luafaudes.cpp

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/** @file luafaudes.cpp Simple Lua stand-alone interpreter for lua/faudes
 
   This lua interpreter is based on a plain copy of the original lua.c 
   provided with the lua 5.4.8 distribution under an MIT license; see
   lua.h or http://www.lua.org
 
   Changes to the original code are signed "//FAUDES". They include
   (a) loading of libFAUDES bindings;
   (b) libFAUDES specific additional options '-d' and '-x'
   (c) Mike Palls "Advanced-Readline patch" has been applied (and adapted)
   (d) be version agniostic to go with Lua 5.1.3 if need be
   
   Thomas Moor, 2008, 2025.
 
 
@ingroup Tutorials
 
 
*/
 
//FAUDES: skip doxygen 
#ifndef FAUDES_DOXYGEN
 
//FAUDES: use my C++ include file (incl. lpb_include.h and, hence, lua.h & friends)
#include "libfaudes.h"
 
//FAUDES: import all libFAUDES
using namespace faudes;
 
//FAUDES: dislike isatty on MSYS (disable via Makefile)
#if defined(LUA_USE_ISATTY)
#include <unistd.h>
#define faudes_stdin_is_tty() isatty(0)
#else
#define faudes_stdin_is_tty() 1 
#endif
 
//FAUDES: version agnostic: 5.1.3 used to def this and we want to override
#ifdef lua_readline
#undef lua_readline
#endif
#ifdef lua_saveline
#undef lua_saveline
#endif
 
//FAUDES: changed name form 'lua' to 'luafaudes'
#if !defined(LUA_PROGNAME)
#define LUA_PROGNAME    "luafaudes"
#endif
 
 
#if !defined(LUA_INIT_VAR)
#define LUA_INIT_VAR    "LUA_INIT"
#endif
 
#define LUA_INITVARVERSION  LUA_INIT_VAR // LUA_VERSUFFIX
 
 
static lua_State *globalL = NULL;
 
static const char *progname = LUA_PROGNAME;
 
 
#if defined(LUA_USE_POSIX)   /* { */
 
/*
** Use 'sigaction' when available.
*/
static void setsignal (int sig, void (*handler)(int)) {
  struct sigaction sa;
  sa.sa_handler = handler;
  sa.sa_flags = 0;
  sigemptyset(&sa.sa_mask);  /* do not mask any signal */
  sigaction(sig, &sa, NULL);
}
 
#else           /* }{ */
 
#define setsignal            signal
 
#endif                               /* } */
 
 
/*
** Hook set by signal function to stop the interpreter.
*/
static void lstop (lua_State *L, lua_Debug *ar) {
  (void)ar;  /* unused arg. */
  lua_sethook(L, NULL, 0, 0);  /* reset hook */
  luaL_error(L, "interrupted!");
}
 
 
/*
** Function to be called at a C signal. Because a C signal cannot
** just change a Lua state (as there is no proper synchronization),
** this function only sets a hook that, when called, will stop the
** interpreter.
*/
static void laction (int i) {
  int flag = LUA_MASKCALL | LUA_MASKRET | LUA_MASKLINE | LUA_MASKCOUNT;
  setsignal(i, SIG_DFL); /* if another SIGINT happens, terminate process */
  lua_sethook(globalL, lstop, flag, 1);
}
 
 
 
 
static void print_usage (const char *badoption) {
  lua_writestringerror("%s: ", progname);
  if (badoption[1] == 'e' || badoption[1] == 'l')
    lua_writestringerror("'%s' needs argument\n", badoption);
  else
    lua_writestringerror("unrecognized option '%s'\n", badoption);
#if LUA_VERSION_NUM >= 504
  /* //FAUDES: original 5.4.8 code */
  lua_writestringerror(
  "usage: %s [options] [script [args]]\n"
  "available options are:\n"
  "  -e stat   execute string 'stat'\n"
  "  -i        enter interactive mode after executing 'script'\n"
  "  -l mod    require library 'mod' into global 'mod'\n"
  "  -l g=mod  require library 'mod' into global 'g'\n"
  "  -v        show version information\n"
  "  -E        ignore environment variables\n"  
  "  -W        turn warnings on\n"
  "  -d        pass on libFAUDES messages to console\n"   /* //FAUDES */
  "  -x flx    load libFAUDES extension 'flx'\n"          /* //FAUDES */
  "  --        stop handling options\n"
  "  -         stop handling options and execute stdin\n"
  ,
  progname);
  /* //FAUDES: end */
#else 
  /* //FAUDES: all of the above except -E and -W  [MS CL wont digest preprocessing within concateneted strings]*/
  lua_writestringerror(
  "usage: %s [options] [script [args]]\n"
  "available options are:\n"
  "  -e stat   execute string 'stat'\n"
  "  -i        enter interactive mode after executing 'script'\n"
  "  -l mod    require library 'mod' into global 'mod'\n"
  "  -l g=mod  require library 'mod' into global 'g'\n"
  "  -v        show version information\n"
  "  -d        pass on libFAUDES messages to console\n"   /* //FAUDES */
  "  -x flx    load libFAUDES extension 'flx'\n"          /* //FAUDES */
  "  --        stop handling options\n"
  "  -         stop handling options and execute stdin\n"
  ,
  progname);
  /* //FAUDES: end */
#endif  
}
 
 
/*
** Prints an error message, adding the program name in front of it
** (if present)
*/
static void l_message (const char *pname, const char *msg) {
  if (pname) lua_writestringerror("%s: ", pname);
  lua_writestringerror("%s\n", msg);
}
 
 
/*
** Check whether 'status' is not OK and, if so, prints the error
** message on the top of the stack.
*/
static int report (lua_State *L, int status) {
  if (status != LUA_OK) {
    const char *msg = lua_tostring(L, -1);
    if (msg == NULL)
      msg = "(error message not a string)";
    l_message(progname, msg);
    lua_pop(L, 1);  /* remove message */
  }
  return status;
}
 
 
/*
** Message handler used to run all chunks
*/
static int msghandler (lua_State *L) {
  const char *msg = lua_tostring(L, 1);
  if (msg == NULL) {  /* is error object not a string? */
    if (luaL_callmeta(L, 1, "__tostring") &&  /* does it have a metamethod */
        lua_type(L, -1) == LUA_TSTRING)  /* that produces a string? */
      return 1;  /* that is the message */
    else
      msg = lua_pushfstring(L, "(error object is a %s value)",
                               luaL_typename(L, 1));
  }
#if LUA_VERSION_NUM >= 504  /* //FAUDES: try to be version agnostic */
  luaL_traceback(L, L, msg, 1);  /* append a standard traceback */
#endif 
  return 1;  /* return the traceback */
}
 
 
/*
** Interface to 'lua_pcall', which sets appropriate message function
** and C-signal handler. Used to run all chunks.
*/
static int docall (lua_State *L, int narg, int nres) {
  int status;
  int base = lua_gettop(L) - narg;  /* function index */
  lua_pushcfunction(L, msghandler);  /* push message handler */
  lua_insert(L, base);  /* put it under function and args */
  globalL = L;  /* to be available to 'laction' */
  setsignal(SIGINT, laction);  /* set C-signal handler */
  status = lua_pcall(L, narg, nres, base);
  setsignal(SIGINT, SIG_DFL); /* reset C-signal handler */
  lua_remove(L, base);  /* remove message handler from the stack */
  return status;
}
 
 
//FAUDES: libFAUDES specific version/greeting.
static void print_version (void) {
  std::stringstream sstr;
  sstr 
    << "welcome to the libFAUDES-Lua console" << std::endl
    << "version: " << VersionString() << " / " << LUA_RELEASE << std::endl
    << "build: " << BuildString() << std::endl
    << "plug-ins: " << PluginsString() << std::endl
    << "credits: this libFAUDES interpreter is based on the projects Lua and SWIG" << std::endl
    << "enter 'faudes.Help()' for a list of faudes related types and functions" << std::endl
    << "press ctrl-c to exit the interpreter";
  lua_writestring(sstr.str().c_str(),sstr.str().length()); 
  lua_writeline();
}
 
 
/*
** Create the 'arg' table, which stores all arguments from the
** command line ('argv'). It should be aligned so that, at index 0,
** it has 'argv[script]', which is the script name. The arguments
** to the script (everything after 'script') go to positive indices;
** other arguments (before the script name) go to negative indices.
** If there is no script name, assume interpreter's name as base.
** (If there is no interpreter's name either, 'script' is -1, so
** table sizes are zero.)
*/
static void createargtable (lua_State *L, char **argv, int argc, int script) {
  int i, narg;
  narg = argc - (script + 1);  /* number of positive indices */
  lua_createtable(L, narg, script + 1);
  for (i = 0; i < argc; i++) {
    lua_pushstring(L, argv[i]);
    lua_rawseti(L, -2, i - script);
  }
  lua_setglobal(L, "arg");
}
 
 
static int dochunk (lua_State *L, int status) {
  if (status == LUA_OK) status = docall(L, 0, 0);
  return report(L, status);
}
 
 
static int dofile (lua_State *L, const char *name) {
  return dochunk(L, luaL_loadfile(L, name));
}
 
 
static int dostring (lua_State *L, const char *s, const char *name) {
  return dochunk(L, luaL_loadbuffer(L, s, strlen(s), name));
}
 
 
/*
** Receives 'globname[=modname]' and runs 'globname = require(modname)'.
** If there is no explicit modname and globname contains a '-', cut
** the suffix after '-' (the "version") to make the global name.
*/
static int dolibrary (lua_State *L, char *globname) {
  int status;
  char *suffix = NULL;
  char *modname = strchr(globname, '=');
  if (modname == NULL) {  /* no explicit name? */
    modname = globname;  /* module name is equal to global name */
    suffix = strchr(modname, *LUA_IGMARK);  /* look for a suffix mark */
  }
  else {
    *modname = '\0';  /* global name ends here */
    modname++;  /* module name starts after the '=' */
  }
  lua_getglobal(L, "require");
  lua_pushstring(L, modname);
  status = docall(L, 1, 1);  /* call 'require(modname)' */
  if (status == LUA_OK) {
    if (suffix != NULL)  /* is there a suffix mark? */
      *suffix = '\0';  /* remove suffix from global name */
    lua_setglobal(L, globname);  /* globname = require(modname) */
  }
  return report(L, status);
}
 
 
/*
** Push on the stack the contents of table 'arg' from 1 to #arg
*/
static int pushargs (lua_State *L) {
  int i, n;
  /* //FAUDES: original 5.4.8 */
  //if (lua_getglobal(L, "arg") != LUA_TTABLE)
  //  luaL_error(L, "'arg' is not a table");
  /* //FAUDES: version agnostic variant */
  lua_getglobal(L, "arg");
  if(lua_type(L, -1) != LUA_TTABLE)
    luaL_error(L, "'arg' is not a table");
  /* //FAUDES: end */
#if LUA_VERSION_NUM >= 504 
  /* //FAUDES: original 5.4.8 */
  n = (int)luaL_len(L, -1);
#else  
  /* //FAUDES: original 5.1.3 */.
  n = 0;
  if(!luaL_callmeta(L, -1, "__len"))
    n= (int) lua_objlen(L,-1);
#endif  
  luaL_checkstack(L, n + 3, "too many arguments to script");
  for (i = 1; i <= n; i++)
    lua_rawgeti(L, -i, i);
  lua_remove(L, -i);  /* remove table from the stack */
  return n;
}
 
 
static int handle_script (lua_State *L, char **argv) {
  int status;
  const char *fname = argv[0];
  if (strcmp(fname, "-") == 0 && strcmp(argv[-1], "--") != 0)
    fname = NULL;  /* stdin */
  status = luaL_loadfile(L, fname);
  if (status == LUA_OK) {
    int n = pushargs(L);  /* push arguments to script */
    status = docall(L, n, LUA_MULTRET);
  }
  return report(L, status);
}
 
 
/* bits of various argument indicators in 'args' */
#define has_error 1 /* bad option */
#define has_i   2 /* -i */
#define has_v   4 /* -v */
#define has_e   8 /* -e */
#define has_E   16  /* -E */
#define has_x   32  /* //FAUDES: -x */
#define has_d   64  /* //FAUDES: -d */
 
 
/*
** Traverses all arguments from 'argv', returning a mask with those
** needed before running any Lua code or an error code if it finds any
** invalid argument. In case of error, 'first' is the index of the bad
** argument.  Otherwise, 'first' is -1 if there is no program name,
** 0 if there is no script name, or the index of the script name.
*/
static int collectargs (char **argv, int *first) {
  int args = 0;
  int i;
  if (argv[0] != NULL) {  /* is there a program name? */
    if (argv[0][0])  /* not empty? */
      progname = argv[0];  /* save it */
  }
  else {  /* no program name */
    *first = -1;
    return 0;
  }
  for (i = 1; argv[i] != NULL; i++) {  /* handle arguments */
    *first = i;
    if (argv[i][0] != '-')  /* not an option? */
        return args;  /* stop handling options */
    switch (argv[i][1]) {  /* else check option */
      case '-':  /* '--' */
        if (argv[i][2] != '\0')  /* extra characters after '--'? */
          return has_error;  /* invalid option */
        *first = i + 1;
        return args;
      case '\0':  /* '-' */
        return args;  /* script "name" is '-' */
      case 'E':
        if (argv[i][2] != '\0')  /* extra characters? */
          return has_error;  /* invalid option */
        args |= has_E;
        break;
      case 'W':
        if (argv[i][2] != '\0')  /* extra characters? */
          return has_error;  /* invalid option */
        break;
      case 'i':
        args |= has_i;  /* (-i implies -v) *//* FALLTHROUGH */
      case 'v':
        if (argv[i][2] != '\0')  /* extra characters? */
          return has_error;  /* invalid option */
        args |= has_v;
        break;
      case 'e':
        args |= has_e;  /* FALLTHROUGH */
      case 'l':  /* both options need an argument */
        if (argv[i][2] == '\0') {  /* no concatenated argument? */
          i++;  /* try next 'argv' */
          if (argv[i] == NULL || argv[i][0] == '-')
            return has_error;  /* no next argument or it is another option */
        }
        break;
      case 'd':     /* //FAUDES: d-option */
        if (argv[i][2] != '\0')  /* extra characters? */
          return has_error;  /* invalid option */
        args |= has_d;
        break;
      case 'x': /* //FAUDES: -x: needs an argument and sets the flag */
        if (argv[i][2] == '\0') {  /* no concatenated argument? */
          i++;  /* try next 'argv' */
          if (argv[i] == NULL || argv[i][0] == '-')
            return has_error;  /* no next argument or it is another option */
        }
        args |= has_x;
        break;
      default:  /* invalid option */
        return has_error;
    }
  }
  *first = 0;  /* no script name */
  return args;
}
 
 
/*
** Processes options 'e' and 'l', which involve running Lua code, and
** 'W', which also affects the state.
** Returns 0 if some code raises an error.
*/
static int runargs (lua_State *L, char **argv, int n) {
  int i;
  for (i = 1; i < n; i++) {
    int option = argv[i][1];
    lua_assert(argv[i][0] == '-');  /* already checked */
    switch (option) {
      case 'e':  case 'l': {
        int status;
        char *extra = argv[i] + 2;  /* both options need an argument */
        if (*extra == '\0') extra = argv[++i];
        lua_assert(extra != NULL);
        status = (option == 'e')
                 ? dostring(L, extra, "=(command line)")
                 : dolibrary(L, extra);
        if (status != LUA_OK) return 0;
        break;
      }
#if LUA_VERSION_NUM >= 504
  /* //FAUDES: original 5.4.8 code (warnings not available in 5.1.3) */ 
      case 'W':
        lua_warning(L, "@on", 0);  /* warnings on */
        break;
#endif  
      case 'x': {  /* //FAUDES: load faudes extension */
        const char *filename = argv[i] + 2;
        if (*filename == '\0') filename = argv[++i];
        lua_assert(filename != NULL);
        if (faudes_loadext(L, filename)) {
          l_message("fatal error: failed to load extension", filename);
          return 1;  /* stop if file fails */
        }
        break;
      }
    }
  }
  return 1;
}
 
 
static int handle_luainit (lua_State *L) {
  const char *name = "=" LUA_INITVARVERSION;
  const char *init = getenv(name + 1);
  if (init == NULL) {
    name = "=" LUA_INIT_VAR;
    init = getenv(name + 1);  /* try alternative name */
  }
  if (init == NULL) return LUA_OK;
  else if (init[0] == '@')
    return dofile(L, init+1);
  else
    return dostring(L, init, name);
}
 
 
/*
** {==================================================================
** Read-Eval-Print Loop (REPL)
** ===================================================================
*/
 
#if !defined(LUA_PROMPT)
#define LUA_PROMPT    "> "
#define LUA_PROMPT2   ">> "
#endif
 
#if !defined(LUA_MAXINPUT)
#define LUA_MAXINPUT    512
#endif
 
 
/*
** lua_stdin_is_tty detects whether the standard input is a 'tty' (that
** is, whether we're running lua interactively).
*/
#if !defined(lua_stdin_is_tty)  /* { */
 
#if defined(LUA_USE_POSIX)  /* { */
 
#include <unistd.h>
#define lua_stdin_is_tty()  isatty(0)
 
#elif defined(LUA_USE_WINDOWS)  /* }{ */
 
#include <io.h>
#include <windows.h>
 
#define lua_stdin_is_tty()  _isatty(_fileno(stdin))
 
#else       /* }{ */
 
/* ISO C definition */
#define lua_stdin_is_tty()  1  /* assume stdin is a tty */
 
#endif        /* } */
 
#endif        /* } */
 
 
/*
** lua_readline defines how to show a prompt and then read a line from
** the standard input.
** lua_saveline defines how to "save" a read line in a "history".
** lua_freeline defines how to free a line read by lua_readline.
*/
#if !defined(lua_readline)  /* { */
 
#if defined(LUA_USE_READLINE) /* { */
 
/*
** //FAUDES: here we to be advanced readline support patch by Mike Pall. However,
** we required some variations for SWIG __index functions and we also wanted identifier-
** completion in DESTool. Thus, we moved the original completer code to LuaState 
** (see lbp_function.cpp and lbp_completer.cpp) and provide a C interface via
** luafaudes_complete() (see lbp_addons.cpp). The below code is reduced to the libreadline 
** interface. The original patch still ships with libFAUDES for reference and can be 
** inspected in plugins/luabindings/lib  
**
** Original License/Copyright
**
** Copyright (C) 2004-2006 Mike Pall. Same license as Lua. See lua.h.
**
*/
 
#include <readline/readline.h>
#include <readline/history.h>
 
static char *lua_rl_hist;
static int lua_rl_histsize;
 
static lua_State *lua_rl_L;  /* User data is not passed to rl callbacks. */
 
/* luafaudes: pass on global state */
static char **faudes_complete_L(const char *text, int start, int end) {
  return faudes_complete(lua_rl_L,text,start,end);
}  
 
/* Initialize readline library. */
static void lua_initreadline(lua_State *L) {
  char *s;
  lua_rl_L = L;
 
  /* This allows for $if lua ... $endif in ~/.inputrc. */
  rl_readline_name = "lua";
  /* Break words at every non-identifier character except '.' and ':'. */
  rl_completer_word_break_characters = (char *) 
    "\t\r\n !\"#$%&'()*+,-/;<=>?@[\\]^`{|}~"; //FAUDES: pragmatic avoidance of compiler warning
 
  rl_completer_quote_characters = "\"'";
  rl_completion_append_character = '\0';
  rl_attempted_completion_function = faudes_complete_L; //FAUDES: use libFAUDES variant
  rl_initialize();
 
  /* Start using history, optionally set history size and load history file. */
  using_history();
  if ((s = getenv("LUA_HISTSIZE")) &&
      (lua_rl_histsize = atoi(s))) stifle_history(lua_rl_histsize);
  if ((lua_rl_hist = getenv("LUA_HISTORY"))) read_history(lua_rl_hist);
}
 
/* Finalize readline library. */
static void lua_exitreadline(lua_State *L) {
  (void) L;
  /* Optionally save history file. */
  if (lua_rl_hist) write_history(lua_rl_hist);
}
 
#define lua_readline(L,b,p) ((void)L, ((b)=readline(p)) != NULL)
#define lua_saveline(L,line)  ((void)L, add_history(line))
#define lua_freeline(L,b) ((void)L, free(b))
 
 
#else       /* }{ */
 
#define lua_initreadline(L)  ((void)L)
#define lua_readline(L,b,p) \
        ((void)L, fputs(p, stdout), fflush(stdout),  /* show prompt */ \
        fgets(b, LUA_MAXINPUT, stdin) != NULL)  /* get line */
#define lua_saveline(L,line)  { (void)L; (void)line; }
#define lua_freeline(L,b) { (void)L; (void)b; }
#define lua_exitreadline(L) { (void)L; }
 
#endif        /* } */
 
#endif        /* } */
 
 
/*
** Return the string to be used as a prompt by the interpreter. Leave
** the string (or nil, if using the default value) on the stack, to keep
** it anchored.
*/
static const char *get_prompt (lua_State *L, int firstline) {
  const char* p;
#if LUA_VERSION_NUM >= 504 
  /* //FAUDES: original Lua 5.4.8 */
  if (lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2") == LUA_TNIL)
   return (firstline ? LUA_PROMPT : LUA_PROMPT2);  /* use the default */
  else {  /* apply 'tostring' over the value */
    const char *p = luaL_tolstring(L, -1, NULL);
    lua_remove(L, -2);  /* remove original value */
    return p;
  }
  /* //FAUDES: end */
#else
  /* //FAUDES: (sort of) original Lua 5.1.3 */
  lua_getglobal(L, firstline ? "_PROMPT" : "_PROMPT2");
  p = lua_tostring(L, -1);
  if (p == NULL) p = (firstline ? LUA_PROMPT : LUA_PROMPT2);
  return p;
  /* //FAUDES: end */
#endif
}
 
/* mark in error messages for incomplete statements */
#define EOFMARK   "<eof>"
#define marklen   (sizeof(EOFMARK)/sizeof(char) - 1)
 
 
/*
** Check whether 'status' signals a syntax error and the error
** message at the top of the stack ends with the above mark for
** incomplete statements.
*/
static int incomplete (lua_State *L, int status) {
  if (status == LUA_ERRSYNTAX) {
    size_t lmsg;
    const char *msg = lua_tolstring(L, -1, &lmsg);
    if (lmsg >= marklen && strcmp(msg + lmsg - marklen, EOFMARK) == 0)
      return 1;
  }
  return 0;  /* else... */
}
 
 
/*
** Prompt the user, read a line, and push it into the Lua stack.
*/
static int pushline (lua_State *L, int firstline) {
  char buffer[LUA_MAXINPUT];
  char *b = buffer;
  size_t l;
  const char *prmt = get_prompt(L, firstline);
  int readstatus = lua_readline(L, b, prmt);
  lua_pop(L, 1);  /* remove prompt */
  if (readstatus == 0)
    return 0;  /* no input */
  l = strlen(b);
  if (l > 0 && b[l-1] == '\n')  /* line ends with newline? */
    b[--l] = '\0';  /* remove it */
  if (firstline && b[0] == '=')  /* for compatibility with 5.2, ... */
    lua_pushfstring(L, "return %s", b + 1);  /* change '=' to 'return' */
  else
    lua_pushlstring(L, b, l);
  lua_freeline(L, b);
  return 1;
}
 
 
/*
** Try to compile line on the stack as 'return <line>;'; on return, stack
** has either compiled chunk or original line (if compilation failed).
*/
static int addreturn (lua_State *L) {
  const char *line = lua_tostring(L, -1);  /* original line */
  const char *retline = lua_pushfstring(L, "return %s;", line);
  int status = luaL_loadbuffer(L, retline, strlen(retline), "=stdin");
  if (status == LUA_OK) {
    lua_remove(L, -2);  /* remove modified line */
    if (line[0] != '\0')  /* non empty? */
      lua_saveline(L, line);  /* keep history */
  }
  else
    lua_pop(L, 2);  /* pop result from 'luaL_loadbuffer' and modified line */
  return status;
}
 
 
/*
** Read multiple lines until a complete Lua statement
*/
static int multiline (lua_State *L) {
  for (;;) {  /* repeat until gets a complete statement */
    size_t len;
    const char *line = lua_tolstring(L, 1, &len);  /* get what it has */
    int status = luaL_loadbuffer(L, line, len, "=stdin");  /* try it */
    if (!incomplete(L, status) || !pushline(L, 0)) {
      lua_saveline(L, line);  /* keep history */
      return status;  /* should not or cannot try to add continuation line */
    }
    lua_remove(L, -2);  /* remove error message (from incomplete line) */
    lua_pushliteral(L, "\n");  /* add newline... */
    lua_insert(L, -2);  /* ...between the two lines */
    lua_concat(L, 3);  /* join them */
  }
}
 
 
/*
** Read a line and try to load (compile) it first as an expression (by
** adding "return " in front of it) and second as a statement. Return
** the final status of load/call with the resulting function (if any)
** in the top of the stack.
*/
static int loadline (lua_State *L) {
  int status;
  lua_settop(L, 0);
  if (!pushline(L, 1))
    return -1;  /* no input */
  if ((status = addreturn(L)) != LUA_OK)  /* 'return ...' did not work? */
    status = multiline(L);  /* try as command, maybe with continuation lines */
  lua_remove(L, 1);  /* remove line from the stack */
  lua_assert(lua_gettop(L) == 1);
  return status;
}
 
 
/*
** Prints (calling the Lua 'print' function) any values on the stack
*/
static void l_print (lua_State *L) {
  int n = lua_gettop(L);
  if (n > 0) {  /* any result to be printed? */
    luaL_checkstack(L, LUA_MINSTACK, "too many results to print");
    lua_getglobal(L, "print");
    lua_insert(L, 1);
    if (lua_pcall(L, n, 0, 0) != LUA_OK)
      l_message(progname, lua_pushfstring(L, "error calling 'print' (%s)",
                                             lua_tostring(L, -1)));
  }
}
 
 
/*
** Do the REPL: repeatedly read (load) a line, evaluate (call) it, and
** print any results.
*/
static void doREPL (lua_State *L) {
  int status;
  const char *oldprogname = progname;
  progname = NULL;  /* no 'progname' on errors in interactive mode */
  lua_initreadline(L);
  while ((status = loadline(L)) != -1) {
    if (status == LUA_OK)
      status = docall(L, 0, LUA_MULTRET);
    if (status == LUA_OK) l_print(L);
    else report(L, status);
  }
  lua_settop(L, 0);  /* clear stack */
  lua_writeline();
  lua_exitreadline(L); /* //FAUDES */
  progname = oldprogname;
}
 
/* }================================================================== */
 
 
/*
** Main body of stand-alone interpreter (to be called in protected mode).
** Reads the options and handles them all.
*/
 
static int pmain (lua_State *L) {
  int argc = (int)lua_tointeger(L, 1);
  char **argv = (char **)lua_touserdata(L, 2);
  int script;
  int args = collectargs(argv, &script);
  int optlim = (script > 0) ? script : argc; /* first argv not an option */
 
  /* //FAUDES: version agnostic (not available in 5.1.3) */
#if LUA_VERSION_NUM >= 504 
  luaL_checkversion(L);  /* check that interpreter has correct version */
#endif
  /* //FAUDES: end */  
  if (args == has_error) {  /* bad arg? */
    print_usage(argv[script]);  /* 'script' has index of bad arg. */
    return 0;
  }
  if (args & has_v)  /* option '-v'? */
    print_version();
  if (args & has_d)  /* //FAUDES: option '-d'? */
    Verbosity(999);
  else
    Verbosity(0);    
#if LUA_VERSION_NUM >= 504 
  /* //FAUDES: original 5.4.8 (not available in 5.1.3) */
  if (args & has_E) {  /* option '-E'? */
    lua_pushboolean(L, 1);  /* signal for libraries to ignore env. vars. */
    lua_setfield(L, LUA_REGISTRYINDEX, "LUA_NOENV");
  }
#endif  
  luaL_openlibs(L);  /* open standard libraries */
  luaopen_faudes_allplugins(L); /* //FAUDES: load all faudes bindings */
  createargtable(L, argv, argc, script);  /* create table 'arg' */
#if LUA_VERSION_NUM >= 504 
  /* //FAUDES: original 5.4.8 */
  lua_gc(L, LUA_GCRESTART);  /* start GC... */
  lua_gc(L, LUA_GCGEN, 0, 0);  /* ...in generational mode */
#else
  /* //FAUDES: 5.1.3 stype */
  lua_gc(L, LUA_GCRESTART,0);  /* start GC... */
#endif    
  if (!(args & has_E)) {  /* no option '-E'? */
    if (handle_luainit(L) != LUA_OK)  /* run LUA_INIT */
      return 0;  /* error running LUA_INIT */
  }
  if (!runargs(L, argv, optlim))  /* execute arguments -e, -l  //FAUDES and -x */
    return 0;  /* something failed */
  if (!(args & has_x))
    faudes_loaddefext(L, argv[0]);  /* //FAUDES: load default extension */
  if (script > 0) {  /* execute main script (if there is one) */
    if (handle_script(L, argv + script) != LUA_OK)
      return 0;  /* interrupt in case of error */
  }
  if (args & has_i)  /* -i option? */
    doREPL(L);  /* do read-eval-print loop */
  else if (script < 1 && !(args & (has_e | has_v))) { /* no active option? */
    if (faudes_stdin_is_tty()) {  /* running in interactive mode? */
      print_version();
      doREPL(L);  /* do read-eval-print loop */
    }
    else dofile(L, NULL);  /* executes stdin as a file */
  }
  lua_pushboolean(L, 1);  /* signal no errors */
  return 1;
}
 
 
int main (int argc, char **argv) {
  int status, result;
  lua_State *L = luaL_newstate();  /* create state */
  if (L == NULL) {
    l_message(argv[0], "cannot create state: not enough memory");
    return EXIT_FAILURE;
  }
#if LUA_VERSION_NUM >= 504 
  /* //FAUDES: original 5.4.8 */
  lua_gc(L, LUA_GCSTOP);  /* stop GC while building state */
#else
  /* //FAUDES: 5.1.3 style */
  lua_gc(L, LUA_GCSTOP,0);  /* stop GC while building state */
#endif    
  lua_pushcfunction(L, &pmain);  /* to call 'pmain' in protected mode */
  lua_pushinteger(L, argc);  /* 1st argument */
  lua_pushlightuserdata(L, argv); /* 2nd argument */
  status = lua_pcall(L, 2, 1, 0);  /* do the call */
  result = lua_toboolean(L, -1);  /* get result */
  report(L, status);
  lua_close(L);
  return (result && status == LUA_OK) ? EXIT_SUCCESS : EXIT_FAILURE;
}
 
 
/* //FAUDES: end skip doxygen */
#endif