Lua As Assembler

I’ve said it before: Let’s use Lua as our new “assembler”.

Meaning: Let’s package algorithms in LUA to make them portable… safely (Lua code runs in an actually tight “sandbox”. There really is no way out of that — other than by returning stuff.)

Here’s an example: Image recognition (pictures) in Lua. I can embed this code directly in a JavaX program, JavaX supports that everywhere.

-- Input:
--   iw = image of word to recognize
--   chars = images of characters & description
-- Output:
--   what is recognized (a string)

-- helper function
function preciseMatch(ic, iw, x1)
  local w, h = iw.w, iw.h
  if ic.h ~= h then return false end
  local x2 = x1+ic.w
  if x2 > w then return false end
  for x = x1, x2-1 do
    for y = 0, h-1 do
      if ic.getBrightness(x-x1, y) ~= iw.getBrightness(x, y) then
        return false
      end
    end
  end
  return true
end

-- main algorithm

local buf = {}

for x=0, iw.w-1 do
  for ic, c in pairs(chars) do
    if preciseMatch(ic, iw, x) then
      table.insert(buf, c)
      x = x + ic.w-1
      goto xloop
    end
  end
  ::xloop::
end

return table.concat(buf)

-- done

Quite short too, innit? Sadly only scores “4 out of 9”. :-) (Do better!!!!)