yukichan/serialization.lua

134 lines
3.6 KiB
Lua

local serialization = {}
-- Important: pretty formatting will allow presenting non-serializable values
-- but may generate output that cannot be unserialized back.
function serialization.serialize(value, pretty)
local kw = {["and"]=true, ["break"]=true, ["do"]=true, ["else"]=true,
["elseif"]=true, ["end"]=true, ["false"]=true, ["for"]=true,
["function"]=true, ["goto"]=true, ["if"]=true, ["in"]=true,
["local"]=true, ["nil"]=true, ["not"]=true, ["or"]=true,
["repeat"]=true, ["return"]=true, ["then"]=true, ["true"]=true,
["until"]=true, ["while"]=true}
local id = "^[%a_][%w_]*$"
local ts = {}
local function s(v, l)
local t = type(v)
if t == "nil" then
return "nil"
elseif t == "boolean" then
return v and "true" or "false"
elseif t == "number" then
if v ~= v then
return "0/0"
elseif v == math.huge then
return "math.huge"
elseif v == -math.huge then
return "-math.huge"
else
return tostring(v)
end
elseif t == "string" then
return string.format("%q", v):gsub("\\\n","\\n")
elseif t == "table" and pretty and getmetatable(v) and getmetatable(v).__tostring then
return tostring(v)
elseif t == "table" then
if ts[v] then
if pretty then
return "recursion"
else
error("tables with cycles are not supported")
end
end
ts[v] = true
local i, r = 1, nil
local f
if pretty then
local ks, sks, oks = {}, {}, {}
for k in pairs(v) do
if type(k) == "number" then
table.insert(ks, k)
elseif type(k) == "string" then
table.insert(sks, k)
else
table.insert(oks, k)
end
end
table.sort(ks)
table.sort(sks)
for _, k in ipairs(sks) do
table.insert(ks, k)
end
for _, k in ipairs(oks) do
table.insert(ks, k)
end
local n = 0
f = table.pack(function()
n = n + 1
local k = ks[n]
if k ~= nil then
return k, v[k]
else
return nil
end
end)
else
f = table.pack(pairs(v))
end
for k, v in table.unpack(f) do
if r then
r = r .. "," .. (pretty and ("\n" .. string.rep(" ", l)) or "")
else
r = "{"
end
local tk = type(k)
if tk == "number" and k == i then
i = i + 1
r = r .. s(v, l + 1)
else
if tk == "string" and not kw[k] and string.match(k, id) then
r = r .. k
else
r = r .. "[" .. s(k, l + 1) .. "]"
end
r = r .. "=" .. s(v, l + 1)
end
end
ts[v] = nil -- allow writing same table more than once
return (r or "{") .. "}"
else
if pretty then
return tostring(t)
else
error("unsupported type: " .. t)
end
end
end
local result = s(value, 1)
local limit = type(pretty) == "number" and pretty or 10
if pretty then
local truncate = 0
while limit > 0 and truncate do
truncate = string.find(result, "\n", truncate + 1, true)
limit = limit - 1
end
if truncate then
return result:sub(1, truncate) .. "..."
end
end
return result
end
function serialization.unserialize(data)
local result, reason = load("return " .. data, "=data", _, {math={huge=math.huge}})
if not result then
return nil, reason
end
local ok, output = pcall(result)
if not ok then
return nil, output
end
return output
end
return serialization