type-fest/source/array-tail.d.ts
2025-05-08 15:21:25 +07:00

77 lines
2.0 KiB
TypeScript

import type {ApplyDefaultOptions, IfArrayReadonly} from './internal/index.d.ts';
import type {UnknownArray} from './unknown-array.d.ts';
/**
@see {@link ArrayTail}
*/
type ArrayTailOptions = {
/**
Return a readonly array if the input array is readonly.
@default false
@example
```
import type {ArrayTail} from 'type-fest';
type Example1 = ArrayTail<readonly [string, number, boolean], {preserveReadonly: true}>;
//=> readonly [number, boolean]
type Example2 = ArrayTail<[string, number, boolean], {preserveReadonly: true}>;
//=> [number, boolean]
type Example3 = ArrayTail<readonly [string, number, boolean], {preserveReadonly: false}>;
//=> [number, boolean]
type Example4 = ArrayTail<[string, number, boolean], {preserveReadonly: false}>;
//=> [number, boolean]
```
*/
preserveReadonly?: boolean;
};
type DefaultArrayTailOptions = {
preserveReadonly: false;
};
/**
Extracts the type of an array or tuple minus the first element.
@example
```
import type {ArrayTail} from 'type-fest';
declare const curry: <Arguments extends unknown[], Return>(
function_: (...arguments_: Arguments) => Return,
...arguments_: ArrayTail<Arguments>
) => (...arguments_: ArrayTail<Arguments>) => Return;
const add = (a: number, b: number) => a + b;
const add3 = curry(add, 3);
add3(4);
//=> 7
```
@see {@link ArrayTailOptions}
@category Array
*/
export type ArrayTail<TArray extends UnknownArray, Options extends ArrayTailOptions = {}> =
ApplyDefaultOptions<ArrayTailOptions, DefaultArrayTailOptions, Options> extends infer ResolvedOptions extends Required<ArrayTailOptions>
? TArray extends UnknownArray // For distributing `TArray`
? _ArrayTail<TArray> extends infer Result
? ResolvedOptions['preserveReadonly'] extends true
? IfArrayReadonly<TArray, Readonly<Result>, Result>
: Result
: never // Should never happen
: never // Should never happen
: never; // Should never happen
type _ArrayTail<TArray extends UnknownArray> = TArray extends readonly [unknown?, ...infer Tail]
? keyof TArray & `${number}` extends never
? []
: Tail
: [];