to-regex-range

Generate a compact regex that matches an integer range — (1, 99) → [1-9]|[1-9][0-9]. A faithful Rust port of the to-regex-range npm package (a micromatch building block). Zero dependencies and #![no_std].

use to_regex_range::{to_regex_range, to_regex_range_with_options, Options};

assert_eq!(to_regex_range(1, 5), "[1-5]");
assert_eq!(to_regex_range(1, 99), "(?:[1-9]|[1-9][0-9])");
assert_eq!(to_regex_range(0, 255), "(?:[0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])");
assert_eq!(to_regex_range(-10, -1), "(?:-[1-9]|-10)");

let opts = Options::default().shorthand(true);
assert_eq!(to_regex_range_with_options(1, 99, &opts), "(?:[1-9]|[1-9]\\d)");

Why to-regex-range?

Matching "a number between 1 and 255" with a regex by hand is tedious and error-prone. This builds the minimal alternation for you — splitting the range at power-of-ten boundaries and turning each sub-range into a character class with the right quantifier. The result is a regex source string; wrap it in your engine of choice (regex, fancy-regex, …).

[dependencies]
to-regex-range = "0.1"

API

Behavior

• min/max may be given in either order; equal bounds yield the literal number.
• Negative ranges are handled, sharing a -? prefix where positive and negative sub-patterns coincide.
• The output is a bare regex source — no anchors or delimiters. Add ^(?:…)$ if you need to match a whole string.
• Integer ranges only; zero-padded ranges (e.g. 001..100) are out of scope.

License

Licensed under either of Apache-2.0 or MIT at your option.