import { InteropObservable, Observable, OperatorFunction, Subject } from 'rxjs';
import { UnknownAction, UnknownActionCreator, UnknownActionCreatorWithPayload, VoidPayload } from './internal/types';
export type Reducer<State, Payload = VoidPayload> = (previousState: State, payload: Payload, namespace?: string) => State;
export type RegisteredReducer<State, Payload = any> = Reducer<State, Payload> & {
    trigger: {
        actions: UnknownActionCreator[];
    } | {
        source$: Observable<Payload>;
    };
};
type ObservableLike<T> = Observable<T> | InteropObservable<T>;
type ReducerCreator = {
    /**
     * Define a reducer for a stream
     *
     * @see combineReducers
     * @param source$ The stream which will trigger this reducer
     * @param reducer The reducer function
     * @template `State` - The state the reducer reduces to
     * @template `Payload` - The type of values `source$` emits
     * @returns A registered reducer that can be passed into `combineReducers`, or
     *          called directly as if it was the `reducer` parameter itself.
     */
    <State, Payload>(source$: ObservableLike<Payload>, reducer: Reducer<State, Payload>): RegisteredReducer<State, Payload>;
    /**
     * Define a reducer for multiple actions with overlapping payload
     *
     * @see combineReducers
     * @param actionCreator The action creator to assign this reducer to and
     *                      extract payload type from
     * @param reducer The reducer function
     * @template `State` - The state the reducer reduces to
     * @template `Payload` - The payload of the action, fed to the reducer together
     *                       with the state. Should be automatically extracted from
     *                       the `actionCreator` parameter
     * @returns A registered reducer that can be passed into `combineReducers`, or
     *          called directly as if it was the `reducer` parameter itself.
     */
    <State, Payload>(actionCreator: UnknownActionCreatorWithPayload<Payload>[], reducer: Reducer<State, Payload>): RegisteredReducer<State, Payload>;
    /**
     * Define a reducer for multiple actions without overlapping payload
     *
     * @see combineReducers
     * @param actionCreator The action creator to assign this reducer to and
     *                      extract payload type from
     * @param reducer The reducer function
     * @template `State` - The state the reducer reduces to
     * @returns A registered reducer that can be passed into `combineReducers`, or
     *          called directly as if it was the `reducer` parameter itself.
     */
    <State>(actionCreator: UnknownActionCreatorWithPayload<unknown>[], reducer: Reducer<State, unknown>): RegisteredReducer<State, unknown>;
    /**
     * Define a reducer for multiple actions without payloads
     *
     * @see combineReducers
     * @param actionCreator The action creator to assign this reducer to and
     *                      extract payload type from
     * @param reducer The reducer function
     * @template `State` - The state the reducer reduces to
     * @returns A registered reducer that can be passed into `combineReducers`, or
     *          called directly as if it was the `reducer` parameter itself.
     */
    <State>(actionCreator: UnknownActionCreator[], reducer: Reducer<State, VoidPayload>): RegisteredReducer<State, VoidPayload>;
    /**
     * Define a reducer for an action with payload
     *
     * @see combineReducers
     * @param actionCreator The action creator to assign this reducer to and
     *                      extract payload type from
     * @param reducer The reducer function
     * @template `State` - The state the reducer reduces to
     * @template `Payload` - The payload of the action, fed to the reducer together
     *                       with the state. Should be automatically extracted from
     *                       the `actionCreator` parameter
     * @returns A registered reducer that can be passed into `combineReducers`, or
     *          called directly as if it was the `reducer` parameter itself.
     */
    <State, Payload>(actionCreator: UnknownActionCreatorWithPayload<Payload>, reducer: Reducer<State, Payload>): RegisteredReducer<State, Payload>;
    /**
     * Define a reducer for an action without payload
     *
     * @see combineReducers
     * @param actionCreator The action creator to assign this reducer to and
     *                      extract payload type from
     * @param reducer The reducer function
     * @template `State` - The state the reducer reduces to
     * @returns A registered reducer that can be passed into `combineReducers`, or
     *          called directly as if it was the `reducer` parameter itself.
     */
    <State>(actionCreator: UnknownActionCreator, reducer: Reducer<State, VoidPayload>): RegisteredReducer<State, VoidPayload>;
};
export declare const reducer: ReducerCreator;
type CombineReducersConfig = {
    errorSubject?: Subject<any>;
    namespace?: string;
};
/**
 * Combine registered reducers into a stream operator
 *
 * Each reducer will receive the previous state (or the seed if it's the first
 * invocation) together with the payloads of the actions of the given reducer,
 * or the emitted values from the stream of the given reducer.
 *
 * The behaviour is undefined if multiple reducers are registered for the same
 * actions.
 *
 * This operator does not change whether the stream is hot or cold.
 *
 * The order of invocation for the reducers is controlled by the rxjs operator
 * `merge`, which is called with all the actions first and then the source
 * streams in the order their reducers are defined in the `reducers` argument.
 *
 * If a reducer throws an error, it will be nexted on the error subject. If the
 * error subject is not explicitly set, it will default to
 * `defaultErrorSubject`, which will rethrow the errors globally, as uncaught
 * exceptions. The stream will not complete or emit any value upon an error.
 *
 * @param seed The initial input to the first reducer call
 * @param reducers The reducer entries that should be combined
 * @param namespace Namespace to pass on to the reducers. Note that this will
 *                  always be passed, regardless of namespaces of the actions.
 * @see rxjs.merge
 */
export declare const combineReducers: <State>(seed: State, reducers: RegisteredReducer<State, any>[], { errorSubject, namespace }?: CombineReducersConfig) => OperatorFunction<UnknownAction, State>;
export {};