Created
March 21, 2024 08:35
-
-
Save jussi-kalliokoski/374f7c0273979abaa82ed14f70e420ab to your computer and use it in GitHub Desktop.
A fully typed route parser.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
// Usage: | |
// let parseRoute = routeParser("/users/{userId}/posts/{postId}"); | |
// let params = parseRoute("/users/123/posts/456"); | |
// console.log(params); // { userId: "123", postId: "456" } | |
const KIND_KEY = "key" as const; | |
const KIND_VALUE = "value" as const; | |
/** | |
* Create a route parser from a route string. | |
* @template {string} Route - A string literal type representing the route. | |
* @param {Route} route - The route string. | |
* @returns {RouteParser<Route>} - A function that takes a path string and returns the route parameters or null if the path does not match the route. | |
*/ | |
export function routeParser<Route extends string>(route: Route): RouteParser<Route> { | |
const parts = routeParts(route); | |
return ((path) => { | |
const result: Record<string, string> = {}; | |
for (let i = 0; i < parts.length; i++) { | |
const part = parts[i]; | |
if (part.kind === KIND_KEY) { | |
if (i === parts.length - 1) { | |
result[part.value] = path; | |
return result; | |
} | |
const nextPart = parts[i + 1]; | |
const nextPartStart = path.indexOf(nextPart.value); | |
if (nextPartStart === -1) { | |
return null; | |
} | |
result[part.value] = path.slice(0, nextPartStart); | |
path = path.slice(nextPartStart); | |
} else { | |
const { value } = part; | |
if (!path.startsWith(value)) { | |
return null; | |
} | |
path = path.slice(value.length); | |
} | |
} | |
return result; | |
}) as RouteParser<Route>; | |
}; | |
function routeParts(route: string): Array<RoutePart> { | |
const parts = []; | |
while (route.length >= 0) { | |
if (route.startsWith("{")) { | |
route = route.slice(1); | |
const end = route.indexOf("}"); | |
parts.push({ kind: KIND_KEY, value: route.slice(0, end) }); | |
route = route.slice(end + 1); | |
if (route.startsWith("{")) { | |
throw new Error("Invalid route: multiple parameters in a row"); | |
} | |
} else { | |
const end = route.indexOf("{"); | |
if (end === -1) { | |
parts.push({ kind: KIND_VALUE, value: route }); | |
break; | |
} | |
parts.push({ kind: KIND_VALUE, value: route.slice(0, end) }); | |
route = route.slice(end); | |
} | |
} | |
return parts; | |
} | |
type RouteParser<Route extends string> = | |
Route extends `${string}}{${string}` | |
? never | |
: (path: string) => (RouteParams<Route> | null); | |
type RoutePart = | |
| { kind: typeof KIND_KEY, value: string } | |
| { kind: typeof KIND_VALUE, value: string }; | |
type RouteParams<Route extends string> = Record<RouteKeys<Route>[number], string>; | |
type RouteKeys<Route extends string, Parts extends Array<string> = []> = | |
Route extends `{${infer Rest}` | |
? RouteKeys<RouteKeysExtractRest<Rest>, [...Parts, RouteKeysExtractKey<Rest>]> | |
: Route extends `${infer Head}{${infer Rest}` | |
? RouteKeys<RouteKeysExtractRest<Rest>, [...RouteKeys<Head, Parts>, RouteKeysExtractKey<Rest>]> | |
: Parts; | |
type RouteKeysExtractRest<Route extends string> = | |
Route extends `${string}}${infer Rest}` | |
? Rest | |
: never; | |
type RouteKeysExtractKey<Route extends string> = | |
Route extends `${infer Key}}${string}` | |
? Key | |
: never; |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment