Module layout 

Parsable representation of ordered glyph tokens for raster font atlases.

An OrdTokenLayout layout string is a series of Token expressions, parsed left to right. The position of a token in the layout determines its AtlasIndex in a raster font atlas. The size of the glyph is dependent on the font’s PackingMode.

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Relationship to Tokens and Sequences

Layouts, tokens, and sequences may appear similar in string form, but they represent different concepts:

• Layout: An ordered list of tokens that define the structure of a font atlas.
• Token: A set of one or more sequences that resolve to one glyph.
• Sequence: An ordered list of chars that form one valid input pattern.

Attempting to parse a layout string as a Token will fail, since a token cannot contain multiple tokens.

See the token module documentation for more information about tokens and sequences.

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Examples

Parsing a simple layout string:

use raster_font::core::OrdTokenLayout;

let layout = OrdTokenLayout::parse("abc");
let unique = layout.unique();
assert_eq!(unique.num_regions, 3);
assert_eq!(unique.sequences.len(), 3);

let mut token_iter = layout.iter_tokens();
assert_eq!(token_iter.next(), Some(&Token::from(Sequence::from('a'))));
assert_eq!(token_iter.next(), Some(&Token::from(Sequence::from('b'))));
assert_eq!(token_iter.next(), Some(&Token::from(Sequence::from('c'))));
assert_eq!(token_iter.next(), None);

Union tokens allow alternate input patterns for a single glyph slot:

use raster_font::core::OrdTokenLayout;

// One glyph slot that accepts either "Hello" or "hello", followed by a "!" slot.
let layout = OrdTokenLayout::parse("$(Hello|hello)!");
let unique = layout.unique();
assert_eq!(unique.num_regions, 1);
assert_eq!(unique.sequences.len(), 2);

let mut token_iter = layout.iter_tokens();
assert_eq!(
    token_iter.next(),
    Some(&Token::from(vec![
        Sequence::from("Hello"),
        Sequence::from("hello")
    ]))
);
assert_eq!(token_iter.next(), Some(&Token::from(Sequence::from('!'))));
assert_eq!(token_iter.next(), None);

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Serialization

OrdTokenLayout implements Serialize and Deserialize, round-tripping through its layout string representation. It also implements Display and FromStr for convenient string conversion.

Structs

OrdTokenLayout

An ordered sequence of font tokens, commonly parsed from a layout string.