import { InjectionToken } from './injection-token.js';
/**
 * A unique object used for retrieving items from the `Injector`.
 *
 * Keys have:
 * - a system-wide unique `id`.
 * - a `token`.
 *
 * `DualKey` is used internally by `Injector` because its system-wide unique `id` allows
 * the injector to store created objects in a more efficient way.
 *
 * `DualKey` should not be created directly. `Injector` creates keys automatically when
 * resolving providers.
 */
export declare class DualKey {
    token: any;
    id: number;
    constructor(token: any, id: number);
}
/**
 * This class is used to automatically create an extension group, which should run before group token.
 */
export declare class BeforeToken<T = any> extends InjectionToken<T> {
}
/**
 * This class is used to automatically create a token for `@inject(token, ctx)`.
 */
export declare class ParamToken<T = any> extends InjectionToken<T> {
}
export declare class KeyRegistry {
    #private;
    /**
     * Retrieves a `DualKey` for a token.
     */
    static get(token: NonNullable<unknown>): DualKey;
    /**
     * @returns the number of keys registered in the system.
     */
    static get numberOfKeys(): number;
    /**
     * Generates a unique token for `groupToken`. This token is used to automatically
     * create an extension group, which should run before `groupToken`.
     */
    static getBeforeToken(groupToken: InjectionToken): BeforeToken;
}
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