/**
 * Transformation applied to the extracted usernames.
 * @typedef {'lowercase' | 'uppercase' | ((username: string) => string) | null} UsernameTransform
 */
export type UsernameTransform = 'lowercase' | 'uppercase' | ((username: string) => string) | null;
export type UsernameRegexOptions = {
    /**
     * The allowed characters for the username part.
     */
    validValues?: string;
    /**
     * The [min, max] length of the username part.
     */
    length?: [number, number];
    /**
     * A regex pattern defining the required characters at the start of the username.
     */
    start?: string;
    /**
     * A regex pattern defining the required characters at the end of the username.
     */
    end?: string;
    /**
     * An optional prefix like '@' or '#'.
     */
    prefix?: string;
    /**
     * A literal domain string (e.g., '@matrix.org'). Will be escaped automatically.
     */
    domain?: string;
    /**
     * A regex pattern for a domain (e.g., '@[a-z0-9.-]+\\.[a-z]{2,}').
     */
    domainPattern?: string;
    /**
     * Optional transformation applied to the extracted usernames.
     */
    transform?: UsernameTransform;
};
export type UsernameOptionsInput = UsernameRegexOptions | UsernameRegexOptions[];
/**
 * Builds the core part of a username regular expression based on character rules and length.
 * @param {UsernameRegexOptions} [options] The options for the core pattern.
 * @returns {string} The regex string for the core username part.
 */
export declare const usernameStringRegexBuilder: ({ validValues, length, }?: UsernameRegexOptions) => string;
/**
 * Constructs a complete regular expression for matching a username.
 * @param {UsernameOptionsInput} [options] The options for constructing the regex.
 * @returns {RegExp} The constructed regular expression object.
 */
export declare function usernameRegex(options?: UsernameOptionsInput): RegExp;
/**
 * Validates whether a string matches the specified username pattern.
 * @param {string} s The input string to validate.
 * @param {UsernameOptionsInput} [options] The regex construction options.
 * @param {RegExp} [regex] - The regex used to execute the function.
 * @returns {boolean} True if the string is a valid username, false otherwise.
 * @throws {TypeError} If the input is not a string.
 */
export declare function isValidUsername(s: string, options?: UsernameOptionsInput, regex?: RegExp): boolean;
/**
 * Generates a global regular expression to find usernames within a text.
 * @param {UsernameOptionsInput} [options] The options for the regex.
 * @returns {RegExp} The global regular expression for finding usernames.
 */
export declare function findUsernameRegex(options?: UsernameOptionsInput): RegExp;
/**
 * Extracts usernames from a text and applies optional transformations.
 * @param {string} text The text to search through.
 * @param {UsernameOptionsInput} [options] The options for extraction.
 * @param {RegExp} [regex] - The regex used to execute the function.
 * @returns {string[]} An array of extracted and transformed usernames.
 * @throws {TypeError} If the input text is not a string.
 */
export declare function extractUsernames(text: string, options?: UsernameOptionsInput, regex?: RegExp): string[];
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