Crate unicode_bidi

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Expand description

This crate implements the Unicode Bidirectional Algorithm for display of mixed right-to-left and left-to-right text. It is written in safe Rust, compatible with the current stable release.


use unicode_bidi::BidiInfo;

// This example text is defined using `concat!` because some browsers
// and text editors have trouble displaying bidi strings.
let text = concat![

// Resolve embedding levels within the text.  Pass `None` to detect the
// paragraph level automatically.
let bidi_info = BidiInfo::new(&text, None);

// This paragraph has embedding level 1 because its first strong character is RTL.
assert_eq!(bidi_info.paragraphs.len(), 1);
let para = &bidi_info.paragraphs[0];
assert_eq!(para.level.number(), 1);
assert_eq!(para.level.is_rtl(), true);

// Re-ordering is done after wrapping each paragraph into a sequence of
// lines. For this example, I'll just use a single line that spans the
// entire paragraph.
let line = para.range.clone();

let display = bidi_info.reorder_line(para, line);
assert_eq!(display, concat![


  • std: Enabled by default, but can be disabled to make unicode_bidi #![no_std] + alloc compatible.
  • hardcoded-data: Enabled by default. Includes hardcoded Unicode bidi data and more convenient APIs.
  • serde: Adds [serde::Serialize] and [serde::Deserialize] implementations to relevant types.




  • Bidi information of the text.
  • Hardcoded Bidi data that ships with the unicode-bidi crate.
  • Initial bidi information of the text.
  • Contains a reference of BidiInfo and one of its paragraphs. And it supports all operation in the Paragraph that needs also its BidiInfo such as direction.
  • Bidi information of text treated as a single paragraph.
  • Bidi information about a single paragraph
  • Iterator over (UTF-8) string slices returning (index, char_len) tuple.




  • Trait that abstracts over a text source for use by the bidi algorithms. We implement this for str (UTF-8) and for u16 (UTF-16, native-endian). (For internal unicode-bidi use; API may be unstable.) This trait is sealed and cannot be implemented for types outside this crate.


Type Aliases

  • A maximal substring of characters with the same embedding level.