/**
 * Regex Validator - ReDoS Protection
 *
 * Validates regex patterns to prevent Regular Expression Denial of Service (ReDoS) attacks.
 * Detects dangerous patterns like nested quantifiers, excessive nesting, and other
 * complexity indicators that can cause catastrophic backtracking.
 *
 * Security Note: This is a defense-in-depth measure. Even with validation,
 * regex execution should have timeout protection (see regex-executor.ts).
 */
export interface RegexValidationOptions {
    /**
     * Maximum pattern length (default: 100 characters)
     * Longer patterns are more likely to be complex/malicious
     */
    maxLength?: number;
    /**
     * Maximum nesting depth of groups (default: 3)
     * Deep nesting can indicate complexity
     */
    maxNestingDepth?: number;
    /**
     * Allow backreferences like \1, \2 (default: false)
     * Backreferences can be slow and are rarely needed
     */
    allowBackreferences?: boolean;
    /**
     * Allow lookaheads/lookbehinds (default: false)
     * These can be slow and are often unnecessary
     */
    allowLookarounds?: boolean;
}
/**
 * Regex pattern validator with ReDoS protection
 */
export declare class RegexValidator {
    /**
     * Validate a regex pattern for safety
     *
     * @throws {SecurityError} if pattern is unsafe or too complex
     */
    static validate(pattern: string, options?: RegexValidationOptions): void;
    /**
     * Detect nested quantifiers like (a+)+, (a*)*, etc.
     * This is the PRIMARY ReDoS vulnerability pattern.
     */
    private static hasNestedQuantifiers;
    /**
     * Find other dangerous patterns
     */
    private static findDangerousPattern;
    /**
     * Calculate maximum nesting depth of parentheses/groups
     */
    private static getMaxNestingDepth;
    /**
     * Detect backreferences: \1, \2, etc.
     */
    private static hasBackreferences;
    /**
     * Detect lookarounds: (?=, ?!, ?<=, ?<!
     */
    private static hasLookarounds;
    /**
     * Quick check if pattern is obviously safe (performance optimization)
     */
    static isSafePattern(pattern: string): boolean;
}
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