arangojs/cursors.d.ts

The official ArangoDB JavaScript driver.

/**
 * ```ts
 * import type { Cursor, BatchCursor } from "arangojs/cursors";
 * ```
 *
 * The "cursors" module provides cursor-related types and interfaces for
 * TypeScript.
 *
 * @packageDocumentation
 */
import { LinkedList } from "./lib/x3-linkedlist.js";
import * as databases from "./databases.js";
/**
 * Additional information about the cursor.
 */
export type CursorExtras = {
    /**
     * Warnings encountered while executing the query.
     */
    warnings: {
        code: number;
        message: string;
    }[];
    /**
     * Query execution plan for the executed query.
     */
    plan?: Record<string, any>;
    /**
     * Additional profiling information for the executed query.
     */
    profile?: Record<string, number>;
    /**
     * Additional statistics about the query execution.
     */
    stats?: CursorStats;
};
/**
 * Additional statics about the query execution of the cursor.
 */
export type CursorStats = {
    /**
     * Total number of index entries read from in-memory caches for indexes of
     * type edge or persistent.
     */
    cacheHits: number;
    /**
     * Total number of cache read attempts for index entries that could not be
     * served from in-memory caches for indexes of type edge or persistent.
     */
    cacheMisses: number;
    /**
     * Total number of cursor objects created during query execution.
     */
    cursorsCreated: number;
    /**
     * Total number of times an existing cursor object was repurposed.
     */
    cursorsRearmed: number;
    /**
     * Total number of data-modification operations successfully executed.
     */
    writesExecuted: number;
    /**
     * Total number of data-modification operations that were unsuccessful, but have been ignored because of query option ignoreErrors.
     */
    writesIgnored: number;
    /**
     * Total number of documents iterated over when scanning a collection without an index.
     */
    scannedFull: number;
    /**
     * Total number of documents iterated over when scanning a collection using an index.
     */
    scannedIndex: number;
    /**
     * Total number of documents that were removed after executing a filter condition in a FilterNode.
     */
    filtered: number;
    /**
     * Maximum memory usage of the query while it was running.
     */
    peakMemoryUsage: number;
    /**
     * Execution time of the query in seconds.
     */
    executionTime: number;
    /**
     * Total number of documents that matched the search condition if the query’s final top-level LIMIT statement were not present.
     */
    fullCount?: number;
    /**
     * Total number of cluster-internal HTTP requests performed.
     */
    httpRequests: number;
    /**
     * Runtime statistics per query execution node if `profile` was set to `2` or greater.
     */
    nodes?: {
        /**
         * Execution node ID to correlate this node with nodes in the `extra.plan`.
         */
        id: number;
        /**
         * Number of calls in this node.
         */
        calls: number;
        /**
         * Number of temporary result items returned by this node.
         */
        items: number;
        filter: number;
        /**
         * Execution time of this node in seconds.
         */
        runtime: number;
    }[];
};
/**
 * A low-level interface for consuming the items of a {@link BatchCursor}.
 */
export interface BatchCursorItemsView<ItemType = any> {
    readonly isEmpty: boolean;
    more(): Promise<void>;
    shift(): ItemType | undefined;
}
/**
 * The `BatchCursor` provides a batch-wise API to an {@link Cursor}.
 *
 * When using TypeScript, cursors can be cast to a specific item type in order
 * to increase type safety.
 *
 * @param ItemType - Type to use for each item. Defaults to `any`.
 *
 * @example
 * ```ts
 * const db = new Database();
 * const query = aql`FOR x IN 1..5 RETURN x`;
 * const cursor = await db.query(query) as Cursor<number>;
 * const batches = cursor.batches;
 * ```
 *
 * @example
 * ```js
 * const db = new Database();
 * const query = aql`FOR x IN 1..10000 RETURN x`;
 * const cursor = await db.query(query, { batchSize: 10 });
 * for await (const batch of cursor.batches) {
 *   // Process all values in a batch in parallel
 *   await Promise.all(batch.map(
 *     value => asyncProcessValue(value)
 *   ));
 * }
 * ```
 */
export declare class BatchCursor<ItemType = any> {
    protected _db: databases.Database;
    protected _batches: LinkedList<LinkedList<ItemType>>;
    protected _count?: number;
    protected _extra: CursorExtras;
    protected _hasMore: boolean;
    protected _nextBatchId?: string;
    protected _id: string | undefined;
    protected _hostUrl?: string;
    protected _allowDirtyRead?: boolean;
    protected _itemsCursor: Cursor<ItemType>;
    /**
     * @internal
     */
    constructor(db: databases.Database, body: {
        extra: CursorExtras;
        result: ItemType[];
        hasMore: boolean;
        nextBatchId?: string;
        id: string;
        count: number;
    }, hostUrl?: string, allowDirtyRead?: boolean);
    protected _more(): Promise<void>;
    /**
     * Database this cursor belongs to.
     */
    get database(): databases.Database;
    /**
     * ID of this cursor.
     */
    get id(): string | undefined;
    /**
     * An {@link Cursor} providing item-wise access to the cursor result set.
     *
     * See also {@link Cursor#batches}.
     */
    get items(): Cursor<ItemType>;
    /**
     * A low-level interface for consuming the items of this {@link BatchCursor}.
     */
    get itemsView(): BatchCursorItemsView<ItemType>;
    /**
     * Additional information about the cursor.
     */
    get extra(): Readonly<CursorExtras>;
    /**
     * Total number of documents in the query result. Only available if the
     * `count` option was used.
     */
    get count(): number | undefined;
    /**
     * Whether the cursor has any remaining batches that haven't yet been
     * fetched. If set to `false`, all batches have been fetched and no
     * additional requests to the server will be made when consuming any
     * remaining batches from this cursor.
     */
    get hasMore(): boolean;
    /**
     * Whether the cursor has more batches. If set to `false`, the cursor has
     * already been depleted and contains no more batches.
     */
    get hasNext(): boolean;
    /**
     * Enables use with `for await` to deplete the cursor by asynchronously
     * yielding every batch in the cursor's remaining result set.
     *
     * **Note**: If the result set spans multiple batches, any remaining batches
     * will only be fetched on demand. Depending on the cursor's TTL and the
     * processing speed, this may result in the server discarding the cursor
     * before it is fully depleted.
     *
     * @example
     * ```js
     * const cursor = await db.query(aql`
     *   FOR user IN users
     *   FILTER user.isActive
     *   RETURN user
     * `);
     * for await (const users of cursor.batches) {
     *   for (const user of users) {
     *     console.log(user.email, user.isAdmin);
     *   }
     * }
     * ```
     */
    [Symbol.asyncIterator](): AsyncGenerator<ItemType[], undefined, undefined>;
    /**
     * Loads all remaining batches from the server.
     *
     * **Warning**: This may impact memory use when working with very large
     * query result sets.
     *
     * @example
     * ```js
     * const cursor = await db.query(
     *   aql`FOR x IN 1..5 RETURN x`,
     *   { batchSize: 1 }
     * );
     * console.log(cursor.hasMore); // true
     * await cursor.batches.loadAll();
     * console.log(cursor.hasMore); // false
     * console.log(cursor.hasNext); // true
     * for await (const item of cursor) {
     *   console.log(item);
     *   // No server roundtrips necessary any more
     * }
     * ```
     */
    loadAll(): Promise<void>;
    /**
     * Depletes the cursor, then returns an array containing all batches in the
     * cursor's remaining result list.
     *
     * @example
     * ```js
     * const cursor = await db.query(
     *   aql`FOR x IN 1..5 RETURN x`,
     *   { batchSize: 2 }
     * );
     * const result = await cursor.batches.all(); // [[1, 2], [3, 4], [5]]
     * console.log(cursor.hasNext); // false
     * ```
     */
    all(): Promise<ItemType[][]>;
    /**
     * Advances the cursor and returns all remaining values in the cursor's
     * current batch. If the current batch has already been exhausted, fetches
     * the next batch from the server and returns it, or `undefined` if the
     * cursor has been depleted.
     *
     * **Note**: If the result set spans multiple batches, any remaining batches
     * will only be fetched on demand. Depending on the cursor's TTL and the
     * processing speed, this may result in the server discarding the cursor
     * before it is fully depleted.
     *
     * @example
     * ```js
     * const cursor = await db.query(
     *   aql`FOR i IN 1..10 RETURN i`,
     *   { batchSize: 5 }
     * );
     * const firstBatch = await cursor.batches.next(); // [1, 2, 3, 4, 5]
     * await cursor.next(); // 6
     * const lastBatch = await cursor.batches.next(); // [7, 8, 9, 10]
     * console.log(cursor.hasNext); // false
     * ```
     */
    next(): Promise<ItemType[] | undefined>;
    /**
     * Advances the cursor by applying the `callback` function to each item in
     * the cursor's remaining result list until the cursor is depleted or
     * `callback` returns the exact value `false`. Returns a promise that
     * evalues to `true` unless the function returned `false`.
     *
     * **Note**: If the result set spans multiple batches, any remaining batches
     * will only be fetched on demand. Depending on the cursor's TTL and the
     * processing speed, this may result in the server discarding the cursor
     * before it is fully depleted.
     *
     * See also:
     * [`Array.prototype.forEach`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach).
     *
     * @param callback - Function to execute on each element.
     *
     * @example
     * ```js
     * const cursor = await db.query(
     *   aql`FOR x IN 1..5 RETURN x`,
     *   { batchSize: 2 }
     * );
     * const result = await cursor.batches.forEach((currentBatch) => {
     *   for (const value of currentBatch) {
     *     console.log(value);
     *   }
     * });
     * console.log(result) // true
     * console.log(cursor.hasNext); // false
     * ```
     *
     * @example
     * ```js
     * const cursor = await db.query(
     *   aql`FOR x IN 1..5 RETURN x`,
     *   { batchSize: 2 }
     * );
     * const result = await cursor.batches.forEach((currentBatch) => {
     *   for (const value of currentBatch) {
     *     console.log(value);
     *   }
     *   return false; // stop after the first batch
     * });
     * console.log(result); // false
     * console.log(cursor.hasNext); // true
     * ```
     */
    forEach(callback: (currentBatch: ItemType[], index: number, self: this) => false | void): Promise<boolean>;
    /**
     * Depletes the cursor by applying the `callback` function to each batch in
     * the cursor's remaining result list. Returns an array containing the
     * return values of `callback` for each batch.
     *
     * **Note**: This creates an array of all return values, which may impact
     * memory use when working with very large query result sets. Consider using
     * {@link BatchCursor#forEach}, {@link BatchCursor#reduce} or
     * {@link BatchCursor#flatMap} instead.
     *
     * See also:
     * [`Array.prototype.map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map).
     *
     * @param R - Return type of the `callback` function.
     * @param callback - Function to execute on each element.
     *
     * @example
     * ```js
     * const cursor = await db.query(
     *   aql`FOR x IN 1..5 RETURN x`,
     *   { batchSize: 2 }
     * );
     * const squares = await cursor.batches.map((currentBatch) => {
     *   return currentBatch.map((value) => value ** 2);
     * });
     * console.log(squares); // [[1, 4], [9, 16], [25]]
     * console.log(cursor.hasNext); // false
     * ```
     */
    map<R>(callback: (currentBatch: ItemType[], index: number, self: this) => R): Promise<R[]>;
    /**
     * Depletes the cursor by applying the `callback` function to each batch in
     * the cursor's remaining result list. Returns an array containing the
     * return values of `callback` for each batch, flattened to a depth of 1.
     *
     * **Note**: If the result set spans multiple batches, any remaining batches
     * will only be fetched on demand. Depending on the cursor's TTL and the
     * processing speed, this may result in the server discarding the cursor
     * before it is fully depleted.
     *
     * See also:
     * [`Array.prototype.flatMap`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/flatMap).
     *
     * @param R - Return type of the `callback` function.
     * @param callback - Function to execute on each element.
     *
     * @example
     * ```js
     * const cursor = await db.query(
     *   aql`FOR x IN 1..5 RETURN x`,
     *   { batchSize: 2 }
     * );
     * const squares = await cursor.batches.flatMap((currentBatch) => {
     *   return currentBatch.map((value) => value ** 2);
     * });
     * console.log(squares); // [1, 1, 2, 4, 3, 9, 4, 16, 5, 25]
     * console.log(cursor.hasNext); // false
     * ```
     *
     * @example
     * ```js
     * const cursor = await db.query(
     *   aql`FOR x IN 1..5 RETURN x`,
     *   { batchSize: 1 }
     * );
     * const odds = await cursor.batches.flatMap((currentBatch) => {
     *   if (currentBatch[0] % 2 === 0) {
     *     return []; // empty array flattens into nothing
     *   }
     *   return currentBatch;
     * });
     * console.logs(odds); // [1, 3, 5]
     * ```
     */
    flatMap<R>(callback: (currentBatch: ItemType[], index: number, self: this) => R | R[]): Promise<R[]>;
    /**
     * Depletes the cursor by applying the `reducer` function to each batch in
     * the cursor's remaining result list. Returns the return value of `reducer`
     * for the last batch.
     *
     * **Note**: Most complex uses of the `reduce` method can be replaced with
     * simpler code using {@link BatchCursor#forEach} or the `for await`
     * syntax.
     *
     * **Note**: If the result set spans multiple batches, any remaining batches
     * will only be fetched on demand. Depending on the cursor's TTL and the
     * processing speed, this may result in the server discarding the cursor
     * before it is fully depleted.
     *
     * See also:
     * [`Array.prototype.reduce`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce).
     *
     * @param R - Return type of the `reducer` function.
     * @param reducer - Function to execute on each element.
     * @param initialValue - Initial value of the `accumulator` value passed to
     * the `reducer` function.
     *
     * @example
     * ```js
     * function largestValue(baseline, values) {
     *   return Math.max(baseline, ...values);
     * }
     * const cursor = await db.query(
     *   aql`FOR x IN 1..5 RETURN x`,
     *   { batchSize: 3 }
     * );
     * const result = await cursor.batches.reduce(largestValue, 0);
     * console.log(result); // 5
     * console.log(cursor.hasNext); // false
     * const emptyResult = await cursor.batches.reduce(largestValue, 0);
     * console.log(emptyResult); // 0
     * ```
     *
     * @example
     * ```js
     * // BAD! NEEDLESSLY COMPLEX!
     * const cursor = await db.query(
     *   aql`FOR x IN 1..5 RETURN x`,
     *   { batchSize: 1 }
     * );
     * const result = await cursor.reduce((accumulator, currentBatch) => {
     *   if (currentBatch[0] % 2 === 0) {
     *     accumulator.even.push(...currentBatch);
     *   } else {
     *     accumulator.odd.push(...currentBatch);
     *   }
     *   return accumulator;
     * }, { odd: [], even: [] });
     * console.log(result); // { odd: [1, 3, 5], even: [2, 4] }
     *
     * // GOOD! MUCH SIMPLER!
     * const cursor = await db.query(aql`FOR x IN 1..5 RETURN x`);
     * const odd = [];
     * const even = [];
     * for await (const currentBatch of cursor) {
     *   if (currentBatch[0] % 2 === 0) {
     *     even.push(...currentBatch);
     *   } else {
     *     odd.push(...currentBatch);
     *   }
     * }
     * console.log({ odd, even }); // { odd: [1, 3, 5], even: [2, 4] }
     * ```
     */
    reduce<R>(reducer: (accumulator: R, currentBatch: ItemType[], index: number, self: this) => R, initialValue: R): Promise<R>;
    /**
     * Depletes the cursor by applying the `reducer` function to each batch in
     * the cursor's remaining result list. Returns the return value of `reducer`
     * for the last batch.
     *
     * **Note**: If the result set spans multiple batches, any remaining batches
     * will only be fetched on demand. Depending on the cursor's TTL and the
     * processing speed, this may result in the server discarding the cursor
     * before it is fully depleted.
     *
     * See also:
     * [`Array.prototype.reduce`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce).
     *
     * @param R - Return type of the `reducer` function.
     * @param reducer - Function to execute on each element.
     *
     * @example
     * ```js
     * function largestValue(values1, values2) {
     *   return [Math.max(...values1, ...values2)];
     * }
     * const cursor = await db.query(
     *   aql`FOR x IN 1..5 RETURN x`,
     *   { batchSize: 3 }
     * );
     * const result = await cursor.batches.reduce(largestValue);
     * console.log(result); // [5]
     * console.log(cursor.hasNext); // false
     * ```
     *
     */
    reduce<R>(reducer: (accumulator: ItemType[] | R, currentBatch: ItemType[], index: number, self: this) => R): Promise<R | undefined>;
    /**
     * Drains the cursor and frees up associated database resources.
     *
     * This method has no effect if all batches have already been consumed.
     *
     * @example
     * ```js
     * const cursor1 = await db.query(aql`FOR x IN 1..5 RETURN x`);
     * console.log(cursor1.hasMore); // false
     * await cursor1.kill(); // no effect
     *
     * const cursor2 = await db.query(
     *   aql`FOR x IN 1..5 RETURN x`,
     *   { batchSize: 2 }
     * );
     * console.log(cursor2.hasMore); // true
     * await cursor2.kill(); // cursor is depleted
     * ```
     */
    kill(): Promise<void>;
}
/**
 * The `Cursor` type represents a cursor returned from a
 * {@link databases.Database#query}.
 *
 * When using TypeScript, cursors can be cast to a specific item type in order
 * to increase type safety.
 *
 * See also {@link BatchCursor}.
 *
 * @param ItemType - Type to use for each item. Defaults to `any`.
 *
 * @example
 * ```ts
 * const db = new Database();
 * const query = aql`FOR x IN 1..5 RETURN x`;
 * const result = await db.query(query) as Cursor<number>;
 * ```
 *
 * @example
 * ```js
 * const db = new Database();
 * const query = aql`FOR x IN 1..10 RETURN x`;
 * const cursor = await db.query(query);
 * for await (const value of cursor) {
 *   // Process each value asynchronously
 *   await processValue(value);
 * }
 * ```
 */
export declare class Cursor<ItemType = any> {
    protected _batches: BatchCursor<ItemType>;
    protected _view: BatchCursorItemsView<ItemType>;
    /**
     * @internal
     */
    constructor(batchedCursor: BatchCursor, view: BatchCursorItemsView<ItemType>);
    /**
     * Database this cursor belongs to.
     */
    get database(): databases.Database;
    /**
     * ID of this cursor.
     */
    get id(): string | undefined;
    /**
     * A {@link BatchCursor} providing batch-wise access to the cursor
     * result set.
     *
     * See also {@link BatchCursor#items}.
     */
    get batches(): BatchCursor<ItemType>;
    /**
     * Additional information about the cursor.
     */
    get extra(): CursorExtras;
    /**
     * Total number of documents in the query result. Only available if the
     * `count` option was used.
     */
    get count(): number | undefined;
    /**
     * Whether the cursor has more values. If set to `false`, the cursor has
     * already been depleted and contains no more items.
     */
    get hasNext(): boolean;
    /**
     * Enables use with `for await` to deplete the cursor by asynchronously
     * yielding every value in the cursor's remaining result set.
     *
     * **Note**: If the result set spans multiple batches, any remaining batches
     * will only be fetched on demand. Depending on the cursor's TTL and the
     * processing speed, this may result in the server discarding the cursor
     * before it is fully depleted.
     *
     * @example
     * ```js
     * const cursor = await db.query(aql`
     *   FOR user IN users
     *   FILTER user.isActive
     *   RETURN user
     * `);
     * for await (const user of cursor) {
     *   console.log(user.email, user.isAdmin);
     * }
     * ```
     */
    [Symbol.asyncIterator](): AsyncGenerator<ItemType, undefined, undefined>;
    /**
     * Depletes the cursor, then returns an array containing all values in the
     * cursor's remaining result list.
     *
     * @example
     * ```js
     * const cursor = await db.query(aql`FOR x IN 1..5 RETURN x`);
     * const result = await cursor.all(); // [1, 2, 3, 4, 5]
     * console.log(cursor.hasNext); // false
     * ```
     */
    all(): Promise<ItemType[]>;
    /**
     * Advances the cursor and returns the next value in the cursor's remaining
     * result list, or `undefined` if the cursor has been depleted.
     *
     * **Note**: If the result set spans multiple batches, any remaining batches
     * will only be fetched on demand. Depending on the cursor's TTL and the
     * processing speed, this may result in the server discarding the cursor
     * before it is fully depleted.
     *
     * @example
     * ```js
     * const cursor = await db.query(aql`FOR x IN 1..3 RETURN x`);
     * const one = await cursor.next(); // 1
     * const two = await cursor.next(); // 2
     * const three = await cursor.next(); // 3
     * const empty = await cursor.next(); // undefined
     * ```
     */
    next(): Promise<ItemType | undefined>;
    /**
     * Advances the cursor by applying the `callback` function to each item in
     * the cursor's remaining result list until the cursor is depleted or
     * `callback` returns the exact value `false`. Returns a promise that
     * evalues to `true` unless the function returned `false`.
     *
     * **Note**: If the result set spans multiple batches, any remaining batches
     * will only be fetched on demand. Depending on the cursor's TTL and the
     * processing speed, this may result in the server discarding the cursor
     * before it is fully depleted.
     *
     * See also:
     * [`Array.prototype.forEach`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach).
     *
     * @param callback - Function to execute on each element.
     *
     * @example
     * ```js
     * const cursor = await db.query(aql`FOR x IN 1..5 RETURN x`);
     * const result = await cursor.forEach((currentValue) => {
     *   console.log(currentValue);
     * });
     * console.log(result) // true
     * console.log(cursor.hasNext); // false
     * ```
     *
     * @example
     * ```js
     * const cursor = await db.query(aql`FOR x IN 1..5 RETURN x`);
     * const result = await cursor.forEach((currentValue) => {
     *   console.log(currentValue);
     *   return false; // stop after the first item
     * });
     * console.log(result); // false
     * console.log(cursor.hasNext); // true
     * ```
     */
    forEach(callback: (currentValue: ItemType, index: number, self: this) => false | void): Promise<boolean>;
    /**
     * Depletes the cursor by applying the `callback` function to each item in
     * the cursor's remaining result list. Returns an array containing the
     * return values of `callback` for each item.
     *
     * **Note**: This creates an array of all return values, which may impact
     * memory use when working with very large query result sets. Consider using
     * {@link Cursor#forEach}, {@link Cursor#reduce} or
     * {@link Cursor#flatMap} instead.
     *
     * See also:
     * [`Array.prototype.map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map).
     *
     * @param R - Return type of the `callback` function.
     * @param callback - Function to execute on each element.
     *
     * @example
     * ```js
     * const cursor = await db.query(aql`FOR x IN 1..5 RETURN x`);
     * const squares = await cursor.map((currentValue) => {
     *   return currentValue ** 2;
     * });
     * console.log(squares); // [1, 4, 9, 16, 25]
     * console.log(cursor.hasNext); // false
     * ```
     */
    map<R>(callback: (currentValue: ItemType, index: number, self: this) => R): Promise<R[]>;
    /**
     * Depletes the cursor by applying the `callback` function to each item in
     * the cursor's remaining result list. Returns an array containing the
     * return values of `callback` for each item, flattened to a depth of 1.
     *
     * **Note**: If the result set spans multiple batches, any remaining batches
     * will only be fetched on demand. Depending on the cursor's TTL and the
     * processing speed, this may result in the server discarding the cursor
     * before it is fully depleted.
     *
     * See also:
     * [`Array.prototype.flatMap`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/flatMap).
     *
     * @param R - Return type of the `callback` function.
     * @param callback - Function to execute on each element.
     *
     * @example
     * ```js
     * const cursor = await db.query(aql`FOR x IN 1..5 RETURN x`);
     * const squares = await cursor.flatMap((currentValue) => {
     *   return [currentValue, currentValue ** 2];
     * });
     * console.log(squares); // [1, 1, 2, 4, 3, 9, 4, 16, 5, 25]
     * console.log(cursor.hasNext); // false
     * ```
     *
     * @example
     * ```js
     * const cursor = await db.query(aql`FOR x IN 1..5 RETURN x`);
     * const odds = await cursor.flatMap((currentValue) => {
     *   if (currentValue % 2 === 0) {
     *     return []; // empty array flattens into nothing
     *   }
     *   return currentValue; // or [currentValue]
     * });
     * console.logs(odds); // [1, 3, 5]
     * ```
     */
    flatMap<R>(callback: (currentValue: ItemType, index: number, self: this) => R | R[]): Promise<R[]>;
    /**
     * Depletes the cursor by applying the `reducer` function to each item in
     * the cursor's remaining result list. Returns the return value of `reducer`
     * for the last item.
     *
     * **Note**: Most complex uses of the `reduce` method can be replaced with
     * simpler code using {@link Cursor#forEach} or the `for await` syntax.
     *
     * **Note**: If the result set spans multiple batches, any remaining batches
     * will only be fetched on demand. Depending on the cursor's TTL and the
     * processing speed, this may result in the server discarding the cursor
     * before it is fully depleted.
     *
     * See also:
     * [`Array.prototype.reduce`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce).
     *
     * @param R - Return type of the `reducer` function.
     * @param reducer - Function to execute on each element.
     * @param initialValue - Initial value of the `accumulator` value passed to
     * the `reducer` function.
     *
     * @example
     * ```js
     * function largestOfTwo(one, two) {
     *   return Math.max(one, two);
     * }
     * const cursor = await db.query(aql`FOR x IN 1..5 RETURN x`);
     * const result = await cursor.reduce(largestOfTwo, 0);
     * console.log(result); // 5
     * console.log(cursor.hasNext); // false
     * const emptyResult = await cursor.reduce(largestOfTwo, 0);
     * console.log(emptyResult); // 0
     * ```
     *
     * @example
     * ```js
     * // BAD! NEEDLESSLY COMPLEX!
     * const cursor = await db.query(aql`FOR x IN 1..5 RETURN x`);
     * const result = await cursor.reduce((accumulator, currentValue) => {
     *   if (currentValue % 2 === 0) {
     *     accumulator.even.push(...currentValue);
     *   } else {
     *     accumulator.odd.push(...currentValue);
     *   }
     *   return accumulator;
     * }, { odd: [], even: [] });
     * console.log(result); // { odd: [1, 3, 5], even: [2, 4] }
     *
     * // GOOD! MUCH SIMPLER!
     * const cursor = await db.query(aql`FOR x IN 1..5 RETURN x`);
     * const odd = [];
     * const even = [];
     * for await (const currentValue of cursor) {
     *   if (currentValue % 2 === 0) {
     *     even.push(currentValue);
     *   } else {
     *     odd.push(currentValue);
     *   }
     * }
     * console.log({ odd, even }); // { odd: [1, 3, 5], even: [2, 4] }
     * ```
     */
    reduce<R>(reducer: (accumulator: R, currentValue: ItemType, index: number, self: this) => R, initialValue: R): Promise<R>;
    /**
     * Depletes the cursor by applying the `reducer` function to each item in
     * the cursor's remaining result list. Returns the return value of `reducer`
     * for the last item.
     *
     * **Note**: If the result set spans multiple batches, any remaining batches
     * will only be fetched on demand. Depending on the cursor's TTL and the
     * processing speed, this may result in the server discarding the cursor
     * before it is fully depleted.
     *
     * See also:
     * [`Array.prototype.reduce`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce).
     *
     * @param R - Return type of the `reducer` function.
     * @param reducer - Function to execute on each element.
     *
     * @example
     * ```js
     * function largestOfTwo(one, two) {
     *   return Math.max(one, two);
     * }
     * const cursor = await db.query(aql`FOR x IN 1..5 RETURN x`);
     * const result = await cursor.reduce(largestOfTwo);
     * console.log(result); // 5
     * console.log(cursor.hasNext); // false
     * const emptyResult = await cursor.reduce(largestOfTwo);
     * console.log(emptyResult); // undefined
     * ```
     */
    reduce<R>(reducer: (accumulator: ItemType | R, currentValue: ItemType, index: number, self: this) => R): Promise<R | undefined>;
    /**
     * Kills the cursor and frees up associated database resources.
     *
     * This method has no effect if all batches have already been fetched.
     *
     * @example
     * ```js
     * const cursor1 = await db.query(aql`FOR x IN 1..5 RETURN x`);
     * console.log(cursor1.hasMore); // false
     * await cursor1.kill(); // no effect
     *
     * const cursor2 = await db.query(
     *   aql`FOR x IN 1..5 RETURN x`,
     *   { batchSize: 2 }
     * );
     * console.log(cursor2.hasMore); // true
     * await cursor2.kill(); // cursor is depleted
     * ```
     */
    kill(): Promise<void>;
}
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