_passes_luhn() — langchain Function Reference

Architecture documentation for the _passes_luhn() function in _redaction.py from the langchain codebase.

Function python LangChainCore Runnables called by 1

Entity Profile

LangChainCore→ Runnables→ _passes_luhn() — langchain Function Reference

Dependency Diagram

graph TD
  2b14d9ef_16cf_fd2a_5e5f_1d51c05d3294["_passes_luhn()"]
  be639235_9a02_cc2d_5a7d_637d822fb3b3["_redaction.py"]
  2b14d9ef_16cf_fd2a_5e5f_1d51c05d3294 -->|defined in| be639235_9a02_cc2d_5a7d_637d822fb3b3
  8ccbd42d_daf9_c9d1_b6b8_ad43da8f7d49["detect_credit_card()"]
  8ccbd42d_daf9_c9d1_b6b8_ad43da8f7d49 -->|calls| 2b14d9ef_16cf_fd2a_5e5f_1d51c05d3294
  style 2b14d9ef_16cf_fd2a_5e5f_1d51c05d3294 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/langchain_v1/langchain/agents/middleware/_redaction.py lines 222–236

def _passes_luhn(card_number: str) -> bool:
    """Validate credit card number using the Luhn checksum."""
    digits = [int(d) for d in card_number if d.isdigit()]
    if not _CARD_NUMBER_MIN_DIGITS <= len(digits) <= _CARD_NUMBER_MAX_DIGITS:
        return False

    checksum = 0
    for index, digit in enumerate(reversed(digits)):
        value = digit
        if index % 2 == 1:
            value *= 2
            if value > 9:  # noqa: PLR2004
                value -= 9
        checksum += value
    return checksum % 10 == 0