/*! *****************************************************************************
Copyright (c) Microsoft Corporation.
Licensed under the Apache License, Version 2.0.

See LICENSE file in the project root for details.
***************************************************************************** */
/**
 * An asynchronous Stack.
 */
export declare class AsyncStack<T> {
    private _available;
    private _pending;
    /**
     * Initializes a new instance of the AsyncStack class.
     *
     * @param iterable An optional iterable of values or promises.
     */
    constructor(iterable?: Iterable<T | PromiseLike<T>>);
    /**
     * Gets the number of entries in the stack.
     * When positive, indicates the number of entries available to get.
     * When negative, indicates the number of requests waiting to be fulfilled.
     */
    get size(): number;
    /**
     * Adds a value to the top of the stack. If the stack is empty but has a pending
     * pop request, the value will be popped and the request fulfilled.
     *
     * @param value A value or promise to add to the stack.
     */
    push(value: T | PromiseLike<T>): void;
    /**
     * Removes and returns a Promise for the top value of the stack. If the stack is empty,
     * returns a Promise for the next value to be pushed on to the stack.
     */
    pop(): Promise<T>;
}