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https://github.com/novusnota/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!
https://github.com/novusnota/tree-sitter-ohm

compilers interpreters ohm ohmjs parsers parsing-expression-grammar peg tree-sitter tree-sitter-parser

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

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# 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`](https://github.com/folke/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:



```lua

-- 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:



```lua

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](https://github.com/nvim-treesitter/nvim-treesitter)

* [nvim-treesitter-textobjects](https://github.com/nvim-treesitter/nvim-treesitter-textobjects)

* [nvim-treesitter-context](https://github.com/nvim-treesitter/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):



```toml

[[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:



```bash

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](https://github.com/tree-sitter/tree-sitter/blob/master/cli/README.md) 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](https://github.com/tree-sitter/tree-sitter/blob/master/cli/README.md#installation).

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](https://github.com/ohmjs/ohm/blob/main/packages/ohm-js/src/ohm-grammar.ohm) — Official grammar specification of Ohm PEG language, written itself in Ohm!



## Useful Ohm links



- [Official Website](https://ohmjs.org/)

- [GitHub.com Source](https://github.com/ohmjs/ohm)

- [Awesome Ohm list](https://github.com/ohmjs/awesome-ohm)

- [VSCode extension](https://github.com/novusnota/vscode-ohm)



## Credits



Examples in `test/sample` directory are taken from [ohmjs/ohm](https://github.com/ohmjs/ohm) under MIT license.



Built with 🤍 by [Novus Nota](https://github.com/novusnota)



## License



[MIT](LICENSE)