/// <reference types="node" />
import { InspectOptions } from 'util';
import { IEquatable, equals } from './Equality';
import { IFilterable } from './IFilterable';
import { IMappable } from './IMappable';
import { IChainable } from './IChainable';
import { Nullable } from './Nullable';
import { Undefinable } from './Undefinable';
import { IEqualityComparer } from './Equality';
import { IInspectable, inspect } from './IInspectable';
import { IInspector } from './IInspector';
/**
 * Error for the optional values not set
 */
export declare class OptionalValueNotSetError extends Error {
    constructor();
}
/**
 * An object to wrap a nullable in an interface to avoid null exeptions.
 *
 * @see https://docs.oracle.com/javase/8/docs/api/java/util/Optional.html
 * @see http://www.baeldung.com/java-optional
 */
export declare class Optional<T> implements IEquatable<Optional<T>>, IFilterable<T>, IMappable<T>, IChainable<T>, IInspectable {
    private readonly _value;
    private readonly _equalityComparer;
    private readonly _inspector;
    /**
     * Creates an empty instance of Optional. No value is present for this Optional.
     * @param equalityComparer An optional equality comparer for the value.
     * @param inspector An optional inspector for the value.
     */
    constructor(value?: undefined, equalityComparer?: IEqualityComparer<T>, inspector?: IInspector<T>);
    /**
     * Creates an instance of Optional describing the specified value, if defined, otherwise returns an empty Optional.
     * @param value A possibly null value.
     * @param equalityComparer An optional equality comparer for the value.
     * @param inspector An optional inspector for the value.
     */
    constructor(value: Undefinable<T>, equalityComparer?: IEqualityComparer<T>, inspector?: IInspector<T>);
    /**
     * Creates an instance of Optional with the specified present non-null and defined value.
     * @param value A non-nullable value.
     * @param equalityComparer An optional equality comparer for the value.
     * @param inspector An optional inspector for the value.
     */
    constructor(value: T, equalityComparer?: IEqualityComparer<T>, inspector?: IInspector<T>);
    /**
     * Creates an instance of Optional describing the specified value, if non-null, otherwise returns an empty Optional.
     * @param value A possibly null value.
     * @param equalityComparer An optional equality comparer for the value.
     * @param inspector An optional inspector for the value.
     */
    constructor(value: Nullable<T>, equalityComparer?: IEqualityComparer<T>, inspector?: IInspector<T>);
    constructor(value: Undefinable<Nullable<T>>, equalityComparer?: IEqualityComparer<T>, inspector?: IInspector<T>);
    [equals](other: Optional<T>): boolean;
    [inspect](options?: InspectOptions): string;
    /**
     * Check if the value is null.
     *
     * @returns True if there is a value present, otherwise false.
     */
    isPresent(): boolean;
    /**
     * If a value is present, invoke the specified callback with the value, otherwise do nothing.
     *
     * @param callback The callback to invoke.
     */
    ifPresent(callback: (value: T) => void): void;
    /**
     * If a value is present, performs the given callback with the value, otherwise performs the given empty-based callback.
     *
     * @param callback The callback to be performed, if a value is present.
     * @param emptyCallback The callback to be performed, if no value is present.
     */
    ifPresentOrElse(callback: (value: T) => void, emptyCallback: () => void): void;
    /**
     * If a value is present, returns an Optional describing the value, otherwise returns an Optional produced by the supplying function.
     *
     * @param supplier The supplying function that produces an Optional to be returned.
     * @returns An Optional describing the value of this Optional, if a value is present, otherwise an Optional produced by the supplying function.
     */
    or(supplier: () => Optional<T>): Optional<T>;
    /**
     * Return the value if not null or a default.
     *
     * @param defaultValue The default value to return.
     * @returns The value if present, otherwise return the default.
     * @description The methods orElse and orElseGet are generally preferable to this method, as they return a substitute value if the value is absent, instead of throwing an exception.
     */
    orElse(supplier: T): T;
    /**
     * Return the value if not null or a default via a callback, to allow for lazy loading.
     *
     * @param callback The callback to invoke to get the default value to return.
     * @returns The value if present, otherwise return the default.
     */
    orElseGet(callback: () => T): T;
    /**
     * Return the contained value, if present, otherwise throw an exception to be created by the provided supplier.
     *
     * @param exceptionSupplier The callback to invoke to get the error to throw.
     * @returns The value if present.
     */
    orElseThrow(exceptionSupplier: () => Error): T;
    /**
     * Return the contained value, if present, otherwise return 'undefined'.
     *
     * @returns {Undefinable<T>}
     */
    orUndefined(): Undefinable<T>;
    /**
     * Return the contained value, if present, otherwise return 'null'.
     *
     * @returns {Undefinable<T>}
     */
    orNull(): Nullable<T>;
    /**
     * If a value is present in this Optional, returns the value, otherwise throws NoSuchElementException.
     *
     * @returns {T} The value if present.
     */
    get(): T;
    filter<S extends T>(predicate: (value: T) => value is S): Optional<S>;
    filter(predicate: (value: T) => boolean): Optional<T>;
    map<U>(callbackfn: (value: T) => U, equalityComparer?: IEqualityComparer<U>): Optional<U>;
    chain<U>(callbackfn: (value: T) => Optional<U>, equalityComparer?: IEqualityComparer<U>): Optional<U>;
    chain<U>(callbackfn: (value: T) => U, equalityComparer?: IEqualityComparer<U>): Optional<U>;
    private isValuePresent;
}