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/*

** $Id: lauxlib.c,v 1.240 2011/12/06 16:33:55 roberto Exp $

** Auxiliary functions for building Lua libraries

** See Copyright Notice in lua.h

*/

#include 

#include 

#include 

#include 

#include 

/* This file uses only the official API of Lua.

** Any function declared here could be written as an application function.

*/

#define lauxlib_c

#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"

/*

** {======================================================

** Traceback

** =======================================================

*/

#define LEVELS1	12	/* size of the first part of the stack */

#define LEVELS2	10	/* size of the second part of the stack */

/*

** search for 'objidx' in table at index -1.

** return 1 + string at top if find a good name.

*/

static int findfield (lua_State *L, int objidx, int level) {

  if (level == 0 || !lua_istable(L, -1))

    return 0;  /* not found */

  lua_pushnil(L);  /* start 'next' loop */

  while (lua_next(L, -2)) {  /* for each pair in table */

    if (lua_type(L, -2) == LUA_TSTRING) {  /* ignore non-string keys */

      if (lua_rawequal(L, objidx, -1)) {  /* found object? */

        lua_pop(L, 1);  /* remove value (but keep name) */

        return 1;

      }

      else if (findfield(L, objidx, level - 1)) {  /* try recursively */

        lua_remove(L, -2);  /* remove table (but keep name) */

        lua_pushliteral(L, ".");

        lua_insert(L, -2);  /* place '.' between the two names */

        lua_concat(L, 3);

        return 1;

      }

    }

    lua_pop(L, 1);  /* remove value */

  }

  return 0;  /* not found */

}

static int pushglobalfuncname (lua_State *L, lua_Debug *ar) {

  int top = lua_gettop(L);

  lua_getinfo(L, "f", ar);  /* push function */

  lua_pushglobaltable(L);

  if (findfield(L, top + 1, 2)) {

    lua_copy(L, -1, top + 1);  /* move name to proper place */

    lua_pop(L, 2);  /* remove pushed values */

    return 1;

  }

  else {

    lua_settop(L, top);  /* remove function and global table */

    return 0;

  }

}

static void pushfuncname (lua_State *L, lua_Debug *ar) {

  if (*ar->namewhat != '\0')  /* is there a name? */

    lua_pushfstring(L, "function " LUA_QS, ar->name);

  else if (*ar->what == 'm')  /* main? */

      lua_pushfstring(L, "main chunk");

  else if (*ar->what == 'C') {

    if (pushglobalfuncname(L, ar)) {

      lua_pushfstring(L, "function " LUA_QS, lua_tostring(L, -1));

      lua_remove(L, -2);  /* remove name */

    }

    else

      lua_pushliteral(L, "?");

  }

  else

    lua_pushfstring(L, "function <%s:%d>", ar->short_src, ar->linedefined);

}

static int countlevels (lua_State *L) {

  lua_Debug ar;

  int li = 1, le = 1;

  /* find an upper bound */

  while (lua_getstack(L, le, &ar)) { li = le; le *= 2; }

  /* do a binary search */

  while (li < le) {

    int m = (li + le)/2;

    if (lua_getstack(L, m, &ar)) li = m + 1;

    else le = m;

  }

  return le - 1;

}

LUALIB_API void luaL_traceback (lua_State *L, lua_State *L1,

                                const char *msg, int level) {

  lua_Debug ar;

  int top = lua_gettop(L);

  int numlevels = countlevels(L1);

  int mark = (numlevels > LEVELS1 + LEVELS2) ? LEVELS1 : 0;

  if (msg) lua_pushfstring(L, "%s\n", msg);

  lua_pushliteral(L, "stack traceback:");

  while (lua_getstack(L1, level++, &ar)) {

    if (level == mark) {  /* too many levels? */

      lua_pushliteral(L, "\n\t...");  /* add a '...' */

      level = numlevels - LEVELS2;  /* and skip to last ones */

    }

    else {

      lua_getinfo(L1, "Slnt", &ar);

      lua_pushfstring(L, "\n\t%s:", ar.short_src);

      if (ar.currentline > 0)

        lua_pushfstring(L, "%d:", ar.currentline);

      lua_pushliteral(L, " in ");

      pushfuncname(L, &ar);

      if (ar.istailcall)

        lua_pushliteral(L, "\n\t(...tail calls...)");

      lua_concat(L, lua_gettop(L) - top);

    }

  }

  lua_concat(L, lua_gettop(L) - top);

}

/* }====================================================== */

/*

** {======================================================

** Error-report functions

** =======================================================

*/

LUALIB_API int luaL_argerror (lua_State *L, int narg, const char *extramsg) {

  lua_Debug ar;

  if (!lua_getstack(L, 0, &ar))  /* no stack frame? */

    return luaL_error(L, "bad argument #%d (%s)", narg, extramsg);

  lua_getinfo(L, "n", &ar);

  if (strcmp(ar.namewhat, "method") == 0) {

    narg--;  /* do not count `self' */

    if (narg == 0)  /* error is in the self argument itself? */

      return luaL_error(L, "calling " LUA_QS " on bad self", ar.name);

  }

  if (ar.name == NULL)

    ar.name = (pushglobalfuncname(L, &ar)) ? lua_tostring(L, -1) : "?";

  return luaL_error(L, "bad argument #%d to " LUA_QS " (%s)",

                        narg, ar.name, extramsg);

}

static int typeerror (lua_State *L, int narg, const char *tname) {

  const char *msg = lua_pushfstring(L, "%s expected, got %s",

                                    tname, luaL_typename(L, narg));

  return luaL_argerror(L, narg, msg);

}

static void tag_error (lua_State *L, int narg, int tag) {

  typeerror(L, narg, lua_typename(L, tag));

}

LUALIB_API void luaL_where (lua_State *L, int level) {

  lua_Debug ar;

  if (lua_getstack(L, level, &ar)) {  /* check function at level */

    lua_getinfo(L, "Sl", &ar);  /* get info about it */

    if (ar.currentline > 0) {  /* is there info? */

      lua_pushfstring(L, "%s:%d: ", ar.short_src, ar.currentline);

      return;

    }

  }

  lua_pushliteral(L, "");  /* else, no information available... */

}

LUALIB_API int luaL_error (lua_State *L, const char *fmt, ...) {

  va_list argp;

  va_start(argp, fmt);

  luaL_where(L, 1);

  lua_pushvfstring(L, fmt, argp);

  va_end(argp);

  lua_concat(L, 2);

  return lua_error(L);

}

LUALIB_API int luaL_fileresult (lua_State *L, int stat, const char *fname) {

  int en = errno;  /* calls to Lua API may change this value */

  if (stat) {

    lua_pushboolean(L, 1);

    return 1;

  }

  else {

    lua_pushnil(L);

    if (fname)

      lua_pushfstring(L, "%s: %s", fname, strerror(en));

    else

      lua_pushfstring(L, "%s", strerror(en));

    lua_pushinteger(L, en);

    return 3;

  }

}

#if !defined(inspectstat)	/* { */

#if defined(LUA_USE_POSIX)

#include 

/*

** use appropriate macros to interpret 'pclose' return status

*/

#define inspectstat(stat,what)  \

   if (WIFEXITED(stat)) { stat = WEXITSTATUS(stat); } \

   else if (WIFSIGNALED(stat)) { stat = WTERMSIG(stat); what = "signal"; }

#else

#define inspectstat(stat,what)  /* no op */

#endif

#endif				/* } */

LUALIB_API int luaL_execresult (lua_State *L, int stat) {

  const char *what = "exit";  /* type of termination */

  if (stat == -1)  /* error? */

    return luaL_fileresult(L, 0, NULL);

  else {

    inspectstat(stat, what);  /* interpret result */

    if (*what == 'e' && stat == 0)  /* successful termination? */

      lua_pushboolean(L, 1);

    else

      lua_pushnil(L);

    lua_pushstring(L, what);

    lua_pushinteger(L, stat);

    return 3;  /* return true/nil,what,code */

  }

}

/* }====================================================== */

/*

** {======================================================

** Userdata's metatable manipulation

** =======================================================

*/

LUALIB_API int luaL_newmetatable (lua_State *L, const char *tname) {

  luaL_getmetatable(L, tname);  /* try to get metatable */

  if (!lua_isnil(L, -1))  /* name already in use? */

    return 0;  /* leave previous value on top, but return 0 */

  lua_pop(L, 1);

  lua_newtable(L);  /* create metatable */

  lua_pushvalue(L, -1);

  lua_setfield(L, LUA_REGISTRYINDEX, tname);  /* registry.name = metatable */

  return 1;

}

LUALIB_API void luaL_setmetatable (lua_State *L, const char *tname) {

  luaL_getmetatable(L, tname);

  lua_setmetatable(L, -2);

}

LUALIB_API void *luaL_testudata (lua_State *L, int ud, const char *tname) {

  void *p = lua_touserdata(L, ud);

  if (p != NULL) {  /* value is a userdata? */

    if (lua_getmetatable(L, ud)) {  /* does it have a metatable? */

      luaL_getmetatable(L, tname);  /* get correct metatable */

      if (!lua_rawequal(L, -1, -2))  /* not the same? */

        p = NULL;  /* value is a userdata with wrong metatable */

      lua_pop(L, 2);  /* remove both metatables */

      return p;

    }

  }

  return NULL;  /* value is not a userdata with a metatable */

}

LUALIB_API void *luaL_checkudata (lua_State *L, int ud, const char *tname) {

  void *p = luaL_testudata(L, ud, tname);

  if (p == NULL) typeerror(L, ud, tname);

  return p;

}

/* }====================================================== */

/*

** {======================================================

** Argument check functions

** =======================================================

*/

LUALIB_API int luaL_checkoption (lua_State *L, int narg, const char *def,

                                 const char *const lst[]) {

  const char *name = (def) ? luaL_optstring(L, narg, def) :

                             luaL_checkstring(L, narg);

  int i;

  for (i=0; lst[i]; i++)

    if (strcmp(lst[i], name) == 0)

      return i;

  return luaL_argerror(L, narg,

                       lua_pushfstring(L, "invalid option " LUA_QS, name));

}

LUALIB_API void luaL_checkstack (lua_State *L, int space, const char *msg) {

  /* keep some extra space to run error routines, if needed */

  const int extra = LUA_MINSTACK;

  if (!lua_checkstack(L, space + extra)) {

    if (msg)

      luaL_error(L, "stack overflow (%s)", msg);

    else

      luaL_error(L, "stack overflow");

  }

}

LUALIB_API void luaL_checktype (lua_State *L, int narg, int t) {

  if (lua_type(L, narg) != t)

    tag_error(L, narg, t);

}

LUALIB_API void luaL_checkany (lua_State *L, int narg) {

  if (lua_type(L, narg) == LUA_TNONE)

    luaL_argerror(L, narg, "value expected");

}

LUALIB_API const char *luaL_checklstring (lua_State *L, int narg, size_t *len) {

  const char *s = lua_tolstring(L, narg, len);

  if (!s) tag_error(L, narg, LUA_TSTRING);

  return s;

}

LUALIB_API const char *luaL_optlstring (lua_State *L, int narg,

                                        const char *def, size_t *len) {

  if (lua_isnoneornil(L, narg)) {

    if (len)

      *len = (def ? strlen(def) : 0);

    return def;

  }

  else return luaL_checklstring(L, narg, len);

}

LUALIB_API lua_Number luaL_checknumber (lua_State *L, int narg) {

  int isnum;

  lua_Number d = lua_tonumberx(L, narg, &isnum);

  if (!isnum)

    tag_error(L, narg, LUA_TNUMBER);

  return d;

}

LUALIB_API lua_Number luaL_optnumber (lua_State *L, int narg, lua_Number def) {

  return luaL_opt(L, luaL_checknumber, narg, def);

}

LUALIB_API lua_Integer luaL_checkinteger (lua_State *L, int narg) {

  int isnum;

  lua_Integer d = lua_tointegerx(L, narg, &isnum);

  if (!isnum)

    tag_error(L, narg, LUA_TNUMBER);

  return d;

}

LUALIB_API lua_Unsigned luaL_checkunsigned (lua_State *L, int narg) {

  int isnum;

  lua_Unsigned d = lua_tounsignedx(L, narg, &isnum);

  if (!isnum)

    tag_error(L, narg, LUA_TNUMBER);

  return d;

}

LUALIB_API lua_Integer luaL_optinteger (lua_State *L, int narg,

                                                      lua_Integer def) {

  return luaL_opt(L, luaL_checkinteger, narg, def);

}

LUALIB_API lua_Unsigned luaL_optunsigned (lua_State *L, int narg,

                                                        lua_Unsigned def) {

  return luaL_opt(L, luaL_checkunsigned, narg, def);

}

/* }====================================================== */

/*

** {======================================================

** Generic Buffer manipulation

** =======================================================

*/

/*

** check whether buffer is using a userdata on the stack as a temporary

** buffer

*/

#define buffonstack(B)	((B)->b != (B)->initb)

/*

** returns a pointer to a free area with at least 'sz' bytes

*/

LUALIB_API char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz) {

  lua_State *L = B->L;

  if (B->size - B->n < sz) {  /* not enough space? */

    char *newbuff;

    size_t newsize = B->size * 2;  /* double buffer size */

    if (newsize - B->n < sz)  /* not bit enough? */

      newsize = B->n + sz;

    if (newsize < B->n || newsize - B->n < sz)

      luaL_error(L, "buffer too large");

    /* create larger buffer */

    newbuff = (char *)lua_newuserdata(L, newsize * sizeof(char));

    /* move content to new buffer */

    memcpy(newbuff, B->b, B->n * sizeof(char));

    if (buffonstack(B))

      lua_remove(L, -2);  /* remove old buffer */

    B->b = newbuff;

    B->size = newsize;

  }

  return &B->b[B->n];

}

LUALIB_API void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l) {

  char *b = luaL_prepbuffsize(B, l);

  memcpy(b, s, l * sizeof(char));

  luaL_addsize(B, l);

}

LUALIB_API void luaL_addstring (luaL_Buffer *B, const char *s) {

  luaL_addlstring(B, s, strlen(s));

}

LUALIB_API void luaL_pushresult (luaL_Buffer *B) {

  lua_State *L = B->L;

  lua_pushlstring(L, B->b, B->n);

  if (buffonstack(B))

    lua_remove(L, -2);  /* remove old buffer */

}

LUALIB_API void luaL_pushresultsize (luaL_Buffer *B, size_t sz) {

  luaL_addsize(B, sz);

  luaL_pushresult(B);

}

LUALIB_API void luaL_addvalue (luaL_Buffer *B) {

  lua_State *L = B->L;

  size_t l;

  const char *s = lua_tolstring(L, -1, &l);

  if (buffonstack(B))

    lua_insert(L, -2);  /* put value below buffer */

  luaL_addlstring(B, s, l);

  lua_remove(L, (buffonstack(B)) ? -2 : -1);  /* remove value */

}

LUALIB_API void luaL_buffinit (lua_State *L, luaL_Buffer *B) {

  B->L = L;

  B->b = B->initb;

  B->n = 0;

  B->size = LUAL_BUFFERSIZE;

}

LUALIB_API char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz) {

  luaL_buffinit(L, B);

  return luaL_prepbuffsize(B, sz);

}

/* }====================================================== */

/*

** {======================================================

** Reference system

** =======================================================

*/

/* index of free-list header */

#define freelist	0

LUALIB_API int luaL_ref (lua_State *L, int t) {

  int ref;

  t = lua_absindex(L, t);

  if (lua_isnil(L, -1)) {

    lua_pop(L, 1);  /* remove from stack */

    return LUA_REFNIL;  /* `nil' has a unique fixed reference */

  }

  lua_rawgeti(L, t, freelist);  /* get first free element */

  ref = (int)lua_tointeger(L, -1);  /* ref = t[freelist] */

  lua_pop(L, 1);  /* remove it from stack */

  if (ref != 0) {  /* any free element? */

    lua_rawgeti(L, t, ref);  /* remove it from list */

    lua_rawseti(L, t, freelist);  /* (t[freelist] = t[ref]) */

  }

  else  /* no free elements */

    ref = (int)lua_rawlen(L, t) + 1;  /* get a new reference */

  lua_rawseti(L, t, ref);

  return ref;

}

LUALIB_API void luaL_unref (lua_State *L, int t, int ref) {

  if (ref >= 0) {

    t = lua_absindex(L, t);

    lua_rawgeti(L, t, freelist);

    lua_rawseti(L, t, ref);  /* t[ref] = t[freelist] */

    lua_pushinteger(L, ref);

    lua_rawseti(L, t, freelist);  /* t[freelist] = ref */

  }

}

/* }====================================================== */

/*

** {======================================================

** Load functions

** =======================================================

*/

typedef struct LoadF {

  int n;  /* number of pre-read characters */

  FILE *f;  /* file being read */

  char buff[LUAL_BUFFERSIZE];  /* area for reading file */

} LoadF;

static const char *getF (lua_State *L, void *ud, size_t *size) {

  LoadF *lf = (LoadF *)ud;

  (void)L;  /* not used */

  if (lf->n > 0) {  /* are there pre-read characters to be read? */

    *size = lf->n;  /* return them (chars already in buffer) */

    lf->n = 0;  /* no more pre-read characters */

  }

  else {  /* read a block from file */

    /* 'fread' can return > 0 *and* set the EOF flag. If next call to

       'getF' called 'fread', it might still wait for user input.

       The next check avoids this problem. */

    if (feof(lf->f)) return NULL;

    *size = fread(lf->buff, 1, sizeof(lf->buff), lf->f);  /* read block */

  }

  return lf->buff;

}

static int errfile (lua_State *L, const char *what, int fnameindex) {

  const char *serr = strerror(errno);

  const char *filename = lua_tostring(L, fnameindex) + 1;

  lua_pushfstring(L, "cannot %s %s: %s", what, filename, serr);

  lua_remove(L, fnameindex);

  return LUA_ERRFILE;

}

static int skipBOM (LoadF *lf) {

  const char *p = "\xEF\xBB\xBF";  /* Utf8 BOM mark */

  int c;

  lf->n = 0;

  do {

    c = getc(lf->f);

    if (c == EOF || c != *(unsigned char *)p++) return c;

    lf->buff[lf->n++] = c;  /* to be read by the parser */

  } while (*p != '\0');

  lf->n = 0;  /* prefix matched; discard it */

  return getc(lf->f);  /* return next character */

}

/*

** reads the first character of file 'f' and skips an optional BOM mark

** in its beginning plus its first line if it starts with '#'. Returns

** true if it skipped the first line.  In any case, '*cp' has the

** first "valid" character of the file (after the optional BOM and

** a first-line comment).

*/

static int skipcomment (LoadF *lf, int *cp) {

  int c = *cp = skipBOM(lf);

  if (c == '#') {  /* first line is a comment (Unix exec. file)? */

    while ((c = getc(lf->f)) != EOF && c != '\n') ;  /* skip first line */

    *cp = getc(lf->f);  /* skip end-of-line */

    return 1;  /* there was a comment */

  }

  else return 0;  /* no comment */

}

LUALIB_API int luaL_loadfilex (lua_State *L, const char *filename,

                                             const char *mode) {

  LoadF lf;

  int status, readstatus;

  int c;

  int fnameindex = lua_gettop(L) + 1;  /* index of filename on the stack */

  if (filename == NULL) {

    lua_pushliteral(L, "=stdin");

    lf.f = stdin;

  }

  else {

    lua_pushfstring(L, "@%s", filename);

    lf.f = fopen(filename, "r");

    if (lf.f == NULL) return errfile(L, "open", fnameindex);

  }

  if (skipcomment(&lf, &c))  /* read initial portion */

    lf.buff[lf.n++] = '\n';  /* add line to correct line numbers */

  if (c == LUA_SIGNATURE[0] && filename) {  /* binary file? */

    lf.f = freopen(filename, "rb", lf.f);  /* reopen in binary mode */

    if (lf.f == NULL) return errfile(L, "reopen", fnameindex);

    skipcomment(&lf, &c);  /* re-read initial portion */

  }

  if (c != EOF)

    lf.buff[lf.n++] = c;  /* 'c' is the first character of the stream */

  status = lua_load(L, getF, &lf, lua_tostring(L, -1), mode);

  readstatus = ferror(lf.f);

  if (filename) fclose(lf.f);  /* close file (even in case of errors) */

  if (readstatus) {

    lua_settop(L, fnameindex);  /* ignore results from `lua_load' */

    return errfile(L, "read", fnameindex);

  }

  lua_remove(L, fnameindex);

  return status;

}

typedef struct LoadS {

  const char *s;

  size_t size;

} LoadS;

static const char *getS (lua_State *L, void *ud, size_t *size) {

  LoadS *ls = (LoadS *)ud;

  (void)L;  /* not used */

  if (ls->size == 0) return NULL;

  *size = ls->size;

  ls->size = 0;

  return ls->s;

}

LUALIB_API int luaL_loadbufferx (lua_State *L, const char *buff, size_t size,

                                 const char *name, const char *mode) {

  LoadS ls;

  ls.s = buff;

  ls.size = size;

  return lua_load(L, getS, &ls, name, mode);

}

LUALIB_API int luaL_loadstring (lua_State *L, const char *s) {

  return luaL_loadbuffer(L, s, strlen(s), s);

}

/* }====================================================== */

LUALIB_API int luaL_getmetafield (lua_State *L, int obj, const char *event) {

  if (!lua_getmetatable(L, obj))  /* no metatable? */

    return 0;

  lua_pushstring(L, event);

  lua_rawget(L, -2);

  if (lua_isnil(L, -1)) {

    lua_pop(L, 2);  /* remove metatable and metafield */

    return 0;

  }

  else {

    lua_remove(L, -2);  /* remove only metatable */

    return 1;

  }

}

LUALIB_API int luaL_callmeta (lua_State *L, int obj, const char *event) {

  obj = lua_absindex(L, obj);

  if (!luaL_getmetafield(L, obj, event))  /* no metafield? */

    return 0;

  lua_pushvalue(L, obj);

  lua_call(L, 1, 1);

  return 1;

}

LUALIB_API int luaL_len (lua_State *L, int idx) {

  int l;

  int isnum;

  lua_len(L, idx);

  l = (int)lua_tointegerx(L, -1, &isnum);

  if (!isnum)

    luaL_error(L, "object length is not a number");

  lua_pop(L, 1);  /* remove object */

  return l;

}

LUALIB_API const char *luaL_tolstring (lua_State *L, int idx, size_t *len) {

  if (!luaL_callmeta(L, idx, "__tostring")) {  /* no metafield? */

    switch (lua_type(L, idx)) {

      case LUA_TNUMBER:

      case LUA_TSTRING:

        lua_pushvalue(L, idx);

        break;

      case LUA_TBOOLEAN:

        lua_pushstring(L, (lua_toboolean(L, idx) ? "true" : "false"));

        break;

      case LUA_TNIL:

        lua_pushliteral(L, "nil");

        break;

      default:

        lua_pushfstring(L, "%s: %p", luaL_typename(L, idx),

                                            lua_topointer(L, idx));

        break;

    }

  }

  return lua_tolstring(L, -1, len);

}

/*

** {======================================================

** Compatibility with 5.1 module functions

** =======================================================

*/

#if defined(LUA_COMPAT_MODULE)

static const char *luaL_findtable (lua_State *L, int idx,

                                   const char *fname, int szhint) {

  const char *e;

  if (idx) lua_pushvalue(L, idx);

  do {

    e = strchr(fname, '.');

    if (e == NULL) e = fname + strlen(fname);

    lua_pushlstring(L, fname, e - fname);

    lua_rawget(L, -2);

    if (lua_isnil(L, -1)) {  /* no such field? */

      lua_pop(L, 1);  /* remove this nil */

      lua_createtable(L, 0, (*e == '.' ? 1 : szhint)); /* new table for field */

      lua_pushlstring(L, fname, e - fname);

      lua_pushvalue(L, -2);

      lua_settable(L, -4);  /* set new table into field */

    }

    else if (!lua_istable(L, -1)) {  /* field has a non-table value? */

      lua_pop(L, 2);  /* remove table and value */

      return fname;  /* return problematic part of the name */

    }

    lua_remove(L, -2);  /* remove previous table */

    fname = e + 1;

  } while (*e == '.');

  return NULL;

}

/*

** Count number of elements in a luaL_Reg list.

*/

static int libsize (const luaL_Reg *l) {

  int size = 0;

  for (; l && l->name; l++) size++;

  return size;

}

/*

** Find or create a module table with a given name. The function

** first looks at the _LOADED table and, if that fails, try a

** global variable with that name. In any case, leaves on the stack

** the module table.

*/

LUALIB_API void luaL_pushmodule (lua_State *L, const char *modname,

                                 int sizehint) {

  luaL_findtable(L, LUA_REGISTRYINDEX, "_LOADED", 1);  /* get _LOADED table */

  lua_getfield(L, -1, modname);  /* get _LOADED[modname] */

  if (!lua_istable(L, -1)) {  /* not found? */

    lua_pop(L, 1);  /* remove previous result */

    /* try global variable (and create one if it does not exist) */

    lua_pushglobaltable(L);

    if (luaL_findtable(L, 0, modname, sizehint) != NULL)

      luaL_error(L, "name conflict for module " LUA_QS, modname);

    lua_pushvalue(L, -1);

    lua_setfield(L, -3, modname);  /* _LOADED[modname] = new table */

  }

  lua_remove(L, -2);  /* remove _LOADED table */

}

LUALIB_API void luaL_openlib (lua_State *L, const char *libname,

                               const luaL_Reg *l, int nup) {

  luaL_checkversion(L);

  if (libname) {

    luaL_pushmodule(L, libname, libsize(l));  /* get/create library table */

    lua_insert(L, -(nup + 1));  /* move library table to below upvalues */

  }

  if (l)

    luaL_setfuncs(L, l, nup);

  else

    lua_pop(L, nup);  /* remove upvalues */

}

#endif

/* }====================================================== */

/*

** set functions from list 'l' into table at top - 'nup'; each

** function gets the 'nup' elements at the top as upvalues.

** Returns with only the table at the stack.

*/

LUALIB_API void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup) {

  luaL_checkstack(L, nup, "too many upvalues");

  for (; l->name != NULL; l++) {  /* fill the table with given functions */

    int i;

    for (i = 0; i < nup; i++)  /* copy upvalues to the top */

      lua_pushvalue(L, -nup);

    lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */

    lua_setfield(L, -(nup + 2), l->name);

  }

  lua_pop(L, nup);  /* remove upvalues */

}

/*

** ensure that stack[idx][fname] has a table and push that table

** into the stack

*/

LUALIB_API int luaL_getsubtable (lua_State *L, int idx, const char *fname) {

  lua_getfield(L, idx, fname);

  if (lua_istable(L, -1)) return 1;  /* table already there */

  else {

    idx = lua_absindex(L, idx);

    lua_pop(L, 1);  /* remove previous result */

    lua_newtable(L);

    lua_pushvalue(L, -1);  /* copy to be left at top */

    lua_setfield(L, idx, fname);  /* assign new table to field */

    return 0;  /* false, because did not find table there */

  }

}

/*

** stripped-down 'require'. Calls 'openf' to open a module,

** registers the result in 'package.loaded' table and, if 'glb'

** is true, also registers the result in the global table.

** Leaves resulting module on the top.

*/

LUALIB_API void luaL_requiref (lua_State *L, const char *modname,

                               lua_CFunction openf, int glb) {

  lua_pushcfunction(L, openf);

  lua_pushstring(L, modname);  /* argument to open function */

  lua_call(L, 1, 1);  /* open module */

  luaL_getsubtable(L, LUA_REGISTRYINDEX, "_LOADED");

  lua_pushvalue(L, -2);  /* make copy of module (call result) */

  lua_setfield(L, -2, modname);  /* _LOADED[modname] = module */

  lua_pop(L, 1);  /* remove _LOADED table */

  if (glb) {

    lua_pushglobaltable(L);

    lua_pushvalue(L, -2);  /* copy of 'mod' */

    lua_setfield(L, -2, modname);  /* _G[modname] = module */

    lua_pop(L, 1);  /* remove _G table */

  }

}

LUALIB_API const char *luaL_gsub (lua_State *L, const char *s, const char *p,

                                                               const char *r) {

  const char *wild;

  size_t l = strlen(p);

  luaL_Buffer b;

  luaL_buffinit(L, &b);

  while ((wild = strstr(s, p)) != NULL) {

    luaL_addlstring(&b, s, wild - s);  /* push prefix */

    luaL_addstring(&b, r);  /* push replacement in place of pattern */

    s = wild + l;  /* continue after `p' */

  }

  luaL_addstring(&b, s);  /* push last suffix */

  luaL_pushresult(&b);

  return lua_tostring(L, -1);

}

static void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) {

  (void)ud; (void)osize;  /* not used */

  if (nsize == 0) {

    free(ptr);

    return NULL;

  }

  else

    return realloc(ptr, nsize);

}

static int panic (lua_State *L) {

  luai_writestringerror("PANIC: unprotected error in call to Lua API (%s)\n",

                   lua_tostring(L, -1));

  return 0;  /* return to Lua to abort */

}

LUALIB_API lua_State *luaL_newstate (void) {

  lua_State *L = lua_newstate(l_alloc, NULL);

  if (L) lua_atpanic(L, &panic);

  return L;

}

LUALIB_API void luaL_checkversion_ (lua_State *L, lua_Number ver) {

  const lua_Number *v = lua_version(L);

  if (v != lua_version(NULL))

    luaL_error(L, "multiple Lua VMs detected");

  else if (*v != ver)

    luaL_error(L, "version mismatch: app. needs %f, Lua core provides %f",

                  ver, *v);

  /* check conversions number -> integer types */

  lua_pushnumber(L, -(lua_Number)0x1234);

  if (lua_tointeger(L, -1) != -0x1234 ||

      lua_tounsigned(L, -1) != (lua_Unsigned)-0x1234)

    luaL_error(L, "bad conversion number->int;"

                  " must recompile Lua with proper settings");

  lua_pop(L, 1);

}