Module validators 

Built-in field validator constructors (required / length / email / range / regex / one-of).

Each function returns a closure suitable for FormField::validate or Validator::new. All matchers are handwritten — there is no regex or email-parsing dependency.

Functions

email

Accept a plausibly-formed email address.

max_len

Require at most n characters (counted as Unicode scalar values).

min_len

Require at least n characters (counted as Unicode scalar values).

one_of

Require the input to be one of the allowed values (exact, case-sensitive).

range_f64

Parse the input as an f64 and require it to fall within lo..=hi.

range_i64

Parse the input as an i64 and require it to fall within lo..=hi.

regex

Match the input against a minimal glob-style pattern.

required

Reject empty or whitespace-only input.