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Treesitter

Treesitter⚑

treesitter it's a neovim parser generator tool and an incremental parsing library. It can build a concrete syntax tree for a source file and efficiently update the syntax tree as the source file is edited. With it you can do nice things like:

Installation⚑

Add these lines to your plugins.lua file:

  use {
    'nvim-treesitter/nvim-treesitter',
    run = function()
        local ts_update = require('nvim-treesitter.install').update({ with_sync = true })
        ts_update()
    end,
  }

Install it with :PackerInstall.

The base configuration is:

require('nvim-treesitter.configs').setup({
  ensure_installed = {
    'bash',
    'beancount',
    'dockerfile',
    'make',
    'terraform',
    'toml',
    'vue',
    'lua',
    'markdown',
    'python',
    'css',
    'html',
    'javascript',
    'json',
    'yaml',
  },
})

Select the languages you want to install from the available ones, close and reopen the vim window to install them.

To do so you need to run:

:TSInstall <language>

To update the parsers run

:TSUpdate

Usage⚑

By default it doesn't enable any feature, you need to enable them yourself.

Highlight code⚑

Enable the feature with:

require('nvim-treesitter.configs').setup({
  highlight = {
    enable = true,
  },
})

Improves the default syntax for the supported languages.

Incremental selection⚑

It lets you select pieces of your code by the function they serve. For example imagine that we have the next snippet:

def function():
  if bool is True:
    print('this is a Test')

And your cursor is in the T of the print statement. If you were to press the Enter key it will enter in visual mode selecting the Test word, if you were to press Enter key again it will increment the scope of the search, so it will select all the contents of the print statement 'this is a Test', if you press Enter again it will increase the scope.

If you went too far, you can use the Return key to reduce the scope. For these keybindings to work you need to set:

require('nvim-treesitter.configs').setup({
  incremental_selection = {
    enable = true,
    keymaps = {
      init_selection = "<cr>", -- set to `false` to disable one of the mappings
      node_incremental = "<cr>",
      node_decremental = "<bs>",
      -- scope_incremental = "grc",
    },
  },
})
Indentation⚑
require'nvim-treesitter.configs'.setup {
  indent = {
    enable = true
  }
}
Folding⚑

Tree-sitter based folding

set.foldmethod = 'expr'
set.foldexpr = 'nvim_treesitter#foldexpr()'
set.foldenable = true                   
set.foldminlines = 3

It won't fold code sections that have have less than 3 lines.

If you add files through telescope you may see an E490: No fold found error when trying to access the folds, there's an open issue that tracks this, the workaround for me was to add this snippet in the telescope configuration::

require('telescope').setup {
    defaults = {
        mappings = {
            i = {
                ["<CR>"] = function()
                    vim.cmd [[:stopinsert]]
                    vim.cmd [[call feedkeys("\<CR>")]]
                end
            }
        }
    }
}

To save the foldings when you save a file use the next snippet. Sorry but I don't know how to translate that into lua.

vim.cmd[[
  augroup remember_folds
    autocmd!
    autocmd BufWinLeave * silent! mkview
    autocmd BufWinEnter * silent! loadview
  augroup END
]]