type-plus/esm/array/array_plus.split_at.d.ts

Provides additional types for TypeScript.

import type { NeverType } from '../never/never_type.js';
import type { IsTuple } from '../tuple/tuple_type.js';
import type { IndexAt } from './array_index.js';
import type { ArrayType } from './array_type.js';
/**
 * ⚗️ *transform*
 *
 * Splits array or tuple `A` into two at the specified `Index`.
 *
 * If the `Index` is out of bounds,
 * it will set to the boundary value.
 *
 * It is the type level `splice()`.
 *
 * @example
 * ```ts
 * SplitAt<[1, 2, 3, 4, 5], 2> // [[1, 2], [3, 4, 5]]
 * SplitAt<[1, 2, 3, 4, 5], -3> // [[1, 2], [3, 4, 5]]
 *
 * SplitAt<[1, 2, 3, 4, 5], 2, 2> // [[1, 2, 5], [3, 4]]
 *
 * SplitAt<[1, 2, 3, 4, 5], 2, 2, ['a', 'b']> // [[1, 2, 'a', 'b', 5], [3, 4]]
 *
 * // out of bound resets to boundary
 * SplitAt<[1, 2, 3, 4, 5], 6> // [[1, 2, 3, 4, 5], []]
 * SplitAt<[1, 2, 3, 4, 5], -6> // [[], [1, 2, 3, 4, 5]]
 * ```
 */
export type SplitAt<A extends unknown[], Index extends number, DeleteCount extends number | never = never, Insert extends unknown[] | never = never> = ArrayType<A, [
    A,
    A
], SplitAt._<A, [], [], IndexAt._<A, Index>, DeleteCount, Insert>>;
export declare namespace SplitAt {
    type _<A extends unknown[], B extends unknown[], C extends unknown[], Index extends number, DeleteCount, Insert extends unknown[]> = 0 extends A['length'] ? IsTuple<Insert, [[...Insert, ...B], C], [B, C]> : (Index extends B['length'] ? _D<A, B, C, DeleteCount, Insert> : (A extends [infer Head, ...infer Tail] ? _<Tail, [...B, Head], [], Index, DeleteCount, Insert> : 'unexpected: A does not extends [Head, ...Tail]'));
    type _D<A extends unknown[], B extends unknown[], C extends unknown[], DeleteCount, Insert extends unknown[]> = NeverType<DeleteCount, [
        B,
        A
    ], DeleteCount extends C['length'] ? IsTuple<Insert, [[...B, ...Insert, ...A], C], [[...B, ...A], C]> : (A extends [infer Head, ...infer Tail] ? _D<Tail, B, [...C, Head], DeleteCount, Insert> : IsTuple<Insert, [[...Insert, ...B], C], [B, C]>)>;
}
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