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Parsing & Validation

Constructors

ConstructorAccepts
Cnpj::parse / Cnpj::newPunctuated or compact strings, any ASCII case
Cnpj::from_bytesExactly 14 pre-normalized ASCII bytes, no punctuation
FromStr / TryFrom<&str>Same as parse, for use in generic code

Cnpj::new is a plain alias for Cnpj::parse; FromStr and TryFrom<&str> both delegate to it too, so "...".parse::<Cnpj>() and Cnpj::try_from("...") behave identically to calling Cnpj::parse directly.

Cnpj::from_bytes is the lower-level constructor: it skips punctuation-stripping and case-folding and expects an already-normalized [u8; 14]. It still runs every validation rule below — it just assumes the caller has already dealt with formatting. Prefer Cnpj::parse unless you’re constructing bytes programmatically (for example, in a generator or migration script).

What Cnpj::parse accepts

  • The conventional punctuated form: AA.AAA.AAA/AAAA-DD.
  • The compact 14-character form: AAAAAAAAAAAADD.
  • Lowercase letters in the alphanumeric portion — they’re folded to uppercase automatically.
  • Extra ASCII spaces, anywhere in the string (leading, trailing, or embedded).
use ftracker_identifiers::Cnpj;

assert!(Cnpj::parse("00.000.000/0001-91").is_ok());
assert!(Cnpj::parse("00000000000191").is_ok());
assert!(Cnpj::parse(" 00.000.000/0001-91 ").is_ok());
assert!(Cnpj::parse("12abc34501de35").is_ok()); // lowercase is folded

Validation rules

The string-based constructors run the following rules, in this order:

  1. Length — after formatting is stripped, the input must contain exactly 14 meaningful characters.
  2. Character class — positions 1–12 accept a digit or an uppercase letter; positions 13–14 accept only a digit.
  3. Not degenerate — the 14 characters cannot all be identical (e.g. "00000000000000"). Such inputs are structurally well-formed, and can even satisfy the checksum for certain repeated digits, but the Receita Federal never issues them — they’re reliably placeholder or data-entry artifacts.
  4. Checksum — both verification digits must match the Módulo 11 algorithm applied to the preceding characters.

Each rule maps to exactly one CnpjError variant — see Error Handling for the full list and how to match on it.

What it doesn’t do

Cnpj::parse validates shape and checksum, not existence. It cannot tell you whether a particular CNPJ has actually been issued, is active, or belongs to the company you think it does — that requires a lookup against the Receita Federal’s own systems (or a data provider), which is out of scope for this crate.