4 releases

0.0.4 Oct 1, 2022
0.0.3 Aug 8, 2022
0.0.2 Feb 15, 2021
0.0.1 Feb 15, 2021

#277 in Text processing

MIT license

1.5K SLoC


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Crate API API trunk

Implements Unicode case mapping for conventionally UTF-8 binary strings.

Case mapping or case conversion is a process whereby strings are converted to a particular form—uppercase, lowercase, or titlecase—possibly for display to the user.

roe can convert conventionally UTF-8 binary strings to capitalized, lowercase, and uppercase forms. This crate is used to implement String#capitalize, Symbol#capitalize, String#downcase, Symbol#downcase, String#upcase, and Symbol#upcase in Artichoke Ruby.

This crate depends on bstr.


This crate is currently a work in progress. When the API is complete, Roe will support lowercase, uppercase, titlecase, and case folding iterators for conventionally UTF-8 byte slices.

Roe will implement support for full, Turkic, ASCII, and case folding transforms.


Add this to your Cargo.toml:

roe = "0.0.4"

Then convert case like:

use roe::{LowercaseMode, UppercaseMode};

    roe::lowercase(b"Artichoke Ruby", LowercaseMode::Ascii).collect::<Vec<_>>(),
    b"artichoke ruby"
    roe::uppercase("Αύριο".as_bytes(), UppercaseMode::Full).collect::<Vec<_>>(),

Crate Features

roe is no_std compatible with an optional dependency on the alloc crate.

roe has several Cargo features, all of which are enabled by default:

  • std - Adds a dependency on std, the Rust Standard Library. This feature enables std::error::Error implementations on error types in this crate. Enabling the std feature also enables the alloc feature.
  • alloc - Adds a dependency on alloc, the Rust allocation and collections library. This feature enables APIs that allocate String or Vec.


roe is licensed under the MIT License (c) Ryan Lopopolo.