MownStr: Maybe Owned String

This crate provides MownStr, a type for storing and exchanging read-only strings that may be either borrowed or owned.

Compared to Cow<str>:

• MownStr is 2/3 smaller,
• MownStr is slightly slower to construct and deference to a str.

So using MownStr makes sense if you need to store a lot of them. Otherwise, Cow<str> may be a better option.

Note also that MownStr can not represent strings longer than usize::MAX/2. This theoretical limitation is not an issue in practice, because

• it still allows for huge string, e.g. 8EiB on a 64-bit architectures;
• it is not even clear that Rust supports strings bigger than that, as from_raw_parts limits the size of a slice to isize::MAX, not usize::MAX (despite sizes being typed as usize).

Benchmark

To run the benchmark, you need the feature criterion:

cargo bench --features criterion

Supported Rust version

This crate is tested with Rust 1.67 and with the latest stable release.