import { DisposableStore } from '../../../base/common/lifecycle';
import { IReader, IObservable, BaseObservable, IObserver, IChangeContext, DebugNameFn } from '../../../base/common/observableInternal/base';
export type EqualityComparer<T> = (a: T, b: T) => boolean;
/**
 * Creates an observable that is derived from other observables.
 */
export declare function derived<T>(computeFn: (reader: IReader) => T): IObservable<T>;
export declare function derived<T>(owner: object, computeFn: (reader: IReader) => T): IObservable<T>;
export declare function derivedOpts<T>(options: {
    owner?: object;
    debugName?: string | (() => string | undefined);
    equalityComparer?: EqualityComparer<T>;
}, computeFn: (reader: IReader) => T): IObservable<T>;
export declare function derivedHandleChanges<T, TChangeSummary>(options: {
    owner?: object;
    debugName?: string | (() => string);
    createEmptyChangeSummary: () => TChangeSummary;
    handleChange: (context: IChangeContext, changeSummary: TChangeSummary) => boolean;
    equalityComparer?: EqualityComparer<T>;
}, computeFn: (reader: IReader, changeSummary: TChangeSummary) => T): IObservable<T>;
export declare function derivedWithStore<T>(computeFn: (reader: IReader, store: DisposableStore) => T): IObservable<T>;
export declare function derivedWithStore<T>(owner: object, computeFn: (reader: IReader, store: DisposableStore) => T): IObservable<T>;
export declare class Derived<T, TChangeSummary = any> extends BaseObservable<T, void> implements IReader, IObserver {
    private readonly _owner;
    private readonly _debugName;
    readonly _computeFn: (reader: IReader, changeSummary: TChangeSummary) => T;
    private readonly createChangeSummary;
    private readonly _handleChange;
    private readonly _handleLastObserverRemoved;
    private readonly _equalityComparator;
    private state;
    private value;
    private updateCount;
    private dependencies;
    private dependenciesToBeRemoved;
    private changeSummary;
    get debugName(): string;
    constructor(_owner: object | undefined, _debugName: DebugNameFn | undefined, _computeFn: (reader: IReader, changeSummary: TChangeSummary) => T, createChangeSummary: (() => TChangeSummary) | undefined, _handleChange: ((context: IChangeContext, summary: TChangeSummary) => boolean) | undefined, _handleLastObserverRemoved: (() => void) | undefined, _equalityComparator: EqualityComparer<T>);
    protected onLastObserverRemoved(): void;
    get(): T;
    private _recomputeIfNeeded;
    toString(): string;
    beginUpdate<T>(_observable: IObservable<T>): void;
    endUpdate<T>(_observable: IObservable<T>): void;
    handlePossibleChange<T>(observable: IObservable<T, unknown>): void;
    handleChange<T, TChange>(observable: IObservable<T, TChange>, change: TChange): void;
    readObservable<T>(observable: IObservable<T>): T;
    addObserver(observer: IObserver): void;
    removeObserver(observer: IObserver): void;
}