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    checkdigit

    Check-digit algorithms and identifier validation for MoonBit: Luhn, Verhoeff, Damm, credit cards, IBAN, IMEI

    checkdigit
    luhn
    iban
    imei
    validation
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    Version
    0.1.0
    License
    Apache-2.0
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    8 hours ago
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    #checkdigit

    Check-digit algorithms and identifier validation for MoonBit.

    license mooncakes

    checkdigit implements the three check-digit algorithms used by most real-world numbering schemes, and builds the identifier formats on top of them: payment cards (ISO/IEC 7812), IBAN bank accounts (ISO 13616), and IMEI device numbers (3GPP TS 23.003).

    fn main {
      // 7992739871 -> check digit 3
      println(luhn_check_digit("7992739871")) // Some(3)
      println(luhn_valid("79927398713"))      // true

      // Brand detection and full card check
      println(detect_brand("378282246310005")) // amex
      println(card_valid("378282246310005"))   // true

      // IBAN accepts spaces and lowercase
      println(iban_valid("gb82 west 1234 5698 7654 32")) // true
      println(iban_format("GB82WEST12345698765432"))     // Some("GB82 WEST 1234 5698 7654 32")
    }

    #What it covers

    AreaFunctions
    Luhn (mod 10)luhn_valid, luhn_check_digit
    Verhoeff (dihedral group D5)verhoeff_valid, verhoeff_check_digit
    Damm (anti-symmetric quasigroup)damm_valid, damm_check_digit
    Payment cardscard_valid, detect_brand, card_format, CardBrand
    IBANiban_valid, iban_country, iban_bban, iban_format, iban_normalize, iban_expected_length, iban_check_digits, iban_assemble
    IMEIimei_valid, imei_check_digit, imei_tac, imei_serial

    All validators are total: they take a String and return Bool, or return None when a value cannot be computed. No exceptions, no panics on bad input.

    #Algorithms

    • Luhn catches any single-digit error and most adjacent transpositions. Used by payment cards, IMEI, and many national identifiers.
    • Verhoeff catches all single-digit errors and all adjacent transpositions, using a multiplication table over the dihedral group D5.
    • Damm also catches all single-digit errors and all adjacent transpositions, but needs a single table lookup per digit instead of a position-dependent permutation.

    #Identifiers

    • Payment cards — brand detection by issuer identification number, then the length rules for that brand, then Luhn. Brands: Visa, Mastercard, American Express, Discover, JCB, Diners Club, UnionPay, Maestro. Overlapping issuer ranges are resolved by testing the most specific range first (Discover's 622126–622925 sits inside UnionPay's 62).
    • IBAN — country code, registered length for that country (75 countries), then the mod-97-10 check. Input is normalised, so spaces and lowercase are accepted. Bank account numbers can also be generated: iban_check_digits computes the two check digits for a country code plus BBAN, and iban_assemble returns the complete IBAN.
    • IMEI — 15 digits with a Luhn check digit, plus TAC (first 8 digits) and serial number (digits 9–14) extraction.

    #Installation

    moon add sssssurf/checkdigit

    #Command line

    The repository also ships a small CLI for trying the validators out:

    moon run cmd/main -- card 378282246310005
moon run cmd/main -- iban "gb82 west 1234 5698 7654 32"
moon run cmd/main -- imei 490154203237518
moon run cmd/main -- luhn 7992739871
moon run cmd/main -- verhoeff 236
moon run cmd/main -- damm 572

    $ moon run cmd/main -- imei 490154203237518
imei: 490154203237518
tac: 49015420
serial: 323751
check digit: 8
status: valid

    #与现有库的关系（互补边界）

    生态里已经有一批通用校验 / schema 库，它们与本库处理的层次不同，因此是互补而非重叠：

    已有库它解决的问题与本库的边界
    Betterlol/moon_zod、cosgammmmma/moonschema、mizchi/jsonschemaJSON / 数据结构的 schema 校验：字段类型、必填、email / uuid / url 等格式约束它们校验数据的形状与格式，不做任何算术校验位运算。本库只做数字标识符的校验位算法，不解析 JSON，也不定义 schema。
    ryota0624/moovalid通用校验组合子（Validated、错误累积、in_range 等）它提供校验框架；本库提供具体领域算法。本库不提供错误累积或组合子 API。
    ZJH-666-ZJH/moonmrzICAO 9303 机读区（护照 / 签证 MRZ）的 7-3-1 校验位唯一的交集是"校验位"这个概念。它面向旅行证件 MRZ 文本，使用 ICAO 9303 的 7-3-1 加权方案；本库面向支付卡 / 银行账号 / 设备号，使用 Luhn、Verhoeff、Damm 与 mod-97。两者的算法、输入格式、应用领域均不同。

    在 mooncakes.io 上以 luhn、iban、imei 检索，目前没有任何模块命中；本库填补的是这一块空白。

    #Testing

    moon test

    29 tests cover the three algorithms against published reference vectors, the issuer-range overlap boundaries, IBAN's published examples, and malformed input.

    #References

    • ISO/IEC 7812 — Identification cards, issuer identification numbers
    • ISO 13616 — International Bank Account Number (IBAN), mod-97-10
    • 3GPP TS 23.003 — Numbering, addressing and identification (IMEI)
    • H. P. Damm, Totally anti-symmetric quasigroups for all orders n ≠ 2 mod 4
    • J. Verhoeff, Error detecting decimal codes

    #License

    Apache-2.0. See LICENSE.

    CardBrand

    source
    pub enum CardBrand {
      Visa
      Mastercard
      Amex
      Discover
      Jcb
      DinersClub
      UnionPay
      Maestro
      Unknown
    }

    Recognised card networks. Unknown means no issuer range matched.
    impl Show for CardBrand

    card_format

    source
    fn card_format(s : String) -> String?

    Group the digits into blocks of four for display, e.g. "3782 8224 6310 005". Returns None unless every character is a digit.

    card_valid

    source
    fn card_valid(s : String) -> Bool

    Full card check: a known brand, a valid length for that brand, and a correct Luhn check digit.

    damm_check_digit

    source
    fn damm_check_digit(payload : String) -> Int?

    Compute the Damm check digit that should be appended to payload.

    damm_valid

    source
    fn damm_valid(s : String) -> Bool

    Validate a number that already carries its Damm check digit.

    detect_brand

    source
    fn detect_brand(s : String) -> CardBrand

    Identify the card network from its issuer range. The most specific ranges are tested first (Discover's 622126-622925 range overlaps UnionPay's 62).

    iban_assemble

    source
    fn iban_assemble(country : String, bban : String) -> String?

    Assemble a complete IBAN from a country code and a BBAN. The result is always check-digit correct; it is not checked against any national BBAN format, only against the ISO 13616 length and check digits.

    iban_bban

    source
    fn iban_bban(s : String) -> String?

    The country part of an IBAN: everything after the four-character header.

    iban_check_digits

    source
    fn iban_check_digits(country : String, bban : String) -> String?

    Compute the two check digits that turn a country code and BBAN into a complete IBAN. For example iban_check_digits("GB", "WEST12345698765432") gives "82". The country must be registered and the total length must match the registered length for that country.

    iban_country

    source
    fn iban_country(s : String) -> String?

    The two-letter country code of an IBAN, or None when it is malformed.

    iban_expected_length

    source
    fn iban_expected_length(cc : String) -> Int?

    The registered IBAN length for a country code, or None if unrecognised.

    iban_format

    source
    fn iban_format(s : String) -> String?

    Group a valid IBAN into blocks of four for display, e.g. "GB82 WEST 1234 5698 7654 32". Returns None when the input is not valid.

    iban_normalize

    source
    fn iban_normalize(s : String) -> String

    Strip spaces and uppercase so a human-formatted IBAN can be checked. Only ASCII letters and digits survive.

    iban_valid

    source
    fn iban_valid(s : String) -> Bool

    Validate an IBAN, ignoring spaces and case. Checks the country code, the registered length for that country, and the mod-97 check digits.

    imei_check_digit

    source
    fn imei_check_digit(first14 : String) -> Int?

    Compute the check digit for the first 14 digits of an IMEI.

    imei_serial

    source
    fn imei_serial(s : String) -> String?

    The 6-digit serial number: digits 9 through 14 of an IMEI.

    imei_tac

    source
    fn imei_tac(s : String) -> String?

    The Type Allocation Code: the first 8 digits of an IMEI.

    imei_valid

    source
    fn imei_valid(s : String) -> Bool

    Validate a complete 15-digit IMEI, including its Luhn check digit.

    luhn_check_digit

    source
    fn luhn_check_digit(payload : String) -> Int?

    Compute the Luhn check digit that should be appended to payload.

    luhn_valid

    source
    fn luhn_valid(s : String) -> Bool

    Validate a number that already carries its Luhn check digit.

    verhoeff_check_digit

    source
    fn verhoeff_check_digit(payload : String) -> Int?

    Compute the Verhoeff check digit that should be appended to payload.

    verhoeff_valid

    source
    fn verhoeff_valid(s : String) -> Bool

    Validate a number that already carries its Verhoeff check digit.

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