/** The lexical categories the {@link tokenize} pass emits. */
export type TokenKind = 'num' | 'str' | 'err' | 'word' | 'sheetq' | 'op' | 'eof';
/** One token: its {@link TokenKind} and the matched source text. */
export interface Token {
    readonly kind: TokenKind;
    readonly text: string;
}
/** Thrown when the source cannot be tokenized (bad character, over-long input). */
export declare class LexError extends Error {
}
/**
 * Tokenize a formula string into a flat token stream terminated by an `eof`
 * token. Whitespace separates tokens but is otherwise dropped.
 *
 * @param src The formula source.
 * @returns The token list, ending with an `eof` token.
 * @throws LexError when `src` exceeds the source cap or holds an unexpected
 *   character / bad error literal.
 */
export declare function tokenize(src: string): Array<Token>;