Tree-sitter Neovim Config Cheatsheet

treesitter is a parser for programming and scripting languages. Tree-sitter helps with syntax highlighting, code formatting and for looking up code function definitions right from your code editor.

What Does a Tree-sitter Parser Do?

1. Syntax Highlighting

Traditional syntax highlighting relies on regex-based matching, which can sometimes be slow or inaccurate. Tree-sitter parsers create a structured tree of the code, which allows Neovim to highlight syntax more accurately, even in complex or nested structures.

1. Code Folding

By understanding the syntax tree, Tree-sitter enables smarter code folding. It knows where logical blocks of code start and end (like functions, loops, or templates).

1. Code Navigation

Tree-sitter parsers allow features like jumping to function definitions, finding usages, or moving through the structure of a file based on its syntax.

1. Error Detection

Tree-sitter can help detect syntax errors in real-time, as it builds a detailed understanding of the language’s structure.

1. Language Awareness for Linting and Refactoring

The syntax tree helps plugins and tools provide advanced features like linting, auto-formatting, and refactoring (e.g., renaming variables).

1. Multi-Language Support

Tree-sitter parsers can handle embedded languages (e.g., JavaScript inside HTML or Twig). This is useful for templating languages or polyglot codebases.

How Does a Tree-sitter Parser Work?

1. Lexical Analysis: The parser tokenizes the input code into meaningful chunks (like keywords, identifiers, or operators).

2. Parsing: It builds a syntax tree by analyzing the relationships between tokens based on the language’s grammar.

3. Output: The result is a syntax tree that tools like Neovim can use for features like highlighting and navigation.

Tree-sitter in Neovim

• Neovim uses Tree-sitter for modern, efficient language parsing.
• Parsers for specific languages are installed via the nvim-treesitter plugin.
• Once installed, Neovim uses the parser for advanced features like highlighting and folding.

Example Configuration

require'nvim-treesitter.configs'.setup {
    ensure_installed = { "javascript", "python", "html", "css", "twig" }, -- Install parsers
    highlight = {
        enable = true, -- Enable syntax highlighting
    },
    indent = {
        enable = true, -- Enable smart indentation
    },
}

Benefits of Tree-sitter

• Accuracy: It understands nested structures better than regex.
• Speed: Efficient and lightweight, even for large files.
• Extensibility: Easy to add custom parsers or extend features for new languages.

Downside

• Parsers need to be developed for each language, and not all languages/templates are supported by default.

Install

Add treesitter to your vim plugins

Plug 'nvim-treesitter/nvim-treesitter', {'do': ':TSUpdate'}

Install parsers

:TSInstall twig

Update all parsers

:TSUpdate all

Load the treesitter init.lua file

When vim starts, load the treesitter init file with a config of your choice

source $HOME/.config/nvim/plug-config/treesitter.lua

treesitter.lua

require'nvim-treesitter.configs'.setup {
  -- A list of parser names, or "all" (the five listed parsers should always be installed)
  ensure_installed = { "c", "lua", "vim", "vimdoc", "query" },

  -- Install parsers synchronously (only applied to `ensure_installed`)
  sync_install = false,

  -- Automatically install missing parsers when entering buffer
  -- Recommendation: set to false if you don't have `tree-sitter` CLI installed locally
  auto_install = true,

  -- List of parsers to ignore installing (for "all")
  ignore_install = { "javascript" },

  ---- If you need to change the installation directory of the parsers (see -> Advanced Setup)
  -- parser_install_dir = "/some/path/to/store/parsers", -- Remember to run vim.opt.runtimepath:append("/some/path/to/store/parsers")!

  highlight = {
    enable = true,

    -- NOTE: these are the names of the parsers and not the filetype. (for example if you want to
    -- disable highlighting for the `tex` filetype, you need to include `latex` in this list as this is
    -- the name of the parser)
    -- list of language that will be disabled
    disable = { "c", "rust" },
    -- Or use a function for more flexibility, e.g. to disable slow treesitter highlight for large files
    disable = function(lang, buf)
        local max_filesize = 100 * 1024 -- 100 KB
        local ok, stats = pcall(vim.loop.fs_stat, vim.api.nvim_buf_get_name(buf))
        if ok and stats and stats.size > max_filesize then
            return true
        end
    end,

    -- Setting this to true will run `:h syntax` and tree-sitter at the same time.
    -- Set this to `true` if you depend on 'syntax' being enabled (like for indentation).
    -- Using this option may slow down your editor, and you may see some duplicate highlights.
    -- Instead of true it can also be a list of languages
    additional_vim_regex_highlighting = false,
  },
}

Check if a parser is installed

:TSInstallInfo

Check health

:checkhealth nvim-treesitter

Ensure all your languages have all the treesitter features enabled

Fixing Language Errors

If the language features are not enabled. You can enable them all by running:

:TSUpdate javascript

Update

If you get errors everytime you open neovim try running

:TSUpdate