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types.ts
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types.ts
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import { Type, identity, InputOf, OutputOf } from './type';
/**
* A number type to be used with `option`
*
* Throws an error when the provided string is not a number
*/
export const number: Type<string, number> = {
async from(str) {
const decoded = parseFloat(str);
if (Number.isNaN(decoded)) {
throw new Error('Not a number');
} else {
return decoded;
}
},
displayName: 'number',
description: 'a number',
};
/**
* A string type to be used with `option`.
*/
export const string: Type<string, string> = {
...identity(),
description: 'a string',
displayName: 'str',
};
/**
* A boolean type to be used with `flag`.
*/
export const boolean: Type<boolean, boolean> = {
...identity(),
description: 'a boolean',
displayName: 'true/false',
defaultValue() {
return false;
},
};
/**
* Makes any type optional, by defaulting to `undefined`.
*/
export function optional<T extends Type<any, any>>(
t: T
): Type<InputOf<T>, OutputOf<T> | undefined> {
return {
...t,
defaultValue(): OutputOf<T> | undefined {
return undefined;
},
};
}
/**
* Transforms any type into an array, useful for `multioption` and `multiflag`.
*/
export function array<T extends Type<any, any>>(
t: T
): Type<InputOf<T>[], OutputOf<T>[]> {
return {
...t,
async from(inputs: InputOf<T>[]): Promise<OutputOf<T>[]> {
return Promise.all(inputs.map((input) => t.from(input)));
},
};
}