Typescript Stubgen Command

[nicoburniske]

Finally upstreaming what was originally done here #451

Introduces new command stubgen that will create all typescript declaration files from the corresponding wit types. There are rust tests for some of the complex cases

• WIT exports get a stub interface type
• Each WIT import interface gets it's own {package}{interface}.d.ts file

WIT Exports

This simple wit, will generate the following "stub" type for the user to then implement and export from their component

package test:basic;

interface greet {
    say-hello: func(name: string) -> string;
}

world test {
    export greet;
}

test.d.ts

export interface Greet {
    sayHello(name: string): string,
}

export interface TestWorld {
    greet: Greet,
}

So then developers can import the types, and implement them.

import { TestWorld, Greet } from './generated/test';

export const greet: Greet = {
  sayHello: (name: string) => {
    return `Hello, ${name}!`;
  }
};

WIT Imports

package test:types;

interface types {
    type dimension = u32;
    record point {
        x: dimension,
        y: dimension,
    }
}

package test:canvas;

interface canvas {
    use test:types/types.{dimension, point};
    type canvas-id = u64;
    draw-line: func(canvas: canvas-id, origin: point, target: point, thickness: dimension);
}

This would generate two typescript files, one for each interface

interfaces/test-canvas-canvas.d.ts

declare module "test:canvas/canvas" {
    import type { Dimension } from "test:types/types";
    import type { Point } from "test:types/types";
    export type CanvasId = bigint;
    export function drawLine(canvas: CanvasId, origin: Point, target: Point, thickness: Dimension): void;
} 

interfaces/test-types-types.d.ts

declare module "test:types/types" {
    export type Dimension = number;
    export interface Point {
        x: Dimension,
        y: Dimension,
    }
}