mingo/types/lazy.d.ts

MongoDB query language for in-memory objects

import { Any, Callback } from "./types";
/**
 * A value produced by a generator
 */
export interface IteratorResult {
    readonly value?: Any;
    readonly done: boolean;
}
/**
 * Represents a stream interface that provides a method to retrieve the next item in a sequence.
 */
export interface Generator {
    next: () => IteratorResult;
}
export type Source = Generator | Callback<IteratorResult> | Iterable<Any>;
/**
 * Creates a lazy iterator from the given source.
 */
export declare function Lazy(source: Source): Iterator;
/**
 * Concatenate multiple iterators and return a new iterator.
 *
 * @param iterators The iterators to concatenate
 * @returns {Iterator} A new iterator
 */
export declare function concat(...iterators: Iterator[]): Iterator;
/**
 * A lazy collection iterator yields a single value at a time upon request.
 */
export declare class Iterator {
    #private;
    constructor(source: Source);
    /**
     * Add an iteratee to this lazy sequence
     */
    private push;
    next(): IteratorResult;
    /**
     * Transform each item in the sequence to a new value
     * @param {Function} f
     */
    map<R, T = R>(f: (o: T, n: number) => R): Iterator;
    /**
     * Select only items matching the given predicate
     * @param {Function} f
     */
    filter<T>(f: (o: T, n: number) => boolean): Iterator;
    /**
     * Take given numbe for values from sequence
     * @param {Number} n A number greater than 0
     */
    take(n: number): Iterator;
    /**
     * Drop a number of values from the sequence
     * @param {Number} n Number of items to drop greater than 0
     */
    drop(n: number): Iterator;
    /**
     * Returns a new lazy object with results of the transformation
     * The entire sequence is realized.
     *
     * @param {Callback<Source, Any[]>} f Tranform function of type (Array) => (Any)
     */
    transform(f: Callback<Source, Any[]>): Iterator;
    /**
     * Retrieves all remaining values from the lazy evaluation and returns them as an array.
     * This method processes the underlying iterator until it is exhausted, storing the results
     * in an internal buffer to ensure subsequent calls return the same data.
     */
    collect<T>(): T[];
    /**
     * Execute the callback for each value.
     * @param f The callback function.
     * @returns {Boolean} Returns false if the callback returned false to break the loop, otherwise true.
     */
    each<T>(f: Callback<T>): boolean;
    /**
     * Returns the reduction of sequence according the reducing function
     *
     * @param f The reducing function
     * @param initialValue The initial value
     */
    reduce<T>(f: Callback<T>, initialValue?: T): T;
    /**
     * Returns the number of matched items in the sequence.
     * The stream is realized and buffered for later retrieval with {@link collect}.
     */
    size(): number;
    [Symbol.iterator](): Iterator;
}