type2type/index.d.ts

TypeScript type-level data structures

type Equals<T1, T2> = T1 extends T2 ? (T2 extends T1 ? true : never) : never;

export type TQueue<Items extends unknown[] = []> = Items;
type AnyTQueue = TQueue<unknown[]>;
export namespace TQueue {
  export type push<Q extends AnyTStack, El> = TQueue<[...Q, El]>;
  export type peek<Q extends AnyTStack> = Q extends [infer Head, ...infer _]
    ? Head
    : never;
  export type pop<Q extends AnyTStack> = Q extends [infer _, ...infer Tail]
    ? TQueue<Tail>
    : Q;
  export type size<Q extends AnyTQueue> = Q["length"];
  export type empty<Q extends AnyTQueue> = Equals<size<Q>, 0>;
}

export type TStack<Items extends unknown[] = []> = Items;
type AnyTStack = TStack<unknown[]>;
export namespace TStack {
  export type push<Q extends AnyTQueue, El> = TQueue<[El, ...Q]>;
  export type peek<Q extends AnyTQueue> = Q extends [infer Head, ...infer _]
    ? Head
    : never;
  export type pop<Q extends AnyTQueue> = Q extends [infer _, ...infer Tail]
    ? TQueue<Tail>
    : Q;
  export type size<Q extends AnyTQueue> = Q["length"];
  export type empty<Q extends AnyTQueue> = Equals<size<Q>, 0>;
}

export type TSet<Items extends unknown[] = []> = Items;
type AnyTSet = TSet<unknown[]>;
export namespace TSet {
  export type has<Set extends AnyTSet, El> = {
    [T in keyof Set]: Equals<Set[T], El>;
  }[number];
  export type add<Set extends AnyTSet, El> = TSet.has<Set, El> extends never
    ? TSet<[...Set, El]>
    : Set;
  export type remove<Set extends AnyTSet, El> = Set extends [
    infer Head,
    ...infer Tail,
  ]
    ? Equals<Head, El> extends never
      ? [Head, ...remove<Tail, El>]
      : remove<Tail, El>
    : Set;

  export type size<Set extends AnyTSet> = Set["length"];
  export type empty<Set extends AnyTSet> = Equals<size<Set>, 0>;

  export type union<
    S1 extends AnyTSet = TSet,
    S2 extends AnyTSet = TSet,
  > = S1 extends [infer Head, ...infer Tail] ? union<Tail, add<S2, Head>> : S2;
  export type intersection<
    S1 extends AnyTSet,
    S2 extends AnyTSet = S1,
  > = S1 extends [infer Head, ...infer Tail]
    ? has<S2, Head> extends never
      ? intersection<Tail, S2>
      : TSet<[Head, ...intersection<Tail, S2>]>
    : TSet;
  export type difference<
    SL extends AnyTSet,
    SR extends AnyTSet = TSet,
  > = SR extends [infer Head, ...infer Tail]
    ? difference<remove<SL, Head>, Tail>
    : SL;

  export type select<S extends AnyTSet, Pred = unknown> = S extends [
    infer Head,
    ...infer Tail,
  ]
    ? Head extends Pred
      ? [Head, ...select<Tail, Pred>]
      : select<Tail, Pred>
    : S;

  export type asUnionType<S extends AnyTSet> = S[number];
}

type TMapItem = [unknown, unknown];
export type TMap<Items extends TMapItem[] = []> = Items;
type AnyTMap = TMap<TMapItem[]>;
export namespace TMap {
  export type get<Q extends AnyTMap, Key> = {
    [T in keyof Q]: Equals<Q[T][0], Key> extends never ? never : Q[T][1];
  }[number];
  export type has<Q extends AnyTMap, Key> = {
    [T in keyof Q]: Equals<Q[T][0], Key>;
  }[number];
  export type set<Q extends AnyTMap, Key, Value> = TMap.has<
    Q,
    Key
  > extends never
    ? [...Q, [Key, Value]]
    : {
        [T in keyof Q]: Equals<Q[T][0], Key> extends never
          ? Q[T]
          : [Key, Value];
      };
  export type remove<Q extends AnyTMap, Key> = Q extends [
    infer Head extends TMapItem,
    ...infer Tail extends TMapItem[],
  ]
    ? Equals<Head[0], Key> extends never
      ? [Head, ...remove<Tail, Key>]
      : remove<Tail, Key>
    : Q;

  export type keys<M extends AnyTMap> = { [T in keyof M]: M[T][0] };
  export type values<M extends AnyTMap> = { [T in keyof M]: M[T][1] };

  export type size<Q extends AnyTMap> = Q["length"];
  export type empty<Q extends AnyTMap> = Equals<size<Q>, 0>;

  export type select<
    M extends AnyTMap,
    Key = unknown,
    Value = unknown,
  > = M extends [infer Head, ...infer Tail extends AnyTMap]
    ? Head extends [Key, Value]
      ? [Head, ...select<Tail, Key, Value>]
      : select<Tail, Key, Value>
    : [];
}