
+        }
+        append(" *")
+        append(attrsAndName)
+    }
+}
+
+internal class ObjCProtocolType(val protocolName: String) : ObjCNonNullReferenceType() {
+
+    override fun render(attrsAndName: String) = "id<$protocolName>".withAttrsAndName(attrsAndName)
+}
+
+internal object ObjCIdType : ObjCNonNullReferenceType() {
+    override fun render(attrsAndName: String) = "id".withAttrsAndName(attrsAndName)
+}
+
+internal object ObjCInstanceType : ObjCNonNullReferenceType() {
+    override fun render(attrsAndName: String): String = "instancetype".withAttrsAndName(attrsAndName)
+}
+
+internal class ObjCBlockPointerType(
+        val returnType: ObjCReferenceType, val parameterTypes: List<ObjCReferenceType>
+) : ObjCNonNullReferenceType() {
+
+    override fun render(attrsAndName: String) = returnType.render(buildString {
+        append("(^")
+        append(attrsAndName)
+        append(")(")
+        if (parameterTypes.isEmpty()) append("void")
+        parameterTypes.joinTo(this) { it.render() }
+        append(')')
+    })
+}
+
+internal class ObjCPrimitiveType(val cName: String) : ObjCType() {
+    override fun render(attrsAndName: String) = cName.withAttrsAndName(attrsAndName)
+}
+
+internal class ObjCPointerType(val pointee: ObjCType, val nullable: Boolean = false) : ObjCType() {
+    override fun render(attrsAndName: String) =
+            pointee.render("*${if (nullable) {
+                " _Nullable".withAttrsAndName(attrsAndName)
+            } else {
+                attrsAndName
+            }}")
+}
+
+internal object ObjCVoidType : ObjCType() {
+    override fun render(attrsAndName: String) = "void".withAttrsAndName(attrsAndName)
+}
+
+internal enum class ObjCValueType(
+        val kotlinValueType: ValueType, // It is here for simplicity.
+        val encoding: String
+) {
+
+    BOOL(ValueType.BOOLEAN, "c"),
+    CHAR(ValueType.BYTE, "c"),
+    UNSIGNED_SHORT(ValueType.CHAR, "S"),
+    SHORT(ValueType.SHORT, "s"),
+    INT(ValueType.INT, "i"),
+    LONG_LONG(ValueType.LONG, "q"),
+    FLOAT(ValueType.FLOAT, "f"),
+    DOUBLE(ValueType.DOUBLE, "d")
+
+    ;
+
+    // UNSIGNED_SHORT -> unsignedShort
+    val nsNumberName = this.name.split('_').mapIndexed { index, s ->
+        val lower = s.toLowerCase()
+        if (index > 0) lower.capitalize() else lower
+    }.joinToString("")
+
+    val nsNumberValueSelector get() = "${nsNumberName}Value"
+    val nsNumberFactorySelector get() = "numberWith${nsNumberName.capitalize()}:"
+}

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

@@ -0,0 +1,53 @@
+package org.jetbrains.kotlin.backend.konan.objcexport
+
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
+import org.jetbrains.kotlin.descriptors.ParameterDescriptor
+import org.jetbrains.kotlin.descriptors.PropertyDescriptor
+
+open class Stub<out D : DeclarationDescriptor>(val name: String, val descriptor: D?)
+
+abstract class ObjCClass<out D : DeclarationDescriptor>(name: String,
+                                                        descriptor: D?,
+                                                        val superProtocols: List<String>,
+                                                        val members: List<Stub<*>>) : Stub<D>(name, descriptor)
+
+class ObjCProtocol(name: String,
+                   descriptor: ClassDescriptor,
+                   superProtocols: List<String>,
+                   members: List<Stub<*>>) : ObjCClass<ClassDescriptor>(name, descriptor, superProtocols, members)
+
+class ObjCInterface(name: String,
+                    val generics: List<String> = emptyList(),
+                    descriptor: ClassDescriptor? = null,
+                    val superClass: String? = null,
+                    superProtocols: List<String> = emptyList(),
+                    val categoryName: String? = null,
+                    members: List<Stub<*>> = emptyList(),
+                    val attributes: List<String> = emptyList()) : ObjCClass<ClassDescriptor>(name, descriptor, superProtocols, members)
+
+class ObjCMethod(descriptor: DeclarationDescriptor?,
+                 val isInstanceMethod: Boolean,
+                 val returnType: ObjCType,
+                 val selectors: List<String>,
+                 val parameters: List<ObjCParameter>,
+                 val attributes: List<String>) : Stub<DeclarationDescriptor>(buildMethodName(selectors, parameters), descriptor)
+
+class ObjCParameter(name: String,
+                    descriptor: ParameterDescriptor?,
+                    val type: ObjCType) : Stub<ParameterDescriptor>(name, descriptor)
+
+class ObjCProperty(name: String,
+                   descriptor: PropertyDescriptor?,
+                   val type: ObjCType,
+                   val attributes: List<String>,
+                   val setterName: String? = null,
+                   val getterName: String? = null) : Stub<PropertyDescriptor>(name, descriptor)
+
+private fun buildMethodName(selectors: List<String>, parameters: List<ObjCParameter>): String =
+        if (selectors.size == 1 && parameters.size == 0) {
+            selectors[0]
+        } else {
+            assert(selectors.size == parameters.size)
+            selectors.joinToString(separator = "")
+        }