-- miniforth2.lua
-- This is a rewrite of (find-angg "miniforth/miniforth1.lua")
-- using empty captures to make the code cleaner.
-- Author and version: Edrx, 2005nov29
-- License: GPL

subj = ""
pos = 0

getword = function ()
  local _, _, word, newpos = string.find(subj, "^[ \t]*([^ \t\n\r]+)()", pos)
  if _ then pos = newpos; return word end
end
getnewline = function ()
  local _, _, newpos = string.find(subj, "^[ \t]*\r?\n()", pos)
  if _ then pos = newpos; return "\n" end
end
geteof = function ()
  local _, _, newpos = string.find(subj, "^[ \t]*()$", pos)
  if _ then pos = newpos; return "" end
end
getword1 = function () return getword() or getnewline() or geteof() end

eval = function (luacode) return assert(loadstring(luacode))() end
getuntillua = function ()
  local _, _, luacode, newpos = string.find(subj, "^(.-)lua>()", pos)
  if _ then pos = newpos; return luacode end
end

forths = {}
forths["\n"] = function () end
forths[""]   = function () interpret = nil end
forths["<lua"] = function () eval(assert(getuntillua())) end

getrestofline = function ()
  local _, _, li, newpos = string.find(subj, "^([^\n]*)\n?()", pos)
  pos = newpos; return li
end
forths["--"] = getrestofline

interpret = function () word = getword1(); (forths[word] or unknown)() end
run = function () while interpret do interpret() end end

-- Usage: subj = "..."; pos = 0; run()

tounix = function (str) return (string.gsub(str, "\r", "")) end
runstr = function (str, interpreter)
    local s, p, i = subj, pos, interpret
    subj, pos, interpret = str, 0, interpreter or interpret
    run()
    subj, pos, interpret = s, p, i
  end
runfile = function (fname) runstr(tounix(readfile(fname))) end

demo = [[
  <lua
    forths["hello"] = function () print("Hello!") end
  lua>
  hello hello
]]

-- PP(arg)
-- (find-sh "lua -l miniforth2.lua -e runstr(demo)")
-- (find-sh "lua -e print(\\\"foo\\\")")