@metaplex-foundation/umi-options
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A TypeScript implementation of Rust Options
88 lines (77 loc) • 2.33 kB
text/typescript
/**
* Defines a type `T` that can also be `null`.
* @category Utils — Options
*/
export type Nullable<T> = T | null;
/**
* Defines a type `T` that can also be `null` or `undefined`.
* @category Utils — Options
*/
export type Nullish<T> = T | null | undefined;
/**
* An implementation of the Rust Option type in JavaScript.
* It can be one of the following:
* - <code>{@link Some}<T></code>: Meaning there is a value of type T.
* - <code>{@link None}</code>: Meaning there is no value.
*
* @category Utils — Options
*/
export type Option<T> = Some<T> | None;
/**
* Defines a looser type that can be used when serializing an {@link Option}.
* This allows us to pass null or the Option value directly whilst still
* supporting the Option type for use-cases that need more type safety.
*
* @category Utils — Options
*/
export type OptionOrNullable<T> = Option<T> | Nullable<T>;
/**
* Represents an option of type `T` that has a value.
*
* @see {@link Option}
* @category Utils — Options
*/
export type Some<T> = { __option: 'Some'; value: T };
/**
* Represents an option of type `T` that has no value.
*
* @see {@link Option}
* @category Utils — Options
*/
export type None = { __option: 'None' };
/**
* Creates a new {@link Option} of type `T` that has a value.
*
* @see {@link Option}
* @category Utils — Options
*/
export const some = <T>(value: T): Option<T> => ({ __option: 'Some', value });
/**
* Creates a new {@link Option} of type `T` that has no value.
*
* @see {@link Option}
* @category Utils — Options
*/
export const none = <T>(): Option<T> => ({ __option: 'None' });
/**
* Whether the given data is an {@link Option}.
* @category Utils — Options
*/
export const isOption = <T = unknown>(input: any): input is Option<T> =>
input &&
typeof input === 'object' &&
'__option' in input &&
((input.__option === 'Some' && 'value' in input) ||
input.__option === 'None');
/**
* Whether the given {@link Option} is a {@link Some}.
* @category Utils — Options
*/
export const isSome = <T>(option: Option<T>): option is Some<T> =>
option.__option === 'Some';
/**
* Whether the given {@link Option} is a {@link None}.
* @category Utils — Options
*/
export const isNone = <T>(option: Option<T>): option is None =>
option.__option === 'None';