hipstr

Yet another string for Rust 🦀

• no copy borrow via borrowed (a const constructor) or from_static
• no alloc small strings (23 bytes on 64-bit platform)
• no copy owned slices
• zero dependency

And bytes too!

⚡ Examples

```rust use hipstr::HipStr;

let simplegreetings = HipStr::fromstatic("Hello world"); let clone = simplegreetings.clone(); // no copy

let user = "John"; let greetings = HipStr::from(format!("Hello {}", user)); let _user = greetings.slice(6..): // no copy ```

✏️ Features

• serde: provides serialization/deserialization support with serde crate
• unstable: exposes internal Backend trait that may change at any moment

☣️ Safety of hipstr

This crate uses unsafe extensively. 🤷

It exploits the 1-bit alignment niche in pointers existing on most platforms (I think all Rustc supported platforms) to distinguish the inline representation from the other representations.

To make things safer, Rust is tested thoroughly on multiple platforms, normally and with [Miri] (the MIR interpreter).

🧪 Testing

☔ Coverage

This crate has near full line coverage:

```bash cargo llvm-cov --all-features --html

or

cargo tarpaulin --all-features --out html --engine llvm ```

Check out the current coverage on [Codecov]:

🖥️ Cross-platform testing

You can easily run the test on various platforms with [cross]:

bash cross test --target mips-unknown-linux-gnu # 32-bit BE cross test --target mips64-unknown-linux-gnuabi64 # 64-bit BE cross test --target i686-unknown-linux-gnu # 32-bit LE cross test --target x86_64-unknown-linux-gnu # 64-bit LE

🔍 [Miri]

This crate runs successfully with Miri:

```bash MIRIFLAGS=-Zmiri-symbolic-alignment-check cargo +nightly miri test

for SEED in $(seq 0 10); do echo "Trying seed: $SEED" MIRIFLAGS="-Zmiri-seed=$SEED" cargo +nightly miri test || { echo "Failing seed: $SEED"; break; }; done ```

To check with different word size and endianness:

```bash

Big endian, 64-bit

cargo +nightly miri test --target mips64-unknown-linux-gnuabi64

Little endian, 32-bit

cargo +nightly miri test --target i686-unknown-linux-gnu ```

📦 Similar crates

#[non_exhaustive]

| Name | Thread-safe cheap-clone | Local cheap-clone | Inline | Cheap slice | Bytes | Cow<'a> | Comment | | ---- | ----------- | ----- | ------ | ------ | ----- | ---- | :------ | | hipstr | 🟢 | 🟢 | 🟢 | 🟢 | 🟢 | 🟢 | obviously! | arcstr | 🟢* | ❌ | ❌ | ❌* | ❌ | ❌ | *use a custom thin Arc, heavy slice (with dedicated substring type) | | flexstr | 🟢 | 🟢 | 🟢 | ❌ | ❌ | ❌ | use an Arc<str> instead of an Arc<String> (remove one level of indirection but use fat pointers) | | imstr | 🟢 | 🟢 | ❌ | 🟢 | ❌ | ❌ | | | faststr | 🟢 | ❌ | 🟢 | 🟢 | ❌ | ❌ | zero-doc with complex API | | fast-str | 🟢 | ❌ | 🟢 | 🟢 | ❌ | ❌ | inline repr is opt-in | | ecow | 🟢 | ❌ | 🟢 | ❌ | 🟢 | ❌ | on two words only 🤤, even any T | cowstr | 🟢 | ❌ | ❌ | ❌ | ❌ | ❌ | heavy slice, *contrary to its name | | compact_str | ❌ | ❌ | 🟢 | ❌ | 🟢* | ❌ | opt-in via smallvec | | inline_string | ❌ | ❌ | 🟢 | ❌ | ❌ | ❌ | | | smartstring | ❌ | ❌ | 🟢 | ❌ | ❌ | ❌ | | | smallstr | ❌ | ❌ | 🟢 | ❌ | ❌ | ❌ | | | smol_str | ❌ | ❌ | 🟢 | ❌ | ❌ | ❌ | *but only inline string, here for reference |

skipping specialized string types like tinystr (ASCII-only, bounded), or bstr, or bytestring, or...

In short, HipStr, one string type to rule them all 😉

🏎️ Performances

While speed is not the main motivator for hipstr, it seems to be doing OK on that front.

On my i7-8550U, under Arch Linux over Windows 11/WSL 2 (yeah I know 😅), the creation of a HipStr from a slice is competitive with other crates and the std:

📖 Author and licenses

For now, just me PoLazarus 👻 \ Help welcome! 🚨

MIT + Apache