# Syntax highlighting

Language support such as tokenizing and highlighting is provided by [Tree-sitter](https://tree-sitter.github.io). Each language requires a Tree-sitter grammar to have tokenization and queries to provide additional features such as syntax highlighting.

## Grammars

To learn more about queries, see [Creating Parsers](https://tree-sitter.github.io/tree-sitter/creating-parsers).

Lapce has select few (Rust, JSON, TOML) grammars built-in for convenience. All other languages need to provide an externally loadable grammar in a form of shared library. Lapce will update all supported grammars by default on start-up.

Grammars are stored in `$LOCAL_DATA_DIR/grammars` directory. Each grammar should be named `${DLL_PREFIX}tree-sitter-${NAME}.${DLL_SUFFIX}` where `${NAME}` refers to language name and `${DLL_PREFIX}`/`${DLL_SUFFIX}` refer to OS defined constants for shared libraries (see [`DLL_PREFIX`](https://doc.rust-lang.org/std/env/consts/constant.DLL_PREFIX.html) and [`DLL_EXTENSION`](https://doc.rust-lang.org/std/env/consts/constant.DLL_EXTENSION.html)).

Grammars are loaded in order:

1. User provided grammar
2. System provider grammar
3. Built-in grammar

## Queries

To learn more about queries, see [Syntax Highlighting#Queries](https://tree-sitter.github.io/tree-sitter/syntax-highlighting#queries).

Queries are stored in `$SETTINGS_DIR/queries/$LANGUAGE`. Currently only `highlights.scm` are supported.

## Language

For Lapce to know how to deal with files, it's required to include a language definition which contains which filenames or extensions to match to language, what indent or comment type it uses and additional configuration (that depends on tree-sitter) such as code lens (unrelated to LSP code lens) or sticky headers tokens.

Languages are defined in [`lapce-core/src/language.rs`](https://github.com/lapce/lapce/blob/master/lapce-core/src/language.rs).

## Language Server Protocol

LSP providers should define `DocumentSelector` via the extension API and/or through `volt.toml` extension manifest. It can be otherwise defined through `language_id_from_path` in [`lapce-proxy/src/buffer.rs`](https://github.com/lapce/lapce/blob/master/lapce-proxy/src/buffer.rs).