36 lines
946 B
TypeScript
36 lines
946 B
TypeScript
// Taken from https://fettblog.eu/typescript-assertion-signatures/
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type InferValue<Prop extends PropertyKey, Desc> = Desc extends {
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get(): any
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value: any
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}
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? never
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: Desc extends { value: infer T }
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? Record<Prop, T>
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: Desc extends { get(): infer T }
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? Record<Prop, T>
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: never
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type DefineProperty<Prop extends PropertyKey, Desc extends PropertyDescriptor> =
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Desc extends { writable: any; set(val: any): any }
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? never
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: Desc extends { writable: any; get(): any }
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? never
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: Desc extends { writable: false }
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? Readonly<InferValue<Prop, Desc>>
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: Desc extends { writable: true }
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? InferValue<Prop, Desc>
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: Readonly<InferValue<Prop, Desc>>
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export default function defineProperty<
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Obj extends object,
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Key extends PropertyKey,
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PDesc extends PropertyDescriptor
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>(
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obj: Obj,
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prop: Key,
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val: PDesc
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): asserts obj is Obj & DefineProperty<Key, PDesc> {
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Object.defineProperty(obj, prop, val)
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}
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