Execute Brain****/Lua

Execute Brain****/Lua is an implementation of Brainf***. Other implementations of Brainf***.

Execute Brain****/Lua is part of RCBF. You may find other members of RCBF at Category:RCBF.

An implementation of a Brainf*** interpreter in Lua. <lang lua>memory = {0} --memory is bounded on one side, at 1

program = io.read() --loads an entire program at once, must not contain newlines

pointer = 1

instruction = 1

retpoints = {}

functions = { [">"] = function()

 pointer = pointer + 1
 if not memory[pointer] then memory[pointer] = 0 end

end, ["<"] = function()

 if pointer == 1 then error"Memory out-of-bounds!" end
 pointer = pointer - 1

end, ["+"] = function()

 memory[pointer] = memory[pointer] + 1

end, ["-"] = function()

 memory[pointer] = memory[pointer] - 1

end, ["["] = function()

 if memory[pointer] ~= 0 then
   table.insert(retpoints, instruction)
 else -- if the memory at the pointer is zero, jump to the matching close bracket
   local b = 1 -- b stores number of unclosed brackets (when b == 0 the match has been found)
   while instruction <= #program and b ~= 0 do
     instruction = instruction + 1
     if program:sub(instruction, instruction) == "[" then
       b = b + 1
     elseif program:sub(instruction, instruction) == "]"
       b = b - 1
     end
   end
   if b ~= 0 then
     error"Missing ']'!"
   end
 end

end, ["]"] = function()

 if #retpoints > 0 then
   if memory[pointer] ~= 0 then
     instruction = retpoints[#retpoints]
   else
     table.remove(retpoints)
   end
 else
   error"Missing '['!"
 end

end, ["."] = function()

 io.write(string.char(memory[pointer]))

end, [","] = function()

 memory[pointer] = io.read():byte()

end} while instruction <= #program do

 local instr = functions[program:sub(instruction,instruction)]
 if instr then instr() end
 instruction = instruction + 1

end</lang>