/**
 * SymbolTable maintains registry of words with its types
 */
declare class SymbolTable {
    private parent?;
    private readonly registry;
    /**
     * Create new symbol table
     * @param {SymbolTable | undefined}parent parent of the symbol table
     */
    constructor(parent?: SymbolTable);
    /**
     * Register new phrase or word in symbol table
     * @param {string} phrase phrase
     * @param {Entity} entity type of the phrase
     * @throws {FcalError} if word is already registered
     */
    set(phrase: string, entity: Entity): void;
    /**
     * search symbol table whether phrase is already registered
     * @param {string} phrase phrase or word
     * @returns {Entity} entity or type of the phrase
     */
    get(phrase: string): Entity | undefined;
}
declare enum Entity {
    FUNCTION = "FUNCTION",
    VARIABLE = "VARIABLE",
    CONSTANT = "CONSTANT",
    OPERATION_PHRASE = "OPERATION PHRASE",
    NS = "NUMBER SYSTEM",
    UNIT = "UNIT",
    CONVERTER = "CONVERTER",
    SCALE = "SCALE"
}
export { Entity, SymbolTable };