import { Slice } from '../slice';
/**
 * Derives a snapshot from a mutable source that is assumed local to the
 * component that is using this hook. The snapshot is considered atomic.
 * "getSnapshot" should be static (dynamic values won't be taken into account).
 *
 * @param getSnapshot - function that returns an immutable atomic snapshot of the source
 * @param slice - the slice of state represented by the snapshot
 * @returns the snapshot
 */
export declare function useSnapshot<Snapshot>(getSnapshot: (currentSnapshot: Snapshot | null) => Snapshot, slice: Slice): Snapshot;
/**
 * Generates a source, and allows to use it safely inside any component.
 *
 * @param init - function that generates the source, it can optionally returns also a "destroy" function
 * @param getSnapshot - function that returns an immutable atomic snapshot of the source
 * @param contract - function to register a callback that is called whenever the source changes
 * @returns the snapshot and a function to lazily initialize the source
 */
export declare function useSource<Source, Snapshot>(init: () => [source: Source, destroy?: (source: Source) => void], contract: (source: Source, onChange: () => void) => void | (() => void), getSnapshot: (source: Source | null, currentSnapshot: Snapshot | null) => Snapshot): readonly [Snapshot, () => Source];
/**
 * Generates a pure source, and allows to use it safely inside any component.
 * The source is re-created every time a dependency changes.
 * The source generation and the contract should be side-effect free.
 * After the contract is signed, the source should be garbage collectable.
 *
 * @param init - function that generates the source
 * @param getSnapshot - function that returns an immutable atomic snapshot of the source
 * @param contract - function to register a callback that is called whenever the source changes
 * @returns the snapshot and the source
 */
export declare function usePureSource<Source, Snapshot>(init: () => Source, contract: (source: Source, onChange: () => void) => void, getSnapshot: (source: Source, currentSnapshot: Snapshot | null) => Snapshot): readonly [Snapshot, Source];