feat(util): get var either from buffer or global

lua/snacks/util.lua

@@ -197,4 +197,24 @@ function M.keycode(str)
   return vim.api.nvim_replace_termcodes(str, true, true, true)
 end
 
+--- Get a buffer or global variable.
+---@generic T
+---@param buf? number
+---@param name string
+---@param default? T
+---@return T
+function M.var(buf, name, default)
+  local ok, ret = pcall(function()
+    return vim.b[buf or 0][name]
+  end)
+  if ok and ret ~= nil then
+    return ret
+  end
+  ret = vim.g[name]
+  if ret ~= nil then
+    return ret
+  end
+  return default
+end
+
 return M