Here's some things this might be used for:
WARNING: This is not completed but was quickly done just an experiment. Fix omissions/bugs and test if you want to use this in production. Particularly pay attention to error handling.
-- lua.lua - Lua 5.1 interpreter (lua.c) reimplemented in Lua. -- -- WARNING: This is not completed but was quickly done just an experiment. -- Fix omissions/bugs and test if you want to use this in production. -- Particularly pay attention to error handling. -- -- (c) David Manura, 2008-08 -- Licensed under the same terms as Lua itself. -- Based on lua.c from Lua 5.1.3. -- Improvements by Shmuel Zeigerman. -- Variables analogous to those in luaconf.h local LUA_INIT = "LUA_INIT" local LUA_PROGNAME = "lua" local LUA_PROMPT = "> " local LUA_PROMPT2 = ">> " local function LUA_QL(x) return "'" .. x .. "'" end -- Variables analogous to those in lua.h local LUA_RELEASE = "Lua 5.1.3" local LUA_COPYRIGHT = "Copyright (C) 1994-2008 Lua.org, PUC-Rio" -- Note: don't allow user scripts to change implementation. -- Check for globals with "cat lua.lua | luac -p -l - | grep ETGLOBAL" local _G = _G local assert = assert local collectgarbage = collectgarbage local loadfile = loadfile local loadstring = loadstring local pcall = pcall local rawget = rawget local select = select local tostring = tostring local type = type local unpack = unpack local xpcall = xpcall local io_stderr = io.stderr local io_stdout = io.stdout local io_stdin = io.stdin local string_format = string.format local string_sub = string.sub local os_getenv = os.getenv local os_exit = os.exit local progname = LUA_PROGNAME -- Use external functions, if available local lua_stdin_is_tty = function() return true end local setsignal = function() end local function print_usage() io_stderr:write(string_format( "usage: %s [options] [script [args]].\n" .. "Available options are:\n" .. " -e stat execute string " .. LUA_QL("stat") .. "\n" .. " -l name require library " .. LUA_QL("name") .. "\n" .. " -i enter interactive mode after executing " .. LUA_QL("script") .. "\n" .. " -v show version information\n" .. " -- stop handling options\n" .. " - execute stdin and stop handling options\n" , progname)) io_stderr:flush() end local function l_message (pname, msg) if pname then io_stderr:write(string_format("%s: ", pname)) end io_stderr:write(string_format("%s\n", msg)) io_stderr:flush() end local function report(status, msg) if not status and msg ~= nil then msg = (type(msg) == 'string' or type(msg) == 'number') and tostring(msg) or "(error object is not a string)" l_message(progname, msg); end return status end local function tuple(...) return {n=select('#', ...), ...} end local function traceback (message) local tp = type(message) if tp ~= "string" and tp ~= "number" then return message end local debug = _G.debug if type(debug) ~= "table" then return message end local tb = debug.traceback if type(tb) ~= "function" then return message end return tb(message, 2) end local function docall(f, ...) local tp = {...} -- no need in tuple (string arguments only) local F = function() return f(unpack(tp)) end setsignal(true) local result = tuple(xpcall(F, traceback)) setsignal(false) -- force a complete garbage collection in case of errors if not result[1] then collectgarbage("collect") end return unpack(result, 1, result.n) end local function dofile(name) local f, msg = loadfile(name) if f then f, msg = docall(f) end return report(f, msg) end local function dostring(s, name) local f, msg = loadstring(s, name) if f then f, msg = docall(f) end return report(f, msg) end local function dolibrary (name) return report(docall(_G.require, name)) end local function print_version() l_message(nil, LUA_RELEASE .. " " .. LUA_COPYRIGHT) end local function getargs (argv, n) local arg = {} for i=1,#argv do arg[i - n] = argv[i] end if _G.arg then local i = 0 while _G.arg[i] do arg[i - n] = _G.arg[i] i = i - 1 end end return arg end --FIX? readline support local history = {} local function saveline(s) -- if #s > 0 then -- history[#history+1] = s -- end end local function get_prompt (firstline) -- use rawget to play fine with require 'strict' local pmt = rawget(_G, firstline and "_PROMPT" or "_PROMPT2") local tp = type(pmt) if tp == "string" or tp == "number" then return tostring(pmt) end return firstline and LUA_PROMPT or LUA_PROMPT2 end local function incomplete (msg) if msg then local ender = LUA_QL("<eof>") if string_sub(msg, -#ender) == ender then return true end end return false end local function pushline (firstline) local prmt = get_prompt(firstline) io_stdout:write(prmt) io_stdout:flush() local b = io_stdin:read'*l' if not b then return end -- no input if firstline and string_sub(b, 1, 1) == '=' then return "return " .. string_sub(b, 2) -- change '=' to `return' else return b end end local function loadline () local b = pushline(true) if not b then return -1 end -- no input local f, msg while true do -- repeat until gets a complete line f, msg = loadstring(b, "=stdin") if not incomplete(msg) then break end -- cannot try to add lines? local b2 = pushline(false) if not b2 then -- no more input? return -1 end b = b .. "\n" .. b2 -- join them end saveline(b) return f, msg end local function dotty () local oldprogname = progname progname = nil while true do local result local status, msg = loadline() if status == -1 then break end if status then result = tuple(docall(status)) status, msg = result[1], result[2] end report(status, msg) if status and result.n > 1 then -- any result to print? status, msg = pcall(_G.print, unpack(result, 2, result.n)) if not status then l_message(progname, string_format( "error calling %s (%s)", LUA_QL("print"), msg)) end end end io_stdout:write"\n" io_stdout:flush() progname = oldprogname end local function handle_script(argv, n) _G.arg = getargs(argv, n) -- collect arguments local fname = argv[n] if fname == "-" and argv[n-1] ~= "--" then fname = nil -- stdin end local status, msg = loadfile(fname) if status then status, msg = docall(status, unpack(_G.arg)) end return report(status, msg) end local function collectargs (argv, p) local i = 1 while i <= #argv do if string_sub(argv[i], 1, 1) ~= '-' then -- not an option? return i end local prefix = string_sub(argv[i], 1, 2) if prefix == '--' then if #argv[i] > 2 then return -1 end return argv[i+1] and i+1 or 0 elseif prefix == '-' then return i elseif prefix == '-i' then if #argv[i] > 2 then return -1 end p.i = true p.v = true elseif prefix == '-v' then if #argv[i] > 2 then return -1 end p.v = true elseif prefix == '-e' then p.e = true if #argv[i] == 2 then i = i + 1 if argv[i] == nil then return -1 end end elseif prefix == '-l' then if #argv[i] == 2 then i = i + 1 if argv[i] == nil then return -1 end end else return -1 -- invalid option end i = i + 1 end return 0 end local function runargs(argv, n) local i = 1 while i <= n do if argv[i] then assert(string_sub(argv[i], 1, 1) == '-') local c = string_sub(argv[i], 2, 2) -- option if c == 'e' then local chunk = string_sub(argv[i], 3) if chunk == '' then i = i + 1; chunk = argv[i] end assert(chunk) if not dostring(chunk, "=(command line)") then return false end elseif c == 'l' then local filename = string_sub(argv[i], 3) if filename == '' then i = i + 1; filename = argv[i] end assert(filename) if not dolibrary(filename) then return false end end i = i + 1 end end return true end local function handle_luainit() local init = os_getenv(LUA_INIT) if init == nil then return -- status OK elseif string_sub(init, 1, 1) == '@' then dofile(string_sub(init, 2)) else dostring(init, "=" .. LUA_INIT) end end local import = _G.import if import then lua_stdin_is_tty = import.lua_stdin_is_tty or lua_stdin_is_tty setsignal = import.setsignal or setsignal LUA_RELEASE = import.LUA_RELEASE or LUA_RELEASE LUA_COPYRIGHT = import.LUA_COPYRIGHT or LUA_COPYRIGHT _G.import = nil end if _G.arg and _G.arg[0] and #_G.arg[0] > 0 then progname = _G.arg[0] end local argv = {...} handle_luainit() local has = {i=false, v=false, e=false} local script = collectargs(argv, has) if script < 0 then -- invalid args? print_usage() os_exit(1) end if has.v then print_version() end local status = runargs(argv, (script > 0) and script-1 or #argv) if not status then os_exit(1) end if script ~= 0 then status = handle_script(argv, script) if not status then os_exit(1) end else _G.arg = nil end if has.i then dotty() elseif script == 0 and not has.e and not has.v then if lua_stdin_is_tty() then print_version() dotty() else dofile(nil) -- executes stdin as a file end end