oom - One Or Many slice types

Took inspirations from the "Parse, don’t validate" article.

This package defines three types: NonEmptySlice, NonEmptyMutSlice and NonEmptyVec. Those types don't implement Deref or DerefMut trait, it is intentional to avoid confusion when resolving methods. If you want &[T], consider using as_slice or as_mut_slice methods.

NonEmptySlice and NonEmptyMutSlice:

are borrowed types (not owned type).
are counterparts of &[T] and &mut [T].
have same size and similar niche as &[T].
cannot be used without borrowing contents from array, slice or Vec.

NonEmptyVec:

is an owned types, a counterpart of Vec<T>.
doesn't have push and pop methods, because those are fallible operations.

The differences from &[T] and Vec<T>:

.len() returns std's NonZeroUsize.
.is_empty() is always false.
These methods don't return None:
- first
- first_mut
- last
- last_mut
- split_first
- split_last
- split_first_mut
- split_last_mut

Notable features

#![no_std]
no external dependencies
no macros
instant build time.

Supported Rust versions

Latest stable. I use the new conditional flows in const fn available only in Rust v1.46.0.

Usage

Add this to your Cargo.toml:

[dependencies]
oom = "0.3.0"

Or assuming you installed cargo-edit, use:

cargo add oom

Alternatives

https://github.com/Soveu/loaf

That crate uses a representation of:

#[repr(C)]
struct Loaf<T> {
    first: [T; 1],
    rest: [T],
}

and use &Loaf<T> or &mut Loaf at runtime.

Thanks for inspirations from

https://github.com/cloudhead/nonempty (MIT license)
https://github.com/yihuang/non-empty-vec (MIT license)

License

All the code in this repository is released under the MIT License, for more information read the COPYRIGHT file.

tesuji / rust-oom