From 0c74eef50041ce6924185691c7d0839160a9e57c Mon Sep 17 00:00:00 2001
From: Roman Artemev <roman.artemev@jetbrains.com>
Date: Fri, 12 Apr 2019 17:35:34 +0300
Subject: [PATCH] Implement IrType context

---
 .../kotlin/ir/types/IrTypeSubstitutor.kt      | 63 +++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/IrTypeSubstitutor.kt

diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/IrTypeSubstitutor.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/IrTypeSubstitutor.kt
new file mode 100644
index 00000000000..6cfe36cd32f
--- /dev/null
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/IrTypeSubstitutor.kt
@@ -0,0 +1,63 @@
+/*
+ * Copyright 2010-2019 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.ir.types
+
+import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
+import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
+import org.jetbrains.kotlin.ir.types.impl.IrSimpleTypeImpl
+import org.jetbrains.kotlin.ir.types.impl.makeTypeProjection
+import org.jetbrains.kotlin.ir.types.impl.originalKotlinType
+import org.jetbrains.kotlin.types.Variance
+
+
+class IrTypeSubstitutor(
+    typeParameters: List<IrTypeParameterSymbol>,
+    typeArguments: List<IrTypeArgument>,
+    private val irBuiltIns: IrBuiltIns
+) {
+    private val substitution = typeParameters.zip(typeArguments).toMap()
+
+    fun substitute(type: IrType) = if (substitution.isNotEmpty()) doSubstituteType(type) else type
+
+    private fun doSubstituteTypeArgument(typeArgument: IrTypeArgument): IrTypeArgument {
+        if (typeArgument is IrStarProjection) return typeArgument
+
+        require(typeArgument is IrTypeProjection)
+
+        return if (typeArgument is IrSimpleType) {
+            val classifier = typeArgument.classifier
+            if (classifier is IrTypeParameterSymbol) substitution.getValue(classifier)
+            else {
+                makeTypeProjection(doSubstituteType(typeArgument), Variance.INVARIANT)
+            }
+        } else makeTypeProjection(doSubstituteType(typeArgument.type), typeArgument.variance)
+    }
+
+    private fun doSubstituteType(type: IrType): IrType = when (type) {
+        is IrErrorType -> type
+        is IrDynamicType -> type
+        is IrSimpleType -> {
+            val classifier = type.classifier
+            if (classifier is IrTypeParameterSymbol) {
+                val argument = substitution.getValue(classifier)
+                if (argument is IrTypeProjection) {
+                    argument.type
+                } else irBuiltIns.anyNType // StarProjection
+            } else {
+                type.run {
+                    IrSimpleTypeImpl(
+                        originalKotlinType,
+                        classifier,
+                        hasQuestionMark,
+                        arguments.map { doSubstituteTypeArgument(it) },
+                        annotations
+                    )
+                }
+            }
+        }
+        else -> error("Unknown type")
+    }
+}