export enum ExternalizeErrorCode {
  /** Returned when passed a zero-length string. */
  ZERO_LENGTH_STRING = 1,
  /** Returned when passed a non-two-byte encoded string. */
  INVALID_STRING_ENCODING = 2,
  /** Returned when unable to convert a MaybeLocal to Local. */
  TO_LOCAL_FAILURE = 3,
  /** Returned when IsExternal returns false. */
  EXTERNALIZATION_FAILURE = 4,
}

/**
 * Returns the externalized string when it succeeds or an integer error code
 * otherwise.
 */
export function externalize(str: string): string | ExternalizeErrorCode;

/**
 *  Returns whether the passed string has previously been externalized.
 */
export function isExternal(str: string): boolean;

/**
 * Returns the object associated with a given external string. Returns `null`
 * if the provided argument is not an externalized string or has no associated
 * data.
 */
export function getProperties<K extends string | symbol, T>(
  str: string,
): Record<K, T> | null;

/**
 * Returns a new, non-externalized string and prepares the previous for GC.
 */
export function internalize(str: string): string;