carbon-lang/utils/tree_sitter/README.md

Tree-sitter grammar for Carbon

Tree-sitter is currently used for syntax highlighting in supported editors.

Development

We use a non-hermetic tree-sitter invocation, so it must be installed locally. To install tree-sitter, run:

npm install -g tree-sitter-cli

Building and Testing

To build and test changes to the grammar using Bazel, provide specific flags to allow the build to access the system tree-sitter binary and environment.

bazel test //utils/tree_sitter:string_tests \
  --strategy=Genrule=local \
  --action_env=PATH \
  --action_env=HOME

• --strategy=Genrule=local: Disables sandboxing for the genrule that runs tree-sitter generate, allowing it to find the system-installed binary.
• --action_env=PATH: Passes your current PATH to the build actions, ensuring tree-sitter can be found. If tree-sitter is not in your default PATH, you can specify it explicitly, for example: --action_env=PATH=/path/to/tree-sitter/bin:$PATH.
• --action_env=HOME: Passes your HOME environment variable, which tree-sitter may need to locate its configuration or cache.

Editor Installation

Helix

1. Install tree-sitter and Nodejs.
2. Install Helix.
3. Run ./helix.sh

Emacs

TODO