import { PropsWithType } from './types';
/**
 * Returns if the given array is `null`, `undefined`, or has no elements.
 *
 * @param array - The array to check if it is empty.
 * @returns `true` if the array is `null`, `undefined`, or has no elements. `false` otherwise.
 * @public
 */
export declare function isArrayEmpty(array: unknown[] | undefined | null): array is undefined | null | [];
/**
 * Reduce an array of strings to an object which properties names are the value of each string,
 * and the value under that property are also the string.
 *
 * @param array - Array of strings that will be used to create the object.
 *
 * @returns New object which properties object[key] contains object of each iteration in the
 * array.
 *
 * @example Converting an array to an object:
 *         arrayToObject(['a', 'b', 'c']) === \{a: 'a', b: 'b', c: 'c'\}
 *
 * @public
 */
export declare function arrayToObject(array: string[]): Record<string, string>;
/**
 * Reduce an array of objects to an object which properties names are the value of each object[key],
 * and the value under that property are each object. 'key' is the the parameter passed to this
 * function.
 *
 * @param array - Array of objects that contains objects which have object[key] string as a property
 * value.
 * @param key - Key used to access to each object[key] value, used for each property name in the new
 * object.
 *
 * @returns New object which properties object[key] contains object of each iteration in the array.
 *
 * @public
 */
export declare function arrayToObject<ArrayType>(array: ArrayType[], key: PropsWithType<ArrayType, string | number>): Record<string, ArrayType>;
/**
 * Groups the array items based on the provided `groupBy` function.
 *
 * @param array - The array to iterate, grouping its items in different arrays based on the
 * `groupBy` function.
 * @param groupBy - A function to determine the group name of a single item.
 * @returns The items grouped in a dictionary.
 *
 * @public
 */
export declare function groupItemsBy<ArrayType, ReturnType extends string | number>(array: ArrayType[], groupBy: (item: ArrayType, index: number) => ReturnType): Record<ReturnType, ArrayType[]>;
/**
 * Filters an array with all elements that pass the test implemented by the given filter
 * function. If an item has another list of items in the `childrenKey` property it recursively
 * filters that new list, adding it to the returned one.
 *
 * @param array - Array to be filtered.
 * @param condition - Predicate function to test each element of the array. It should return `true`
 * to keep the element; or `false` otherwise.
 * @param childrenKey - Property name within the array used to perform a recursive call.
 *
 * @example
 * Input - Output example
 *
 * ```
 * const hierarchicalFilters: Filter[] = [
 *   {
 *     id: 'filter1'
 *     selected: true,
 *     children: [
 *       {
 *         id: 'filter1-1'
 *         selected: true,
 *         children: []
 *       },
 *       {
 *         id: 'filter1-2'
 *         selected: false,
 *         children: []
 *       }
 *     ]
 *   },
 *   {
 *     id: 'filter2',
 *     selected: false,
 *     children: [
 *      {
 *        id: 'filter2-1',
 *        selected: true // not should happen
 *      }
 *     ]
 *   }
 * ]
 *
 *  const filteredArray: Filter[] = deepFilterArray(
 *    hierarchicalFilters,
 *    filter => filter.selected,
 *    'children'
 *  )
 *
 *  /*
 *    filteredArray = [
 *      {
 *        id: 'filter1'
 *        selected: true,
 *        children: [
 *          {
 *            id: 'filter1-1'
 *            selected: true,
 *            children: []
 *          },
 *          {
 *            id: 'filter1-2'
 *            selected: false,
 *            children: []
 *          }
 *        ]
 *      },
 *      {
 *        id: 'filter1-1'
 *        selected: true,
 *        children: []
 *      }
 *    ]
 * ```
 *
 * @returns A new array with the elements that pass the condition, or an empty array if no one
 * pass the test.
 *
 * @public
 */
export declare function deepFilter<Item extends {
    [key in Key]?: Item[];
}, Key extends keyof Item>(array: Item[], condition: (item: Item) => boolean, childrenKey: Key): Item[];
/**
 * Flat an `Item[]` deeply using the given `childrenKey` to access to his children.
 *
 * @param array - The list of items to flat. Each item may have another list of items of
 * the same type to flat.
 * @param childrenKey - Property name where each of the items of the given array may have another
 * list of items to be flattened.
 *
 * @returns A flat list with all the found items.
 *
 * @public
 */
export declare function deepFlat<Item extends {
    [key in Key]?: Item[];
}, Key extends keyof Item>(array: Item[], childrenKey: Key): Item[];
/**
 * Creates an Emitter filter function to compare two arrays and filter those that are equal.
 *
 * @param comparator - String with the name of the field of the arrays items to compare, or function
 * to compare items directly.
 * @returns The comparator function that receives two arrays to compare them.
 *
 * @internal
 */
export declare function createEmitterArrayFilter<T>(comparator: keyof T | ((item1: T, item2: T) => boolean)): (newCollection: Array<T>, oldCollection: Array<T>) => boolean;
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