const_ranged_int

const_ranged_int is a very simple Rust crate provides ranged values that are const safe. It allows you to define values within a specific (inclusive) range. The new function will assert that the value is within range, which is optimized out by the compiler for constants. The corresponding value function uses std::hint::unreachable_unchecked() to tell the compiler that the values are within MIN..=MAX.

This crate does not use any unstable features.

This crate is not very ambitious, it is designed mostly to be used for lookup tables that have constrained values. For example, if you had a lookup table that contains the values 0..=7 and you used this value to lookup in another array, this crate would let you avoid a bounds check in the second lookup. It also allows you to put ranges into the contract of your function, and avoid range checks later on.

Important note: the range is INCLUSIVE vs the normal Rust exclusive range notation. The reason for this is that if values that are maxint are used, then it would be impossible to express maxint+1 for specifying the range.

Usage

Add this crate to your Cargo.toml:

[dependencies]
ranged_const = "0.1"

Then, in your Rust code:

use const_ranged_int::ConstRangedU8;

// single constant (panics at compile time if values are out of range)
const VALUE: ConstRangedU8<1, 10> = ConstRangedU8::<1, 10>::new(5);

// array of constants (panics at compile time if values are out of range)
const CONTARRAY: [ConstRangedU8<1, 10>; 5] =
       ConstRangedU8::<1, 10>::into_array([1, 2, 3, 4, 5]);


println!("{}", VALUE.value());