Calculadora em TypeScript

calculator.ts

type IncrementTable = {
    '0': '1',
    '1': '2',
    '2': '3',
    '3': '4',
    '4': '5',
    '5': '6',
    '6': '7',
    '7': '8',
    '8': '9',
    '9': '0',
}

type Increment<A extends string> = A extends `${infer FirstPart}9`
    ? (
        FirstPart extends '' ? '10' : `${Increment<FirstPart>}0`
    ) : (
        A extends `${infer A1 extends keyof IncrementTable}${infer A2}`
        ? (
            A2 extends '' ? IncrementTable[A1] : `${A1}${Increment<A2>}`
        ) : never
    );

type DecrementTable = {
    '1': '0',
    '2': '1',
    '3': '2',
    '4': '3',
    '5': '4',
    '6': '5',
    '7': '6',
    '8': '7',
    '9': '8',
    '0': '9',
}

type Remove0<T> = T extends `0${infer Anything}` ? Remove0<Anything> : T;

type Decrement<A extends string> = A extends `${infer FirstPart}0`
    ? Remove0<(
        FirstPart extends '' ? '' : `${Decrement<FirstPart>}9`
    )> : (
        A extends `${infer A1 extends keyof DecrementTable}${infer A2}`
        ? (
            A2 extends '' ? DecrementTable[A1] : `${A1}${Decrement<A2>}`
        ) : never
    );

type AddAuxiliar<A extends string, B extends string> = B extends '0' ? A : Add<Increment<A>, Decrement<B>>;

type Add<A extends string, B extends string> = B extends '0' ? A : Add<Increment<A>, Decrement<B>>;

type XXXX = Increment<'22'>;
type XXXXX = Decrement<'1'>;

type TwoPlusFive = Add<'1995', '28'>;