pico-8 cartridge // http://www.pico-8.com
version 42
__lua__
-- splubp data transport
-- by kistaro windrider

-- main

-- >8
-- utilities

-- generate standard "overlay"
-- constructor for type tt.
-- if tt.init is defined, generated
-- new calls tt.init(ret) after
-- ret is definitely not nil,
-- after calling setmetatable.
-- use to initialize mutables.
--
-- if there was a previous new,
-- it is invoked before
-- setting tt's metatable, so
-- each new will see its
-- inheritance chain.
function mknew(tt)
 local mt,oldinit,more = {__index=tt},tt.superinit,rawget(tt, "init")
 tt.new=function(ret)
  if(not ret) ret = {}
  ret.new = false
  setmetatable(ret, mt)
  if(oldinit) oldinit(ret)
  if (more) more(ret)
  return ret
 end

 if oldinit and more then
  tt.superinit = function(ret)
   oldinit(ret)
   more(ret)
  end
 elseif more then
  tt.superinit = more
 end
 return tt
end

function set(t)
 local ret = {}
 for v in all(t) do
  ret[v]=true
 end
 return ret
end

whitespace = set(split" ,\t,\n")

function trim(s)
 local f, e = 1, #s
 while (f <= e and whitespace[s[f]]) f += 1
 while (e >= f and whitespace[s[e]]) e -= 1
 if (f<e) return sub(s,f,e)
 return ""
end

-- >8
-- writer

splubp_writer = mknew{
 init = function(self)
  -- fill from single file
  self.fmts = self.fmts or {}
  if self.ffile then
   for f in all(split(self.ffile, "===", false)) do
    local ext, fmt = split(f, "---")
    self.fmts[trim(ext)] = trim(fmt)
   end
  end
 end
}


-->8
-- loader

-- essay: `e` directive
-- reads int16 char count,
-- then parses that many bytes
-- into a string (via chr).
-- returns string, new read offset.
function splubp_read_essay(addr)
 local cs, n = {}, %addr
 for a2 = addr+2, addr+n+1 do
  add(cs, @a2)
 end
 return chr(unpack(cs)), addr+2+n
end