43 lines
1.4 KiB
Plaintext
43 lines
1.4 KiB
Plaintext
import type {IsTuple} from './is-tuple';
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import type {UnknownArray} from './unknown-array';
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import type {IfAny} from './if-any';
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/**
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Transforms a tuple into an object, mapping each tuple index to its corresponding type as a key-value pair.
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Note: Tuple labels are [lost in the transformation process](https://stackoverflow.com/a/70398429/11719314). For example, `TupleToObject<[x: number, y: number]>` produces `{0: number; 1: number}`, and not `{x: number; y: number}`.
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@example
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```
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type Example1 = TupleToObject<[number, string, boolean]>;
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//=> { 0: number; 1: string; 2: boolean }
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// Tuples with optional indices
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type Example2 = TupleToObject<[number, string?, boolean?]>;
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//=> { 0: number; 1?: string; 2?: boolean }
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// Readonly tuples
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type Example3 = TupleToObject<readonly [number, string?]>;
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//=> { readonly 0: number; readonly 1?: string }
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// Non-tuple arrays get transformed into index signatures
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type Example4 = TupleToObject<string[]>;
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//=> { [x: number]: string }
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// Tuples with rest elements
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type Example5 = TupleToObject<[number, string, ...boolean[]]>;
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//=> { [x: number]: number | string | boolean; 0: number; 1: string }
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// Tuple labels are not preserved
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type Example6 = TupleToObject<[x: number, y: number]>;
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//=> { 0: number; 1: number }
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```
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@category Array
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*/
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export type TupleToObject<TArray extends UnknownArray> = IfAny<TArray, any, {
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[
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Key in keyof TArray as Key & (`${number}` | (IsTuple<TArray> extends true ? never : number))
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]: TArray[Key];
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}>;
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