unchecked-index

Unchecked indexing through the regular index syntax.

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

• crates.io: https://crates.io/crates/unchecked-index
• travis: https://travis-ci.org/bluss/unchecked-index

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.

Example

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