feat(router): add req.params type-safety via string patterns; (#16)

Shoutout to @dummdidumm for reminding me! https://www.typescriptlang.org/play?ts=4.2.3#code/C4TwDgpgBACghgJzgWwM5QLxQEoQMYD2CAJgDyrAICWAdgOYA0UF19AfANwBQokOBAV2AR4SNKQAqUCAA9hNYumyDh8YMIQ02mLgEgps+YqgADACQBvWgDMICKAGUAvgC5LNu7CcB+APTuaW3tcCicTPV1vKAsoAG0AaShaWABdbxdmSlo6KCcoADJ+IRFEFFRSEOA2LigoDIM5CAV0cytAz2c3NqCvf27PSrCIqJiEpJpYKAAfKABrCBACayLVUvFKthSMlmzcmrqoBqMWgJ7O088YH3DdSOi4xOSYNO2s+j3a+ulG5tML+3O-XsVxud1Gjwmz1erByTn2GQsTm4PHA0GUxTUGgmWFwdAAojIwNNMjDuLxoAAJOAKAA2dlIMG+x1ga3QWFEZW0WAAFAgIABHDK4fkCCAUAr3MCsjKMpxMPmoIVisAEGioCAASkw2gAbgQqMRkcR8DTENBrAIaHhgFRVVA4MQyEcmsZcQSwGxucgIMAABYEYjQ7LylQQepMX3U4h0hAZKm0+kctBsDUZPUG7jGvCmvlQC1Wm12h1Opku9A7dhen3+wMk4NQBCh8NQSMJ2NQePR+no1ZicoSNgptP6w1cFF8ACCmBWJT7pAA5L5rAQCPPquSoAAhac92dlBe+FzL1fr1FQADCO9DSfKi6PK+8a7HG4nAEYrxjWQfj4eAEaIJ8N03d8cWvL87x-Fx-wQQCz3PECZxvA97wIPwoIA08+AAEQQ3ckIgh8-0QR9qnHaAJwAJg-Xt90XSDoN8f8AC9YL4TcqNAz85wIggiIQRi4BYzDoHPDjEPAw9jzQhjmNY6AsLEvCJJQ6TiIEoTnzPCcAGZqL3cQ6JXdS+LkrddM4miDMkozmJM4SL3M8TuOs1DjPQmD7KwxylOclS3Ogkix2Lbl5wAcTxCR5yYQzeJcA1HyYXkBXlMUtQwbQLH2XxfCgAABYBUAAWlkSBrWKhBGwQfY+X5AA6KU+1qmgUAgLgnA1ILHRC8LIuipcjLi4g0Oa70oqgJL+RS1A0oy6qBXq1kmpatqOq4YKwoisb+t4xKaqmmbojmuqGrKJbvRWsc1q6+cYAAeQcXqoB4saau1Q7ahqhbGuPFagA
lukeed · Mar 24, 2021 · b048388 · b048388
1 parent fbd318c
commit b048388
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Showing 4 changed files with 104 additions and 7 deletions.
diff --git a/src/request.d.ts b/src/request.d.ts
@@ -120,7 +120,7 @@ export interface IncomingCloudflareProperties {
 	timezone?: string;
 }
 
-export declare class ServerRequest {
+export declare class ServerRequest<P extends Params = Params> {
 	constructor(event: FetchEvent);
 	url: string;
 	path: string;
@@ -131,7 +131,7 @@ export declare class ServerRequest {
 	extend: FetchEvent['waitUntil'];
 	cf: IncomingCloudflareProperties;
 	headers: Headers;
-	params: Params;
+	params: P;
 	body: {
 		<T>(): Promise<T|void>;
 		json<T=any>(): Promise<T>;

diff --git a/src/router.d.ts b/src/router.d.ts
@@ -26,10 +26,24 @@ export function reply(handler: ResponseHandler): FetchHandler;
 export function listen(handler: ResponseHandler): void;
 
 export type Route = { params: Params; handler: Handler | false };
-export type Handler = (req: ServerRequest, res: ServerResponse) => Promisable<Response|void>;
+export type Handler<P extends Params = Params> = (req: ServerRequest<P>, res: ServerResponse) => Promisable<Response|void>;
+
+// TODO: wildcard
+export type RouteParams<T extends string> =
+  T extends `${infer S}:${infer P}?/${infer Rest}`
+		? { [K in P]?: string } & RouteParams<Rest>
+  : T extends `${infer S}:${infer P}/${infer Rest}`
+		? { [K in P | keyof RouteParams<Rest>]: string }
+  : T extends `${infer S}:${infer P}?`
+		? { [K in P]?: string }
+  : T extends `${infer S}:${infer P}`
+		? { [K in P]: string }
+  : {};
 
 export declare class Router {
-	add(method: string, route: RegExp | string, handler: Handler): void;
+	add<T extends RegExp>(method: string, route: T, handler: Handler<Params>): void;
+	add<T extends string>(method: string, route: T, handler: Handler<RouteParams<T>>): void;
+
 	find(method: string, pathname: string): Route;
 	run(event: FetchEvent): Promise<Response>;
 	onerror(req: ServerRequest, res: ServerResponse, status?: number, error?: Error): Promisable<Response>;

diff --git a/src/router.ts b/src/router.ts
@@ -42,7 +42,7 @@ export function Router(): RR {
 	let $: RR, tree: Tree = {};
 
 	return $ = {
-		add(method, route, handler) {
+		add(method: string, route: RegExp | string, handler: Handler) {
 			let dict = tree[method];
 
 			if (dict === void 0) {

diff --git a/types/check.ts b/types/check.ts
@@ -6,8 +6,8 @@ import { byteLength, HEX, uid, uuid } from 'worktop/utils';
 import { listen, reply, Router, STATUS_CODES } from 'worktop';
 
 import type { KV } from 'worktop/kv';
-import type { FetchHandler, Route } from 'worktop';
-import type { ServerRequest, IncomingCloudflareProperties } from 'worktop/request';
+import type { FetchHandler, Route, RouteParams } from 'worktop';
+import type { Params, ServerRequest, IncomingCloudflareProperties } from 'worktop/request';
 
 declare function assert<T>(value: T): void;
 
@@ -199,6 +199,89 @@ Cache.reply(API.run);
 Cache.listen(reply(API.run));
 Cache.listen(API.run);
 
+/**
+ * WORKTOP/ROUTER
+ * > PATTERNS & PARAMS
+ */
+
+let foo='', bar='';
+
+// @ts-expect-error
+assert<RouteParams<'/:foo'>>({ /*empty*/ });
+assert<RouteParams<'/:foo'>>({ foo });
+assert<RouteParams<'/:foo?'>>({ foo });
+assert<RouteParams<'/:foo?'>>({ /*empty*/ });
+assert<RouteParams<'/foo'>>({ /*empty*/ });
+
+// @ts-expect-error
+assert<RouteParams<'/foo/:bar'>>({ /*empty*/ });
+assert<RouteParams<'/foo/:bar'>>({ bar });
+// @ts-expect-error
+assert<RouteParams<'/:foo/:bar'>>({ bar });
+assert<RouteParams<'/:foo/:bar'>>({ foo, bar });
+// @ts-expect-error
+assert<RouteParams<'/:foo?/:bar'>>({ /*empty*/ });
+assert<RouteParams<'/:foo?/:bar'>>({ foo, bar });
+assert<RouteParams<'/:foo?/:bar'>>({ bar });
+assert<RouteParams<'/:foo?/:bar?'>>({ /*empty*/ });
+
+// @ts-expect-error
+assert<RouteParams<'/foo/:bar/baz'>>({ /*empty*/ });
+assert<RouteParams<'/foo/:bar/baz'>>({ bar });
+assert<RouteParams<'/:foo/:bar/baz'>>({ foo, bar});
+assert<RouteParams<'/:foo?/:bar/baz'>>({ foo, bar });
+assert<RouteParams<'/:foo?/:bar/baz'>>({ bar });
+assert<RouteParams<'/:foo?/:bar?/baz'>>({ /*empty*/ });
+assert<RouteParams<'/:foo?/:bar?/baz'>>({ foo, bar });
+assert<RouteParams<'/:foo?/:bar?/baz'>>({ bar });
+
+// @ts-expect-error
+assert<RouteParams<'/foo/baz/:bar'>>({ /*empty*/ });
+assert<RouteParams<'/foo/baz/:bar'>>({ bar });
+// @ts-expect-error
+assert<RouteParams<'/:foo/baz/:bar'>>({ /*empty*/ });
+// @ts-expect-error
+assert<RouteParams<'/:foo/baz/:bar'>>({ foo });
+assert<RouteParams<'/:foo/baz/:bar'>>({ foo, bar });
+// @ts-expect-error
+assert<RouteParams<'/:foo?/baz/:bar'>>({ /*empty*/ });
+assert<RouteParams<'/:foo?/baz/:bar'>>({ foo, bar });
+assert<RouteParams<'/:foo?/baz/:bar'>>({ bar });
+// @ts-expect-error
+assert<RouteParams<'/:foo?/baz/:bar?'>>({ hello: 'x' });
+assert<RouteParams<'/:foo?/baz/:bar?'>>({ /*empty*/ });
+assert<RouteParams<'/:foo?/baz/:bar?'>>({ foo, bar });
+assert<RouteParams<'/:foo?/baz/:bar?'>>({ bar });
+
+API.add('GET', '/foo', (req) => {
+	assert<{}>(req.params);
+	// @ts-expect-error
+	req.params.anything;
+});
+
+API.add('GET', '/foo/:bar', (req) => {
+	assert<{ bar: string }>(req.params);
+	assert<string>(req.params.bar);
+	// @ts-expect-error
+	req.params.hello;
+});
+
+API.add('GET', '/foo/:bar?/:baz', (req) => {
+	assert<{ bar?: string, baz: string }>(req.params);
+	assert<string|undefined>(req.params.bar);
+	assert<string>(req.params.baz);
+	// @ts-expect-error
+	assert<string>(req.params.bar);
+	// @ts-expect-error
+	req.params.hello;
+});
+
+API.add('GET', /^[/]foobar[/]?/, (req) => {
+	assert<{}>(req.params);
+	assert<Params>(req.params);
+	assert<string>(req.params.anything);
+});
+
 
 /**
  * WORKTOP/CACHE