feat(remix-server-runtime): bring Serialize type more in line with …

…`type-fest`'s `Jsonify` type

packages/remix-server-runtime/serialize.ts

@@ -1,51 +1,90 @@
 import type { AppData } from "./data";
 import type { TypedDeferredData, TypedResponse } from "./responses";
 
-type JsonPrimitive =
-  | string
-  | number
-  | boolean
-  | String
-  | Number
-  | Boolean
-  | null;
-type NonJsonPrimitive = undefined | Function | symbol;
+type JsonPrimitive = boolean | number | string | null;
+type NotJsonable = ((...arguments_: any[]) => any) | undefined | symbol; // Note: The return value has to be `any` and not `unknown` so it can match `void`
 
 /*
  * `any` is the only type that can let you equate `0` with `1`
  * See https://stackoverflow.com/a/49928360/1490091
  */
 type IsAny<T> = 0 extends 1 & T ? true : false;
+type IsNever<T> = [T] extends [never] ? true : false;
+
+// eslint-disable-next-line @typescript-eslint/no-loss-of-precision
+type PositiveInfinity = 1e999;
+// eslint-disable-next-line @typescript-eslint/no-loss-of-precision
+type NegativeInfinity = -1e999;
+
+declare const emptyObjectSymbol: unique symbol;
+type EmptyObject = { [emptyObjectSymbol]?: never };
+
+type TypedArray =
+  | Int8Array
+  | Uint8Array
+  | Uint8ClampedArray
+  | Int16Array
+  | Uint16Array
+  | Int32Array
+  | Uint32Array
+  | Float32Array
+  | Float64Array
+  | BigInt64Array
+  | BigUint64Array;
+
+type JsonArray = JsonValue[] | readonly JsonValue[];
+type JsonObject = { [Key in string]: JsonValue } & {
+  [Key in string]?: JsonValue | undefined;
+};
+type JsonValue = JsonPrimitive | JsonObject | JsonArray;
 
 // prettier-ignore
-type Serialize<T> =
+type Jsonify<T> =
   IsAny<T> extends true ? any :
-  T extends TypedDeferredData<infer U> ? SerializeDeferred<U> :
+  T extends PositiveInfinity | NegativeInfinity ? null :
+  T extends Boolean ? boolean :
+  T extends Number ? number :
+  T extends String ? string :
+  T extends Map<any, any> | Set<any> ? EmptyObject :
+  T extends TypedArray ? Record<string, number> :
+  T extends NotJsonable ? never :
   T extends JsonPrimitive ? T :
-  T extends NonJsonPrimitive ? never :
-  T extends { toJSON(): infer U } ? U :
+  T extends { toJSON(): infer J } ? ((() => J) extends () => JsonValue ? J : Jsonify<J>) :
   T extends [] ? [] :
-  T extends [unknown, ...unknown[]] ? SerializeTuple<T> :
-  T extends ReadonlyArray<infer U> ? (U extends NonJsonPrimitive ? null : Serialize<U>)[] :
-  T extends object ? SerializeObject<UndefinedToOptional<T>> :
-  never
-;
+  T extends [unknown, ...unknown[]] ? JsonifyList<T> :
+  T extends ReadonlyArray<infer U> ? Array<U extends NotJsonable ? null : Jsonify<U>> :
+  T extends object ? JsonifyObject<UndefinedToOptional<T>> :
+  never;
 
+type FilterNonNever<T extends unknown[]> = T extends [infer F, ...infer R]
+  ? IsNever<F> extends true
+    ? FilterNonNever<R>
+    : [F, ...FilterNonNever<R>]
+  : IsNever<T[number]> extends true
+  ? []
+  : T;
 /** JSON serialize [tuples](https://www.typescriptlang.org/docs/handbook/2/objects.html#tuple-types) */
-type SerializeTuple<T extends unknown[]> = T extends [infer F, ...infer R]
-  ? [Serialize<F>, ...SerializeTuple<R>]
-  : [];
+type JsonifyList<T extends unknown[]> = T extends [infer F, ...infer R]
+  ? FilterNonNever<[Jsonify<F>, ...JsonifyList<R>]>
+  : Array<Jsonify<T[number]>>;
 
 /** JSON serialize objects (not including arrays) and classes */
-type SerializeObject<T extends object> = {
-  [k in keyof T as T[k] extends NonJsonPrimitive ? never : k]: Serialize<T[k]>;
+type JsonifyObject<T extends object> = {
+  [Key in keyof Pick<T, FilterJsonableKeys<T>>]: Jsonify<T[Key]>;
 };
+type FilterJsonableKeys<T extends object> = {
+  [Key in keyof T]: T[Key] extends NotJsonable ? never : Key;
+}[keyof T];
+
+type Serialize<T> = T extends TypedDeferredData<infer U>
+  ? SerializeDeferred<U>
+  : Jsonify<T>;
 
 // prettier-ignore
 type SerializeDeferred<T extends Record<string, unknown>> = {
   [k in keyof T as
     T[k] extends Promise<unknown> ? k :
-    T[k] extends NonJsonPrimitive ? never :
+    T[k] extends NotJsonable ? never :
     k
   ]:
     T[k] extends Promise<infer U>
@@ -60,15 +99,50 @@ type SerializeDeferred<T extends Record<string, unknown>> = {
  * Example: { a: string | undefined} --> { a?: string}
  */
 type UndefinedToOptional<T extends object> = {
-  // Property is not a union with `undefined`, keep as-is
-  [k in keyof T as undefined extends T[k] ? never : k]: T[k];
+  // Property is not a union with `undefined`, keep it as-is.
+  [Key in keyof Pick<T, FilterDefinedKeys<T>>]: T[Key];
 } & {
-  // Property _is_ a union with `defined`. Set as optional (via `?`) and remove `undefined` from the union
-  [k in keyof T as undefined extends T[k] ? k : never]?: Exclude<
-    T[k],
-    undefined
-  >;
+  // Property _is_ a union with defined value. Set as optional (via `?`) and remove `undefined` from the union.
+  [Key in keyof Pick<T, FilterOptionalKeys<T>>]?: Exclude<T[Key], undefined>;
 };
+// Returns `never` if the key or property is not jsonable without testing whether the property is required or optional otherwise return the key.
+type BaseKeyFilter<Type, Key extends keyof Type> = Key extends symbol
+  ? never
+  : Type[Key] extends symbol
+  ? never
+  : [(...args: any[]) => any] extends [Type[Key]]
+  ? never
+  : Key;
+/**
+ Returns the required keys.
+ */
+type FilterDefinedKeys<T extends object> = Exclude<
+  {
+    [Key in keyof T]: IsAny<T[Key]> extends true
+      ? Key
+      : undefined extends T[Key]
+      ? never
+      : T[Key] extends undefined
+      ? never
+      : BaseKeyFilter<T, Key>;
+  }[keyof T],
+  undefined
+>;
+/**
+ Returns the optional keys.
+ */
+type FilterOptionalKeys<T extends object> = Exclude<
+  {
+    [Key in keyof T]: IsAny<T[Key]> extends true
+      ? never
+      : undefined extends T[Key]
+      ? T[Key] extends undefined
+        ? never
+        : BaseKeyFilter<T, Key>
+      : never;
+  }[keyof T],
+  undefined
+>;
 
 type ArbitraryFunction = (...args: any[]) => unknown;