是否可以使用Lua“向后”读取文件？

在io库中定义函数io.linesbackward(filename)：

function io.linesbackward(filename)
  local file = assert(io.open(filename))
  local chunk_size = 4*1024
  local iterator = function() return "" end
  local tail = ""
  local chunk_index = math.ceil(file:seek"end" / chunk_size)
  return 
    function()
      while true do
        local lineEOL,line = iterator()
        if lineEOL ~= "" then 
          return line:reverse() 
        end
        repeat
          chunk_index = chunk_index - 1
          if chunk_index < 0 then 
            file:close()
            iterator = function() 
                         error('No more lines in file "'..filename..'"',3) 
                       end  
            return 
          end
          file:seek("set",chunk_index * chunk_size)
          local chunk = file:read(chunk_size)
          local pattern = "^(.-"..(chunk_index > 0 and "n" or "")..")(.*)"
          local new_tail,lines = chunk:match(pattern)
          iterator = lines and (lines..tail):reverse():gmatch"(n?r?([^n]*))"
          tail = new_tail or chunk..tail
        until iterator
      end
    end
end

用法：

local filename = "your_file.txt"
print("--- backward: ---------------------------")
for line in io.linesbackward(filename) do
  print(line)
end
print("--- forward: ----------------------------")
for line in io.lines(filename) do
  print(line)
end
print("-----------------------------------------")