serpent.lua

---@diagnostic disable
--[[
Copy of serpent, formatted with stylua. See
https://github.com/pkulchenko/serpent

Factorio has this in game. It is very helpful to have it out of the game for
testing by hand.  Installing Lua libraries is a pain, so let's just grab a copy.
]]

local n, v = "serpent", "0.303" -- (C) 2012-18 Paul Kulchenko; MIT License
local c, d = "Paul Kulchenko", "Lua serializer and pretty printer"
local snum = {
   [tostring(1 / 0)] = "1/0 --[[math.huge]]",
   [tostring(-1 / 0)] = "-1/0 --[[-math.huge]]",
   [tostring(0 / 0)] = "0/0",
}
local badtype = { thread = true, userdata = true, cdata = true }
local getmetatable = debug and debug.getmetatable or getmetatable
local pairs = function(t)
   return next, t
end -- avoid using __pairs in Lua 5.2+
local keyword, globals, G = {}, {}, (_G or _ENV)
for _, k in ipairs({
   "and",
   "break",
   "do",
   "else",
   "elseif",
   "end",
   "false",
   "for",
   "function",
   "goto",
   "if",
   "in",
   "local",
   "nil",
   "not",
   "or",
   "repeat",
   "return",
   "then",
   "true",
   "until",
   "while",
}) do
   keyword[k] = true
end
for k, v in pairs(G) do
   globals[v] = k
end -- build func to name mapping
for _, g in ipairs({ "coroutine", "debug", "io", "math", "string", "table", "os" }) do
   for k, v in pairs(type(G[g]) == "table" and G[g] or {}) do
      globals[v] = g .. "." .. k
   end
end

local function s(t, opts)
   local name, indent, fatal, maxnum = opts.name, opts.indent, opts.fatal, opts.maxnum
   local sparse, custom, huge = opts.sparse, opts.custom, not opts.nohuge
   local space, maxl = (opts.compact and "" or " "), (opts.maxlevel or math.huge)
   local maxlen, metatostring = tonumber(opts.maxlength), opts.metatostring
   local iname, comm = "_" .. (name or ""), opts.comment and (tonumber(opts.comment) or math.huge)
   local numformat = opts.numformat or "%.17g"
   local seen, sref, syms, symn = {}, { "local " .. iname .. "={}" }, {}, 0
   local function gensym(val)
      return "_"
         .. (
            tostring(tostring(val)):gsub("[^%w]", ""):gsub(
               "(%d%w+)",
               -- tostring(val) is needed because __tostring may return a non-string value
               function(s)
                  if not syms[s] then
                     symn = symn + 1
                     syms[s] = symn
                  end
                  return tostring(syms[s])
               end
            )
         )
   end
   local function safestr(s)
      return type(s) == "number" and (huge and snum[tostring(s)] or numformat:format(s))
         or type(s) ~= "string" and tostring(s) -- escape NEWLINE/010 and EOF/026
         or ("%q"):format(s):gsub("\010", "n"):gsub("\026", "\\026")
   end
   -- handle radix changes in some locales
   if opts.fixradix and (".1f"):format(1.2) ~= "1.2" then
      local origsafestr = safestr
      safestr = function(s)
         return type(s) == "number" and (nohuge and snum[tostring(s)] or numformat:format(s):gsub(",", "."))
            or origsafestr(s)
      end
   end
   local function comment(s, l)
      return comm and (l or 0) < comm and " --[[" .. select(2, pcall(tostring, s)) .. "]]" or ""
   end
   local function globerr(s, l)
      return globals[s] and globals[s] .. comment(s, l)
         or not fatal and safestr(select(2, pcall(tostring, s)))
         or error("Can't serialize " .. tostring(s))
   end
   local function safename(path, name) -- generates foo.bar, foo[3], or foo['b a r']
      local n = name == nil and "" or name
      local plain = type(n) == "string" and n:match("^[%l%u_][%w_]*$") and not keyword[n]
      local safe = plain and n or "[" .. safestr(n) .. "]"
      return (path or "") .. (plain and path and "." or "") .. safe, safe
   end
   local alphanumsort = type(opts.sortkeys) == "function" and opts.sortkeys
      or function(k, o, n) -- k=keys, o=originaltable, n=padding
         local maxn, to = tonumber(n) or 12, { number = "a", string = "b" }
         local function padnum(d)
            return ("%0" .. tostring(maxn) .. "d"):format(tonumber(d))
         end
         table.sort(k, function(a, b)
            -- sort numeric keys first: k[key] is not nil for numerical keys
            return (k[a] ~= nil and 0 or to[type(a)] or "z") .. (tostring(a):gsub("%d+", padnum))
               < (k[b] ~= nil and 0 or to[type(b)] or "z") .. (tostring(b):gsub("%d+", padnum))
         end)
      end
   local function val2str(t, name, indent, insref, path, plainindex, level)
      local ttype, level, mt = type(t), (level or 0), getmetatable(t)
      local spath, sname = safename(path, name)
      local tag = plainindex and ((type(name) == "number") and "" or name .. space .. "=" .. space)
         or (name ~= nil and sname .. space .. "=" .. space or "")
      if seen[t] then -- already seen this element
         sref[#sref + 1] = spath .. space .. "=" .. space .. seen[t]
         return tag .. "nil" .. comment("ref", level)
      end
      -- protect from those cases where __tostring may fail
      if type(mt) == "table" and metatostring ~= false then
         local to, tr = pcall(function()
            return mt.__tostring(t)
         end)
         local so, sr = pcall(function()
            return mt.__serialize(t)
         end)
         if to or so then -- knows how to serialize itself
            seen[t] = insref or spath
            t = so and sr or tr
            ttype = type(t)
         end -- new value falls through to be serialized
      end
      if ttype == "table" then
         if level >= maxl then return tag .. "{}" .. comment("maxlvl", level) end
         seen[t] = insref or spath
         if next(t) == nil then return tag .. "{}" .. comment(t, level) end -- table empty
         if maxlen and maxlen < 0 then return tag .. "{}" .. comment("maxlen", level) end
         local maxn, o, out = math.min(#t, maxnum or #t), {}, {}
         for key = 1, maxn do
            o[key] = key
         end
         if not maxnum or #o < maxnum then
            local n = #o -- n = n + 1; o[n] is much faster than o[#o+1] on large tables
            for key in pairs(t) do
               if o[key] ~= key then
                  n = n + 1
                  o[n] = key
               end
            end
         end
         if maxnum and #o > maxnum then o[maxnum + 1] = nil end
         if opts.sortkeys and #o > maxn then alphanumsort(o, t, opts.sortkeys) end
         local sparse = sparse and #o > maxn -- disable sparsness if only numeric keys (shorter output)
         for n, key in ipairs(o) do
            local value, ktype, plainindex = t[key], type(key), n <= maxn and not sparse
            if
               opts.valignore and opts.valignore[value] -- skip ignored values; do nothing
               or opts.keyallow and not opts.keyallow[key]
               or opts.keyignore and opts.keyignore[key]
               or opts.valtypeignore and opts.valtypeignore[type(value)] -- skipping ignored value types
               or sparse and value == nil
            then -- skipping nils; do nothing
            elseif ktype == "table" or ktype == "function" or badtype[ktype] then
               if not seen[key] and not globals[key] then
                  sref[#sref + 1] = "placeholder"
                  local sname = safename(iname, gensym(key)) -- iname is table for local variables
                  sref[#sref] = val2str(key, sname, indent, sname, iname, true)
               end
               sref[#sref + 1] = "placeholder"
               local path = seen[t] .. "[" .. tostring(seen[key] or globals[key] or gensym(key)) .. "]"
               sref[#sref] = path .. space .. "=" .. space .. tostring(seen[value] or val2str(value, nil, indent, path))
            else
               out[#out + 1] = val2str(value, key, indent, nil, seen[t], plainindex, level + 1)
               if maxlen then
                  maxlen = maxlen - #out[#out]
                  if maxlen < 0 then break end
               end
            end
         end
         local prefix = string.rep(indent or "", level)
         local head = indent and "{\n" .. prefix .. indent or "{"
         local body = table.concat(out, "," .. (indent and "\n" .. prefix .. indent or space))
         local tail = indent and "\n" .. prefix .. "}" or "}"
         return (custom and custom(tag, head, body, tail, level) or tag .. head .. body .. tail) .. comment(t, level)
      elseif badtype[ttype] then
         seen[t] = insref or spath
         return tag .. globerr(t, level)
      elseif ttype == "function" then
         seen[t] = insref or spath
         if opts.nocode then return tag .. "function() --[[..skipped..]] end" .. comment(t, level) end
         local ok, res = pcall(string.dump, t)
         local func = ok and "((loadstring or load)(" .. safestr(res) .. ",'@serialized'))" .. comment(t, level)
         return tag .. (func or globerr(t, level))
      else
         return tag .. safestr(t)
      end -- handle all other types
   end
   local sepr = indent and "\n" or ";" .. space
   local body = val2str(t, name, indent) -- this call also populates sref
   local tail = #sref > 1 and table.concat(sref, sepr) .. sepr or ""
   local warn = opts.comment and #sref > 1 and space .. "--[[incomplete output with shared/self-references skipped]]"
      or ""
   return not name and body .. warn or "do local " .. body .. sepr .. tail .. "return " .. name .. sepr .. "end"
end

local function deserialize(data, opts)
   local env = (opts and opts.safe == false) and G
      or setmetatable({}, {
         __index = function(t, k)
            return t
         end,
         __call = function(t, ...)
            error("cannot call functions")
         end,
      })
   local f, res = (loadstring or load)("return " .. data, nil, nil, env)
   if not f then
      f, res = (loadstring or load)(data, nil, nil, env)
   end
   if not f then return f, res end
   if setfenv then setfenv(f, env) end
   return pcall(f)
end

local function merge(a, b)
   if b then
      for k, v in pairs(b) do
         a[k] = v
      end
   end
   return a
end
return {
   _NAME = n,
   _COPYRIGHT = c,
   _DESCRIPTION = d,
   _VERSION = v,
   serialize = s,
   load = deserialize,
   dump = function(a, opts)
      return s(a, merge({ name = "_", compact = true, sparse = true }, opts))
   end,
   line = function(a, opts)
      return s(a, merge({ sortkeys = true, comment = true }, opts))
   end,
   block = function(a, opts)
      return s(a, merge({ indent = "  ", sortkeys = true, comment = true }, opts))
   end,
}