Struct unicode_bidi::BidiInfo

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pub struct BidiInfo<'text> {
    pub text: &'text str,
    pub original_classes: Vec<BidiClass>,
    pub levels: Vec<Level>,
    pub paragraphs: Vec<ParagraphInfo>,
}

Expand description

Bidi information of the text.

The original_classes and levels vectors are indexed by byte offsets into the text. If a character is multiple bytes wide, then its class and level will appear multiple times in these vectors.

Fields§

§text: &'text str

The text

§original_classes: Vec<BidiClass>

The BidiClass of the character at each byte in the text.

§levels: Vec<Level>

The directional embedding level of each byte in the text.

§paragraphs: Vec<ParagraphInfo>

The boundaries and paragraph embedding level of each paragraph within the text.

TODO: Use SmallVec or similar to avoid overhead when there are only one or two paragraphs? Or just don’t include the first paragraph, which always starts at 0?

Implementations§

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impl<'text> BidiInfo<'text>

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pub fn new(text: &str, default_para_level: Option<Level>) -> BidiInfo<'_>

Split the text into paragraphs and determine the bidi embedding levels for each paragraph.

The hardcoded-data Cargo feature (enabled by default) must be enabled to use this.

TODO: In early steps, check for special cases that allow later steps to be skipped. like text that is entirely LTR. See the nsBidi class from Gecko for comparison.

TODO: Support auto-RTL base direction

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pub fn new_with_data_source<'a, D: BidiDataSource>( data_source: &D, text: &'a str, default_para_level: Option<Level> ) -> BidiInfo<'a>

Split the text into paragraphs and determine the bidi embedding levels for each paragraph, with a custom BidiDataSource for Bidi data. If you just wish to use the hardcoded Bidi data, please use BidiInfo::new() instead (enabled with tbe default hardcoded-data Cargo feature).

TODO: In early steps, check for special cases that allow later steps to be skipped. like text that is entirely LTR. See the nsBidi class from Gecko for comparison.

TODO: Support auto-RTL base direction

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pub fn reordered_levels( &self, para: &ParagraphInfo, line: Range<usize> ) -> Vec<Level>

Re-order a line based on resolved levels and return only the embedding levels, one Level per byte.

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pub fn reordered_levels_per_char( &self, para: &ParagraphInfo, line: Range<usize> ) -> Vec<Level>

Re-order a line based on resolved levels and return only the embedding levels, one Level per character.

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pub fn reorder_line( &self, para: &ParagraphInfo, line: Range<usize> ) -> Cow<'text, str>

Re-order a line based on resolved levels and return the line in display order.

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pub fn reorder_visual(levels: &[Level]) -> Vec<usize>

Reorders pre-calculated levels of a sequence of characters.

NOTE: This is a convenience method that does not use a Paragraph object. It is intended to be used when an application has determined the levels of the objects (character sequences) and just needs to have them reordered.

the index map will result in indexMap[visualIndex]==logicalIndex.

This only runs Rule L2 as it does not have information about the actual text.

Furthermore, if levels is an array that is aligned with code units, bytes within a codepoint may be reversed. You may need to fix up the map to deal with this. Alternatively, only pass in arrays where each Level is for a single code point.

# Example

use unicode_bidi::BidiInfo;
use unicode_bidi::Level;

let l0 = Level::from(0);
let l1 = Level::from(1);
let l2 = Level::from(2);

let levels = vec![l0, l0, l0, l0];
let index_map = BidiInfo::reorder_visual(&levels);
assert_eq!(levels.len(), index_map.len());
assert_eq!(index_map, [0, 1, 2, 3]);

let levels: Vec<Level> = vec![l0, l0, l0, l1, l1, l1, l2, l2];
let index_map = BidiInfo::reorder_visual(&levels);
assert_eq!(levels.len(), index_map.len());
assert_eq!(index_map, [0, 1, 2, 6, 7, 5, 4, 3]);