import { StringRuleChecker } from './string-rule-checker';
import { Base64Implementation } from './string-types';
import { GuardResult } from '../../core/guard-result';
/**
 * Base64 standard pattern:
 * - Uppercase alpha characters A-Z.
 * - Lowercase alpha characters a-z.
 * - Number characters 0–9.
 * - Characters + and /.
 * - The = character is used for padding.
 */
export declare const BASE64_STANDARD_PATTERN = "^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$";
/**
 * Base64 file name pattern:
 * - Uppercase alpha characters A-Z.
 * - Lowercase alpha characters a-z.
 * - Number characters 0–9.
 * - Characters + and -.
 * - The = character is used for padding.
 */
export declare const BASE64_FILE_NAME_PATTERN = "^(?:[A-Za-z0-9+-]{4})*(?:[A-Za-z0-9+-]{2}==|[A-Za-z0-9+-]{3}=|[A-Za-z0-9+-]{4})$";
/**
 * Base64 url pattern:
 * - Uppercase alpha characters A-Z.
 * - Lowercase alpha characters a-z.
 * - Number characters 0–9.
 * - Characters - and _.
 * - No padding.
 */
export declare const BASE64_URL_SAFE_PATTERN = "^[A-Za-z0-9-_]+$";
export declare class StringIsBase64 extends StringRuleChecker<{
    type: 'isBase64';
    impl: Base64Implementation;
}> {
    constructor(rule: {
        type: 'isBase64';
        impl: Base64Implementation;
    }, value: string);
    /**
     * @override
     */
    exec(): GuardResult;
    private isBase64Standard;
    private isBase64FileName;
    private isBase64UrlSafe;
}