/**
 * @module icu
 * ICU message format support for internationalization.
 * Provides pluralization, select, and value interpolation.
 *
 * @example
 * // Simple interpolation
 * formatICU('Hello, {name}!', { name: 'World' });
 * // Returns: 'Hello, World!'
 *
 * @example
 * // Pluralization
 * formatICU('{count, plural, one {# item} other {# items}}', { count: 5 });
 * // Returns: '5 items'
 *
 * @example
 * // Select
 * formatICU('{gender, select, male {He} female {She} other {They}}', { gender: 'female' });
 * // Returns: 'She'
 */
/**
 * Function type for message formatters.
 * Implement this to provide custom message formatting.
 */
export type MessageFormatter = (message: string, values?: Record<string, any>, locale?: string) => string;
/**
 * Default ICU message formatter implementation.
 * Supports simple interpolation, pluralization with exact matches, and select.
 *
 * @param message - ICU format message string
 * @param values - Values to interpolate
 * @param locale - Locale for plural rules (default: 'en')
 * @returns Formatted message string
 *
 * @example
 * defaultFormatICU('{n, plural, =0 {none} one {# item} other {# items}}', { n: 0 }, 'en');
 * // Returns: 'none'
 *
 * @example
 * defaultFormatICU('{role, select, admin {Full access} other {Limited access}}', { role: 'admin' });
 * // Returns: 'Full access'
 */
export declare function defaultFormatICU(message: string, values: Record<string, any>, locale?: string): string;
/**
 * The active message formatter. Defaults to `defaultFormatICU`.
 * Can be replaced with `setMessageFormatter` for custom formatting.
 */
export declare let formatICU: MessageFormatter;
/**
 * Replaces the default message formatter with a custom implementation.
 * Use this to integrate with external i18n libraries like FormatJS.
 *
 * @param formatter - The custom formatter function
 *
 * @example
 * // Use FormatJS IntlMessageFormat
 * import { IntlMessageFormat } from 'intl-messageformat';
 *
 * setMessageFormatter((message, values, locale) => {
 *     const fmt = new IntlMessageFormat(message, locale);
 *     return fmt.format(values);
 * });
 */
export declare function setMessageFormatter(formatter: MessageFormatter): void;