Tree-sitter Highlight

[!IMPORTANT] This crate is a fork of tree-sitter-highlight-wasm that works in a WebAssembly context.

Usage

Add this crate, and the language-specific crates for whichever languages you want to parse, to your Cargo.toml:

[dependencies]
tree-sitter-highlight-wasm = "0.25"
tree-sitter-javascript = "0.25"

Define the list of highlight names that you will recognize:

let highlight_names = [
    "attribute",
    "comment",
    "constant",
    "constant.builtin",
    "constructor",
    "embedded",
    "function",
    "function.builtin",
    "keyword",
    "module",
    "number",
    "operator",
    "property",
    "property.builtin",
    "punctuation",
    "punctuation.bracket",
    "punctuation.delimiter",
    "punctuation.special",
    "string",
    "string.special",
    "tag",
    "type",
    "type.builtin",
    "variable",
    "variable.builtin",
    "variable.parameter",
];

Create a highlighter. You need one of these for each thread that you're using for syntax highlighting:

use tree_sitter_highlight::Highlighter;

let mut highlighter = Highlighter::new();

Load some highlighting queries from the queries directory of the language repository:

use tree_sitter_highlight::HighlightConfiguration;

let javascript_language = tree_sitter_javascript::LANGUAGE;

let mut javascript_config = HighlightConfiguration::new(
    javascript_language.into(),
    "javascript",
    tree_sitter_javascript::HIGHLIGHT_QUERY,
    tree_sitter_javascript::INJECTIONS_QUERY,
    tree_sitter_javascript::LOCALS_QUERY,
).unwrap();

Configure the recognized names:

javascript_config.configure(&highlight_names);

Highlight some code:

use tree_sitter_highlight::HighlightEvent;

let highlights = highlighter.highlight(
    &javascript_config,
    b"const x = new Y();",
    None,
    |_| None
).unwrap();

for event in highlights {
    match event.unwrap() {
        HighlightEvent::Source {start, end} => {
            eprintln!("source: {start}-{end}");
        },
        HighlightEvent::HighlightStart(s) => {
            eprintln!("highlight style started: {s:?}");
        },
        HighlightEvent::HighlightEnd => {
            eprintln!("highlight style ended");
        },
    }
}

The last parameter to highlight is a language injection callback. This allows other languages to be retrieved when Tree-sitter detects an embedded document (for example, a piece of JavaScript code inside a script tag within HTML).