@cuppachino/type-space/dist/strings/split-at.d.ts

A collection of type utilities for TypeScript.

import type { Assert } from '../assert';
import type { Chars } from './chars';
import type { IndexOf } from '../index-of';
import type { IntoNumber } from '../into/into-number';
import type { Join } from '../join';
import type { Length } from '../length';
import type { NumberLike } from '../number-like';
import type { PopBy } from '../tuples/pop-by';
import type { ShiftBy } from '../tuples/shift-by';
import type { Stringifiable } from '../stringifiable';
import type { Subtract } from '../math/subtract';
/**
 * Splits a string literal at a given index, non-inclusive.
 *
 * @param S - The string literal to split.
 * @param I - A number or number literal. Must be an index of `S`.
 * @example
 * ```
 * type A = SplitAt<'david', '2'> // ['da', 'vid']
 * type B = SplitAt<'david', 5> // ['david', '']
 * ```
 */
export type SplitAt<S extends string, I extends NumberLike<IndexOf<[...Chars<S>]>> = Assert<NumberLike<0>, NumberLike<IndexOf<[...Chars<S>]>>>> = Chars<S> extends infer C extends Stringifiable[] ? [
    Join<PopBy<C, Subtract<Length<C>, IntoNumber<I>>>>,
    Join<ShiftBy<C, IntoNumber<I>>>
] : never;