/**
 * Represents a Handlebars instance for registering and compiling templates.
 */
export interface HandlebarsInstance {
    registerHelper: (name: string, fn: (...args: unknown[]) => unknown) => void;
    unregisterHelper: (name: string) => void;
    compile: (template: string) => (data: unknown) => string;
    helpers: Record<string, unknown>;
}
export type Handlebars = HandlebarsInstance;
/**
 * Describes a filter for selecting helpers by name or category.
 */
export type HelperFilter = {
    name?: string;
    category?: string;
};
/**
 * Represents a single Handlebars helper.
 */
export type Helper = {
    name: string;
    category: string;
    fn: (...arguments_: unknown[]) => unknown;
};
/**
 * Registry for managing Handlebars helpers.
 */
export declare class HelperRegistry {
    private readonly _helpers;
    /**
     * Creates a new HelperRegistry and initializes it.
     */
    constructor();
    /**
     * Initializes the helper registry. Override to add custom initialization logic.
     */
    init(): void;
    /**
     * Registers a helper.
     * @param helper - The helper to register.
     * @returns True if the helper was registered, false if it already exists.
     */
    register(helper: Helper): boolean;
    /**
     * Registers multiple helpers.
     * @param helpers - The helpers to register.
     */
    registerHelpers(helpers: Helper[]): void;
    /**
     * Checks if a helper is registered.
     * @param name - The name of the helper.
     * @returns True if the helper is registered, false if it is not.
     */
    has(name: string): boolean;
    /**
     * Filters helpers by name and/or category.
     * @param filter - The filter to apply.
     * @returns The filtered helpers.
     */
    filter(filter: HelperFilter): Helper[];
    /**
     * Loads all registered helpers into a Handlebars instance.
     * @param handlebars - The Handlebars instance.
     */
    loadHandlebars(handlebars: HandlebarsInstance | {
        registerHelper: (name: string, fn: (...args: unknown[]) => unknown) => void;
    }): void;
    /**
     * Swaps (replaces) helpers in a Handlebars instance with the registered helpers.
     * @param handlebars - The Handlebars instance.
     */
    swapHelpers(handlebars: HandlebarsInstance): void;
}