Created
September 1, 2022 05:31
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schema から型定義を作る
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| // 文字列リテラル型を対応するプリミティブ型に変換する | |
| type Lift<T> = T extends readonly [ string, ...string[] ] ? LiftTuple<T> | |
| : T extends 'null' ? null | |
| : T extends 'boolean' ? boolean | |
| : T extends 'object' ? { [ key: string ]: any } | |
| : T extends 'array' ? any[] | |
| : T extends 'string' ? string | |
| : T extends 'number' | 'integer' ? number | |
| : any; | |
| // 上記の変換のタプル版、空タプルは受け付けない | |
| type LiftTuple<T> = T extends readonly [ infer Head, ...infer Tail ] | |
| ? Tail extends [ string, ...string[] ] | |
| ? Lift<Head> | LiftTuple<Tail> | |
| : Lift<Head> | |
| : never; | |
| // ↓↓↓ 使ってみる | |
| type T1 = Lift<'string'>; | |
| // ^ = string | |
| type T2 = Lift<'integer'>; | |
| // ^ = number | |
| type T3 = Lift<readonly [ 'string', 'integer', 'null' ]>; | |
| // ^ string | number | null | |
| // ========================================================================== // | |
| // schema から型定義を作る | |
| type InferSchema<T extends { [key: string]: { type: string | readonly string[] } }> | |
| = { [K in keyof T]: Lift<T[K]['type']> } | |
| // ↓↓↓ 使ってみる | |
| const attributes = { | |
| foo: { type: 'string', default: '' }, | |
| bar: { type: 'integer' }, | |
| buz: { type: 'boolean' }, | |
| qux: { type: [ 'string', 'null' ] } | |
| } as const; | |
| type Attributes = InferSchema<typeof attributes>; | |
| // ^ = { | |
| // readonly foo: string; | |
| // readonly bar: number; | |
| // readonly buz: boolean; | |
| // readonly qux: string | null; | |
| // } |
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