tree-sitter/highlight/README.md
Douglas Creager 234bd79591 Update tree-sitter-{highlight,tags} READMEs
We now have an easier way to get at the language-specific configuration
in Rust, since we publish each language grammar as a crate with useful
accessor functions and globals.
2021-03-31 09:56:24 -04:00

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# `tree-sitter-highlight`
[![Build Status](https://travis-ci.org/tree-sitter/tree-sitter.svg?branch=master)](https://travis-ci.org/tree-sitter/tree-sitter)
[![Build status](https://ci.appveyor.com/api/projects/status/vtmbd6i92e97l55w/branch/master?svg=true)](https://ci.appveyor.com/project/maxbrunsfeld/tree-sitter/branch/master)
[![Crates.io](https://img.shields.io/crates/v/tree-sitter-highlight.svg)](https://crates.io/crates/tree-sitter-highlight)
### Usage
Add this crate, and the language-specific crates for whichever languages you want to parse, to your `Cargo.toml`:
```toml
[dependencies]
tree-sitter-highlight = "0.19"
tree-sitter-html = "0.19"
tree-sitter-javascript = "0.19"
```
Define the list of highlight names that you will recognize:
```rust
let highlight_names : Vec<String> = [
"attribute",
"constant",
"function.builtin",
"function",
"keyword",
"operator",
"property",
"punctuation",
"punctuation.bracket",
"punctuation.delimiter",
"string",
"string.special",
"tag",
"type",
"type.builtin",
"variable",
"variable.builtin",
"variable.parameter",
]
.iter()
.cloned()
.map(String::from)
.collect();
```
Create a highlighter. You need one of these for each thread that you're using for syntax highlighting:
```rust
use tree_sitter_highlight::Highlighter;
let highlighter = Highlighter::new();
```
Load some highlighting queries from the `queries` directory of some language repositories:
```rust
use tree_sitter_highlight::HighlightConfiguration;
let html_language = unsafe { tree_sitter_html() };
let javascript_language = unsafe { tree_sitter_javascript() };
let html_config = HighlightConfiguration::new(
tree_sitter_html::language(),
tree_sitter_html::HIGHLIGHTS_QUERY,
tree_sitter_html::INJECTIONS_QUERY,
"",
).unwrap();
let javascript_config = HighlightConfiguration::new(
tree_sitter_javascript::language(),
tree_sitter_javascript::HIGHLIGHTS_QUERY,
tree_sitter_javascript::INJECTIONS_QUERY,
tree_sitter_javascript::LCOALS_QUERY,
).unwrap();
```
Configure the recognized names:
```rust
javascript_config.configure(&highlight_names);
```
Highlight some code:
```rust
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 of a `script` tag within HTML).