Introduction

This PR adds support for Swift Optionals when exporting Swift funcionality to JS / TS using BridgeJS plugin.

Overview

• Swift Optionals are represented byT | null union, asnull explicitly represents intentional absent of value, which aligns with Swift's nil.
• for each parameter additional "isSome" flag is used to represent optionality.
• new sharedextension Optionals were added toBridgeJSIntrinsics to keep generated Swift glue code sparse and reuse existing patterns. This required new protocols for case and associated enum value types, which
• for support of return values, new bjs module methods were added for JS lowering_swift_js_return_optional_<type>
• support for different Optional syntax was added (including typealiasing), so all of the below should work identically:

@JSfunc test(name:String?)->String?@JS func test(name:Optional<String>)->Optional<String>@JSfunc test(name:Swift.Optional<String>)->Swift.Optional<String>@JSfunc test(name:Swift.Optional<String>)->Swift.Optional<String.>typealias OptionalName= String?@JSfunc test(name: OptionalName)->OptionalName

Examples

@JSclassUserService{varuserId:Int?func findUser(id:Int)->User?func process(data:String?)->String}

Generated TypeScript:

exportinterfaceUserServiceextendsSwiftHeapObject{userId:number|null;findUser(id:number|null):User|null;process(data:string|null):string;}

Testing

Added tests for different scenarios for all supported optional data types, including parameters, properties and return value usage.

Documentation

Extended current documentation with newExporting-Swift-Optional.md