import type { firestore } from 'firebase-admin';
import type { DefaultMigrator, Traversable, TraversalConfig, Traverser } from './interfaces';
/**
 * Creates a migrator that facilitates database migrations. Accepts a custom traverser object as argument which the
 * migrator will use when traversing the collection and writing to documents. This migrator does not use atomic batch
 * writes so it is possible that when a write fails other writes go through.
 *
 * @param traverser - The traverser object that this migrator will use when traversing the collection and writing to documents.
 * @returns A new {@link DefaultMigrator} object.
 */
export declare function createMigrator<D = firestore.DocumentData>(traverser: Traverser<D>): DefaultMigrator<D>;
/**
 * Creates a migrator that facilitates database migrations. The migrator creates a default traverser that
 * it uses when traversing the collection and writing to documents. This migrator does not use atomic batch writes
 * so it is possible that when a write fails other writes go through.
 *
 * @param traversable - A collection-like traversable group of documents to migrate.
 * @param traversalConfig - Optional. The traversal configuration with which the default traverser will be created.
 * @returns A new {@link DefaultMigrator} object.
 * @throws {@link InvalidConfigError} Thrown if the specified `traversalConfig` is invalid.
 */
export declare function createMigrator<D = firestore.DocumentData>(traversable: Traversable<D>, traversalConfig?: Partial<TraversalConfig>): DefaultMigrator<D>;