/**
 * A formatter receives the raw `data` value, parsed options from the
 * placeholder, and the resolved locale, and returns the substituted string.
 * Register one via `Ilingo.registerFormatter(name, fn)` or the
 * `Options.formatters` constructor option; the built-ins are `number`,
 * `date`, and `list`.
 */
export type Formatter = (value: unknown, options: Record<string, unknown>, locale: string) => string;
export type FormatterOptions = Record<string, unknown>;
/**
 * Parse the options-string segment of a template modifier.
 *
 * `currency=EUR, style=currency, minimumFractionDigits=2`
 *   → `{ currency: 'EUR', style: 'currency', minimumFractionDigits: 2 }`
 *
 * Numbers and booleans are auto-coerced; everything else stays a string.
 */
export declare function parseFormatterOptions(input: string | undefined): FormatterOptions;
export declare function parseModifier(input: string): {
    name: string;
    options: string | undefined;
} | undefined;
/**
 * Per-instance formatter registry. Caches `Intl.*Format` instances keyed by
 * `(formatter, locale, JSON-encoded options)` so repeated template renders
 * don't reallocate.
 */
export declare class FormatterRegistry {
    protected entries: Map<string, Formatter>;
    protected cache: Map<string, Intl.NumberFormat | Intl.DateTimeFormat | Intl.ListFormat>;
    constructor();
    register(name: string, formatter: Formatter): void;
    get(name: string): Formatter | undefined;
    has(name: string): boolean;
    /**
     * Look up or construct the `Intl.*Format` instance for `(kind, locale,
     * options)`. Returns `undefined` if either the cache-key generation or
     * the constructor throws — built-in formatters then fall back to a plain
     * `String(value)` rendering rather than letting a typo in a translator's
     * options crash the entire render.
     *
     * Options are stringified with sorted keys so callers that happen to pass
     * the same logical options in a different order share a cache entry.
     */
    protected intl<T extends Intl.NumberFormat | Intl.DateTimeFormat | Intl.ListFormat>(kind: string, locale: string, options: FormatterOptions, create: () => T): T | undefined;
}