打印出所有Lua保留关键字

使用下面的代码可以打印出当前环境中定义的所有 Lua 关键词 (and, break, do, else, elseif, end, false, for, function, if, in, local, nil, not, or, repeat, return, then, true, until, while):

for k, v in pairs(_G) do
  if type(v) == "function" then
    local info = debug.getinfo(v, "S")
    local src = info.source
    if src:sub(1,1) == "@" then
      src = src:sub(2)
    end
    if src == "[C]" then
      src = "builtin"
    end
    if info.linedefined <= 0 then
      print(k .. ": " .. src)
    else
      print(k .. ": " .. src .. ":" .. info.linedefined)
    end
  end
end