Function getOrUpdate

src/utils.ts:52–62

(
    map: Map<K, V> | (K extends object ? WeakMap<K, V> : never),
    key: K,
    getDefaultValue: () => NoInfer<V>
)

type NoInfer<T> = [T][T extends any ? 0 : never];

export function getOrUpdate<K, V>(
    map: Map<K, V> | (K extends object ? WeakMap<K, V> : never),
    key: K,
    getDefaultValue: () => NoInfer<V>
): V {
    if (!map.has(key)) {
        map.set(key, getDefaultValue());
    }

    return map.get(key)!;
}

export function isNonNull<T>(value: T | null | undefined): value is T {
    return value != null;