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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 | 4x 10x 4x 10x 10x 10x 5x 5x 10x | import { isUndefined } from "@benneq/object";
/**
* @mutation
*
* @remark
* only returns `undefined` if `mappingFunction` returns `undefined`
*
* @example
* Compute the new value based on the old {@link Map} entry
* ```ts
* const map = new Map();
* compute(map)(1, (key, value) => value ?? 2);
* console.log(map); // Map([[1, 2]])
* ```
*
* @typeParam K - the {@link Map} key type
* @typeParam V - the {@link Map} value type
* @param map - the {@link Map} to set the entry
*/
export const compute =
<K, V>(map: Map<K, V>) =>
<T extends V | undefined>(
key: K,
remappingFunction: (key: K, value: T) => V | undefined
): V | undefined => {
const newValue = remappingFunction(key, map.get(key) as T);
if (isUndefined(newValue)) {
map.delete(key);
} else {
map.set(key, newValue);
}
return newValue;
};
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