yeast 算法 编码解码

README.md

yeast 算法 的 Lua 版 实现

local yeast = require "yeast"

local ts = 1780208984973

local ystr = yeast.encode(ts)
print(ystr)
print(yeast.decode(ystr) == ts, yeast.decode(ystr))

``bash PvykMED true 1780208984973

yeast.lua

local ch2idx = {
  ['0']=0,  ['1']=1,  ['2']=2,  ['3']=3,  ['4']=4,  ['5']=5,  ['6']=6,  ['7']=7,  ['8']=8,  ['9']=9,
  ['A']=10, ['B']=11, ['C']=12, ['D']=13, ['E']=14, ['F']=15, ['G']=16, ['H']=17, ['I']=18, ['J']=19,
  ['K']=20, ['L']=21, ['M']=22, ['N']=23, ['O']=24, ['P']=25, ['Q']=26, ['R']=27, ['S']=28, ['T']=29,
  ['U']=30, ['V']=31, ['W']=32, ['X']=33, ['Y']=34, ['Z']=35,
  ['a']=36, ['b']=37, ['c']=38, ['d']=39, ['e']=40, ['f']=41, ['g']=42, ['h']=43, ['i']=44, ['j']=45,
  ['k']=46, ['l']=47, ['m']=48, ['n']=49, ['o']=50, ['p']=51, ['q']=52, ['r']=53, ['s']=54, ['t']=55,
  ['u']=56, ['v']=57, ['w']=58, ['x']=59, ['y']=60, ['z']=61,
  ['-']=62, ['_']=63,
}

local idx2ch = {
  '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
  'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
  'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
  'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
  'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
  '-', '_'
}

local yeast = { }

---comment `yeast` 编码
---@param now number
---@return string
function yeast.encode(now)
  local list = { }
  local i = 7
  while i > 0 do
    local n = now & 63
    list[i] = idx2ch[n+1]
    now = (now - n) >> 6
    i = i - 1
  end
  return table.concat(list)
end

---comment `yeast` 解码
---@param ystr string
---@return number?
function yeast.decode(ystr)
  local result = 0
  for i = 1, #ystr do
    local v = ch2idx[ystr:sub(i, i)]
    if not v then
      return nil
    end
    result = result * 64 + v
  end
  return result
end

return yeast