export interface CounterSnapshot {
    exists: boolean;
    data: () => number;
}
import { DocumentReference, WriteResult } from "firebase-admin/firestore";
export declare class Counter {
    private doc;
    private field;
    /**
     * Constructs a sharded counter object that references to a field
     * in a document that is a counter.
     *
     * @param doc A reference to a document with a counter field.
     * @param field A path to a counter field in the above document.
     */
    constructor(doc: DocumentReference, field: string);
    /**
     * Get latency compensated view of the counter.
     *
     * All local increments will be reflected in the counter even if the main
     * counter hasn't been updated yet.
     */
    get(options?: any): Promise<number>;
    /**
     * Listen to latency compensated view of the counter.
     *
     * All local increments to this counter will be immediately visible in the
     * snapshot.
     */
    onSnapshot(observable: (next: CounterSnapshot) => void): void;
    /**
     * Increment the counter by a given value.
     *
     * e.g.
     * const counter = new sharded.Counter(db.doc("path/document"), "counter");
     * counter.incrementBy(1);
     */
    incrementBy(val: number): Promise<WriteResult>;
    /**
     * Access the assigned shard directly. Useful to update multiple counters
     * at the same time, batches or transactions.
     *
     * e.g.
     * const counter = new sharded.Counter(db.doc("path/counter"), "");
     * const shardRef = counter.shard();
     * shardRef.set({"counter1", firestore.FieldValue.Increment(1),
     *               "counter2", firestore.FieldValue.Increment(1));
     */
    shard(): DocumentReference;
}