Basic support for conditional types

src/converter/plugins/convertConditionalType.ts

@@ -0,0 +1,16 @@
+import ts, {ConditionalTypeNode} from "typescript";
+import {createSimplePlugin} from "../plugin.js";
+import {TypeScriptService, typeScriptServiceKey} from "./TypeScriptPlugin.js";
+import {isPossiblyNullableType} from "./NullableUnionTypePlugin.js";
+
+export const convertConditionalType = createSimplePlugin((node, context, render) => {
+    if (!ts.isConditionalTypeNode(node)) return null
+
+    const typeScriptService = context.lookupService<TypeScriptService>(typeScriptServiceKey)
+
+    const isNullableTrue = isPossiblyNullableType(node.trueType, context)
+    const isNullableFalse = isPossiblyNullableType(node.falseType, context)
+    const isNullable = isNullableTrue || isNullableFalse
+
+    return `Any${isNullable ? "?" : ""} /* ${typeScriptService?.printNode(node)} */`;
+})

src/defaultPlugins.ts

@@ -59,6 +59,7 @@ import {convertLiteral} from "./converter/plugins/convertLiteral.js";
 import {inheritedTypeLiteralPlugin} from "./converter/plugins/InheritedTypeLiteralPlugin.js";
 import {Injection} from "./converter/injection.js";
 import {InjectionPlugin} from "./converter/plugins/InjectionPlugin.js";
+import {convertConditionalType} from "./converter/plugins/convertConditionalType.js";
 
 const hasKind = (kind: ts.SyntaxKind) => (node: Node) => node.kind === kind
 
@@ -149,4 +150,5 @@ export const createPlugins = (
     convertMappedType,
     convertIndexedSignatureDeclaration,
     convertTypeQuery,
+    convertConditionalType,
 ]

test/functional/base/generated/conditionalType/simple.kt

@@ -0,0 +1,14 @@
+// Generated by Karakum - do not modify it manually!
+
+@file:JsModule("sandbox-base/conditionalType/simple")
+@file:Suppress(
+    "NON_EXTERNAL_DECLARATION_IN_INAPPROPRIATE_FILE",
+)
+
+package sandbox.base.conditionalType
+
+
+
+typealias TestConditional<S> = Any /* S extends () => infer P ? Promise<P> : Promise<void> */
+
+typealias TestNullableConditional<S> = Any? /* S extends () => infer P ? Promise<P> | null : Promise<void> */

test/functional/base/lib/conditionalType/simple.d.ts

@@ -0,0 +1,3 @@
+type TestConditional<S> = S extends () => infer P ? Promise<P> : Promise<void>;
+
+type TestNullableConditional<S> = S extends () => infer P ? Promise<P> | null : Promise<void>;