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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 | 1x 2x 1x 2x 2x 1x 1x | import { Mapper } from "@benneq/function";
import { compute } from "./compute";
/**
* @mutation
*
* @remark
* only returns `undefined` if `mappingFunction` returns `undefined`
*
* @example
* Set a {@link Map} entry if the key is absent
* ```ts
* const map = new Map();
* computeIfAbsent(map)(1, key => key + 1);
* 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 computeIfAbsent =
<K, V>(map: Map<K, V>) =>
(key: K, mappingFunction: Mapper<K, V>): V | undefined => {
if (!map.has(key)) {
return compute(map)(key, mappingFunction);
}
return map.get(key);
};
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