Utote

Stack allocated uint multiset implementation on rust stable, with optional SIMD implementations available using rust nightly.

The SIMD implementation uses packed_simd (behind a feature flag). packed_simd was chosen over alternatives due to it's simplicity and based on the assumption that when std::simd is stabilised it will look similar in API structure to packed_simd as it is now.

The implementations in utote are built using macros rather than generics because there is no generic interface available for the SIMD types available from packed_simd. Although there are crates available that enable generic implementation of SIMD code they either lack features in comparison to packed_simd, increase the complexity of the code, or are unstable themselves. The other benefit of using macros is that the actual implementation code is straightforward.

Since multisets are essentially collections of counters + some useful methods on those counters, and to keep things simple, implementations are only provided for uint types. The current Multiset is thus quite low level, perhaps better serving as a backend for a higher level multiset that works for any given type.

Please see the docs for the API and more information!

Future Development

• Build an implementation of Multiset, for scalar and SIMD types, which uses Vec.
• Build a Multiset implementation for any T which uses the uint implementations as a backend to handle the element counters.
• Once std::simd is more fully implemented it should be possible to replace most of the macros with generic implementations. And once this feature is stabilised it will be possible to enable all the SIMD implementations on the stable toolchain.

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Acknowledgements

The implementations in this crate are inspired by generic-array, nalgebra and simba.

Changelog

0.4.0 (Breaking)

• Deprecate direct SIMD implementation
• Utilise const generics (removing generic-array & typenum)

0.3.5

• fix choose_random implementations

0.3.4

• impl Send & Sync for Multiset
• re-export typenum

0.3.3

• impl FromIterator of refs for Multisets
• re-export simd types and generic-array traits

0.3.2

• Move to manual implementations of common traits on Multiset
• Manually define type aliases

0.3.1

• Make rng generic in choose_random

0.3.0

• Made rand dependency optional
• Switched from StdRng to SmallRng