feat: add option to auto-install missing parsers (#3130)

4 files changed, 25 insertions, 1 deletions

diff --git a/README.md b/README.md
index c8659fa9a..be070d5c4 100644
--- a/README.md
+++ b/README.md
@@ -109,6 +109,9 @@ require'nvim-treesitter.configs'.setup {
   -- Install parsers synchronously (only applied to `ensure_installed`)
   sync_install = false,
 
+  -- Automatically install missing parsers when entering buffer
+  auto_install = true,
+
   -- List of parsers to ignore installing (for "all")
   ignore_install = { "javascript" },
 
@@ -381,7 +384,7 @@ This directory must be writeable and must be explicitly added to the
 
 If this option is not included in the setup options, or is explicitly set to
 `nil` then the default install directories will be used. If this value is set
-the default directories will be ignored. 
+the default directories will be ignored.
 
 Bear in mind that any parser installed into a parser folder on the runtime path
 will still be considered installed. (For example if
diff --git a/doc/nvim-treesitter.txt b/doc/nvim-treesitter.txt
index e870ab352..6fc65d001 100644
--- a/doc/nvim-treesitter.txt
+++ b/doc/nvim-treesitter.txt
@@ -51,6 +51,9 @@ To enable supported features, put this in your `init.lua` file:
     -- Install parsers synchronously (only applied to `ensure_installed`)
     sync_install = false,
 
+    -- Automatically install missing parsers when entering buffer
+    auto_install = false,
+
     -- List of parsers to ignore installing (for "all")
     ignore_install = { "javascript" },
 
diff --git a/lua/nvim-treesitter/configs.lua b/lua/nvim-treesitter/configs.lua
index ee01f3ede..41310f544 100644
--- a/lua/nvim-treesitter/configs.lua
+++ b/lua/nvim-treesitter/configs.lua
@@ -13,6 +13,7 @@ local config = {
   modules = {},
   sync_install = false,
   ensure_installed = {},
+  auto_install = false,
   ignore_install = {},
   update_strategy = "lockfile",
   parser_install_dir = nil,
@@ -386,6 +387,11 @@ function M.setup(user_data)
     config.parser_install_dir = vim.fn.expand(config.parser_install_dir, ":p")
   end
 
+  config.auto_install = user_data.auto_install or false
+  if config.auto_install then
+    require("nvim-treesitter.install").setup_auto_install()
+  end
+
   local ensure_installed = user_data.ensure_installed or {}
   if #ensure_installed > 0 then
     if user_data.sync_install then
diff --git a/lua/nvim-treesitter/install.lua b/lua/nvim-treesitter/install.lua
index e709849ad..be980ca0f 100644
--- a/lua/nvim-treesitter/install.lua
+++ b/lua/nvim-treesitter/install.lua
@@ -425,6 +425,18 @@ local function install(options)
   end
 end
 
+function M.setup_auto_install()
+  vim.api.nvim_create_autocmd("FileType", {
+    pattern = { "*" },
+    callback = function()
+      local lang = parsers.get_buf_lang()
+      if parsers.get_parser_configs()[lang] and not parsers.has_parser(lang) then
+        install { ask_reinstall = true } { lang }
+      end
+    end,
+  })
+end
+
 function M.update(options)
   options = options or {}
   return function(...)