tree-sitter-ohm

🌳 Tree-sitter grammar for the Ohm domain-specific language. Quickly build parsers, interpreters, and compilers for programming languages with Ohm's parsing toolkit!

🎨 Structure

Grammar definition resides in grammar.js:

• Actual grammar and bindings are generated from it via Tree-sitter.
• Queries and tests rely on its namings of nodes and fields.

Generic queries are structured as follows:

queries/
|-- highlights.scm -- syntax highlighting queries (generic, for Tree-sitter & GitHub)
|-- locals.scm -- fixed set of capture names to track local scopes and variables (and alike)
|-- injections.scm -- specification for embedded syntaxes (mainly used for TODO/FIXME highlighting in comments)
`-- tags.scm -- tagging queries for code navigation systems (as used on GitHub)

To find highlighting and other queries for specific editors, look in the editor_queries/ directory.

🚀 Usage

Neovim

Installation assumes you're using lazy.nvim as a plugin manager:

Instructions

1. Clone the repo to any convenient place: git clone https://github.com/novusnota/tree-sitter-ohm ~/.local/git/tree-sitter-ohm (~/.local/git is exemplary, you may choose another directory)

2. Add the following (partly or as a whole) to your ~/.config/nvim/init.lua (Or ~\AppData\Local\nvim\init.lua on Windows):

For the general Tree-sitter support:

-- lazy.nvim package manager
require('lazy').setup({
  -- ...
	{
    -- Highlight, edit, and navigate code
    'nvim-treesitter/nvim-treesitter',
    build = ':TSUpdate',

    -- Optional, may be removed:
    dependencies = {
      -- adds syntax aware text-objects, select, move, swap, and peek support
      -- see: https://github.com/nvim-treesitter/nvim-treesitter-textobjects
      'nvim-treesitter/nvim-treesitter-textobjects',

      -- adds a sticky context header on top as you scroll through file contents
      -- see: https://github.com/nvim-treesitter/nvim-treesitter-context
      'nvim-treesitter/nvim-treesitter-context'
    },
  },
  -- ...
}, {})

For the tree-sitter-ohm support:

local parser_config = require "nvim-treesitter.parsers".get_parser_configs()

-- Adds tree-sitter-ohm support
parser_config.ohm = {
  install_info = {
    url = "~/.local/git/tree-sitter-ohm", -- a path to the cloned repo
    files = {"src/parser.c", "src/scanner.c"},
    branch = "main",
    generate_requires_npm = false,
    requires_generate_from_grammar = false,
  }
}

-- Adds filetype recognition for .ohm files and simple indentation rules
vim.api.nvim_create_autocmd({"BufEnter", "BufWinEnter"}, {
  pattern = "*.ohm",
  callback = function()
    vim.bo.filetype = "ohm"
    vim.bo.expandtab = true
    vim.bo.softtabstop = 2
    vim.bo.shiftwidth = 2
  end
})

3. Create a folder for queries under your Neovim runtime directory, if not exists:

• Windows: mkdir -p ~\AppData\Local\nvim\queries
• Linux, macOS, *NIX: mkdir -p ~/.config/nvim/queries

4. Symlink the editor_queries/neovim sub-directory, this will add all the queries:

• Windows: mklink /D ~\AppData\Local\nvim\queries\ohm ~\.local\git\tree-sitter-ohm\editor_queries\neovim
• Linux, macOS, *NIX: ln -s ~/.local/git/tree-sitter-ohm/editor_queries/neovim ~/.config/nvim/queries/ohm

5. Finally, run the :TSInstall ohm inside the Neovim.

6. For further configuration and customization, refer to the following repositories:

• nvim-treesitter
• nvim-treesitter-textobjects
• nvim-treesitter-context

Queries bundled (see editor_queries/neovim):

• highlights.scm — syntax highlighting
• locals.scm — used to extract keyword definitions, scopes, references, etc., but NOT used for highlighting (unlike Generic or Helix queries)
• injections.scm — highlighting of TODO, FIXME and related in single-line comments
• folds.scm — syntax folds (note, that folding has to be enabled in config in order to use those)
• indents.scm — indentation levels
• textobjects.scm — syntax aware text-objects, select, move, swap, and peek support.
• context.scm — shows sticky context on top of the editor as you scroll through file contents

Helix

Instructions

1. Clone the repo to any convenient place: git clone https://github.com/novusnota/tree-sitter-ohm ~/.local/git/tree-sitter-ohm (~/.local/git is exemplary, you may choose another directory)

2. Create a folder for queries under your Helix runtime directory, if not exists:

• Windows: mkdir -p ~\AppData\Roaming\helix\runtime\queries
• Linux, macOS, *NIX: mkdir -p ~/.config/helix/runtime/queries

3. Symlink the editor_queries/helix sub-directory, this will add all the queries:

• Windows: mklink /D ~\AppData\Roaming\helix\runtime\queries\ohm ~\.local\git\tree-sitter-ohm\editor_queries\helix
• Linux, macOS, *NIX: ln -s ~/.local/git/tree-sitter-ohm/editor_queries/helix ~/.config/helix/runtime/queries/ohm

4. Add the following to your ~/.config/helix/languages.toml (Or ~\AppData\Roaming\helix\languages.toml on Windows):

[[language]]
name = "ohm"
scope = "source.ohm"
injection-regex = "ohm"
file-types = ["ohm"]
comment-token = "//"
indent = { tab-width = 2, unit = "  " }
roots = []

[language.auto-pairs]
'"' = '"'
'{' = '}'
'(' = ')'
'<' = '>'

[[grammar]]
name = "ohm"
source = { path = "/absolute/path/to/your/home/directory/.local/git/tree-sitter-ohm" }  # TODO: replace with your full path to downloaded repo

5. Finally, run the following commands to update all Tree-sitter grammars, including ohm's:

hx --grammar fetch
hx --grammar build

Queries bundled (see editor_queries/helix):

• highlights.scm — syntax highlighting
• injections.scm — highlighting of TODO, FIXME and related in single-line comments
• indents.scm — indentation levels
• textobjects.scm — syntax aware text-objects

💲 CLI Usage

Tree-sitter grammars have limited utility on their own and are best used as parsers that can be embedded in other projects. However, tree-sitter-cli can be used with this grammar to show generated parse trees and syntax highlighting for a given ohm file.

For a quick demo of tree-sitter-cli usage:

1. Clone this repo.
2. Install Node.js dependencies (by npm i, pnpm i or yarn).
3. Execute relevant commands from the scripts tag in package.json.

For a more streamlined experience, you may:

1. Install tree-sitter-cli.
2. Create a tree-sitters directory in your home directory.
3. Clone this repository (or symlink it) into the new ~/tree-sitters/ directory.
4. Run tree-sitter parse path/to/file.ohm to be shown the parse tree for the file.
5. Run tree-sitter highlight path/to/file.ohm to be shown the file with syntax highlighting applied.

⚙ References

• ohm-grammar.ohm — Official grammar specification of Ohm PEG language, written itself in Ohm!

Useful Ohm links

• Official Website
• GitHub.com Source
• Awesome Ohm list
• VSCode extension

Credits

Examples in test/sample directory are taken from ohmjs/ohm under MIT license.

Built with 🤍 by Novus Nota

License

MIT