text: /*
  ** $Id: lauxlib.c,v 1.159.1.3 2008/01/21 13:20:51 roberto Exp $
  ** Auxiliary functions for building Lua libraries
  ** See Copyright Notice in lua.h
  */
  
  
  #include <ctype.h>
  #include <errno.h>
  #include <stdarg.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  
  /* 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"
  
  
  #define FREELIST_REF	0	/* free list of references */
  
  
  /* convert a stack index to positive */
  #define abs_index(L, i)		((i) > 0 || (i) <= LUA_REGISTRYINDEX ? (i) : \
  					lua_gettop(L) + (i) + 1)
  
  
  /*
  ** {======================================================
  ** 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 (%s)",
                             ar.name, extramsg);
    }
    if (ar.name == NULL)
      ar.name = "?";
    return luaL_error(L, "bad argument #%d to " LUA_QS " (%s)",
                          narg, ar.name, extramsg);
  }
  
  
  LUALIB_API int luaL_typerror (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) {
    luaL_typerror(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_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 int luaL_newmetatable (lua_State *L, const char *tname) {
    lua_getfield(L, LUA_REGISTRYINDEX, tname);  /* get registry.name */
    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_checkudata (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? */
        lua_getfield(L, LUA_REGISTRYINDEX, tname);  /* get correct metatable */
        if (lua_rawequal(L, -1, -2)) {  /* does it have the correct mt? */
          lua_pop(L, 2);  /* remove both metatables */
          return p;
        }
      }
    }
    luaL_typerror(L, ud, tname);  /* else error */
    return NULL;  /* to avoid warnings */
  }
  
  
  LUALIB_API void luaL_checkstack (lua_State *L, int space, const char *mes) {
    if (!lua_checkstack(L, space))
      luaL_error(L, "stack overflow (%s)", mes);
  }
  
  
  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) {
    lua_Number d = lua_tonumber(L, narg);
    if (d == 0 && !lua_isnumber(L, narg))  /* avoid extra test when d is not 0 */
      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) {
    lua_Integer d = lua_tointeger(L, narg);
    if (d == 0 && !lua_isnumber(L, narg))  /* avoid extra test when d is not 0 */
      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 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 = abs_index(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 void (luaL_register) (lua_State *L, const char *libname,
                                  const luaL_Reg *l) {
    luaI_openlib(L, libname, l, 0);
  }
  
  
  static int libsize (const luaL_Reg *l) {
    int size = 0;
    for (; l->name; l++) size++;
    return size;
  }
  
  
  LUALIB_API void luaI_openlib (lua_State *L, const char *libname,
                                const luaL_Reg *l, int nup) {
    if (libname) {
      int size = libsize(l);
      /* check whether lib already exists */
      luaL_findtable(L, LUA_REGISTRYINDEX, "_LOADED", 1);
      lua_getfield(L, -1, libname);  /* get _LOADED[libname] */
      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) */
        if (luaL_findtable(L, LUA_GLOBALSINDEX, libname, size) != NULL)
          luaL_error(L, "name conflict for module " LUA_QS, libname);
        lua_pushvalue(L, -1);
        lua_setfield(L, -3, libname);  /* _LOADED[libname] = new table */
      }
      lua_remove(L, -2);  /* remove _LOADED table */
      lua_insert(L, -(nup+1));  /* move library table to below upvalues */
    }
    for (; l->name; l++) {
      int i;
      for (i=0; i<nup; i++)  /* copy upvalues to the top */
        lua_pushvalue(L, -nup);
      lua_pushcclosure(L, l->func, nup);
      lua_setfield(L, -(nup+2), l->name);
    }
    lua_pop(L, nup);  /* remove upvalues */
  }
  
  
  
  /*
  ** {======================================================
  ** getn-setn: size for arrays
  ** =======================================================
  */
  
  #if defined(LUA_COMPAT_GETN)
  
  static int checkint (lua_State *L, int topop) {
    int n = (lua_type(L, -1) == LUA_TNUMBER) ? lua_tointeger(L, -1) : -1;
    lua_pop(L, topop);
    return n;
  }
  
  
  static void getsizes (lua_State *L) {
    lua_getfield(L, LUA_REGISTRYINDEX, "LUA_SIZES");
    if (lua_isnil(L, -1)) {  /* no `size' table? */
      lua_pop(L, 1);  /* remove nil */
      lua_newtable(L);  /* create it */
      lua_pushvalue(L, -1);  /* `size' will be its own metatable */
      lua_setmetatable(L, -2);
      lua_pushliteral(L, "kv");
      lua_setfield(L, -2, "__mode");  /* metatable(N).__mode = "kv" */
      lua_pushvalue(L, -1);
      lua_setfield(L, LUA_REGISTRYINDEX, "LUA_SIZES");  /* store in register */
    }
  }
  
  
  LUALIB_API void luaL_setn (lua_State *L, int t, int n) {
    t = abs_index(L, t);
    lua_pushliteral(L, "n");
    lua_rawget(L, t);
    if (checkint(L, 1) >= 0) {  /* is there a numeric field `n'? */
      lua_pushliteral(L, "n");  /* use it */
      lua_pushinteger(L, n);
      lua_rawset(L, t);
    }
    else {  /* use `sizes' */
      getsizes(L);
      lua_pushvalue(L, t);
      lua_pushinteger(L, n);
      lua_rawset(L, -3);  /* sizes[t] = n */
      lua_pop(L, 1);  /* remove `sizes' */
    }
  }
  
  
  LUALIB_API int luaL_getn (lua_State *L, int t) {
    int n;
    t = abs_index(L, t);
    lua_pushliteral(L, "n");  /* try t.n */
    lua_rawget(L, t);
    if ((n = checkint(L, 1)) >= 0) return n;
    getsizes(L);  /* else try sizes[t] */
    lua_pushvalue(L, t);
    lua_rawget(L, -2);
    if ((n = checkint(L, 2)) >= 0) return n;
    return (int)lua_objlen(L, t);
  }
  
  #endif
  
  /* }====================================================== */
  
  
  
  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);
  }
  
  
  LUALIB_API const char *luaL_findtable (lua_State *L, int idx,
                                         const char *fname, int szhint) {
    const char *e;
    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;
  }
  
  
  
  /*
  ** {======================================================
  ** Generic Buffer manipulation
  ** =======================================================
  */
  
  
  #define bufflen(B)	((B)->p - (B)->buffer)
  #define bufffree(B)	((size_t)(LUAL_BUFFERSIZE - bufflen(B)))
  
  #define LIMIT	(LUA_MINSTACK/2)
  
  
  static int emptybuffer (luaL_Buffer *B) {
    size_t l = bufflen(B);
    if (l == 0) return 0;  /* put nothing on stack */
    else {
      lua_pushlstring(B->L, B->buffer, l);
      B->p = B->buffer;
      B->lvl++;
      return 1;
    }
  }
  
  
  static void adjuststack (luaL_Buffer *B) {
    if (B->lvl > 1) {
      lua_State *L = B->L;
      int toget = 1;  /* number of levels to concat */
      size_t toplen = lua_strlen(L, -1);
      do {
        size_t l = lua_strlen(L, -(toget+1));
        if (B->lvl - toget + 1 >= LIMIT || toplen > l) {
          toplen += l;
          toget++;
        }
        else break;
      } while (toget < B->lvl);
      lua_concat(L, toget);
      B->lvl = B->lvl - toget + 1;
    }
  }
  
  
  LUALIB_API char *luaL_prepbuffer (luaL_Buffer *B) {
    if (emptybuffer(B))
      adjuststack(B);
    return B->buffer;
  }
  
  
  LUALIB_API void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l) {
    while (l--)
      luaL_addchar(B, *s++);
  }
  
  
  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) {
    emptybuffer(B);
    lua_concat(B->L, B->lvl);
    B->lvl = 1;
  }
  
  
  LUALIB_API void luaL_addvalue (luaL_Buffer *B) {
    lua_State *L = B->L;
    size_t vl;
    const char *s = lua_tolstring(L, -1, &vl);
    if (vl <= bufffree(B)) {  /* fit into buffer? */
      memcpy(B->p, s, vl);  /* put it there */
      B->p += vl;
      lua_pop(L, 1);  /* remove from stack */
    }
    else {
      if (emptybuffer(B))
        lua_insert(L, -2);  /* put buffer before new value */
      B->lvl++;  /* add new value into B stack */
      adjuststack(B);
    }
  }
  
  
  LUALIB_API void luaL_buffinit (lua_State *L, luaL_Buffer *B) {
    B->L = L;
    B->p = B->buffer;
    B->lvl = 0;
  }
  
  /* }====================================================== */
  
  
  LUALIB_API int luaL_ref (lua_State *L, int t) {
    int ref;
    t = abs_index(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_REF);  /* get first free element */
    ref = (int)lua_tointeger(L, -1);  /* ref = t[FREELIST_REF] */
    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_REF);  /* (t[FREELIST_REF] = t[ref]) */
    }
    else {  /* no free elements */
      ref = (int)lua_objlen(L, t);
      ref++;  /* create 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 = abs_index(L, t);
      lua_rawgeti(L, t, FREELIST_REF);
      lua_rawseti(L, t, ref);  /* t[ref] = t[FREELIST_REF] */
      lua_pushinteger(L, ref);
      lua_rawseti(L, t, FREELIST_REF);  /* t[FREELIST_REF] = ref */
    }
  }
  
  
  
  /*
  ** {======================================================
  ** Load functions
  ** =======================================================
  */
  
  typedef struct LoadF {
    int extraline;
    FILE *f;
    char buff[LUAL_BUFFERSIZE];
  } LoadF;
  
  
  static const char *getF (lua_State *L, void *ud, size_t *size) {
    LoadF *lf = (LoadF *)ud;
    (void)L;
    if (lf->extraline) {
      lf->extraline = 0;
      *size = 1;
      return "\n";
    }
    if (feof(lf->f)) return NULL;
    *size = fread(lf->buff, 1, sizeof(lf->buff), lf->f);
    return (*size > 0) ? lf->buff : NULL;
  }
  
  
  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;
  }
  
  
  LUALIB_API int luaL_loadfile (lua_State *L, const char *filename) {
    LoadF lf;
    int status, readstatus;
    int c;
    int fnameindex = lua_gettop(L) + 1;  /* index of filename on the stack */
    lf.extraline = 0;
    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);
    }
    c = getc(lf.f);
    if (c == '#') {  /* Unix exec. file? */
      lf.extraline = 1;
      while ((c = getc(lf.f)) != EOF && c != '\n') ;  /* skip first line */
      if (c == '\n') c = getc(lf.f);
    }
    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);
      /* skip eventual `#!...' */
     while ((c = getc(lf.f)) != EOF && c != LUA_SIGNATURE[0]) ;
      lf.extraline = 0;
    }
    ungetc(c, lf.f);
    status = lua_load(L, getF, &lf, lua_tostring(L, -1));
    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;
    if (ls->size == 0) return NULL;
    *size = ls->size;
    ls->size = 0;
    return ls->s;
  }
  
  
  LUALIB_API int luaL_loadbuffer (lua_State *L, const char *buff, size_t size,
                                  const char *name) {
    LoadS ls;
    ls.s = buff;
    ls.size = size;
    return lua_load(L, getS, &ls, name);
  }
  
  
  LUALIB_API int (luaL_loadstring) (lua_State *L, const char *s) {
    return luaL_loadbuffer(L, s, strlen(s), s);
  }
  
  
  
  /* }====================================================== */
  
  
  static void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) {
    (void)ud;
    (void)osize;
    if (nsize == 0) {
      free(ptr);
      return NULL;
    }
    else
      return realloc(ptr, nsize);
  }
  
  
  static int panic (lua_State *L) {
    (void)L;  /* to avoid warnings */
    fprintf(stderr, "PANIC: unprotected error in call to Lua API (%s)\n",
                     lua_tostring(L, -1));
    return 0;
  }
  
  
  LUALIB_API lua_State *luaL_newstate (void) {
    lua_State *L = lua_newstate(l_alloc, NULL);
    if (L) lua_atpanic(L, &panic);
    return L;
  }
  
  