import { Event } from '../../../util/vs/base/common/event';
/**
 * An event describing the change in treatments.
 */
export interface TreatmentsChangeEvent {
    /**
     * List of changed treatments
     */
    affectedTreatmentVariables: string[];
}
/**
 * Experimentation service provides A/B experimentation functionality.
 * Currently it's per design to be able to only allow querying one flight at the time.
 * This is in order for us to control events and telemetry whenever these methods are called.
 */
export interface IExperimentationService {
    readonly _serviceBrand: undefined;
    /**
     * Emitted whenever a treatment values have changes based on user account information or refresh.
     */
    onDidTreatmentsChange: Event<TreatmentsChangeEvent>;
    /**
     * Promise that resolves when the experimentation service has completed
     * its first request to the Treatment Assignment Service. If this request
     * is successful, flights are up-to-date. Flights can change when the user
     * changes their account.
     */
    hasTreatments(): Promise<void>;
    /**
     * Returns the value of the treatment variable, or undefined if not found.
     * It uses the values currently in memory, so the experimentation service
     * must be initialized before calling.
     * @param name name of the treatment variable.
     */
    getTreatmentVariable<T extends boolean | number | string>(name: string): T | undefined;
    /**
     * Sets the filters for the completions experiments.
     * @param filters Map of filter names to their values.
     * @deprecated This will be removed once we have fully migrated to the new completions implementation.
     */
    setCompletionsFilters(filters: Map<string, string>): void;
}
export declare const IExperimentationService: import("../../../util/common/services").ServiceIdentifier<IExperimentationService>;
export declare class NullExperimentationService implements IExperimentationService {
    readonly _serviceBrand: undefined;
    private readonly _onDidTreatmentsChange;
    readonly onDidTreatmentsChange: Event<TreatmentsChangeEvent>;
    hasTreatments(): Promise<void>;
    hasAccountBasedTreatments(): Promise<void>;
    getTreatmentVariable<T extends boolean | number | string>(_name: string): T | undefined;
    setCompletionsFilters(filters: Map<string, string>): Promise<void>;
}
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