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+/**
+ * Firebase Realtime Database
+ *
+ * @packageDocumentation
+ */
+
+import { AppCheckInternalComponentName } from '@firebase/app-check-interop-types';
+import { AppCheckTokenListener } from '@firebase/app-check-interop-types';
+import { AppCheckTokenResult } from '@firebase/app-check-interop-types';
+import { EmulatorMockTokenOptions } from '@firebase/util';
+import { FirebaseApp } from '@firebase/app';
+import { FirebaseApp as FirebaseApp_2 } from '@firebase/app-types';
+import { FirebaseAppCheckInternal } from '@firebase/app-check-interop-types';
+import { FirebaseAuthInternal } from '@firebase/auth-interop-types';
+import { FirebaseAuthInternalName } from '@firebase/auth-interop-types';
+import { FirebaseAuthTokenData } from '@firebase/app-types/private';
+import { Provider } from '@firebase/component';
+
+/**
+ * Abstraction around AppCheck's token fetching capabilities.
+ */
+declare class AppCheckTokenProvider {
+    private appCheckProvider?;
+    private appCheck?;
+    private serverAppAppCheckToken?;
+    private appName;
+    constructor(app: FirebaseApp, appCheckProvider?: Provider<AppCheckInternalComponentName>);
+    getToken(forceRefresh?: boolean): Promise<AppCheckTokenResult>;
+    addTokenChangeListener(listener: AppCheckTokenListener): void;
+    notifyForInvalidToken(): void;
+}
+
+declare interface AuthTokenProvider {
+    getToken(forceRefresh: boolean): Promise<FirebaseAuthTokenData>;
+    addTokenChangeListener(listener: (token: string | null) => void): void;
+    removeTokenChangeListener(listener: (token: string | null) => void): void;
+    notifyForInvalidToken(): void;
+}
+
+/**
+ * A cache node only stores complete children. Additionally it holds a flag whether the node can be considered fully
+ * initialized in the sense that we know at one point in time this represented a valid state of the world, e.g.
+ * initialized with data from the server, or a complete overwrite by the client. The filtered flag also tracks
+ * whether a node potentially had children removed due to a filter.
+ */
+declare class CacheNode {
+    private node_;
+    private fullyInitialized_;
+    private filtered_;
+    constructor(node_: Node_2, fullyInitialized_: boolean, filtered_: boolean);
+    /**
+     * Returns whether this node was fully initialized with either server data or a complete overwrite by the client
+     */
+    isFullyInitialized(): boolean;
+    /**
+     * Returns whether this node is potentially missing children due to a filter applied to the node
+     */
+    isFiltered(): boolean;
+    isCompleteForPath(path: Path): boolean;
+    isCompleteForChild(key: string): boolean;
+    getNode(): Node_2;
+}
+
+declare class CancelEvent implements Event_2 {
+    eventRegistration: EventRegistration;
+    error: Error;
+    path: Path;
+    constructor(eventRegistration: EventRegistration, error: Error, path: Path);
+    getPath(): Path;
+    getEventType(): string;
+    getEventRunner(): () => void;
+    toString(): string;
+}
+
+declare interface Change {
+    /** @param type - The event type */
+    type: ChangeType;
+    /** @param snapshotNode - The data */
+    snapshotNode: Node_2;
+    /** @param childName - The name for this child, if it's a child even */
+    childName?: string;
+    /** @param oldSnap - Used for intermediate processing of child changed events */
+    oldSnap?: Node_2;
+    /**  * @param prevName - The name for the previous child, if applicable */
+    prevName?: string | null;
+}
+
+declare const enum ChangeType {
+    /** Event type for a child added */
+    CHILD_ADDED = "child_added",
+    /** Event type for a child removed */
+    CHILD_REMOVED = "child_removed",
+    /** Event type for a child changed */
+    CHILD_CHANGED = "child_changed",
+    /** Event type for a child moved */
+    CHILD_MOVED = "child_moved",
+    /** Event type for a value change */
+    VALUE = "value"
+}
+
+/**
+ * Gets a `Reference` for the location at the specified relative path.
+ *
+ * The relative path can either be a simple child name (for example, "ada") or
+ * a deeper slash-separated path (for example, "ada/name/first").
+ *
+ * @param parent - The parent location.
+ * @param path - A relative path from this location to the desired child
+ *   location.
+ * @returns The specified child location.
+ */
+export declare function child(parent: DatabaseReference, path: string): DatabaseReference;
+
+declare class ChildChangeAccumulator {
+    private readonly changeMap;
+    trackChildChange(change: Change): void;
+    getChanges(): Change[];
+}
+
+/**
+ * @license
+ * Copyright 2017 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * @fileoverview Implementation of an immutable SortedMap using a Left-leaning
+ * Red-Black Tree, adapted from the implementation in Mugs
+ * (http://mads379.github.com/mugs/) by Mads Hartmann Jensen
+ * (mads379\@gmail.com).
+ *
+ * Original paper on Left-leaning Red-Black Trees:
+ *   http://www.cs.princeton.edu/~rs/talks/LLRB/LLRB.pdf
+ *
+ * Invariant 1: No red node has a red child
+ * Invariant 2: Every leaf path has the same number of black nodes
+ * Invariant 3: Only the left child can be red (left leaning)
+ */
+declare type Comparator<K> = (key1: K, key2: K) => number;
+
+/**
+ * Since updates to filtered nodes might require nodes to be pulled in from "outside" the node, this interface
+ * can help to get complete children that can be pulled in.
+ * A class implementing this interface takes potentially multiple sources (e.g. user writes, server data from
+ * other views etc.) to try it's best to get a complete child that might be useful in pulling into the view.
+ *
+ * @interface
+ */
+declare interface CompleteChildSource {
+    getCompleteChild(childKey: string): Node_2 | null;
+    getChildAfterChild(index: Index, child: NamedNode, reverse: boolean): NamedNode | null;
+}
+
+/**
+ * This class holds a collection of writes that can be applied to nodes in unison. It abstracts away the logic with
+ * dealing with priority writes and multiple nested writes. At any given path there is only allowed to be one write
+ * modifying that path. Any write to an existing path or shadowing an existing path will modify that existing write
+ * to reflect the write added.
+ */
+declare class CompoundWrite {
+    writeTree_: ImmutableTree<Node_2>;
+    constructor(writeTree_: ImmutableTree<Node_2>);
+    static empty(): CompoundWrite;
+}
+
+/**
+ * Modify the provided instance to communicate with the Realtime Database
+ * emulator.
+ *
+ * <p>Note: This method must be called before performing any other operation.
+ *
+ * @param db - The instance to modify.
+ * @param host - The emulator host (ex: localhost)
+ * @param port - The emulator port (ex: 8080)
+ * @param options.mockUserToken - the mock auth token to use for unit testing Security Rules
+ */
+export declare function connectDatabaseEmulator(db: Database, host: string, port: number, options?: {
+    mockUserToken?: EmulatorMockTokenOptions | string;
+}): void;
+
+/**
+ * Class representing a Firebase Realtime Database.
+ */
+export declare class Database implements _FirebaseService {
+    _repoInternal: Repo;
+    /** The {@link @firebase/app#FirebaseApp} associated with this Realtime Database instance. */
+    readonly app: FirebaseApp;
+    /** Represents a `Database` instance. */
+    readonly 'type' = "database";
+    /** Track if the instance has been used (root or repo accessed) */
+    _instanceStarted: boolean;
+    /** Backing state for root_ */
+    private _rootInternal?;
+    /** @hideconstructor */
+    constructor(_repoInternal: Repo, 
+    /** The {@link @firebase/app#FirebaseApp} associated with this Realtime Database instance. */
+    app: FirebaseApp);
+    get _repo(): Repo;
+    get _root(): _ReferenceImpl;
+    _delete(): Promise<void>;
+    _checkNotDeleted(apiName: string): void;
+}
+
+/**
+ * A `DatabaseReference` represents a specific location in your Database and can be used
+ * for reading or writing data to that Database location.
+ *
+ * You can reference the root or child location in your Database by calling
+ * `ref()` or `ref("child/path")`.
+ *
+ * Writing is done with the `set()` method and reading can be done with the
+ * `on*()` method. See {@link
+ * https://firebase.google.com/docs/database/web/read-and-write}
+ */
+export declare interface DatabaseReference extends Query {
+    /**
+     * The last part of the `DatabaseReference`'s path.
+     *
+     * For example, `"ada"` is the key for
+     * `https://<DATABASE_NAME>.firebaseio.com/users/ada`.
+     *
+     * The key of a root `DatabaseReference` is `null`.
+     */
+    readonly key: string | null;
+    /**
+     * The parent location of a `DatabaseReference`.
+     *
+     * The parent of a root `DatabaseReference` is `null`.
+     */
+    readonly parent: DatabaseReference | null;
+    /** The root `DatabaseReference` of the Database. */
+    readonly root: DatabaseReference;
+}
+
+/**
+ * A `DataSnapshot` contains data from a Database location.
+ *
+ * Any time you read data from the Database, you receive the data as a
+ * `DataSnapshot`. A `DataSnapshot` is passed to the event callbacks you attach
+ * with `on()` or `once()`. You can extract the contents of the snapshot as a
+ * JavaScript object by calling the `val()` method. Alternatively, you can
+ * traverse into the snapshot by calling `child()` to return child snapshots
+ * (which you could then call `val()` on).
+ *
+ * A `DataSnapshot` is an efficiently generated, immutable copy of the data at
+ * a Database location. It cannot be modified and will never change (to modify
+ * data, you always call the `set()` method on a `Reference` directly).
+ */
+export declare class DataSnapshot {
+    readonly _node: Node_2;
+    /**
+     * The location of this DataSnapshot.
+     */
+    readonly ref: DatabaseReference;
+    readonly _index: Index;
+    /**
+     * @param _node - A SnapshotNode to wrap.
+     * @param ref - The location this snapshot came from.
+     * @param _index - The iteration order for this snapshot
+     * @hideconstructor
+     */
+    constructor(_node: Node_2, 
+    /**
+     * The location of this DataSnapshot.
+     */
+    ref: DatabaseReference, _index: Index);
+    /**
+     * Gets the priority value of the data in this `DataSnapshot`.
+     *
+     * Applications need not use priority but can order collections by
+     * ordinary properties (see
+     * {@link https://firebase.google.com/docs/database/web/lists-of-data#sorting_and_filtering_data |Sorting and filtering data}
+     * ).
+     */
+    get priority(): string | number | null;
+    /**
+     * The key (last part of the path) of the location of this `DataSnapshot`.
+     *
+     * The last token in a Database location is considered its key. For example,
+     * "ada" is the key for the /users/ada/ node. Accessing the key on any
+     * `DataSnapshot` will return the key for the location that generated it.
+     * However, accessing the key on the root URL of a Database will return
+     * `null`.
+     */
+    get key(): string | null;
+    /** Returns the number of child properties of this `DataSnapshot`. */
+    get size(): number;
+    /**
+     * Gets another `DataSnapshot` for the location at the specified relative path.
+     *
+     * Passing a relative path to the `child()` method of a DataSnapshot returns
+     * another `DataSnapshot` for the location at the specified relative path. The
+     * relative path can either be a simple child name (for example, "ada") or a
+     * deeper, slash-separated path (for example, "ada/name/first"). If the child
+     * location has no data, an empty `DataSnapshot` (that is, a `DataSnapshot`
+     * whose value is `null`) is returned.
+     *
+     * @param path - A relative path to the location of child data.
+     */
+    child(path: string): DataSnapshot;
+    /**
+     * Returns true if this `DataSnapshot` contains any data. It is slightly more
+     * efficient than using `snapshot.val() !== null`.
+     */
+    exists(): boolean;
+    /**
+     * Exports the entire contents of the DataSnapshot as a JavaScript object.
+     *
+     * The `exportVal()` method is similar to `val()`, except priority information
+     * is included (if available), making it suitable for backing up your data.
+     *
+     * @returns The DataSnapshot's contents as a JavaScript value (Object,
+     *   Array, string, number, boolean, or `null`).
+     */
+    exportVal(): any;
+    /**
+     * Enumerates the top-level children in the `IteratedDataSnapshot`.
+     *
+     * Because of the way JavaScript objects work, the ordering of data in the
+     * JavaScript object returned by `val()` is not guaranteed to match the
+     * ordering on the server nor the ordering of `onChildAdded()` events. That is
+     * where `forEach()` comes in handy. It guarantees the children of a
+     * `DataSnapshot` will be iterated in their query order.
+     *
+     * If no explicit `orderBy*()` method is used, results are returned
+     * ordered by key (unless priorities are used, in which case, results are
+     * returned by priority).
+     *
+     * @param action - A function that will be called for each child DataSnapshot.
+     * The callback can return true to cancel further enumeration.
+     * @returns true if enumeration was canceled due to your callback returning
+     * true.
+     */
+    forEach(action: (child: IteratedDataSnapshot) => boolean | void): boolean;
+    /**
+     * Returns true if the specified child path has (non-null) data.
+     *
+     * @param path - A relative path to the location of a potential child.
+     * @returns `true` if data exists at the specified child path; else
+     *  `false`.
+     */
+    hasChild(path: string): boolean;
+    /**
+     * Returns whether or not the `DataSnapshot` has any non-`null` child
+     * properties.
+     *
+     * You can use `hasChildren()` to determine if a `DataSnapshot` has any
+     * children. If it does, you can enumerate them using `forEach()`. If it
+     * doesn't, then either this snapshot contains a primitive value (which can be
+     * retrieved with `val()`) or it is empty (in which case, `val()` will return
+     * `null`).
+     *
+     * @returns true if this snapshot has any children; else false.
+     */
+    hasChildren(): boolean;
+    /**
+     * Returns a JSON-serializable representation of this object.
+     */
+    toJSON(): object | null;
+    /**
+     * Extracts a JavaScript value from a `DataSnapshot`.
+     *
+     * Depending on the data in a `DataSnapshot`, the `val()` method may return a
+     * scalar type (string, number, or boolean), an array, or an object. It may
+     * also return null, indicating that the `DataSnapshot` is empty (contains no
+     * data).
+     *
+     * @returns The DataSnapshot's contents as a JavaScript value (Object,
+     *   Array, string, number, boolean, or `null`).
+     */
+    val(): any;
+}
+export { EmulatorMockTokenOptions }
+
+/**
+ * Logs debugging information to the console.
+ *
+ * @param enabled - Enables logging if `true`, disables logging if `false`.
+ * @param persistent - Remembers the logging state between page refreshes if
+ * `true`.
+ */
+export declare function enableLogging(enabled: boolean, persistent?: boolean): any;
+
+/**
+ * Logs debugging information to the console.
+ *
+ * @param logger - A custom logger function to control how things get logged.
+ */
+export declare function enableLogging(logger: (message: string) => unknown): any;
+
+/**
+ * Creates a `QueryConstraint` with the specified ending point.
+ *
+ * Using `startAt()`, `startAfter()`, `endBefore()`, `endAt()` and `equalTo()`
+ * allows you to choose arbitrary starting and ending points for your queries.
+ *
+ * The ending point is inclusive, so children with exactly the specified value
+ * will be included in the query. The optional key argument can be used to
+ * further limit the range of the query. If it is specified, then children that
+ * have exactly the specified value must also have a key name less than or equal
+ * to the specified key.
+ *
+ * You can read more about `endAt()` in
+ * {@link https://firebase.google.com/docs/database/web/lists-of-data#filtering_data | Filtering data}.
+ *
+ * @param value - The value to end at. The argument type depends on which
+ * `orderBy*()` function was used in this query. Specify a value that matches
+ * the `orderBy*()` type. When used in combination with `orderByKey()`, the
+ * value must be a string.
+ * @param key - The child key to end at, among the children with the previously
+ * specified priority. This argument is only allowed if ordering by child,
+ * value, or priority.
+ */
+export declare function endAt(value: number | string | boolean | null, key?: string): QueryConstraint;
+
+/**
+ * Creates a `QueryConstraint` with the specified ending point (exclusive).
+ *
+ * Using `startAt()`, `startAfter()`, `endBefore()`, `endAt()` and `equalTo()`
+ * allows you to choose arbitrary starting and ending points for your queries.
+ *
+ * The ending point is exclusive. If only a value is provided, children
+ * with a value less than the specified value will be included in the query.
+ * If a key is specified, then children must have a value less than or equal
+ * to the specified value and a key name less than the specified key.
+ *
+ * @param value - The value to end before. The argument type depends on which
+ * `orderBy*()` function was used in this query. Specify a value that matches
+ * the `orderBy*()` type. When used in combination with `orderByKey()`, the
+ * value must be a string.
+ * @param key - The child key to end before, among the children with the
+ * previously specified priority. This argument is only allowed if ordering by
+ * child, value, or priority.
+ */
+export declare function endBefore(value: number | string | boolean | null, key?: string): QueryConstraint;
+
+/**
+ * Creates a `QueryConstraint` that includes children that match the specified
+ * value.
+ *
+ * Using `startAt()`, `startAfter()`, `endBefore()`, `endAt()` and `equalTo()`
+ * allows you to choose arbitrary starting and ending points for your queries.
+ *
+ * The optional key argument can be used to further limit the range of the
+ * query. If it is specified, then children that have exactly the specified
+ * value must also have exactly the specified key as their key name. This can be
+ * used to filter result sets with many matches for the same value.
+ *
+ * You can read more about `equalTo()` in
+ * {@link https://firebase.google.com/docs/database/web/lists-of-data#filtering_data | Filtering data}.
+ *
+ * @param value - The value to match for. The argument type depends on which
+ * `orderBy*()` function was used in this query. Specify a value that matches
+ * the `orderBy*()` type. When used in combination with `orderByKey()`, the
+ * value must be a string.
+ * @param key - The child key to start at, among the children with the
+ * previously specified priority. This argument is only allowed if ordering by
+ * child, value, or priority.
+ */
+export declare function equalTo(value: number | string | boolean | null, key?: string): QueryConstraint;
+
+/**
+ * Encapsulates the data needed to raise an event
+ * @interface
+ */
+declare interface Event_2 {
+    getPath(): Path;
+    getEventType(): string;
+    getEventRunner(): () => void;
+    toString(): string;
+}
+
+/**
+ * An EventGenerator is used to convert "raw" changes (Change) as computed by the
+ * CacheDiffer into actual events (Event) that can be raised.  See generateEventsForChanges()
+ * for details.
+ *
+ */
+declare class EventGenerator {
+    query_: QueryContext;
+    index_: Index;
+    constructor(query_: QueryContext);
+}
+
+declare interface EventList {
+    events: Event_2[];
+    path: Path;
+}
+
+/**
+ * The event queue serves a few purposes:
+ * 1. It ensures we maintain event order in the face of event callbacks doing operations that result in more
+ *    events being queued.
+ * 2. raiseQueuedEvents() handles being called reentrantly nicely.  That is, if in the course of raising events,
+ *    raiseQueuedEvents() is called again, the "inner" call will pick up raising events where the "outer" call
+ *    left off, ensuring that the events are still raised synchronously and in order.
+ * 3. You can use raiseEventsAtPath and raiseEventsForChangedPath to ensure only relevant previously-queued
+ *    events are raised synchronously.
+ *
+ * NOTE: This can all go away if/when we move to async events.
+ *
+ */
+declare class EventQueue {
+    eventLists_: EventList[];
+    /**
+     * Tracks recursion depth of raiseQueuedEvents_, for debugging purposes.
+     */
+    recursionDepth_: number;
+}
+
+/**
+ * An EventRegistration is basically an event type ('value', 'child_added', etc.) and a callback
+ * to be notified of that type of event.
+ *
+ * That said, it can also contain a cancel callback to be notified if the event is canceled.  And
+ * currently, this code is organized around the idea that you would register multiple child_ callbacks
+ * together, as a single EventRegistration.  Though currently we don't do that.
+ */
+declare interface EventRegistration {
+    /**
+     * True if this container has a callback to trigger for this event type
+     */
+    respondsTo(eventType: string): boolean;
+    createEvent(change: Change, query: QueryContext): Event_2;
+    /**
+     * Given event data, return a function to trigger the user's callback
+     */
+    getEventRunner(eventData: Event_2): () => void;
+    createCancelEvent(error: Error, path: Path): CancelEvent | null;
+    matches(other: EventRegistration): boolean;
+    /**
+     * False basically means this is a "dummy" callback container being used as a sentinel
+     * to remove all callback containers of a particular type.  (e.g. if the user does
+     * ref.off('value') without specifying a specific callback).
+     *
+     * (TODO: Rework this, since it's hacky)
+     *
+     */
+    hasAnyCallback(): boolean;
+}
+
+/**
+ * One of the following strings: "value", "child_added", "child_changed",
+ * "child_removed", or "child_moved."
+ */
+export declare type EventType = 'value' | 'child_added' | 'child_changed' | 'child_moved' | 'child_removed';
+
+/* Excluded from this release type: _FirebaseService */
+
+/**
+ * Force the use of longPolling instead of websockets. This will be ignored if websocket protocol is used in databaseURL.
+ */
+export declare function forceLongPolling(): void;
+
+/**
+ * Force the use of websockets instead of longPolling.
+ */
+export declare function forceWebSockets(): void;
+
+/**
+ * Gets the most up-to-date result for this query.
+ *
+ * @param query - The query to run.
+ * @returns A `Promise` which resolves to the resulting DataSnapshot if a value is
+ * available, or rejects if the client is unable to return a value (e.g., if the
+ * server is unreachable and there is nothing cached).
+ */
+export declare function get(query: Query): Promise<DataSnapshot>;
+
+/**
+ * Returns the instance of the Realtime Database SDK that is associated with the provided
+ * {@link @firebase/app#FirebaseApp}. Initializes a new instance with default settings if
+ * no instance exists or if the existing instance uses a custom database URL.
+ *
+ * @param app - The {@link @firebase/app#FirebaseApp} instance that the returned Realtime
+ * Database instance is associated with.
+ * @param url - The URL of the Realtime Database instance to connect to. If not
+ * provided, the SDK connects to the default instance of the Firebase App.
+ * @returns The `Database` instance of the provided app.
+ */
+export declare function getDatabase(app?: FirebaseApp, url?: string): Database;
+
+/**
+ * Disconnects from the server (all Database operations will be completed
+ * offline).
+ *
+ * The client automatically maintains a persistent connection to the Database
+ * server, which will remain active indefinitely and reconnect when
+ * disconnected. However, the `goOffline()` and `goOnline()` methods may be used
+ * to control the client connection in cases where a persistent connection is
+ * undesirable.
+ *
+ * While offline, the client will no longer receive data updates from the
+ * Database. However, all Database operations performed locally will continue to
+ * immediately fire events, allowing your application to continue behaving
+ * normally. Additionally, each operation performed locally will automatically
+ * be queued and retried upon reconnection to the Database server.
+ *
+ * To reconnect to the Database and begin receiving remote events, see
+ * `goOnline()`.
+ *
+ * @param db - The instance to disconnect.
+ */
+export declare function goOffline(db: Database): void;
+
+/**
+ * Reconnects to the server and synchronizes the offline Database state
+ * with the server state.
+ *
+ * This method should be used after disabling the active connection with
+ * `goOffline()`. Once reconnected, the client will transmit the proper data
+ * and fire the appropriate events so that your client "catches up"
+ * automatically.
+ *
+ * @param db - The instance to reconnect.
+ */
+export declare function goOnline(db: Database): void;
+
+/**
+ * A tree with immutable elements.
+ */
+declare class ImmutableTree<T> {
+    readonly value: T | null;
+    readonly children: SortedMap<string, ImmutableTree<T>>;
+    static fromObject<T>(obj: {
+        [k: string]: T;
+    }): ImmutableTree<T>;
+    constructor(value: T | null, children?: SortedMap<string, ImmutableTree<T>>);
+    /**
+     * True if the value is empty and there are no children
+     */
+    isEmpty(): boolean;
+    /**
+     * Given a path and predicate, return the first node and the path to that node
+     * where the predicate returns true.
+     *
+     * TODO Do a perf test -- If we're creating a bunch of `{path: value:}`
+     * objects on the way back out, it may be better to pass down a pathSoFar obj.
+     *
+     * @param relativePath - The remainder of the path
+     * @param predicate - The predicate to satisfy to return a node
+     */
+    findRootMostMatchingPathAndValue(relativePath: Path, predicate: (a: T) => boolean): {
+        path: Path;
+        value: T;
+    } | null;
+    /**
+     * Find, if it exists, the shortest subpath of the given path that points a defined
+     * value in the tree
+     */
+    findRootMostValueAndPath(relativePath: Path): {
+        path: Path;
+        value: T;
+    } | null;
+    /**
+     * @returns The subtree at the given path
+     */
+    subtree(relativePath: Path): ImmutableTree<T>;
+    /**
+     * Sets a value at the specified path.
+     *
+     * @param relativePath - Path to set value at.
+     * @param toSet - Value to set.
+     * @returns Resulting tree.
+     */
+    set(relativePath: Path, toSet: T | null): ImmutableTree<T>;
+    /**
+     * Removes the value at the specified path.
+     *
+     * @param relativePath - Path to value to remove.
+     * @returns Resulting tree.
+     */
+    remove(relativePath: Path): ImmutableTree<T>;
+    /**
+     * Gets a value from the tree.
+     *
+     * @param relativePath - Path to get value for.
+     * @returns Value at path, or null.
+     */
+    get(relativePath: Path): T | null;
+    /**
+     * Replace the subtree at the specified path with the given new tree.
+     *
+     * @param relativePath - Path to replace subtree for.
+     * @param newTree - New tree.
+     * @returns Resulting tree.
+     */
+    setTree(relativePath: Path, newTree: ImmutableTree<T>): ImmutableTree<T>;
+    /**
+     * Performs a depth first fold on this tree. Transforms a tree into a single
+     * value, given a function that operates on the path to a node, an optional
+     * current value, and a map of child names to folded subtrees
+     */
+    fold<V>(fn: (path: Path, value: T, children: {
+        [k: string]: V;
+    }) => V): V;
+    /**
+     * Recursive helper for public-facing fold() method
+     */
+    private fold_;
+    /**
+     * Find the first matching value on the given path. Return the result of applying f to it.
+     */
+    findOnPath<V>(path: Path, f: (path: Path, value: T) => V | null): V | null;
+    private findOnPath_;
+    foreachOnPath(path: Path, f: (path: Path, value: T) => void): ImmutableTree<T>;
+    private foreachOnPath_;
+    /**
+     * Calls the given function for each node in the tree that has a value.
+     *
+     * @param f - A function to be called with the path from the root of the tree to
+     * a node, and the value at that node. Called in depth-first order.
+     */
+    foreach(f: (path: Path, value: T) => void): void;
+    private foreach_;
+    foreachChild(f: (name: string, value: T) => void): void;
+}
+
+/**
+ * Returns a placeholder value that can be used to atomically increment the
+ * current database value by the provided delta.
+ *
+ * @param delta - the amount to modify the current value atomically.
+ * @returns A placeholder value for modifying data atomically server-side.
+ */
+export declare function increment(delta: number): object;
+
+declare abstract class Index {
+    abstract compare(a: NamedNode, b: NamedNode): number;
+    abstract isDefinedOn(node: Node_2): boolean;
+    /**
+     * @returns A standalone comparison function for
+     * this index
+     */
+    getCompare(): Comparator<NamedNode>;
+    /**
+     * Given a before and after value for a node, determine if the indexed value has changed. Even if they are different,
+     * it's possible that the changes are isolated to parts of the snapshot that are not indexed.
+     *
+     *
+     * @returns True if the portion of the snapshot being indexed changed between oldNode and newNode
+     */
+    indexedValueChanged(oldNode: Node_2, newNode: Node_2): boolean;
+    /**
+     * @returns a node wrapper that will sort equal to or less than
+     * any other node wrapper, using this index
+     */
+    minPost(): NamedNode;
+    /**
+     * @returns a node wrapper that will sort greater than or equal to
+     * any other node wrapper, using this index
+     */
+    abstract maxPost(): NamedNode;
+    abstract makePost(indexValue: unknown, name: string): NamedNode;
+    /**
+     * @returns String representation for inclusion in a query spec
+     */
+    abstract toString(): string;
+}
+
+/* Excluded from this release type: _initStandalone */
+
+/**
+ * Represents a child snapshot of a `Reference` that is being iterated over. The key will never be undefined.
+ */
+export declare interface IteratedDataSnapshot extends DataSnapshot {
+    key: string;
+}
+
+/**
+ * Creates a new `QueryConstraint` that if limited to the first specific number
+ * of children.
+ *
+ * The `limitToFirst()` method is used to set a maximum number of children to be
+ * synced for a given callback. If we set a limit of 100, we will initially only
+ * receive up to 100 `child_added` events. If we have fewer than 100 messages
+ * stored in our Database, a `child_added` event will fire for each message.
+ * However, if we have over 100 messages, we will only receive a `child_added`
+ * event for the first 100 ordered messages. As items change, we will receive
+ * `child_removed` events for each item that drops out of the active list so
+ * that the total number stays at 100.
+ *
+ * You can read more about `limitToFirst()` in
+ * {@link https://firebase.google.com/docs/database/web/lists-of-data#filtering_data | Filtering data}.
+ *
+ * @param limit - The maximum number of nodes to include in this query.
+ */
+export declare function limitToFirst(limit: number): QueryConstraint;
+
+/**
+ * Creates a new `QueryConstraint` that is limited to return only the last
+ * specified number of children.
+ *
+ * The `limitToLast()` method is used to set a maximum number of children to be
+ * synced for a given callback. If we set a limit of 100, we will initially only
+ * receive up to 100 `child_added` events. If we have fewer than 100 messages
+ * stored in our Database, a `child_added` event will fire for each message.
+ * However, if we have over 100 messages, we will only receive a `child_added`
+ * event for the last 100 ordered messages. As items change, we will receive
+ * `child_removed` events for each item that drops out of the active list so
+ * that the total number stays at 100.
+ *
+ * You can read more about `limitToLast()` in
+ * {@link https://firebase.google.com/docs/database/web/lists-of-data#filtering_data | Filtering data}.
+ *
+ * @param limit - The maximum number of nodes to include in this query.
+ */
+export declare function limitToLast(limit: number): QueryConstraint;
+
+/** An options objects that can be used to customize a listener. */
+export declare interface ListenOptions {
+    /** Whether to remove the listener after its first invocation. */
+    readonly onlyOnce?: boolean;
+}
+
+declare interface ListenProvider {
+    startListening(query: QueryContext, tag: number | null, hashFn: () => string, onComplete: (a: string, b?: unknown) => Event_2[]): Event_2[];
+    stopListening(a: QueryContext, b: number | null): void;
+}
+
+/**
+ * Represents an empty node (a leaf node in the Red-Black Tree).
+ */
+declare class LLRBEmptyNode<K, V> {
+    key: K;
+    value: V;
+    left: LLRBNode<K, V> | LLRBEmptyNode<K, V>;
+    right: LLRBNode<K, V> | LLRBEmptyNode<K, V>;
+    color: boolean;
+    /**
+     * Returns a copy of the current node.
+     *
+     * @returns The node copy.
+     */
+    copy(key: K | null, value: V | null, color: boolean | null, left: LLRBNode<K, V> | LLRBEmptyNode<K, V> | null, right: LLRBNode<K, V> | LLRBEmptyNode<K, V> | null): LLRBEmptyNode<K, V>;
+    /**
+     * Returns a copy of the tree, with the specified key/value added.
+     *
+     * @param key - Key to be added.
+     * @param value - Value to be added.
+     * @param comparator - Comparator.
+     * @returns New tree, with item added.
+     */
+    insert(key: K, value: V, comparator: Comparator<K>): LLRBNode<K, V>;
+    /**
+     * Returns a copy of the tree, with the specified key removed.
+     *
+     * @param key - The key to remove.
+     * @param comparator - Comparator.
+     * @returns New tree, with item removed.
+     */
+    remove(key: K, comparator: Comparator<K>): LLRBEmptyNode<K, V>;
+    /**
+     * @returns The total number of nodes in the tree.
+     */
+    count(): number;
+    /**
+     * @returns True if the tree is empty.
+     */
+    isEmpty(): boolean;
+    /**
+     * Traverses the tree in key order and calls the specified action function
+     * for each node.
+     *
+     * @param action - Callback function to be called for each
+     * node.  If it returns true, traversal is aborted.
+     * @returns True if traversal was aborted.
+     */
+    inorderTraversal(action: (k: K, v: V) => unknown): boolean;
+    /**
+     * Traverses the tree in reverse key order and calls the specified action function
+     * for each node.
+     *
+     * @param action - Callback function to be called for each
+     * node.  If it returns true, traversal is aborted.
+     * @returns True if traversal was aborted.
+     */
+    reverseTraversal(action: (k: K, v: V) => void): boolean;
+    minKey(): null;
+    maxKey(): null;
+    check_(): number;
+    /**
+     * @returns Whether this node is red.
+     */
+    isRed_(): boolean;
+}
+
+/**
+ * Represents a node in a Left-leaning Red-Black tree.
+ */
+declare class LLRBNode<K, V> {
+    key: K;
+    value: V;
+    color: boolean;
+    left: LLRBNode<K, V> | LLRBEmptyNode<K, V>;
+    right: LLRBNode<K, V> | LLRBEmptyNode<K, V>;
+    /**
+     * @param key - Key associated with this node.
+     * @param value - Value associated with this node.
+     * @param color - Whether this node is red.
+     * @param left - Left child.
+     * @param right - Right child.
+     */
+    constructor(key: K, value: V, color: boolean | null, left?: LLRBNode<K, V> | LLRBEmptyNode<K, V> | null, right?: LLRBNode<K, V> | LLRBEmptyNode<K, V> | null);
+    static RED: boolean;
+    static BLACK: boolean;
+    /**
+     * Returns a copy of the current node, optionally replacing pieces of it.
+     *
+     * @param key - New key for the node, or null.
+     * @param value - New value for the node, or null.
+     * @param color - New color for the node, or null.
+     * @param left - New left child for the node, or null.
+     * @param right - New right child for the node, or null.
+     * @returns The node copy.
+     */
+    copy(key: K | null, value: V | null, color: boolean | null, left: LLRBNode<K, V> | LLRBEmptyNode<K, V> | null, right: LLRBNode<K, V> | LLRBEmptyNode<K, V> | null): LLRBNode<K, V>;
+    /**
+     * @returns The total number of nodes in the tree.
+     */
+    count(): number;
+    /**
+     * @returns True if the tree is empty.
+     */
+    isEmpty(): boolean;
+    /**
+     * Traverses the tree in key order and calls the specified action function
+     * for each node.
+     *
+     * @param action - Callback function to be called for each
+     *   node.  If it returns true, traversal is aborted.
+     * @returns The first truthy value returned by action, or the last falsey
+     *   value returned by action
+     */
+    inorderTraversal(action: (k: K, v: V) => unknown): boolean;
+    /**
+     * Traverses the tree in reverse key order and calls the specified action function
+     * for each node.
+     *
+     * @param action - Callback function to be called for each
+     * node.  If it returns true, traversal is aborted.
+     * @returns True if traversal was aborted.
+     */
+    reverseTraversal(action: (k: K, v: V) => void): boolean;
+    /**
+     * @returns The minimum node in the tree.
+     */
+    private min_;
+    /**
+     * @returns The maximum key in the tree.
+     */
+    minKey(): K;
+    /**
+     * @returns The maximum key in the tree.
+     */
+    maxKey(): K;
+    /**
+     * @param key - Key to insert.
+     * @param value - Value to insert.
+     * @param comparator - Comparator.
+     * @returns New tree, with the key/value added.
+     */
+    insert(key: K, value: V, comparator: Comparator<K>): LLRBNode<K, V>;
+    /**
+     * @returns New tree, with the minimum key removed.
+     */
+    private removeMin_;
+    /**
+     * @param key - The key of the item to remove.
+     * @param comparator - Comparator.
+     * @returns New tree, with the specified item removed.
+     */
+    remove(key: K, comparator: Comparator<K>): LLRBNode<K, V> | LLRBEmptyNode<K, V>;
+    /**
+     * @returns Whether this is a RED node.
+     */
+    isRed_(): boolean;
+    /**
+     * @returns New tree after performing any needed rotations.
+     */
+    private fixUp_;
+    /**
+     * @returns New tree, after moveRedLeft.
+     */
+    private moveRedLeft_;
+    /**
+     * @returns New tree, after moveRedRight.
+     */
+    private moveRedRight_;
+    /**
+     * @returns New tree, after rotateLeft.
+     */
+    private rotateLeft_;
+    /**
+     * @returns New tree, after rotateRight.
+     */
+    private rotateRight_;
+    /**
+     * @returns Newt ree, after colorFlip.
+     */
+    private colorFlip_;
+    /**
+     * For testing.
+     *
+     * @returns True if all is well.
+     */
+    private checkMaxDepth_;
+    check_(): number;
+}
+
+declare class NamedNode {
+    name: string;
+    node: Node_2;
+    constructor(name: string, node: Node_2);
+    static Wrap(name: string, node: Node_2): NamedNode;
+}
+
+/**
+ * Node is an interface defining the common functionality for nodes in
+ * a DataSnapshot.
+ *
+ * @interface
+ */
+declare interface Node_2 {
+    /**
+     * Whether this node is a leaf node.
+     * @returns Whether this is a leaf node.
+     */
+    isLeafNode(): boolean;
+    /**
+     * Gets the priority of the node.
+     * @returns The priority of the node.
+     */
+    getPriority(): Node_2;
+    /**
+     * Returns a duplicate node with the new priority.
+     * @param newPriorityNode - New priority to set for the node.
+     * @returns Node with new priority.
+     */
+    updatePriority(newPriorityNode: Node_2): Node_2;
+    /**
+     * Returns the specified immediate child, or null if it doesn't exist.
+     * @param childName - The name of the child to retrieve.
+     * @returns The retrieved child, or an empty node.
+     */
+    getImmediateChild(childName: string): Node_2;
+    /**
+     * Returns a child by path, or null if it doesn't exist.
+     * @param path - The path of the child to retrieve.
+     * @returns The retrieved child or an empty node.
+     */
+    getChild(path: Path): Node_2;
+    /**
+     * Returns the name of the child immediately prior to the specified childNode, or null.
+     * @param childName - The name of the child to find the predecessor of.
+     * @param childNode - The node to find the predecessor of.
+     * @param index - The index to use to determine the predecessor
+     * @returns The name of the predecessor child, or null if childNode is the first child.
+     */
+    getPredecessorChildName(childName: string, childNode: Node_2, index: Index): string | null;
+    /**
+     * Returns a duplicate node, with the specified immediate child updated.
+     * Any value in the node will be removed.
+     * @param childName - The name of the child to update.
+     * @param newChildNode - The new child node
+     * @returns The updated node.
+     */
+    updateImmediateChild(childName: string, newChildNode: Node_2): Node_2;
+    /**
+     * Returns a duplicate node, with the specified child updated.  Any value will
+     * be removed.
+     * @param path - The path of the child to update.
+     * @param newChildNode - The new child node, which may be an empty node
+     * @returns The updated node.
+     */
+    updateChild(path: Path, newChildNode: Node_2): Node_2;
+    /**
+     * True if the immediate child specified exists
+     */
+    hasChild(childName: string): boolean;
+    /**
+     * @returns True if this node has no value or children.
+     */
+    isEmpty(): boolean;
+    /**
+     * @returns The number of children of this node.
+     */
+    numChildren(): number;
+    /**
+     * Calls action for each child.
+     * @param action - Action to be called for
+     * each child.  It's passed the child name and the child node.
+     * @returns The first truthy value return by action, or the last falsey one
+     */
+    forEachChild(index: Index, action: (a: string, b: Node_2) => void): unknown;
+    /**
+     * @param exportFormat - True for export format (also wire protocol format).
+     * @returns Value of this node as JSON.
+     */
+    val(exportFormat?: boolean): unknown;
+    /**
+     * @returns hash representing the node contents.
+     */
+    hash(): string;
+    /**
+     * @param other - Another node
+     * @returns -1 for less than, 0 for equal, 1 for greater than other
+     */
+    compareTo(other: Node_2): number;
+    /**
+     * @returns Whether or not this snapshot equals other
+     */
+    equals(other: Node_2): boolean;
+    /**
+     * @returns This node, with the specified index now available
+     */
+    withIndex(indexDefinition: Index): Node_2;
+    isIndexed(indexDefinition: Index): boolean;
+}
+
+/**
+ * NodeFilter is used to update nodes and complete children of nodes while applying queries on the fly and keeping
+ * track of any child changes. This class does not track value changes as value changes depend on more
+ * than just the node itself. Different kind of queries require different kind of implementations of this interface.
+ * @interface
+ */
+declare interface NodeFilter_2 {
+    /**
+     * Update a single complete child in the snap. If the child equals the old child in the snap, this is a no-op.
+     * The method expects an indexed snap.
+     */
+    updateChild(snap: Node_2, key: string, newChild: Node_2, affectedPath: Path, source: CompleteChildSource, optChangeAccumulator: ChildChangeAccumulator | null): Node_2;
+    /**
+     * Update a node in full and output any resulting change from this complete update.
+     */
+    updateFullNode(oldSnap: Node_2, newSnap: Node_2, optChangeAccumulator: ChildChangeAccumulator | null): Node_2;
+    /**
+     * Update the priority of the root node
+     */
+    updatePriority(oldSnap: Node_2, newPriority: Node_2): Node_2;
+    /**
+     * Returns true if children might be filtered due to query criteria
+     */
+    filtersNodes(): boolean;
+    /**
+     * Returns the index filter that this filter uses to get a NodeFilter that doesn't filter any children.
+     */
+    getIndexedFilter(): NodeFilter_2;
+    /**
+     * Returns the index that this filter uses
+     */
+    getIndex(): Index;
+}
+
+/**
+ * Detaches a callback previously attached with the corresponding `on*()` (`onValue`, `onChildAdded`) listener.
+ * Note: This is not the recommended way to remove a listener. Instead, please use the returned callback function from
+ * the respective `on*` callbacks.
+ *
+ * Detach a callback previously attached with `on*()`. Calling `off()` on a parent listener
+ * will not automatically remove listeners registered on child nodes, `off()`
+ * must also be called on any child listeners to remove the callback.
+ *
+ * If a callback is not specified, all callbacks for the specified eventType
+ * will be removed. Similarly, if no eventType is specified, all callbacks
+ * for the `Reference` will be removed.
+ *
+ * Individual listeners can also be removed by invoking their unsubscribe
+ * callbacks.
+ *
+ * @param query - The query that the listener was registered with.
+ * @param eventType - One of the following strings: "value", "child_added",
+ * "child_changed", "child_removed", or "child_moved." If omitted, all callbacks
+ * for the `Reference` will be removed.
+ * @param callback - The callback function that was passed to `on()` or
+ * `undefined` to remove all callbacks.
+ */
+export declare function off(query: Query, eventType?: EventType, callback?: (snapshot: DataSnapshot, previousChildName?: string | null) => unknown): void;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onChildAdded` event will be triggered once for each initial child at this
+ * location, and it will be triggered again every time a new child is added. The
+ * `DataSnapshot` passed into the callback will reflect the data for the
+ * relevant child. For ordering purposes, it is passed a second argument which
+ * is a string containing the key of the previous sibling child by sort order,
+ * or `null` if it is the first child.
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs.
+ * The callback will be passed a DataSnapshot and a string containing the key of
+ * the previous child, by sort order, or `null` if it is the first child.
+ * @param cancelCallback - An optional callback that will be notified if your
+ * event subscription is ever canceled because your client does not have
+ * permission to read this data (or it had permission but has now lost it).
+ * This callback will be passed an `Error` object indicating why the failure
+ * occurred.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onChildAdded(query: Query, callback: (snapshot: DataSnapshot, previousChildName?: string | null) => unknown, cancelCallback?: (error: Error) => unknown): Unsubscribe;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onChildAdded` event will be triggered once for each initial child at this
+ * location, and it will be triggered again every time a new child is added. The
+ * `DataSnapshot` passed into the callback will reflect the data for the
+ * relevant child. For ordering purposes, it is passed a second argument which
+ * is a string containing the key of the previous sibling child by sort order,
+ * or `null` if it is the first child.
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs.
+ * The callback will be passed a DataSnapshot and a string containing the key of
+ * the previous child, by sort order, or `null` if it is the first child.
+ * @param options - An object that can be used to configure `onlyOnce`, which
+ * then removes the listener after its first invocation.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onChildAdded(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, options: ListenOptions): Unsubscribe;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onChildAdded` event will be triggered once for each initial child at this
+ * location, and it will be triggered again every time a new child is added. The
+ * `DataSnapshot` passed into the callback will reflect the data for the
+ * relevant child. For ordering purposes, it is passed a second argument which
+ * is a string containing the key of the previous sibling child by sort order,
+ * or `null` if it is the first child.
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs.
+ * The callback will be passed a DataSnapshot and a string containing the key of
+ * the previous child, by sort order, or `null` if it is the first child.
+ * @param cancelCallback - An optional callback that will be notified if your
+ * event subscription is ever canceled because your client does not have
+ * permission to read this data (or it had permission but has now lost it).
+ * This callback will be passed an `Error` object indicating why the failure
+ * occurred.
+ * @param options - An object that can be used to configure `onlyOnce`, which
+ * then removes the listener after its first invocation.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onChildAdded(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, cancelCallback: (error: Error) => unknown, options: ListenOptions): Unsubscribe;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onChildChanged` event will be triggered when the data stored in a child
+ * (or any of its descendants) changes. Note that a single `child_changed` event
+ * may represent multiple changes to the child. The `DataSnapshot` passed to the
+ * callback will contain the new child contents. For ordering purposes, the
+ * callback is also passed a second argument which is a string containing the
+ * key of the previous sibling child by sort order, or `null` if it is the first
+ * child.
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs.
+ * The callback will be passed a DataSnapshot and a string containing the key of
+ * the previous child, by sort order, or `null` if it is the first child.
+ * @param cancelCallback - An optional callback that will be notified if your
+ * event subscription is ever canceled because your client does not have
+ * permission to read this data (or it had permission but has now lost it).
+ * This callback will be passed an `Error` object indicating why the failure
+ * occurred.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onChildChanged(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, cancelCallback?: (error: Error) => unknown): Unsubscribe;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onChildChanged` event will be triggered when the data stored in a child
+ * (or any of its descendants) changes. Note that a single `child_changed` event
+ * may represent multiple changes to the child. The `DataSnapshot` passed to the
+ * callback will contain the new child contents. For ordering purposes, the
+ * callback is also passed a second argument which is a string containing the
+ * key of the previous sibling child by sort order, or `null` if it is the first
+ * child.
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs.
+ * The callback will be passed a DataSnapshot and a string containing the key of
+ * the previous child, by sort order, or `null` if it is the first child.
+ * @param options - An object that can be used to configure `onlyOnce`, which
+ * then removes the listener after its first invocation.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onChildChanged(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, options: ListenOptions): Unsubscribe;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onChildChanged` event will be triggered when the data stored in a child
+ * (or any of its descendants) changes. Note that a single `child_changed` event
+ * may represent multiple changes to the child. The `DataSnapshot` passed to the
+ * callback will contain the new child contents. For ordering purposes, the
+ * callback is also passed a second argument which is a string containing the
+ * key of the previous sibling child by sort order, or `null` if it is the first
+ * child.
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs.
+ * The callback will be passed a DataSnapshot and a string containing the key of
+ * the previous child, by sort order, or `null` if it is the first child.
+ * @param cancelCallback - An optional callback that will be notified if your
+ * event subscription is ever canceled because your client does not have
+ * permission to read this data (or it had permission but has now lost it).
+ * This callback will be passed an `Error` object indicating why the failure
+ * occurred.
+ * @param options - An object that can be used to configure `onlyOnce`, which
+ * then removes the listener after its first invocation.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onChildChanged(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, cancelCallback: (error: Error) => unknown, options: ListenOptions): Unsubscribe;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onChildMoved` event will be triggered when a child's sort order changes
+ * such that its position relative to its siblings changes. The `DataSnapshot`
+ * passed to the callback will be for the data of the child that has moved. It
+ * is also passed a second argument which is a string containing the key of the
+ * previous sibling child by sort order, or `null` if it is the first child.
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs.
+ * The callback will be passed a DataSnapshot and a string containing the key of
+ * the previous child, by sort order, or `null` if it is the first child.
+ * @param cancelCallback - An optional callback that will be notified if your
+ * event subscription is ever canceled because your client does not have
+ * permission to read this data (or it had permission but has now lost it).
+ * This callback will be passed an `Error` object indicating why the failure
+ * occurred.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onChildMoved(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, cancelCallback?: (error: Error) => unknown): Unsubscribe;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onChildMoved` event will be triggered when a child's sort order changes
+ * such that its position relative to its siblings changes. The `DataSnapshot`
+ * passed to the callback will be for the data of the child that has moved. It
+ * is also passed a second argument which is a string containing the key of the
+ * previous sibling child by sort order, or `null` if it is the first child.
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs.
+ * The callback will be passed a DataSnapshot and a string containing the key of
+ * the previous child, by sort order, or `null` if it is the first child.
+ * @param options - An object that can be used to configure `onlyOnce`, which
+ * then removes the listener after its first invocation.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onChildMoved(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, options: ListenOptions): Unsubscribe;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onChildMoved` event will be triggered when a child's sort order changes
+ * such that its position relative to its siblings changes. The `DataSnapshot`
+ * passed to the callback will be for the data of the child that has moved. It
+ * is also passed a second argument which is a string containing the key of the
+ * previous sibling child by sort order, or `null` if it is the first child.
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs.
+ * The callback will be passed a DataSnapshot and a string containing the key of
+ * the previous child, by sort order, or `null` if it is the first child.
+ * @param cancelCallback - An optional callback that will be notified if your
+ * event subscription is ever canceled because your client does not have
+ * permission to read this data (or it had permission but has now lost it).
+ * This callback will be passed an `Error` object indicating why the failure
+ * occurred.
+ * @param options - An object that can be used to configure `onlyOnce`, which
+ * then removes the listener after its first invocation.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onChildMoved(query: Query, callback: (snapshot: DataSnapshot, previousChildName: string | null) => unknown, cancelCallback: (error: Error) => unknown, options: ListenOptions): Unsubscribe;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onChildRemoved` event will be triggered once every time a child is
+ * removed. The `DataSnapshot` passed into the callback will be the old data for
+ * the child that was removed. A child will get removed when either:
+ *
+ * - a client explicitly calls `remove()` on that child or one of its ancestors
+ * - a client calls `set(null)` on that child or one of its ancestors
+ * - that child has all of its children removed
+ * - there is a query in effect which now filters out the child (because it's
+ *   sort order changed or the max limit was hit)
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs.
+ * The callback will be passed a DataSnapshot and a string containing the key of
+ * the previous child, by sort order, or `null` if it is the first child.
+ * @param cancelCallback - An optional callback that will be notified if your
+ * event subscription is ever canceled because your client does not have
+ * permission to read this data (or it had permission but has now lost it).
+ * This callback will be passed an `Error` object indicating why the failure
+ * occurred.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onChildRemoved(query: Query, callback: (snapshot: DataSnapshot) => unknown, cancelCallback?: (error: Error) => unknown): Unsubscribe;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onChildRemoved` event will be triggered once every time a child is
+ * removed. The `DataSnapshot` passed into the callback will be the old data for
+ * the child that was removed. A child will get removed when either:
+ *
+ * - a client explicitly calls `remove()` on that child or one of its ancestors
+ * - a client calls `set(null)` on that child or one of its ancestors
+ * - that child has all of its children removed
+ * - there is a query in effect which now filters out the child (because it's
+ *   sort order changed or the max limit was hit)
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs.
+ * The callback will be passed a DataSnapshot and a string containing the key of
+ * the previous child, by sort order, or `null` if it is the first child.
+ * @param options - An object that can be used to configure `onlyOnce`, which
+ * then removes the listener after its first invocation.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onChildRemoved(query: Query, callback: (snapshot: DataSnapshot) => unknown, options: ListenOptions): Unsubscribe;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onChildRemoved` event will be triggered once every time a child is
+ * removed. The `DataSnapshot` passed into the callback will be the old data for
+ * the child that was removed. A child will get removed when either:
+ *
+ * - a client explicitly calls `remove()` on that child or one of its ancestors
+ * - a client calls `set(null)` on that child or one of its ancestors
+ * - that child has all of its children removed
+ * - there is a query in effect which now filters out the child (because it's
+ *   sort order changed or the max limit was hit)
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs.
+ * The callback will be passed a DataSnapshot and a string containing the key of
+ * the previous child, by sort order, or `null` if it is the first child.
+ * @param cancelCallback - An optional callback that will be notified if your
+ * event subscription is ever canceled because your client does not have
+ * permission to read this data (or it had permission but has now lost it).
+ * This callback will be passed an `Error` object indicating why the failure
+ * occurred.
+ * @param options - An object that can be used to configure `onlyOnce`, which
+ * then removes the listener after its first invocation.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onChildRemoved(query: Query, callback: (snapshot: DataSnapshot) => unknown, cancelCallback: (error: Error) => unknown, options: ListenOptions): Unsubscribe;
+
+/**
+ * The `onDisconnect` class allows you to write or clear data when your client
+ * disconnects from the Database server. These updates occur whether your
+ * client disconnects cleanly or not, so you can rely on them to clean up data
+ * even if a connection is dropped or a client crashes.
+ *
+ * The `onDisconnect` class is most commonly used to manage presence in
+ * applications where it is useful to detect how many clients are connected and
+ * when other clients disconnect. See
+ * {@link https://firebase.google.com/docs/database/web/offline-capabilities | Enabling Offline Capabilities in JavaScript}
+ * for more information.
+ *
+ * To avoid problems when a connection is dropped before the requests can be
+ * transferred to the Database server, these functions should be called before
+ * writing any data.
+ *
+ * Note that `onDisconnect` operations are only triggered once. If you want an
+ * operation to occur each time a disconnect occurs, you'll need to re-establish
+ * the `onDisconnect` operations each time you reconnect.
+ */
+export declare class OnDisconnect {
+    private _repo;
+    private _path;
+    /** @hideconstructor */
+    constructor(_repo: Repo, _path: Path);
+    /**
+     * Cancels all previously queued `onDisconnect()` set or update events for this
+     * location and all children.
+     *
+     * If a write has been queued for this location via a `set()` or `update()` at a
+     * parent location, the write at this location will be canceled, though writes
+     * to sibling locations will still occur.
+     *
+     * @returns Resolves when synchronization to the server is complete.
+     */
+    cancel(): Promise<void>;
+    /**
+     * Ensures the data at this location is deleted when the client is disconnected
+     * (due to closing the browser, navigating to a new page, or network issues).
+     *
+     * @returns Resolves when synchronization to the server is complete.
+     */
+    remove(): Promise<void>;
+    /**
+     * Ensures the data at this location is set to the specified value when the
+     * client is disconnected (due to closing the browser, navigating to a new page,
+     * or network issues).
+     *
+     * `set()` is especially useful for implementing "presence" systems, where a
+     * value should be changed or cleared when a user disconnects so that they
+     * appear "offline" to other users. See
+     * {@link https://firebase.google.com/docs/database/web/offline-capabilities | Enabling Offline Capabilities in JavaScript}
+     * for more information.
+     *
+     * Note that `onDisconnect` operations are only triggered once. If you want an
+     * operation to occur each time a disconnect occurs, you'll need to re-establish
+     * the `onDisconnect` operations each time.
+     *
+     * @param value - The value to be written to this location on disconnect (can
+     * be an object, array, string, number, boolean, or null).
+     * @returns Resolves when synchronization to the Database is complete.
+     */
+    set(value: unknown): Promise<void>;
+    /**
+     * Ensures the data at this location is set to the specified value and priority
+     * when the client is disconnected (due to closing the browser, navigating to a
+     * new page, or network issues).
+     *
+     * @param value - The value to be written to this location on disconnect (can
+     * be an object, array, string, number, boolean, or null).
+     * @param priority - The priority to be written (string, number, or null).
+     * @returns Resolves when synchronization to the Database is complete.
+     */
+    setWithPriority(value: unknown, priority: number | string | null): Promise<void>;
+    /**
+     * Writes multiple values at this location when the client is disconnected (due
+     * to closing the browser, navigating to a new page, or network issues).
+     *
+     * The `values` argument contains multiple property-value pairs that will be
+     * written to the Database together. Each child property can either be a simple
+     * property (for example, "name") or a relative path (for example, "name/first")
+     * from the current location to the data to update.
+     *
+     * As opposed to the `set()` method, `update()` can be use to selectively update
+     * only the referenced properties at the current location (instead of replacing
+     * all the child properties at the current location).
+     *
+     * @param values - Object containing multiple values.
+     * @returns Resolves when synchronization to the Database is complete.
+     */
+    update(values: object): Promise<void>;
+}
+
+/**
+ * Returns an `OnDisconnect` object - see
+ * {@link https://firebase.google.com/docs/database/web/offline-capabilities | Enabling Offline Capabilities in JavaScript}
+ * for more information on how to use it.
+ *
+ * @param ref - The reference to add OnDisconnect triggers for.
+ */
+export declare function onDisconnect(ref: DatabaseReference): OnDisconnect;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onValue` event will trigger once with the initial data stored at this
+ * location, and then trigger again each time the data changes. The
+ * `DataSnapshot` passed to the callback will be for the location at which
+ * `on()` was called. It won't trigger until the entire contents has been
+ * synchronized. If the location has no data, it will be triggered with an empty
+ * `DataSnapshot` (`val()` will return `null`).
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs. The
+ * callback will be passed a DataSnapshot.
+ * @param cancelCallback - An optional callback that will be notified if your
+ * event subscription is ever canceled because your client does not have
+ * permission to read this data (or it had permission but has now lost it).
+ * This callback will be passed an `Error` object indicating why the failure
+ * occurred.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onValue(query: Query, callback: (snapshot: DataSnapshot) => unknown, cancelCallback?: (error: Error) => unknown): Unsubscribe;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onValue` event will trigger once with the initial data stored at this
+ * location, and then trigger again each time the data changes. The
+ * `DataSnapshot` passed to the callback will be for the location at which
+ * `on()` was called. It won't trigger until the entire contents has been
+ * synchronized. If the location has no data, it will be triggered with an empty
+ * `DataSnapshot` (`val()` will return `null`).
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs. The
+ * callback will be passed a DataSnapshot.
+ * @param options - An object that can be used to configure `onlyOnce`, which
+ * then removes the listener after its first invocation.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onValue(query: Query, callback: (snapshot: DataSnapshot) => unknown, options: ListenOptions): Unsubscribe;
+
+/**
+ * Listens for data changes at a particular location.
+ *
+ * This is the primary way to read data from a Database. Your callback
+ * will be triggered for the initial data and again whenever the data changes.
+ * Invoke the returned unsubscribe callback to stop receiving updates. See
+ * {@link https://firebase.google.com/docs/database/web/retrieve-data | Retrieve Data on the Web}
+ * for more details.
+ *
+ * An `onValue` event will trigger once with the initial data stored at this
+ * location, and then trigger again each time the data changes. The
+ * `DataSnapshot` passed to the callback will be for the location at which
+ * `on()` was called. It won't trigger until the entire contents has been
+ * synchronized. If the location has no data, it will be triggered with an empty
+ * `DataSnapshot` (`val()` will return `null`).
+ *
+ * @param query - The query to run.
+ * @param callback - A callback that fires when the specified event occurs. The
+ * callback will be passed a DataSnapshot.
+ * @param cancelCallback - An optional callback that will be notified if your
+ * event subscription is ever canceled because your client does not have
+ * permission to read this data (or it had permission but has now lost it).
+ * This callback will be passed an `Error` object indicating why the failure
+ * occurred.
+ * @param options - An object that can be used to configure `onlyOnce`, which
+ * then removes the listener after its first invocation.
+ * @returns A function that can be invoked to remove the listener.
+ */
+export declare function onValue(query: Query, callback: (snapshot: DataSnapshot) => unknown, cancelCallback: (error: Error) => unknown, options: ListenOptions): Unsubscribe;
+
+/**
+ * Creates a new `QueryConstraint` that orders by the specified child key.
+ *
+ * Queries can only order by one key at a time. Calling `orderByChild()`
+ * multiple times on the same query is an error.
+ *
+ * Firebase queries allow you to order your data by any child key on the fly.
+ * However, if you know in advance what your indexes will be, you can define
+ * them via the .indexOn rule in your Security Rules for better performance. See
+ * the{@link https://firebase.google.com/docs/database/security/indexing-data}
+ * rule for more information.
+ *
+ * You can read more about `orderByChild()` in
+ * {@link https://firebase.google.com/docs/database/web/lists-of-data#sort_data | Sort data}.
+ *
+ * @param path - The path to order by.
+ */
+export declare function orderByChild(path: string): QueryConstraint;
+
+/**
+ * Creates a new `QueryConstraint` that orders by the key.
+ *
+ * Sorts the results of a query by their (ascending) key values.
+ *
+ * You can read more about `orderByKey()` in
+ * {@link https://firebase.google.com/docs/database/web/lists-of-data#sort_data | Sort data}.
+ */
+export declare function orderByKey(): QueryConstraint;
+
+/**
+ * Creates a new `QueryConstraint` that orders by priority.
+ *
+ * Applications need not use priority but can order collections by
+ * ordinary properties (see
+ * {@link https://firebase.google.com/docs/database/web/lists-of-data#sort_data | Sort data}
+ * for alternatives to priority.
+ */
+export declare function orderByPriority(): QueryConstraint;
+
+/**
+ * Creates a new `QueryConstraint` that orders by value.
+ *
+ * If the children of a query are all scalar values (string, number, or
+ * boolean), you can order the results by their (ascending) values.
+ *
+ * You can read more about `orderByValue()` in
+ * {@link https://firebase.google.com/docs/database/web/lists-of-data#sort_data | Sort data}.
+ */
+export declare function orderByValue(): QueryConstraint;
+
+/**
+ * @license
+ * Copyright 2017 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * An immutable object representing a parsed path.  It's immutable so that you
+ * can pass them around to other functions without worrying about them changing
+ * it.
+ */
+declare class Path {
+    pieces_: string[];
+    pieceNum_: number;
+    /**
+     * @param pathOrString - Path string to parse, or another path, or the raw
+     * tokens array
+     */
+    constructor(pathOrString: string | string[], pieceNum?: number);
+    toString(): string;
+}
+
+/**
+ * Firebase connection.  Abstracts wire protocol and handles reconnecting.
+ *
+ * NOTE: All JSON objects sent to the realtime connection must have property names enclosed
+ * in quotes to make sure the closure compiler does not minify them.
+ */
+declare class PersistentConnection extends ServerActions {
+    private repoInfo_;
+    private applicationId_;
+    private onDataUpdate_;
+    private onConnectStatus_;
+    private onServerInfoUpdate_;
+    private authTokenProvider_;
+    private appCheckTokenProvider_;
+    private authOverride_?;
+    id: number;
+    private log_;
+    private interruptReasons_;
+    private readonly listens;
+    private outstandingPuts_;
+    private outstandingGets_;
+    private outstandingPutCount_;
+    private outstandingGetCount_;
+    private onDisconnectRequestQueue_;
+    private connected_;
+    private reconnectDelay_;
+    private maxReconnectDelay_;
+    private securityDebugCallback_;
+    lastSessionId: string | null;
+    private establishConnectionTimer_;
+    private visible_;
+    private requestCBHash_;
+    private requestNumber_;
+    private realtime_;
+    private authToken_;
+    private appCheckToken_;
+    private forceTokenRefresh_;
+    private invalidAuthTokenCount_;
+    private invalidAppCheckTokenCount_;
+    private firstConnection_;
+    private lastConnectionAttemptTime_;
+    private lastConnectionEstablishedTime_;
+    private static nextPersistentConnectionId_;
+    /**
+     * Counter for number of connections created. Mainly used for tagging in the logs
+     */
+    private static nextConnectionId_;
+    /**
+     * @param repoInfo_ - Data about the namespace we are connecting to
+     * @param applicationId_ - The Firebase App ID for this project
+     * @param onDataUpdate_ - A callback for new data from the server
+     */
+    constructor(repoInfo_: RepoInfo, applicationId_: string, onDataUpdate_: (a: string, b: unknown, c: boolean, d: number | null) => void, onConnectStatus_: (a: boolean) => void, onServerInfoUpdate_: (a: unknown) => void, authTokenProvider_: AuthTokenProvider, appCheckTokenProvider_: AppCheckTokenProvider, authOverride_?: object | null);
+    protected sendRequest(action: string, body: unknown, onResponse?: (a: unknown) => void): void;
+    get(query: QueryContext): Promise<string>;
+    listen(query: QueryContext, currentHashFn: () => string, tag: number | null, onComplete: (a: string, b: unknown) => void): void;
+    private sendGet_;
+    private sendListen_;
+    private static warnOnListenWarnings_;
+    refreshAuthToken(token: string): void;
+    private reduceReconnectDelayIfAdminCredential_;
+    refreshAppCheckToken(token: string | null): void;
+    /**
+     * Attempts to authenticate with the given credentials. If the authentication attempt fails, it's triggered like
+     * a auth revoked (the connection is closed).
+     */
+    tryAuth(): void;
+    /**
+     * Attempts to authenticate with the given token. If the authentication
+     * attempt fails, it's triggered like the token was revoked (the connection is
+     * closed).
+     */
+    tryAppCheck(): void;
+    /**
+     * @inheritDoc
+     */
+    unlisten(query: QueryContext, tag: number | null): void;
+    private sendUnlisten_;
+    onDisconnectPut(pathString: string, data: unknown, onComplete?: (a: string, b: string) => void): void;
+    onDisconnectMerge(pathString: string, data: unknown, onComplete?: (a: string, b: string) => void): void;
+    onDisconnectCancel(pathString: string, onComplete?: (a: string, b: string) => void): void;
+    private sendOnDisconnect_;
+    put(pathString: string, data: unknown, onComplete?: (a: string, b: string) => void, hash?: string): void;
+    merge(pathString: string, data: unknown, onComplete: (a: string, b: string | null) => void, hash?: string): void;
+    putInternal(action: string, pathString: string, data: unknown, onComplete: (a: string, b: string | null) => void, hash?: string): void;
+    private sendPut_;
+    reportStats(stats: {
+        [k: string]: unknown;
+    }): void;
+    private onDataMessage_;
+    private onDataPush_;
+    private onReady_;
+    private scheduleConnect_;
+    private initConnection_;
+    private onVisible_;
+    private onOnline_;
+    private onRealtimeDisconnect_;
+    private establishConnection_;
+    interrupt(reason: string): void;
+    resume(reason: string): void;
+    private handleTimestamp_;
+    private cancelSentTransactions_;
+    private onListenRevoked_;
+    private removeListen_;
+    private onAuthRevoked_;
+    private onAppCheckRevoked_;
+    private onSecurityDebugPacket_;
+    private restoreState_;
+    /**
+     * Sends client stats for first connection
+     */
+    private sendConnectStats_;
+    private shouldReconnect_;
+}
+
+declare class PriorityIndex extends Index {
+    compare(a: NamedNode, b: NamedNode): number;
+    isDefinedOn(node: Node_2): boolean;
+    indexedValueChanged(oldNode: Node_2, newNode: Node_2): boolean;
+    minPost(): NamedNode;
+    maxPost(): NamedNode;
+    makePost(indexValue: unknown, name: string): NamedNode;
+    /**
+     * @returns String representation for inclusion in a query spec
+     */
+    toString(): string;
+}
+
+/**
+ * Generates a new child location using a unique key and returns its
+ * `Reference`.
+ *
+ * This is the most common pattern for adding data to a collection of items.
+ *
+ * If you provide a value to `push()`, the value is written to the
+ * generated location. If you don't pass a value, nothing is written to the
+ * database and the child remains empty (but you can use the `Reference`
+ * elsewhere).
+ *
+ * The unique keys generated by `push()` are ordered by the current time, so the
+ * resulting list of items is chronologically sorted. The keys are also
+ * designed to be unguessable (they contain 72 random bits of entropy).
+ *
+ * See {@link https://firebase.google.com/docs/database/web/lists-of-data#append_to_a_list_of_data | Append to a list of data}.
+ * See {@link https://firebase.googleblog.com/2015/02/the-2120-ways-to-ensure-unique_68.html | The 2^120 Ways to Ensure Unique Identifiers}.
+ *
+ * @param parent - The parent location.
+ * @param value - Optional value to be written at the generated location.
+ * @returns Combined `Promise` and `Reference`; resolves when write is complete,
+ * but can be used immediately as the `Reference` to the child location.
+ */
+export declare function push(parent: DatabaseReference, value?: unknown): ThenableReference;
+
+/**
+ * @license
+ * Copyright 2021 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * A `Query` sorts and filters the data at a Database location so only a subset
+ * of the child data is included. This can be used to order a collection of
+ * data by some attribute (for example, height of dinosaurs) as well as to
+ * restrict a large list of items (for example, chat messages) down to a number
+ * suitable for synchronizing to the client. Queries are created by chaining
+ * together one or more of the filter methods defined here.
+ *
+ * Just as with a `DatabaseReference`, you can receive data from a `Query` by using the
+ * `on*()` methods. You will only receive events and `DataSnapshot`s for the
+ * subset of the data that matches your query.
+ *
+ * See {@link https://firebase.google.com/docs/database/web/lists-of-data#sorting_and_filtering_data}
+ * for more information.
+ */
+export declare interface Query extends QueryContext {
+    /** The `DatabaseReference` for the `Query`'s location. */
+    readonly ref: DatabaseReference;
+    /**
+     * Returns whether or not the current and provided queries represent the same
+     * location, have the same query parameters, and are from the same instance of
+     * `FirebaseApp`.
+     *
+     * Two `DatabaseReference` objects are equivalent if they represent the same location
+     * and are from the same instance of `FirebaseApp`.
+     *
+     * Two `Query` objects are equivalent if they represent the same location,
+     * have the same query parameters, and are from the same instance of
+     * `FirebaseApp`. Equivalent queries share the same sort order, limits, and
+     * starting and ending points.
+     *
+     * @param other - The query to compare against.
+     * @returns Whether or not the current and provided queries are equivalent.
+     */
+    isEqual(other: Query | null): boolean;
+    /**
+     * Returns a JSON-serializable representation of this object.
+     *
+     * @returns A JSON-serializable representation of this object.
+     */
+    toJSON(): string;
+    /**
+     * Gets the absolute URL for this location.
+     *
+     * The `toString()` method returns a URL that is ready to be put into a
+     * browser, curl command, or a `refFromURL()` call. Since all of those expect
+     * the URL to be url-encoded, `toString()` returns an encoded URL.
+     *
+     * Append '.json' to the returned URL when typed into a browser to download
+     * JSON-formatted data. If the location is secured (that is, not publicly
+     * readable), you will get a permission-denied error.
+     *
+     * @returns The absolute URL for this location.
+     */
+    toString(): string;
+}
+
+/**
+ * Creates a new immutable instance of `Query` that is extended to also include
+ * additional query constraints.
+ *
+ * @param query - The Query instance to use as a base for the new constraints.
+ * @param queryConstraints - The list of `QueryConstraint`s to apply.
+ * @throws if any of the provided query constraints cannot be combined with the
+ * existing or new constraints.
+ */
+export declare function query(query: Query, ...queryConstraints: QueryConstraint[]): Query;
+
+/**
+ * A `QueryConstraint` is used to narrow the set of documents returned by a
+ * Database query. `QueryConstraint`s are created by invoking {@link endAt},
+ * {@link endBefore}, {@link startAt}, {@link startAfter}, {@link
+ * limitToFirst}, {@link limitToLast}, {@link orderByChild},
+ * {@link orderByChild}, {@link orderByKey} , {@link orderByPriority} ,
+ * {@link orderByValue}  or {@link equalTo} and
+ * can then be passed to {@link query} to create a new query instance that
+ * also contains this `QueryConstraint`.
+ */
+export declare abstract class QueryConstraint {
+    /** The type of this query constraints */
+    abstract readonly type: QueryConstraintType;
+    /**
+     * Takes the provided `Query` and returns a copy of the `Query` with this
+     * `QueryConstraint` applied.
+     */
+    abstract _apply<T>(query: _QueryImpl): _QueryImpl;
+}
+
+/** Describes the different query constraints available in this SDK. */
+export declare type QueryConstraintType = 'endAt' | 'endBefore' | 'startAt' | 'startAfter' | 'limitToFirst' | 'limitToLast' | 'orderByChild' | 'orderByKey' | 'orderByPriority' | 'orderByValue' | 'equalTo';
+
+declare interface QueryContext {
+    readonly _queryIdentifier: string;
+    readonly _queryObject: object;
+    readonly _repo: Repo;
+    readonly _path: Path;
+    readonly _queryParams: _QueryParams;
+}
+
+/* Excluded from this release type: _QueryImpl */
+
+/* Excluded from this release type: _QueryParams */
+
+/**
+ *
+ * Returns a `Reference` representing the location in the Database
+ * corresponding to the provided path. If no path is provided, the `Reference`
+ * will point to the root of the Database.
+ *
+ * @param db - The database instance to obtain a reference for.
+ * @param path - Optional path representing the location the returned
+ *   `Reference` will point. If not provided, the returned `Reference` will
+ *   point to the root of the Database.
+ * @returns If a path is provided, a `Reference`
+ *   pointing to the provided path. Otherwise, a `Reference` pointing to the
+ *   root of the Database.
+ */
+export declare function ref(db: Database, path?: string): DatabaseReference;
+
+/* Excluded from this release type: _ReferenceImpl */
+
+/**
+ * Returns a `Reference` representing the location in the Database
+ * corresponding to the provided Firebase URL.
+ *
+ * An exception is thrown if the URL is not a valid Firebase Database URL or it
+ * has a different domain than the current `Database` instance.
+ *
+ * Note that all query parameters (`orderBy`, `limitToLast`, etc.) are ignored
+ * and are not applied to the returned `Reference`.
+ *
+ * @param db - The database instance to obtain a reference for.
+ * @param url - The Firebase URL at which the returned `Reference` will
+ *   point.
+ * @returns A `Reference` pointing to the provided
+ *   Firebase URL.
+ */
+export declare function refFromURL(db: Database, url: string): DatabaseReference;
+
+/**
+ * Removes the data at this Database location.
+ *
+ * Any data at child locations will also be deleted.
+ *
+ * The effect of the remove will be visible immediately and the corresponding
+ * event 'value' will be triggered. Synchronization of the remove to the
+ * Firebase servers will also be started, and the returned Promise will resolve
+ * when complete. If provided, the onComplete callback will be called
+ * asynchronously after synchronization has finished.
+ *
+ * @param ref - The location to remove.
+ * @returns Resolves when remove on server is complete.
+ */
+export declare function remove(ref: DatabaseReference): Promise<void>;
+
+/**
+ * A connection to a single data repository.
+ */
+declare class Repo {
+    repoInfo_: RepoInfo;
+    forceRestClient_: boolean;
+    authTokenProvider_: AuthTokenProvider;
+    appCheckProvider_: AppCheckTokenProvider;
+    /** Key for uniquely identifying this repo, used in RepoManager */
+    readonly key: string;
+    dataUpdateCount: number;
+    infoSyncTree_: SyncTree;
+    serverSyncTree_: SyncTree;
+    stats_: StatsCollection;
+    statsListener_: StatsListener | null;
+    eventQueue_: EventQueue;
+    nextWriteId_: number;
+    server_: ServerActions;
+    statsReporter_: StatsReporter;
+    infoData_: SnapshotHolder;
+    interceptServerDataCallback_: ((a: string, b: unknown) => void) | null;
+    /** A list of data pieces and paths to be set when this client disconnects. */
+    onDisconnect_: SparseSnapshotTree;
+    /** Stores queues of outstanding transactions for Firebase locations. */
+    transactionQueueTree_: Tree<Transaction[]>;
+    persistentConnection_: PersistentConnection | null;
+    constructor(repoInfo_: RepoInfo, forceRestClient_: boolean, authTokenProvider_: AuthTokenProvider, appCheckProvider_: AppCheckTokenProvider);
+    /**
+     * @returns The URL corresponding to the root of this Firebase.
+     */
+    toString(): string;
+}
+
+/**
+ * A class that holds metadata about a Repo object
+ */
+declare class RepoInfo {
+    readonly secure: boolean;
+    readonly namespace: string;
+    readonly webSocketOnly: boolean;
+    readonly nodeAdmin: boolean;
+    readonly persistenceKey: string;
+    readonly includeNamespaceInQueryParams: boolean;
+    readonly isUsingEmulator: boolean;
+    readonly emulatorOptions: RepoInfoEmulatorOptions | null;
+    private _host;
+    private _domain;
+    internalHost: string;
+    /**
+     * @param host - Hostname portion of the url for the repo
+     * @param secure - Whether or not this repo is accessed over ssl
+     * @param namespace - The namespace represented by the repo
+     * @param webSocketOnly - Whether to prefer websockets over all other transports (used by Nest).
+     * @param nodeAdmin - Whether this instance uses Admin SDK credentials
+     * @param persistenceKey - Override the default session persistence storage key
+     */
+    constructor(host: string, secure: boolean, namespace: string, webSocketOnly: boolean, nodeAdmin?: boolean, persistenceKey?: string, includeNamespaceInQueryParams?: boolean, isUsingEmulator?: boolean, emulatorOptions?: RepoInfoEmulatorOptions | null);
+    isCacheableHost(): boolean;
+    isCustomHost(): boolean;
+    get host(): string;
+    set host(newHost: string);
+    toString(): string;
+    toURLString(): string;
+}
+
+declare interface RepoInfoEmulatorOptions {
+    mockUserToken?: string | EmulatorMockTokenOptions;
+}
+
+/* Excluded from this release type: _repoManagerDatabaseFromApp */
+
+/**
+ * Atomically modifies the data at this location.
+ *
+ * Atomically modify the data at this location. Unlike a normal `set()`, which
+ * just overwrites the data regardless of its previous value, `runTransaction()` is
+ * used to modify the existing value to a new value, ensuring there are no
+ * conflicts with other clients writing to the same location at the same time.
+ *
+ * To accomplish this, you pass `runTransaction()` an update function which is
+ * used to transform the current value into a new value. If another client
+ * writes to the location before your new value is successfully written, your
+ * update function will be called again with the new current value, and the
+ * write will be retried. This will happen repeatedly until your write succeeds
+ * without conflict or you abort the transaction by not returning a value from
+ * your update function.
+ *
+ * Note: Modifying data with `set()` will cancel any pending transactions at
+ * that location, so extreme care should be taken if mixing `set()` and
+ * `runTransaction()` to update the same data.
+ *
+ * Note: When using transactions with Security and Firebase Rules in place, be
+ * aware that a client needs `.read` access in addition to `.write` access in
+ * order to perform a transaction. This is because the client-side nature of
+ * transactions requires the client to read the data in order to transactionally
+ * update it.
+ *
+ * @param ref - The location to atomically modify.
+ * @param transactionUpdate - A developer-supplied function which will be passed
+ * the current data stored at this location (as a JavaScript object). The
+ * function should return the new value it would like written (as a JavaScript
+ * object). If `undefined` is returned (i.e. you return with no arguments) the
+ * transaction will be aborted and the data at this location will not be
+ * modified.
+ * @param options - An options object to configure transactions.
+ * @returns A `Promise` that can optionally be used instead of the `onComplete`
+ * callback to handle success and failure.
+ */
+export declare function runTransaction(ref: DatabaseReference, transactionUpdate: (currentData: any) => unknown, options?: TransactionOptions): Promise<TransactionResult>;
+
+/**
+ * Interface defining the set of actions that can be performed against the Firebase server
+ * (basically corresponds to our wire protocol).
+ *
+ * @interface
+ */
+declare abstract class ServerActions {
+    abstract listen(query: QueryContext, currentHashFn: () => string, tag: number | null, onComplete: (a: string, b: unknown) => void): void;
+    /**
+     * Remove a listen.
+     */
+    abstract unlisten(query: QueryContext, tag: number | null): void;
+    /**
+     * Get the server value satisfying this query.
+     */
+    abstract get(query: QueryContext): Promise<string>;
+    put(pathString: string, data: unknown, onComplete?: (a: string, b: string) => void, hash?: string): void;
+    merge(pathString: string, data: unknown, onComplete: (a: string, b: string | null) => void, hash?: string): void;
+    /**
+     * Refreshes the auth token for the current connection.
+     * @param token - The authentication token
+     */
+    refreshAuthToken(token: string): void;
+    /**
+     * Refreshes the app check token for the current connection.
+     * @param token The app check token
+     */
+    refreshAppCheckToken(token: string): void;
+    onDisconnectPut(pathString: string, data: unknown, onComplete?: (a: string, b: string) => void): void;
+    onDisconnectMerge(pathString: string, data: unknown, onComplete?: (a: string, b: string) => void): void;
+    onDisconnectCancel(pathString: string, onComplete?: (a: string, b: string) => void): void;
+    reportStats(stats: {
+        [k: string]: unknown;
+    }): void;
+}
+
+/**
+ * @license
+ * Copyright 2020 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * Returns a placeholder value for auto-populating the current timestamp (time
+ * since the Unix epoch, in milliseconds) as determined by the Firebase
+ * servers.
+ */
+export declare function serverTimestamp(): object;
+
+/**
+ * Writes data to this Database location.
+ *
+ * This will overwrite any data at this location and all child locations.
+ *
+ * The effect of the write will be visible immediately, and the corresponding
+ * events ("value", "child_added", etc.) will be triggered. Synchronization of
+ * the data to the Firebase servers will also be started, and the returned
+ * Promise will resolve when complete. If provided, the `onComplete` callback
+ * will be called asynchronously after synchronization has finished.
+ *
+ * Passing `null` for the new value is equivalent to calling `remove()`; namely,
+ * all data at this location and all child locations will be deleted.
+ *
+ * `set()` will remove any priority stored at this location, so if priority is
+ * meant to be preserved, you need to use `setWithPriority()` instead.
+ *
+ * Note that modifying data with `set()` will cancel any pending transactions
+ * at that location, so extreme care should be taken if mixing `set()` and
+ * `transaction()` to modify the same data.
+ *
+ * A single `set()` will generate a single "value" event at the location where
+ * the `set()` was performed.
+ *
+ * @param ref - The location to write to.
+ * @param value - The value to be written (string, number, boolean, object,
+ *   array, or null).
+ * @returns Resolves when write to server is complete.
+ */
+export declare function set(ref: DatabaseReference, value: unknown): Promise<void>;
+
+/**
+ * Sets a priority for the data at this Database location.
+ *
+ * Applications need not use priority but can order collections by
+ * ordinary properties (see
+ * {@link https://firebase.google.com/docs/database/web/lists-of-data#sorting_and_filtering_data | Sorting and filtering data}
+ * ).
+ *
+ * @param ref - The location to write to.
+ * @param priority - The priority to be written (string, number, or null).
+ * @returns Resolves when write to server is complete.
+ */
+export declare function setPriority(ref: DatabaseReference, priority: string | number | null): Promise<void>;
+
+/* Excluded from this release type: _setSDKVersion */
+
+/**
+ * Writes data the Database location. Like `set()` but also specifies the
+ * priority for that data.
+ *
+ * Applications need not use priority but can order collections by
+ * ordinary properties (see
+ * {@link https://firebase.google.com/docs/database/web/lists-of-data#sorting_and_filtering_data | Sorting and filtering data}
+ * ).
+ *
+ * @param ref - The location to write to.
+ * @param value - The value to be written (string, number, boolean, object,
+ *   array, or null).
+ * @param priority - The priority to be written (string, number, or null).
+ * @returns Resolves when write to server is complete.
+ */
+export declare function setWithPriority(ref: DatabaseReference, value: unknown, priority: string | number | null): Promise<void>;
+
+/**
+ * Mutable object which basically just stores a reference to the "latest" immutable snapshot.
+ */
+declare class SnapshotHolder {
+    private rootNode_;
+    getNode(path: Path): Node_2;
+    updateSnapshot(path: Path, newSnapshotNode: Node_2): void;
+}
+
+/**
+ * An immutable sorted map implementation, based on a Left-leaning Red-Black
+ * tree.
+ */
+declare class SortedMap<K, V> {
+    private comparator_;
+    private root_;
+    /**
+     * Always use the same empty node, to reduce memory.
+     */
+    static EMPTY_NODE: LLRBEmptyNode<unknown, unknown>;
+    /**
+     * @param comparator_ - Key comparator.
+     * @param root_ - Optional root node for the map.
+     */
+    constructor(comparator_: Comparator<K>, root_?: LLRBNode<K, V> | LLRBEmptyNode<K, V>);
+    /**
+     * Returns a copy of the map, with the specified key/value added or replaced.
+     * (TODO: We should perhaps rename this method to 'put')
+     *
+     * @param key - Key to be added.
+     * @param value - Value to be added.
+     * @returns New map, with item added.
+     */
+    insert(key: K, value: V): SortedMap<K, V>;
+    /**
+     * Returns a copy of the map, with the specified key removed.
+     *
+     * @param key - The key to remove.
+     * @returns New map, with item removed.
+     */
+    remove(key: K): SortedMap<K, V>;
+    /**
+     * Returns the value of the node with the given key, or null.
+     *
+     * @param key - The key to look up.
+     * @returns The value of the node with the given key, or null if the
+     * key doesn't exist.
+     */
+    get(key: K): V | null;
+    /**
+     * Returns the key of the item *before* the specified key, or null if key is the first item.
+     * @param key - The key to find the predecessor of
+     * @returns The predecessor key.
+     */
+    getPredecessorKey(key: K): K | null;
+    /**
+     * @returns True if the map is empty.
+     */
+    isEmpty(): boolean;
+    /**
+     * @returns The total number of nodes in the map.
+     */
+    count(): number;
+    /**
+     * @returns The minimum key in the map.
+     */
+    minKey(): K | null;
+    /**
+     * @returns The maximum key in the map.
+     */
+    maxKey(): K | null;
+    /**
+     * Traverses the map in key order and calls the specified action function
+     * for each key/value pair.
+     *
+     * @param action - Callback function to be called
+     * for each key/value pair.  If action returns true, traversal is aborted.
+     * @returns The first truthy value returned by action, or the last falsey
+     *   value returned by action
+     */
+    inorderTraversal(action: (k: K, v: V) => unknown): boolean;
+    /**
+     * Traverses the map in reverse key order and calls the specified action function
+     * for each key/value pair.
+     *
+     * @param action - Callback function to be called
+     * for each key/value pair.  If action returns true, traversal is aborted.
+     * @returns True if the traversal was aborted.
+     */
+    reverseTraversal(action: (k: K, v: V) => void): boolean;
+    /**
+     * Returns an iterator over the SortedMap.
+     * @returns The iterator.
+     */
+    getIterator<T>(resultGenerator?: (k: K, v: V) => T): SortedMapIterator<K, V, T>;
+    getIteratorFrom<T>(key: K, resultGenerator?: (k: K, v: V) => T): SortedMapIterator<K, V, T>;
+    getReverseIteratorFrom<T>(key: K, resultGenerator?: (k: K, v: V) => T): SortedMapIterator<K, V, T>;
+    getReverseIterator<T>(resultGenerator?: (k: K, v: V) => T): SortedMapIterator<K, V, T>;
+}
+
+/**
+ * An iterator over an LLRBNode.
+ */
+declare class SortedMapIterator<K, V, T> {
+    private isReverse_;
+    private resultGenerator_;
+    private nodeStack_;
+    /**
+     * @param node - Node to iterate.
+     * @param isReverse_ - Whether or not to iterate in reverse
+     */
+    constructor(node: LLRBNode<K, V> | LLRBEmptyNode<K, V>, startKey: K | null, comparator: Comparator<K>, isReverse_: boolean, resultGenerator_?: ((k: K, v: V) => T) | null);
+    getNext(): T;
+    hasNext(): boolean;
+    peek(): T;
+}
+
+/**
+ * Helper class to store a sparse set of snapshots.
+ */
+declare interface SparseSnapshotTree {
+    value: Node_2 | null;
+    readonly children: Map<string, SparseSnapshotTree>;
+}
+
+/**
+ * Creates a `QueryConstraint` with the specified starting point (exclusive).
+ *
+ * Using `startAt()`, `startAfter()`, `endBefore()`, `endAt()` and `equalTo()`
+ * allows you to choose arbitrary starting and ending points for your queries.
+ *
+ * The starting point is exclusive. If only a value is provided, children
+ * with a value greater than the specified value will be included in the query.
+ * If a key is specified, then children must have a value greater than or equal
+ * to the specified value and a a key name greater than the specified key.
+ *
+ * @param value - The value to start after. The argument type depends on which
+ * `orderBy*()` function was used in this query. Specify a value that matches
+ * the `orderBy*()` type. When used in combination with `orderByKey()`, the
+ * value must be a string.
+ * @param key - The child key to start after. This argument is only allowed if
+ * ordering by child, value, or priority.
+ */
+export declare function startAfter(value: number | string | boolean | null, key?: string): QueryConstraint;
+
+/**
+ * Creates a `QueryConstraint` with the specified starting point.
+ *
+ * Using `startAt()`, `startAfter()`, `endBefore()`, `endAt()` and `equalTo()`
+ * allows you to choose arbitrary starting and ending points for your queries.
+ *
+ * The starting point is inclusive, so children with exactly the specified value
+ * will be included in the query. The optional key argument can be used to
+ * further limit the range of the query. If it is specified, then children that
+ * have exactly the specified value must also have a key name greater than or
+ * equal to the specified key.
+ *
+ * You can read more about `startAt()` in
+ * {@link https://firebase.google.com/docs/database/web/lists-of-data#filtering_data | Filtering data}.
+ *
+ * @param value - The value to start at. The argument type depends on which
+ * `orderBy*()` function was used in this query. Specify a value that matches
+ * the `orderBy*()` type. When used in combination with `orderByKey()`, the
+ * value must be a string.
+ * @param key - The child key to start at. This argument is only allowed if
+ * ordering by child, value, or priority.
+ */
+export declare function startAt(value?: number | string | boolean | null, key?: string): QueryConstraint;
+
+/**
+ * @license
+ * Copyright 2017 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * Tracks a collection of stats.
+ */
+declare class StatsCollection {
+    private counters_;
+    incrementCounter(name: string, amount?: number): void;
+    get(): {
+        [k: string]: number;
+    };
+}
+
+/**
+ * Returns the delta from the previous call to get stats.
+ *
+ * @param collection_ - The collection to "listen" to.
+ */
+declare class StatsListener {
+    private collection_;
+    private last_;
+    constructor(collection_: StatsCollection);
+    get(): {
+        [k: string]: number;
+    };
+}
+
+declare class StatsReporter {
+    private server_;
+    private statsListener_;
+    statsToReport_: {
+        [k: string]: boolean;
+    };
+    constructor(collection: StatsCollection, server_: ServerActions);
+    private reportStats_;
+}
+
+/**
+ * SyncPoint represents a single location in a SyncTree with 1 or more event registrations, meaning we need to
+ * maintain 1 or more Views at this location to cache server data and raise appropriate events for server changes
+ * and user writes (set, transaction, update).
+ *
+ * It's responsible for:
+ *  - Maintaining the set of 1 or more views necessary at this location (a SyncPoint with 0 views should be removed).
+ *  - Proxying user / server operations to the views as appropriate (i.e. applyServerOverwrite,
+ *    applyUserOverwrite, etc.)
+ */
+declare class SyncPoint {
+    /**
+     * The Views being tracked at this location in the tree, stored as a map where the key is a
+     * queryId and the value is the View for that query.
+     *
+     * NOTE: This list will be quite small (usually 1, but perhaps 2 or 3; any more is an odd use case).
+     */
+    readonly views: Map<string, View>;
+}
+
+/**
+ * SyncTree is the central class for managing event callback registration, data caching, views
+ * (query processing), and event generation.  There are typically two SyncTree instances for
+ * each Repo, one for the normal Firebase data, and one for the .info data.
+ *
+ * It has a number of responsibilities, including:
+ *  - Tracking all user event callbacks (registered via addEventRegistration() and removeEventRegistration()).
+ *  - Applying and caching data changes for user set(), transaction(), and update() calls
+ *    (applyUserOverwrite(), applyUserMerge()).
+ *  - Applying and caching data changes for server data changes (applyServerOverwrite(),
+ *    applyServerMerge()).
+ *  - Generating user-facing events for server and user changes (all of the apply* methods
+ *    return the set of events that need to be raised as a result).
+ *  - Maintaining the appropriate set of server listens to ensure we are always subscribed
+ *    to the correct set of paths and queries to satisfy the current set of user event
+ *    callbacks (listens are started/stopped using the provided listenProvider).
+ *
+ * NOTE: Although SyncTree tracks event callbacks and calculates events to raise, the actual
+ * events are returned to the caller rather than raised synchronously.
+ *
+ */
+declare class SyncTree {
+    listenProvider_: ListenProvider;
+    /**
+     * Tree of SyncPoints.  There's a SyncPoint at any location that has 1 or more views.
+     */
+    syncPointTree_: ImmutableTree<SyncPoint>;
+    /**
+     * A tree of all pending user writes (user-initiated set()'s, transaction()'s, update()'s, etc.).
+     */
+    pendingWriteTree_: WriteTree;
+    readonly tagToQueryMap: Map<number, string>;
+    readonly queryToTagMap: Map<string, number>;
+    /**
+     * @param listenProvider_ - Used by SyncTree to start / stop listening
+     *   to server data.
+     */
+    constructor(listenProvider_: ListenProvider);
+}
+
+/* Excluded from this release type: _TEST_ACCESS_forceRestClient */
+
+/* Excluded from this release type: _TEST_ACCESS_hijackHash */
+
+/**
+ * A `Promise` that can also act as a `DatabaseReference` when returned by
+ * {@link push}. The reference is available immediately and the `Promise` resolves
+ * as the write to the backend completes.
+ */
+export declare interface ThenableReference extends DatabaseReference, Pick<Promise<DatabaseReference>, 'then' | 'catch'> {
+    key: string;
+    parent: DatabaseReference;
+}
+
+declare interface Transaction {
+    path: Path;
+    update: (a: unknown) => unknown;
+    onComplete: (error: Error | null, committed: boolean, node: Node_2 | null) => void;
+    status: TransactionStatus;
+    order: number;
+    applyLocally: boolean;
+    retryCount: number;
+    unwatcher: () => void;
+    abortReason: string | null;
+    currentWriteId: number;
+    currentInputSnapshot: Node_2 | null;
+    currentOutputSnapshotRaw: Node_2 | null;
+    currentOutputSnapshotResolved: Node_2 | null;
+}
+
+/** An options object to configure transactions. */
+export declare interface TransactionOptions {
+    /**
+     * By default, events are raised each time the transaction update function
+     * runs. So if it is run multiple times, you may see intermediate states. You
+     * can set this to false to suppress these intermediate states and instead
+     * wait until the transaction has completed before events are raised.
+     */
+    readonly applyLocally?: boolean;
+}
+
+/**
+ * A type for the resolve value of {@link runTransaction}.
+ */
+export declare class TransactionResult {
+    /** Whether the transaction was successfully committed. */
+    readonly committed: boolean;
+    /** The resulting data snapshot. */
+    readonly snapshot: DataSnapshot;
+    /** @hideconstructor */
+    constructor(
+    /** Whether the transaction was successfully committed. */
+    committed: boolean, 
+    /** The resulting data snapshot. */
+    snapshot: DataSnapshot);
+    /** Returns a JSON-serializable representation of this object. */
+    toJSON(): object;
+}
+
+declare const enum TransactionStatus {
+    RUN = 0,
+    SENT = 1,
+    COMPLETED = 2,
+    SENT_NEEDS_ABORT = 3,
+    NEEDS_ABORT = 4
+}
+
+/**
+ * A light-weight tree, traversable by path.  Nodes can have both values and children.
+ * Nodes are not enumerated (by forEachChild) unless they have a value or non-empty
+ * children.
+ */
+declare class Tree<T> {
+    readonly name: string;
+    readonly parent: Tree<T> | null;
+    node: TreeNode<T>;
+    /**
+     * @param name - Optional name of the node.
+     * @param parent - Optional parent node.
+     * @param node - Optional node to wrap.
+     */
+    constructor(name?: string, parent?: Tree<T> | null, node?: TreeNode<T>);
+}
+
+/**
+ * Node in a Tree.
+ */
+declare interface TreeNode<T> {
+    children: Record<string, TreeNode<T>>;
+    childCount: number;
+    value?: T;
+}
+
+/** A callback that can invoked to remove a listener. */
+export declare type Unsubscribe = () => void;
+
+/**
+ * Writes multiple values to the Database at once.
+ *
+ * The `values` argument contains multiple property-value pairs that will be
+ * written to the Database together. Each child property can either be a simple
+ * property (for example, "name") or a relative path (for example,
+ * "name/first") from the current location to the data to update.
+ *
+ * As opposed to the `set()` method, `update()` can be use to selectively update
+ * only the referenced properties at the current location (instead of replacing
+ * all the child properties at the current location).
+ *
+ * The effect of the write will be visible immediately, and the corresponding
+ * events ('value', 'child_added', etc.) will be triggered. Synchronization of
+ * the data to the Firebase servers will also be started, and the returned
+ * Promise will resolve when complete. If provided, the `onComplete` callback
+ * will be called asynchronously after synchronization has finished.
+ *
+ * A single `update()` will generate a single "value" event at the location
+ * where the `update()` was performed, regardless of how many children were
+ * modified.
+ *
+ * Note that modifying data with `update()` will cancel any pending
+ * transactions at that location, so extreme care should be taken if mixing
+ * `update()` and `transaction()` to modify the same data.
+ *
+ * Passing `null` to `update()` will remove the data at this location.
+ *
+ * See
+ * {@link https://firebase.googleblog.com/2015/09/introducing-multi-location-updates-and_86.html | Introducing multi-location updates and more}.
+ *
+ * @param ref - The location to write to.
+ * @param values - Object containing multiple values.
+ * @returns Resolves when update on server is complete.
+ */
+export declare function update(ref: DatabaseReference, values: object): Promise<void>;
+
+/* Excluded from this release type: _UserCallback */
+
+/* Excluded from this release type: _validatePathString */
+
+/* Excluded from this release type: _validateWritablePath */
+
+/**
+ * A view represents a specific location and query that has 1 or more event registrations.
+ *
+ * It does several things:
+ *  - Maintains the list of event registrations for this location/query.
+ *  - Maintains a cache of the data visible for this location/query.
+ *  - Applies new operations (via applyOperation), updates the cache, and based on the event
+ *    registrations returns the set of events to be raised.
+ */
+declare class View {
+    private query_;
+    processor_: ViewProcessor;
+    viewCache_: ViewCache;
+    eventRegistrations_: EventRegistration[];
+    eventGenerator_: EventGenerator;
+    constructor(query_: QueryContext, initialViewCache: ViewCache);
+    get query(): QueryContext;
+}
+
+/**
+ * Stores the data we have cached for a view.
+ *
+ * serverSnap is the cached server data, eventSnap is the cached event data (server data plus any local writes).
+ */
+declare interface ViewCache {
+    readonly eventCache: CacheNode;
+    readonly serverCache: CacheNode;
+}
+
+declare interface ViewProcessor {
+    readonly filter: NodeFilter_2;
+}
+
+/**
+ * Defines a single user-initiated write operation. May be the result of a set(), transaction(), or update() call. In
+ * the case of a set() or transaction, snap will be non-null.  In the case of an update(), children will be non-null.
+ */
+declare interface WriteRecord {
+    writeId: number;
+    path: Path;
+    snap?: Node_2 | null;
+    children?: {
+        [k: string]: Node_2;
+    } | null;
+    visible: boolean;
+}
+
+/**
+ * WriteTree tracks all pending user-initiated writes and has methods to calculate the result of merging them
+ * with underlying server data (to create "event cache" data).  Pending writes are added with addOverwrite()
+ * and addMerge(), and removed with removeWrite().
+ */
+declare interface WriteTree {
+    /**
+     * A tree tracking the result of applying all visible writes.  This does not include transactions with
+     * applyLocally=false or writes that are completely shadowed by other writes.
+     */
+    visibleWrites: CompoundWrite;
+    /**
+     * A list of all pending writes, regardless of visibility and shadowed-ness.  Used to calculate arbitrary
+     * sets of the changed data, such as hidden writes (from transactions) or changes with certain writes excluded (also
+     * used by transactions).
+     */
+    allWrites: WriteRecord[];
+    lastWriteId: number;
+}
+
+export { }