New J2K: Add TypeParametersNullabilityConversion

j2k/newSrc/org/jetbrains/kotlin/j2k/ConversionsRunner.kt

@@ -58,6 +58,7 @@ object ConversionsRunner {
             +ForConversion(context)
             +ForInConversion()
             +CollectionOperationsConversion(context)
+            +TypeParametersNullabilityConversion()
             +ArrayOperationsConversion(context)
             +TypeMappingConversion(context)
             +ImplicitCastsConversion(context)

j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/TypeParametersNullabilityConversion.kt

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. 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.j2k.conversions
+
+import org.jetbrains.kotlin.j2k.ast.Nullability
+import org.jetbrains.kotlin.j2k.tree.*
+import org.jetbrains.kotlin.j2k.tree.impl.*
+
+
+class TypeParametersNullabilityConversion : RecursiveApplicableConversionBase() {
+    override fun applyToElement(element: JKTreeElement): JKTreeElement {
+        if (element !is JKTypeParameterList) return recurse(element)
+        val typeParametersNullabilityMap =
+            element.typeParameters.map { typeParameter ->
+                typeParameter.name.value to typeParameter.hasNullableUpperBounds()
+            }.toMap()
+        return JKTypeParameterListImpl(
+            element.typeParameters.map { typeParameter ->
+                val name = typeParameter.name.value
+                JKTypeParameterImpl(
+                    JKNameIdentifierImpl(name),
+                    typeParameter.upperBounds.map { upperBoundTypeElement ->
+                        JKTypeElementImpl(
+                            upperBoundTypeElement.type.makeTypeParametersNotNull(typeParametersNullabilityMap)
+                        )
+                    }
+                )
+            }
+        )
+    }
+
+    private fun JKType.makeTypeParametersNotNull(nullabilityMap: Map<String, Boolean>): JKType =
+        when (this) {
+            is JKClassType ->
+                JKClassTypeImpl(
+                    classReference,
+                    parameters.map { it.makeTypeParametersNotNull(nullabilityMap) },
+                    nullability
+                )
+            is JKTypeParameterType ->
+                nullabilityMap[name]
+                    ?.takeIf { nullability == Nullability.Default }
+                    ?.let { isNullable ->
+                        JKTypeParameterTypeImpl(
+                            name,
+                            if (isNullable) Nullability.NotNull else Nullability.Nullable
+                        )
+                    } ?: this
+
+            is JKVarianceTypeParameterType ->
+                JKVarianceTypeParameterTypeImpl(
+                    variance,
+                    boundType.makeTypeParametersNotNull(nullabilityMap)
+                )
+            else -> this
+        }
+
+    private fun JKTypeParameter.hasNullableUpperBounds(): Boolean =
+        upperBounds.any { it.type.isNullable() }
+}