padded-number - For numbers containing significant leading zeros

Used when "0" and "00" should be considered as distinct values. Encapsulated in an efficient PaddedNumber type with, length bounds, ordering, and arithmetic features included.

use padded_number::padded_number;

// macro creates a valid `PaddedNumber` at compile time
assert_eq!(padded_number!("001"), padded_number!("001"));
assert_ne!(padded_number!("0"), padded_number!("00"));

Length bounds

use std::str::FromStr;
use padded_number::{PaddedNumber, bound_padded_number};

let from_macro = bound_padded_number!(2, 3, "123");
let from_str = PaddedNumber::<2, 3>::from_str("123").unwrap();
assert_eq!(from_macro, from_str);

// try_new is const fn compared to `FromStr`
assert!(PaddedNumber::<2, 3>::try_new("0").is_err());
assert!(PaddedNumber::<2, 3>::try_new("0000").is_err());

Ordering

use padded_number::padded_number;

let a = padded_number!("0");
let b = padded_number!("00");
assert!(a < b);

let u = padded_number!("10");
let v = padded_number!("001");
assert!(u < v);

Addition and subtraction with u64 as right-hand-side

Zeros being their own step is required to make padded number arithmetic consistent.

use padded_number::padded_number;

assert_eq!(
  padded_number!("9") + 1,
  padded_number!("00")
);

assert_eq!(
  padded_number!("000") - 1,
  padded_number!("99")
);

Feature flags

All are disabled by default.

• macros - Enables the padded_number! and bound_padded_number! macros.
• serde - Enables serde support for PaddedNumber. Serialization is done to and from a plain string.
• phf - Implements phf::PhfHash for PaddedNumber.
• unstable-nightly - Enables methods on PaddedNumber which in turn rely on the unstable generic_const_exprs feature.