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[英]How to filter element depending on the previous element in an array of arrays
[英]Typescript: Array type depending on previous array element
在 Typescript 中是否可以实现一个无限数组(不是元组),其类型取决于数组的前一个元素?
下面是一些伪打字稿代码来举例:
class B<T, U> {}
function foo<X, Y>(...args: [B<X, Z0>, B<Z0, Z1>, B<Z1, Z2>, ..., B<ZN, Y>]) {}
foo<string, number>(new B<string, number>, new B<number, boolean>, new B<boolean, number>); // Correct
foo<string, number>(new B<string, number, new B<number, boolean>); // Incorrect
foo<string, number>(new B<string, number>, new B<boolean, number>); // Incorrect
我应该用什么替换“ [B<X, Z0>, B<Z0, Z1>, B<Z1, Z2>, ..., B<ZN, Y>]
来完成这项工作? 这甚至可能吗?
谢谢!
我最近遇到了类似的问题。 我的问题涉及创建一个长的 pipe 流。 output 的 ZF7B44CFFAFD5C52223D5498196C8A2E7BZ 我必须是 stream i+1 等的输入。我这样解决了:
type OmitFirst<T extends any[]> = T extends [any, ...infer R] ? R : never
type GetValueOrDefault<Thing, Key, Default = never> = Key extends keyof Thing ? Thing[Key] : Default
type Pipe<Start, Finish, Inputs extends [Start, ...any[]], Outputs extends any[] = OmitFirst<Inputs>> = {
[I in keyof Inputs]: DuplexConstructor<Inputs[I], GetValueOrDefault<Outputs, I, Finish>>
}
export function pipe<F, L, P extends [F, ...any[]]>(
...streams: [ReadableConstructor<F>, ...Pipe<F, L, P>, WritableConstructor<L>]
): Writable {
const source = streams[0]
const duplexes = streams.slice(1, -1) as Pipe<F, L, P>
const sink = streams[streams.length - 1] as WritableConstructor<L>
let tail = readable(source)
duplexes.forEach((dp) => (tail = tail.pipe(duplex(dp))))
return tail.pipe(writable(sink))
}
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