@monstermann/fn/dist/set/addOrElse.js

A utility library for TypeScript.

import { dfdlT } from "@monstermann/dfdl";
import { cloneSet } from "@monstermann/remmi";

//#region src/set/addOrElse.ts
/**
* `addOrElse(target, value, orElse)`
*
* Adds a `value` to the `target` set and returns a new set. If the value already exists in the set, calls the `orElse` function with the target set and returns its result.
*
* ```ts
* addOrElse(new Set([1, 2]), 3, (set) => set.size); // Set([1, 2, 3])
* addOrElse(new Set([1, 2]), 2, (set) => set.size); // 2
* ```
*
* ```ts
* pipe(
*     new Set([1, 2]),
*     addOrElse(3, (set) => set.size),
* ); // Set([1, 2, 3])
*
* pipe(
*     new Set([1, 2]),
*     addOrElse(2, (set) => set.size),
* ); // 2
* ```
*/
const addOrElse = dfdlT((target, value, orElse) => {
	if (target.has(value)) return orElse(target);
	const result = cloneSet(target);
	result.add(value);
	return result;
}, 3);

//#endregion
export { addOrElse };