Short summary
Given:
Tuple: A tuple typeValues: A type containing a union of all values that are expected to be inTuple
Provide:
A validation type that returns Tuple only if it contains every value in Values (regardless of order). Otherwise, it returns never.
Potential definition
type TupleOf<Tuple extends ReadonlyArray<Values>, Values> =
IsEqual<Values, TupleToUnion<Tuple>> extends true ? Tuple : never;Example usage
type abc = 'a'|'b'|'c';
function tupleOfAbc<Tuple extends ReadonlyArray<abc>>(valueOrder: TupleOf<Tuple, abc>): void {}
tupleOfAbc(['a', 'b', 'c']); // Valid
tupleOfAbc(['b', 'a', 'c']); // Valid
tupleOfAbc(['a', 'c']); // InvalidUse case
Constructing an array that indicates the correct ordering of a known set of values:
function sort<Values, SortOrder extends ReadonlyArray<Values>>(values: Set<Values>, sortOrder: TupleOf<SortOrder, Values>) {
return [...values].sort((a, b) => sortOrder.indexOf(a) - sortOrder.indexOf(b));
}
const ABC_SORT_ORDER = ['a', 'b', 'c'] as const;
const myValues = new Set<abc>(['c', 'a']);
console.log(sort(myValues, ABC_SORT_ORDER));The TupleOf type allows us to ensure that the sort order is exhaustive for the type in question.
sindresorhus / type-fest
A collection of essential TypeScript types
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