import { IContextFreeGrammar, IContextFreeGrammarInput } from './types';
/**
 *
 * @param productionRuleEntries An array of tuples (production rule variable, production rule substitutions)
 * **Example**: `["A", ["a b A", "b a b"]]`
 * @param callBackFn A callback function that will be called for each production rule substitution
 * @returns A tuple ([production rule variable, production rule substitution tokens, production rule substitution index ]) if a rule was found else null
 */
export declare function findSubstitution(productionRuleEntries: [string, string[]][], callBackFn: (tokens: string[]) => boolean): [string, string[], number] | null;
/**
 *  Returns the first production rule whose `tokens.length > 2`
 * @param productionRuleEntries An array of tuples (production rule variable, production rule substitutions)
 * **Example**: `["A", ["a b A", "b a b"]]`
 * @returns A tuple ([production rule variable, production rule substitution tokens, production rule substitution index ]) if a long rule was found else null
 */
export declare function findLongSubstitution(productionRuleEntries: [string, string[]][]): [string, string[], number] | null;
/**
 * Removes all the rules that have more than 2 tokens and add them as new production rules
 * Which will result in all substitutions to have chunk length of at-most 2
 * @param cfg production rules record and variables array of cfg
 */
export declare function processLongSubstitutions(cfg: Pick<IContextFreeGrammar, 'productionRules' | 'variables'>): void;
/**
 *  Returns the first production rule whose `tokens.length === 2`
 * @param productionRuleEntries An array of tuples (production rule variable, production rule substitutions)
 * **Example**: `["A", ["a b A", "b a b"]]`
 * @returns A tuple ([production rule variable, production rule substitution tokens, production rule substitution index ]) if a substitution was found else null
 */
export declare function findSubstitutionOfLengthTwo(productionRuleEntries: Array<[string, string[]]>, variables: string[]): [string, string[], number] | null;
/**
 * Processes all substitutions of chunk length two
 * @param cfg Production rules record, variables and terminals array of cfg
 */
export declare function processSubstitutionsOfLengthTwo(cfg: Pick<IContextFreeGrammar, 'productionRules' | 'variables' | 'terminals'>): void;
/**
 * Check if a variable references itself in its production rule
 * @param rules Production rules for the variable
 * @param variable Producing variable
 */
export declare function checkForSelfReference(rules: string[], variable: string): boolean;
/**
 * Converts a cfg to cnf
 * @param cfg Input cfg to convert to cnf
 * @returns Resultant cfg converted to cnf
 */
export declare function convertToCnf(inputCfg: IContextFreeGrammarInput): IContextFreeGrammar;