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Strongly typed deepmerge implementation.
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| type IsObject<T> = T extends object ? T extends any[] ? false : true : false; | |
| function isObject<T>(v: T): IsObject<T> { | |
| return (typeof v === 'object' && !Array.isArray(v)) as IsObject<T>; | |
| } | |
| type Merge2<T, U> = IsObject<T> & IsObject<U> extends true ? { | |
| [K in keyof T]: K extends keyof U ? Merge2<T[K], U[K]> : T[K]; | |
| } & U : U; | |
| function merge2<T, U>(a: T, b: U): Merge2<T, U> { | |
| return ( | |
| isObject(a) && isObject(b) | |
| ? Object.assign({}, a, Object.fromEntries(Object.entries(b).map(([k, v]) => [k, merge2((a as any)[k], v)]))) | |
| : b | |
| ) as Merge2<T, U>; | |
| } | |
| export type Merge<T extends unknown[]> = { | |
| 0: T[0], | |
| 1: T extends [infer Car, ...infer Cdr] ? Merge2<Car, Merge<Cdr>> : T, | |
| }[T extends [unknown, unknown, ...unknown[]] ? 1 : 0]; | |
| export function merge<T extends unknown[]>(...objs: T): Merge<T> { | |
| if (objs.length < 2) return objs[0]; | |
| return merge2(objs[0], merge(...objs.slice(1))); | |
| } |
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