ai/src/util/deep-partial.ts

AI SDK by Vercel - The AI Toolkit for TypeScript and JavaScript

// License for this File only:
//
// MIT License
//
// Copyright (c) Sindre Sorhus <sindresorhus@gmail.com> (https://sindresorhus.com)
// Copyright (c) Vercel, Inc. (https://vercel.com)
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import { FlexibleSchema, InferSchema } from '@ai-sdk/provider-utils';

/**
 * Create a type from an object with all keys and nested keys set to optional.
 * The helper supports normal objects and schemas (which are resolved automatically).
 * It always recurses into arrays.
 *
 * Adopted from [type-fest](https://github.com/sindresorhus/type-fest/tree/main) PartialDeep.
 */

export type DeepPartial<T> = T extends FlexibleSchema
  ? DeepPartialInternal<InferSchema<T>> // resolve schemas first to prevent infinite recursion
  : DeepPartialInternal<T>;

type DeepPartialInternal<T> = T extends
  | null
  | undefined
  | string
  | number
  | boolean
  | symbol
  | bigint
  | void
  | Date
  | RegExp
  | ((...arguments_: any[]) => unknown)
  | (new (...arguments_: any[]) => unknown)
  ? T
  : T extends Map<infer KeyType, infer ValueType>
    ? PartialMap<KeyType, ValueType>
    : T extends Set<infer ItemType>
      ? PartialSet<ItemType>
      : T extends ReadonlyMap<infer KeyType, infer ValueType>
        ? PartialReadonlyMap<KeyType, ValueType>
        : T extends ReadonlySet<infer ItemType>
          ? PartialReadonlySet<ItemType>
          : T extends object
            ? T extends ReadonlyArray<infer ItemType> // Test for arrays/tuples, per https://github.com/microsoft/TypeScript/issues/35156
              ? ItemType[] extends T // Test for arrays (non-tuples) specifically
                ? readonly ItemType[] extends T // Differentiate readonly and mutable arrays
                  ? ReadonlyArray<DeepPartialInternal<ItemType | undefined>>
                  : Array<DeepPartialInternal<ItemType | undefined>>
                : PartialObject<T> // Tuples behave properly
              : PartialObject<T>
            : unknown;

type PartialMap<KeyType, ValueType> = {} & Map<
  DeepPartialInternal<KeyType>,
  DeepPartialInternal<ValueType>
>;

type PartialSet<T> = {} & Set<DeepPartialInternal<T>>;

type PartialReadonlyMap<KeyType, ValueType> = {} & ReadonlyMap<
  DeepPartialInternal<KeyType>,
  DeepPartialInternal<ValueType>
>;

type PartialReadonlySet<T> = {} & ReadonlySet<DeepPartialInternal<T>>;

type PartialObject<ObjectType extends object> = {
  [KeyType in keyof ObjectType]?: DeepPartialInternal<ObjectType[KeyType]>;
};