import { BaseComponent } from '@microsoft/sp-component-base';
import type ExtensionContext from './ExtensionContext';
/**
 * @internal
 */
export interface IAdditionalInitParameters {
}
/**
 * The base class for all client-side extensions.
 *
 * @public
 */
export default abstract class BaseExtension<TProperties> extends BaseComponent {
    /**
     * {@inheritDoc @microsoft/sp-component-base#BaseComponent.context}
     */
    protected readonly context: ExtensionContext;
    private _initPromise;
    private _properties;
    /** @internal */
    constructor();
    /**
     * @internal
     */
    _init(context: ExtensionContext, propertiesJson: string | undefined, additionalInitParameters: IAdditionalInitParameters | undefined): Promise<void>;
    /**
     * This method can be overriden by different extension types (e.g. app customizers) to do specific initialization.
     * virtual
     * @internal
     */
    protected _initializeExtensionType(): void;
    /**
     * Extension properties is a JavaScript object that are passed in by the application that initializes the extension.
     *
     * @remarks
     * Properties can be used in the extension code to define configurable behaviors. The application has control over
     * what properties to provide to an instance of the extension, however the most common way would be to have it
     * stored on the server as JSON and pass it as is to the extension on initialization.
     *
     * @readonly
     */
    protected get properties(): TProperties;
    /**
     * This event method is called when the client-side extension is first activated on the page.
     * virtual
     */
    protected onInit(): Promise<void>;
    private _deserializeProperties;
}
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