/**
 * Unicode security checks for the pre-scanner.
 * Detects BiDi attacks, invisible characters, and homograph attacks.
 *
 * @module pre-scanner/checks/unicode-check
 */
import type { PreScannerConfig } from '../config';
import type { ScanState } from '../scan-state';
/**
 * BiDi (Bidirectional) override characters used in Trojan Source attacks.
 * CVE-2021-42574: "Trojan Source: Invisible Vulnerabilities"
 *
 * These characters can be used to make code appear different than it actually executes.
 */
export declare const BIDI_OVERRIDE_CHARS: {
    readonly LRE: "‪";
    readonly RLE: "‫";
    readonly PDF: "‬";
    readonly LRO: "‭";
    readonly RLO: "‮";
    readonly LRI: "⁦";
    readonly RLI: "⁧";
    readonly FSI: "⁨";
    readonly PDI: "⁩";
};
/**
 * All BiDi control characters to check for
 */
export declare const ALL_BIDI_CHARS: ("‪" | "‫" | "‬" | "‭" | "‮" | "⁦" | "⁧" | "⁨" | "⁩")[];
/**
 * Regex pattern matching any BiDi override character
 */
export declare const BIDI_PATTERN: RegExp;
/**
 * Invisible/zero-width characters that can be used in attacks
 */
export declare const INVISIBLE_CHARS: {
    readonly ZWSP: "​";
    readonly ZWNJ: "‌";
    readonly ZWJ: "‍";
    readonly WORD_JOINER: "⁠";
    readonly FEFF: "";
    readonly SHY: "­";
    readonly CGJ: "͏";
};
/**
 * All invisible characters to check for
 */
export declare const ALL_INVISIBLE_CHARS: ("​" | "‌" | "‍" | "⁠" | "" | "­" | "͏")[];
/**
 * Regex pattern matching invisible characters
 * Note: We allow ZWNJ and ZWJ in some contexts for legitimate use
 * Using unicode escapes for security-relevant invisible character detection
 */
export declare const INVISIBLE_PATTERN: RegExp;
/**
 * Check for BiDi override characters (Trojan Source attacks).
 *
 * These characters can make code appear visually different from what executes.
 * For example, RLO (Right-to-Left Override) can make "abc" display as "cba"
 * while still executing as "abc".
 *
 * @param source - The source code to check
 * @param config - Pre-scanner configuration
 * @param state - Scan state for recording issues
 */
export declare function checkBidiPatterns(source: string, config: PreScannerConfig, state: ScanState): void;
/**
 * Check for invisible/zero-width characters.
 *
 * These characters can be used to:
 * - Create visually identical but different identifiers
 * - Hide malicious code within seemingly normal code
 * - Bypass security checks that match on visible text
 *
 * @param source - The source code to check
 * @param config - Pre-scanner configuration
 * @param state - Scan state for recording issues
 */
export declare function checkInvisibleChars(source: string, config: PreScannerConfig, state: ScanState): void;
/**
 * Check for homograph attacks using confusable characters.
 * This is a basic check for common confusables in identifiers.
 *
 * @param source - The source code to check
 * @param config - Pre-scanner configuration
 * @param state - Scan state for recording issues
 */
export declare function checkHomographs(source: string, config: PreScannerConfig, state: ScanState): void;
/**
 * Perform all Unicode security checks.
 *
 * @param source - The source code to check
 * @param config - Pre-scanner configuration
 * @param state - Scan state for recording issues
 */
export declare function performUnicodeChecks(source: string, config: PreScannerConfig, state: ScanState): void;