Motivation

• Make it easier to support imported/exported type mixed signature in the future. (e.g. using imported JS type in exported API signature, vice versa) [BridgeJS] Support imported TS type usage on exported interface #497
• Allow developers to import JS APIs without writing TS declaration (a part of [BridgeJS] Support @JS var declarations for global scope imports #466)
• Allow other tools to easily generate imported JS interfaces from non-TS sources
  • e.g. WebIDL, WebGPU dawn.json, etc...

Example

Given bridge-js.d.ts:

export class Greeter {
  constructor(name: string);
  greet(): string;
  get name(): string;
  set name(value: string);
}

ts2swift now emits human-read/writable Swift declarations:

@_spi(Experimental) import JavaScriptKit

@JSClass struct Greeter: _JSBridgedClass {
    @JSFunction init(_ name: String) throws (JSException)
    @JSFunction func greet() throws (JSException) -> String
    @JSGetter var name: String
    @JSSetter func setName(_ value: String) throws (JSException)
}

Then the macro-annotated importing declarations are processed by ImportSwiftMacros, then it produces ImportedModuleSkeleton.
ImportTS takes the generated ImportedModuleSkeleton and produce Swift glue code. Note that now ImportTS is not responsible to generate user-facing interface like class declarations, but just generate thunk implementations. (maybe the Swift macro might generate thunks directly in the future).

graph LR
    subgraph ModuleA
        A.swift --> G1[bridge-js generate]
        B.swift --> G1
        B1[bridge-js.d.ts] --> T1[[ts2swift]]
        T1 --> M1[BridgeJS.Macros.swift]
        M1 --> G1
        G1 --> G3[BridgeJS.json]
        G1 --> G2[BridgeJS.swift]
    end

    subgraph ModuleB
        C.swift --> G4[bridge-js generate]
        D.swift --> G4
        B2[bridge-js.d.ts] --> T2[[ts2swift]]
        T2 --> M2[BridgeJS.Macros.swift]
        M2 --> G4
        G4 --> G5[BridgeJS.swift]
        G4 --> G6[BridgeJS.json]
    end

    G3 --> L1[[bridge-js link]]
    G6 --> L1

    L1 --> F1[bridge-js.js]
    L1 --> F2[bridge-js.d.ts]
    ModuleA -----> App[App.wasm]
    ModuleB -----> App

    App --> PKG[[PackageToJS]]
    F1 --> PKG
    F2 --> PKG