import type { Noop } from '../../utils/noop';
export type Batch<TKey, TValue> = {
    items: BatchItem<TKey, TValue>[];
    cancel: Noop;
};
export type BatchItem<TKey, TValue> = {
    aborted: boolean;
    key: TKey;
    resolve: ((value: TValue) => void) | null;
    reject: ((error: Error) => void) | null;
    batch: Batch<TKey, TValue> | null;
};
export type BatchLoader<TKey = any, TValue = any> = {
    /**
     * Determines whether the current operation fits in the same batch.
     */
    validate: (keys: TKey[]) => boolean;
    /**
     * Queues a request.
     */
    fetch: BatchFetcher<TKey, TValue>;
};
export type BatchFetcher<TKey, TValue> = (keys: TKey[], unitResolver: (index: number, value: NonNullable<TValue>) => void) => {
    promise: Promise<TValue[]>;
    cancel: Noop;
};
export declare class BatchError extends Error {
    constructor(message?: string);
}
/**
 * {@see https://github.com/graphql/dataloader}
 *
 * Less configuration, no caching, and allows you to cancel requests.
 * When cancelling a single fetch the whole batch will be cancelled only when _all_ items are cancelled.
 */
export declare function batchedDataLoader<TKey, TValue>(loader: BatchLoader<TKey, TValue>): {
    load: (key: TKey) => {
        promise: Promise<TValue>;
        cancel: () => void;
    };
};
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