import { Source, Sink, START, DATA, END, Callbag } from 'callbag';
export declare type ChangeTraceLeaf<T> = {
    from: T | undefined;
    to: T | undefined;
};
export declare type ChangeTraceNode<T> = {
    subs: (T extends Array<unknown> ? {
        [index: number]: ChangeTrace<T[number]>;
    } : Partial<{
        [K in keyof T]: ChangeTrace<T[K]>;
    }>) | {};
};
export declare type ChangeTrace<T> = ChangeTraceLeaf<T> | ChangeTraceNode<T>;
export interface Change<T> {
    value: T | undefined;
    trace?: ChangeTrace<T> | undefined;
}
export declare function isLeaf<T>(c: ChangeTrace<T> | undefined): c is ChangeTraceLeaf<T> | undefined;
export declare type Downstream<T> = Source<Change<T>>;
export declare type Upstream<T> = Sink<Change<T>>;
export declare type MsgType = START | DATA | END;
export declare type StateMsgType = MsgType | typeof _Latest | typeof _Downstream | typeof _Upstream;
export declare type StateLike<T> = Callbag<T, T | undefined> & {
    get(): T | undefined;
    set(t: T): void;
    clear(): void;
    sub<K extends keyof T>(key: K): SubState<T, K>;
    downstream(): Downstream<T | undefined>;
    upstream(): Upstream<T>;
};
export declare type SubState<T, K extends keyof T> = StateLike<T[K]>;
export declare type State<T> = Callbag<T, T> & {
    get(): T;
    set(t: T): void;
    clear(): void;
    sub<K extends keyof T>(key: K): SubState<T, K>;
    downstream(): Downstream<T>;
    upstream(): Upstream<T>;
};
export declare function isState<T>(cb: Source<T>): cb is State<T>;
export declare const _Start = 0;
export declare const _Data = 1;
export declare const _End = 2;
export declare const _Latest = 100;
export declare const _Downstream = 101;
export declare const _Upstream = 102;