feat(treesitter): upstream get_node_at_cursor()

Util from the nvim-treesitter project.

runtime/lua/vim/treesitter.lua

@@ -81,7 +81,7 @@ end
 --- If needed this will create the parser.
 --- Unconditionally attach the provided callback
 ---
----@param bufnr number|nil Buffer the parser should be tied to: (default current buffer)
+---@param bufnr number|nil Buffer the parser should be tied to (default: current buffer)
 ---@param lang string |nil Filetype of this parser (default: buffer filetype)
 ---@param opts table|nil Options to pass to the created language tree
 ---
@@ -245,6 +245,27 @@ function M.get_captures_at_position(bufnr, row, col)
   return matches
 end
 
+--- Gets the smallest named node under the cursor
+---
+---@param winnr number Window handle or 0 for current window
+---@param opts table Options table
+---@param opts.ignore_injections boolean (default true) Ignore injected languages.
+---
+---@returns (table) The named node under the cursor
+function M.get_node_at_cursor(winnr, opts)
+  winnr = winnr or 0
+  local cursor = a.nvim_win_get_cursor(winnr)
+  local ts_cursor_range = { cursor[1] - 1, cursor[2], cursor[1] - 1, cursor[2] }
+
+  local buf = a.nvim_win_get_buf(winnr)
+  local root_lang_tree = M.get_parser(buf)
+  if not root_lang_tree then
+    return
+  end
+
+  return root_lang_tree:named_node_for_range(ts_cursor_range, opts)
+end
+
 --- Start treesitter highlighting for a buffer
 ---
 --- Can be used in an ftplugin or FileType autocommand