/**
 * CronParser
 * Parses and validates cron expressions.
 */
import type { CronObject, CronTuple, ParsedCronExpression } from './types';
/** Parses and validates cron expressions into structured objects. */
export declare class CronParser {
  private static readonly SPLIT;
  private static instance?;
  /** Get the CronParser instance. */
  static getInstance(): CronParser;
  private constructor();
  /** Expand a special alias into its 5-field equivalent. */
  private expandAlias;
  /** Split a cron expression string into its five field tokens. */
  private splitFields;
  /** Expand a named alias (e.g. JAN) to its numeric value for the given field. */
  private resolveAlias;
  /** Parse a single field token into components. */
  private parseFieldToken;
  /** Compute and validate the full set of matching integers from parsed components. */
  private computeValues;
  /**
   * Convert a cron expression into a ordered CronTuple.
   *
   * @param expr - A standard 5-field cron string or special alias.
   * @returns A CronTuple with ordered cron fields
   * @throws Error if the expression is malformed.
   *
   * @example
   * parser.toTuple( '0 1 * * SAT,SUN' );
   */
  toTuple(expr: string): CronTuple;
  /**
   * Convert a cron expression into a structured CronObject.
   *
   * @param expr - A standard 5-field cron string or special alias.
   * @returns A CronObject containing the raw field values.
   * @throws Error if the expression is malformed.
   *
   * @example
   * parser.toObject( '0 9 * * MON' );
   */
  toObject(expr: string): CronObject;
  /**
   * Parse a cron expression into a fully validated internal representation.
   *
   * The returned object contains the parsed field definitions together with
   * pre-computed value sets for efficient schedule evaluation.
   *
   * @param expr - A standard 5-field cron string or special alias.
   * @returns A fully parsed cron expression.
   * @throws Error if the expression is malformed or contains invalid values.
   *
   * @example
   * const parsed = parser.parse( '* 9-17 * JAN,MAR MON-FRI' );
   */
  parse(expr: string): ParsedCronExpression;
  /**
   * Validate a cron expression without throwing.
   *
   * @param expr - The cron expression to validate.
   * @returns true if valid, false otherwise.
   *
   * @example
   * parser.validate( '0 9 * * MON' );  // true
   * parser.validate( '99 * * * *' );   // false
   */
  validate(expr: string): boolean;
}