Function removeDuplicates

src/util/model.ts:1333–1358

(
    arr: (TItem | NullUndefined)[],
    getKey: (item: TItem) => string,
    // `existingCount`: the count before this item is added.
    resolve: ((item: TItem, existingCount: number) => void) | NullUndefined,
)

 *  - Callers need to handle null/undefined (if existing) in `getKey`.
 */
export function removeDuplicates<TItem>(
    arr: (TItem | NullUndefined)[],
    getKey: (item: TItem) => string,
    // `existingCount`: the count before this item is added.
    resolve: ((item: TItem, existingCount: number) => void) | NullUndefined,
): void {
    const dupMap = createHashMap<number, string>();
    let writeIdx = 0;
    each(arr, function (item) {
        const key = getKey(item);
        if (__DEV__) {
            assert(isString(key));
        }
        const count = dupMap.get(key) || 0;
        if (resolve) {
            resolve(item, count);
        }
        if (!count && !resolve) {
            arr[writeIdx++] = item;
        }
        dupMap.set(key, count + 1);
    });
    if (!resolve) {
        arr.length = writeIdx;
    }
}

export function removeDuplicatesGetKeyFromValueProp<TValue extends (string | number)>(
    item: {value: TValue}