unchecked-index 0.2.2

Unchecked indexing wrapper using regular index syntax.


Unchecked indexing through the regular index syntax.

Using a wrapper type that requires an unsafe block to create.

Note: All unchecked indexing here is actually “checked” with debug assertions when they are enabled (they are off by default in release builds). This is a feature! Debug checking does not make your code safe, but it helps finding bugs in unsafe code. Test your code responsibly.


use unchecked_index::unchecked_index;

/// unsafe because: trusts the permutation to be correct
unsafe fn apply_permutation<T>(perm: &mut [usize], v: &mut [T]) {
    debug_assert_eq!(perm.len(), v.len());
    // use unchecked (in reality, debug-checked) indexing throughout
    let mut perm = unchecked_index(perm);
    for i in 0..perm.len() {
        let mut current = i;
        while i != perm[current] {
            let next = perm[current];
            // move element from next to current
            v.swap(next, current);
            perm[current] = current;
            current = next;
        perm[current] = current;

How to contribute:

  • Fix a bug or implement a new thing
  • Include tests for your new feature
  • Make a pull request

Recent Changes

  • 0.2.2

    • The crate is now always no_std.
  • 0.2.1

    • Improve the (debug) assertion messages; fix a typo and always include the relevant quantities (start, end, length)
  • 0.2.0

    • Add support for unchecked indexing with ranges (“slicing”)
    • Add two free functions, get_unchecked and get_unchecked_mut
  • 0.1.1

    • Add Copy impl (for shared slices)
  • 0.1.0

    • Initial release