Iosevka/shared/utils/ptr.ts

import { type Dispatch, type SetStateAction, useState } from "react";

export type Ptr<T> = { val: T; set: Dispatch<SetStateAction<T>> };
export const Ptr = {
	Default<T>(x: T): Ptr<T> {
		return { val: x, set: () => {} };
	},

	Lens<T, K extends keyof T>(ptr: Ptr<T>, key: K): Ptr<T[K]> {
		return {
			val: ptr.val[key],
			set: val => {
				if (val instanceof Function) {
					ptr.set((a: T) => ({ ...a, [key]: val(a[key]) }));
				} else {
					ptr.set((a: T) => ({ ...a, [key]: val }));
				}
			},
		};
	},
};
export function useStatePtr<T>(defaultValue: T): Ptr<T> {
	const [get, set] = useState<T>(defaultValue);
	return { val: get, set };
}