IR: introduce StubGeneratorExtensions for ExternalDependenciesGenerator

This is a refactoring to simplify the API of
ExternalDependenciesGenerator and to constrain future additions of
platform-specific stub generator extensions.

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/DeclarationStubGenerator.kt

@@ -36,9 +36,8 @@ class DeclarationStubGenerator(
     moduleDescriptor: ModuleDescriptor,
     val symbolTable: SymbolTable,
     languageVersionSettings: LanguageVersionSettings,
-    private val externalDeclarationOrigin: ((DeclarationDescriptor) -> IrDeclarationOrigin)? = null,
     private val irProviders: List<IrProvider> = emptyList(),
-    private val facadeClassGenerator: (DeserializedContainerSource) -> IrClass? = { null }
+    private val extensions: StubGeneratorExtensions = StubGeneratorExtensions.EMPTY
 ) {
     private val lazyTable = symbolTable.lazyWrapper
 
@@ -49,7 +48,8 @@ class DeclarationStubGenerator(
         }
 
 
-    val typeTranslator = TypeTranslator(lazyTable, languageVersionSettings, moduleDescriptor.builtIns, LazyScopedTypeParametersResolver(lazyTable), true)
+    val typeTranslator =
+        TypeTranslator(lazyTable, languageVersionSettings, moduleDescriptor.builtIns, LazyScopedTypeParametersResolver(lazyTable), true)
     private val constantValueGenerator = ConstantValueGenerator(moduleDescriptor, lazyTable)
 
     private val facadeClassMap = mutableMapOf<DeserializedContainerSource, IrClass?>()
@@ -79,7 +79,7 @@ class DeclarationStubGenerator(
         val packageFragment = directMember.containingDeclaration as? PackageFragmentDescriptor ?: return null
         val containerSource = directMember.safeAs<DescriptorWithContainerSource>()?.containerSource ?: return null
         return facadeClassMap.getOrPut(containerSource) {
-            facadeClassGenerator(containerSource)?.also { facade ->
+            extensions.generateFacadeClass(containerSource)?.also { facade ->
                 val packageStub = generateOrGetEmptyExternalPackageFragmentStub(packageFragment)
                 facade.parent = packageStub
                 packageStub.declarations.add(facade)
@@ -106,7 +106,7 @@ class DeclarationStubGenerator(
         }
 
     private fun computeOrigin(descriptor: DeclarationDescriptor): IrDeclarationOrigin =
-        externalDeclarationOrigin?.invoke(descriptor) ?: IrDeclarationOrigin.IR_EXTERNAL_DECLARATION_STUB
+        extensions.computeExternalDeclarationOrigin(descriptor) ?: IrDeclarationOrigin.IR_EXTERNAL_DECLARATION_STUB
 
     internal fun generatePropertyStub(
         descriptor: PropertyDescriptor,

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/ExternalDependenciesGenerator.kt

@@ -16,34 +16,28 @@
 
 package org.jetbrains.kotlin.ir.util
 
-import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
 import org.jetbrains.kotlin.descriptors.ModuleDescriptor
-import org.jetbrains.kotlin.ir.declarations.IrClass
-import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
 import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
-import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedContainerSource
 import kotlin.math.min
 
 class ExternalDependenciesGenerator(
     moduleDescriptor: ModuleDescriptor,
     val symbolTable: SymbolTable,
     val irBuiltIns: IrBuiltIns,
-    externalDeclarationOrigin: ((DeclarationDescriptor) -> IrDeclarationOrigin)? = null,
     private val deserializer: IrDeserializer? = null,
     irProviders: List<IrProvider> = emptyList(),
-    facadeClassGenerator: (DeserializedContainerSource) -> IrClass? = { null }
+    extensions: StubGeneratorExtensions = StubGeneratorExtensions.EMPTY
 ) {
     private val stubGenerator = DeclarationStubGenerator(
-        moduleDescriptor, symbolTable, irBuiltIns.languageVersionSettings, externalDeclarationOrigin,
-            listOfNotNull(deserializer) + irProviders, facadeClassGenerator
+        moduleDescriptor, symbolTable, irBuiltIns.languageVersionSettings, listOfNotNull(deserializer) + irProviders, extensions
     )
 
     fun generateUnboundSymbolsAsDependencies() {
         stubGenerator.unboundSymbolGeneration = true
         do {
             fun <T> haveNotStabilized(prev: ArrayList<T>, cur: Set<T>) =
-                    cur.isNotEmpty() && (prev.size != cur.size || prev.any { !cur.contains(it) })
+                cur.isNotEmpty() && (prev.size != cur.size || prev.any { !cur.contains(it) })
 
             val unboundClasses = ArrayList(symbolTable.unboundClasses)
             val unboundConstructors = ArrayList(symbolTable.unboundConstructors)
@@ -89,4 +83,4 @@ class ExternalDependenciesGenerator(
                     s.toList().subList(0, min(10, s.size)).joinToString(separator = "\n") { it.descriptor.toString() }
         }
     }
-}
+}

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/StubGeneratorExtensions.kt

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.ir.util
+
+import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
+import org.jetbrains.kotlin.ir.declarations.IrClass
+import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
+import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedContainerSource
+
+open class StubGeneratorExtensions {
+    open fun computeExternalDeclarationOrigin(descriptor: DeclarationDescriptor): IrDeclarationOrigin? = null
+
+    open fun generateFacadeClass(source: DeserializedContainerSource): IrClass? = null
+
+    companion object {
+        @JvmField
+        val EMPTY = StubGeneratorExtensions()
+    }
+}