86 lines
2.6 KiB
TypeScript
86 lines
2.6 KiB
TypeScript
import type {BuiltIns} from './internal';
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/**
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Convert `object`s, `Map`s, `Set`s, and `Array`s and all of their keys/elements into immutable structures recursively.
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This is useful when a deeply nested structure needs to be exposed as completely immutable, for example, an imported JSON module or when receiving an API response that is passed around.
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Please upvote [this issue](https://github.com/microsoft/TypeScript/issues/13923) if you want to have this type as a built-in in TypeScript.
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@example
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```
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// data.json
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{
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"foo": ["bar"]
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}
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// main.ts
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import type {ReadonlyDeep} from 'type-fest';
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import dataJson = require('./data.json');
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const data: ReadonlyDeep<typeof dataJson> = dataJson;
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export default data;
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// test.ts
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import data from './main';
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data.foo.push('bar');
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//=> error TS2339: Property 'push' does not exist on type 'readonly string[]'
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```
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@category Object
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@category Array
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@category Set
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@category Map
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*/
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export type ReadonlyDeep<T> = T extends BuiltIns
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? T
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: T extends (...arguments: any[]) => unknown
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? {} extends ReadonlyObjectDeep<T>
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? T
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: HasMultipleCallSignatures<T> extends true
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? T
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: ((...arguments: Parameters<T>) => ReturnType<T>) & ReadonlyObjectDeep<T>
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: T extends Readonly<ReadonlyMap<infer KeyType, infer ValueType>>
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? ReadonlyMapDeep<KeyType, ValueType>
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: T extends Readonly<ReadonlySet<infer ItemType>>
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? ReadonlySetDeep<ItemType>
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: T extends object
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? ReadonlyObjectDeep<T>
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: unknown;
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/**
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Same as `ReadonlyDeep`, but accepts only `ReadonlyMap`s as inputs. Internal helper for `ReadonlyDeep`.
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*/
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interface ReadonlyMapDeep<KeyType, ValueType>
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extends Readonly<ReadonlyMap<ReadonlyDeep<KeyType>, ReadonlyDeep<ValueType>>> {}
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/**
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Same as `ReadonlyDeep`, but accepts only `ReadonlySet`s as inputs. Internal helper for `ReadonlyDeep`.
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*/
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interface ReadonlySetDeep<ItemType>
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extends Readonly<ReadonlySet<ReadonlyDeep<ItemType>>> {}
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/**
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Same as `ReadonlyDeep`, but accepts only `object`s as inputs. Internal helper for `ReadonlyDeep`.
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*/
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type ReadonlyObjectDeep<ObjectType extends object> = {
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readonly [KeyType in keyof ObjectType]: ReadonlyDeep<ObjectType[KeyType]>
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};
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/**
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Test if the given function has multiple call signatures.
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Needed to handle the case of a single call signature with properties.
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Multiple call signatures cannot currently be supported due to a TypeScript limitation.
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@see https://github.com/microsoft/TypeScript/issues/29732
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*/
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type HasMultipleCallSignatures<T extends (...arguments: any[]) => unknown> =
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T extends {(...arguments: infer A): unknown; (...arguments: any[]): unknown}
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? unknown[] extends A
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? false
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: true
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: false;
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