Module highlight 

Syntax highlighting as runs (docs/texteditor.md §9): a tokenizer is a pure function from text to Vec<TextRun>, and TextEditor::highlight re-runs it on every edit and pushes the runs back as an attributes patch, so the caret and the undo stack stay where they are. Nothing here touches a toolkit; the same runs restyle all eight arms, and a test asserts them on the headless one.

The grammars are small on purpose: an API client’s bodies (JSON, XML, GraphQL), Day’s own samples (Rust), and the template tags Yaak-style clients write inside any of them (${[ name ]}). A full grammar engine is a dependency this crate does not want; a new language is a function below.

Structs

Palette

The colors a highlighter paints with. Every one is readable on a light and on a dark surface, which matters because the editor’s background is the platform’s and changes with the theme while the runs do not.

Enums

Language

What a text is written in.

Functions

highlight

Tokenize text into runs covering every byte: claimed tokens in their colors, the gaps between them in the palette’s base style. Byte offsets throughout, which is what the document indexes by, and why a multi-byte character in a comment cannot shift the styling of what follows it.

highlight_with_templates

highlight, then every ${[ … ]} template tag painted over whatever token it sits in.

highlighter

A closure for TextEditor::highlight: language tokens, template tags on top when templates is set.

template_tags

Paint every ${[ … ]} tag in text over runs, splitting the runs it overlaps. The tag is what a Yaak-style client renders a variable or a function call as; an unclosed ${[ is left as it was typed.