lapi.cpp

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  StkId t;
  lua_lock(L);
  t = index2adr(L, idx);
  api_checkvalidindex(L, t);
  luaV_gettable(L, t, L->top - 1, L->top - 1);
  lua_unlock(L);
}


LUA_API void lua_getfield (lua_State *L, int idx, const char *k) {
  StkId t;
  TValue key;
  lua_lock(L);
  t = index2adr(L, idx);
  api_checkvalidindex(L, t);
  setsvalue(L, &key, luaS_new(L, k));
  luaV_gettable(L, t, &key, L->top);
  api_incr_top(L);
  lua_unlock(L);
}


LUA_API void lua_rawget (lua_State *L, int idx) {
  StkId t;
  lua_lock(L);
  t = index2adr(L, idx);
  api_check(L, ttistable(t));
  setobj2s(L, L->top - 1, luaH_get(hvalue(t), L->top - 1));
  lua_unlock(L);
}


LUA_API void lua_rawgeti (lua_State *L, int idx, int n) {
  StkId o;
  lua_lock(L);
  o = index2adr(L, idx);
  api_check(L, ttistable(o));
  setobj2s(L, L->top, luaH_getnum(hvalue(o), n));
  api_incr_top(L);
  lua_unlock(L);
}


LUA_API void lua_createtable (lua_State *L, int narray, int nrec) {
  lua_lock(L);
  luaC_checkGC(L);
  sethvalue(L, L->top, luaH_new(L, narray, nrec));
  api_incr_top(L);
  lua_unlock(L);
}


LUA_API int lua_getmetatable (lua_State *L, int objindex) {
  const TValue *obj;
  Table *mt = NULL;
  int res;
  lua_lock(L);
  obj = index2adr(L, objindex);
  switch (ttype(obj)) {
    case LUA_TTABLE:
      mt = hvalue(obj)->metatable;
      break;
    case LUA_TUSERDATA:
      mt = uvalue(obj)->metatable;
      break;
    default:
      mt = G(L)->mt[ttype(obj)];
      break;
  }
  if (mt == NULL)
    res = 0;
  else {
    sethvalue(L, L->top, mt);
    api_incr_top(L);
    res = 1;
  }
  lua_unlock(L);
  return res;
}


LUA_API void lua_getfenv (lua_State *L, int idx) {
  StkId o;
  lua_lock(L);
  o = index2adr(L, idx);
  api_checkvalidindex(L, o);
  switch (ttype(o)) {
    case LUA_TFUNCTION:
      sethvalue(L, L->top, clvalue(o)->c.env);
      break;
    case LUA_TUSERDATA:
      sethvalue(L, L->top, uvalue(o)->env);
      break;
    case LUA_TTHREAD:
      setobj2s(L, L->top,  gt(thvalue(o)));
      break;
    default:
      setnilvalue(L->top);
      break;
  }
  api_incr_top(L);
  lua_unlock(L);
}


/*
** set functions (stack -> Lua)
*/


LUA_API void lua_settable (lua_State *L, int idx) {
  StkId t;
  lua_lock(L);
  api_checknelems(L, 2);
  t = index2adr(L, idx);
  api_checkvalidindex(L, t);
  luaV_settable(L, t, L->top - 2, L->top - 1);
  L->top -= 2;  /* pop index and value */
  lua_unlock(L);
}


LUA_API void lua_setfield (lua_State *L, int idx, const char *k) {
  StkId t;
  TValue key;
  lua_lock(L);
  api_checknelems(L, 1);
  t = index2adr(L, idx);
  api_checkvalidindex(L, t);
  setsvalue(L, &key, luaS_new(L, k));
  luaV_settable(L, t, &key, L->top - 1);
  L->top--;  /* pop value */
  lua_unlock(L);
}


LUA_API void lua_rawset (lua_State *L, int idx) {
  StkId t;
  lua_lock(L);
  api_checknelems(L, 2);
  t = index2adr(L, idx);
  api_check(L, ttistable(t));
  setobj2t(L, luaH_set(L, hvalue(t), L->top-2), L->top-1);
  luaC_barriert(L, hvalue(t), L->top-1);
  L->top -= 2;
  lua_unlock(L);
}


LUA_API void lua_rawseti (lua_State *L, int idx, int n) {
  StkId o;
  lua_lock(L);
  api_checknelems(L, 1);
  o = index2adr(L, idx);
  api_check(L, ttistable(o));
  setobj2t(L, luaH_setnum(L, hvalue(o), n), L->top-1);
  luaC_barriert(L, hvalue(o), L->top-1);
  L->top--;
  lua_unlock(L);
}


LUA_API int lua_setmetatable (lua_State *L, int objindex) {
  TValue *obj;
  Table *mt;
  lua_lock(L);
  api_checknelems(L, 1);
  obj = index2adr(L, objindex);
  api_checkvalidindex(L, obj);
  if (ttisnil(L->top - 1))
    mt = NULL;
  else {
    api_check(L, ttistable(L->top - 1));
    mt = hvalue(L->top - 1);
  }
  switch (ttype(obj)) {
    case LUA_TTABLE: {
      hvalue(obj)->metatable = mt;
      if (mt)
        luaC_objbarriert(L, hvalue(obj), mt);
      break;
    }
    case LUA_TUSERDATA: {
      uvalue(obj)->metatable = mt;
      if (mt)
        luaC_objbarrier(L, rawuvalue(obj), mt);
      break;
    }
    default: {
      G(L)->mt[ttype(obj)] = mt;
      break;
    }
  }
  L->top--;
  lua_unlock(L);
  return 1;
}


LUA_API int lua_setfenv (lua_State *L, int idx) {
  StkId o;
  int res = 1;
  lua_lock(L);
  api_checknelems(L, 1);
  o = index2adr(L, idx);
  api_checkvalidindex(L, o);
  api_check(L, ttistable(L->top - 1));
  switch (ttype(o)) {
    case LUA_TFUNCTION:
      clvalue(o)->c.env = hvalue(L->top - 1);
      break;
    case LUA_TUSERDATA:
      uvalue(o)->env = hvalue(L->top - 1);
      break;
    case LUA_TTHREAD:
      sethvalue(L, gt(thvalue(o)), hvalue(L->top - 1));
      break;
    default:
      res = 0;
      break;
  }
  luaC_objbarrier(L, gcvalue(o), hvalue(L->top - 1));
  L->top--;
  lua_unlock(L);
  return res;
}


/*
** `load' and `call' functions (run Lua code)
*/


#define adjustresults(L,nres) \
    { if (nres == LUA_MULTRET && L->top >= L->ci->top) L->ci->top = L->top; }


#define checkresults(L,na,nr) \
     api_check(L, (nr) == LUA_MULTRET || (L->ci->top - L->top >= (nr) - (na)))
	

LUA_API void lua_call (lua_State *L, int nargs, int nresults) {
  StkId func;
  lua_lock(L);
  api_checknelems(L, nargs+1);
  checkresults(L, nargs, nresults);
  func = L->top - (nargs+1);
  luaD_call(L, func, nresults);
  adjustresults(L, nresults);
  lua_unlock(L);
}



/*
** Execute a protected call.
*/
struct CallS {  /* data to `f_call' */
  StkId func;
  int nresults;
};


static void f_call (lua_State *L, void *ud) {
  struct CallS *c = cast(struct CallS *, ud);
  luaD_call(L, c->func, c->nresults);
}



LUA_API int lua_pcall (lua_State *L, int nargs, int nresults, int errfunc) {
  struct CallS c;
  int status;
  ptrdiff_t func;
  lua_lock(L);
  api_checknelems(L, nargs+1);
  checkresults(L, nargs, nresults);
  if (errfunc == 0)
    func = 0;
  else {
    StkId o = index2adr(L, errfunc);
    api_checkvalidindex(L, o);
    func = savestack(L, o);
  }
  c.func = L->top - (nargs+1);  /* function to be called */
  c.nresults = nresults;
  status = luaD_pcall(L, f_call, &c, savestack(L, c.func), func);
  adjustresults(L, nresults);
  lua_unlock(L);
  return status;
}


/*
** Execute a protected C call.
*/
struct CCallS {  /* data to `f_Ccall' */
  lua_CFunction func;
  void *ud;
};


static void f_Ccall (lua_State *L, void *ud) {
  struct CCallS *c = cast(struct CCallS *, ud);
  Closure *cl;
  cl = luaF_newCclosure(L, 0, getcurrenv(L));
  cl->c.f = c->func;
  setclvalue(L, L->top, cl);  /* push function */
  api_incr_top(L);
  setpvalue(L->top, c->ud);  /* push only argument */
  api_incr_top(L);
  luaD_call(L, L->top - 2, 0);
}


LUA_API int lua_cpcall (lua_State *L, lua_CFunction func, void *ud) {
  struct CCallS c;
  int status;
  lua_lock(L);
  c.func = func;
  c.ud = ud;
  status = luaD_pcall(L, f_Ccall, &c, savestack(L, L->top), 0);
  lua_unlock(L);
  return status;
}


LUA_API int lua_load (lua_State *L, lua_Reader reader, void *data,
                      const char *chunkname) {
  ZIO z;
  int status;
  lua_lock(L);
  if (!chunkname) chunkname = "?";
  luaZ_init(L, &z, reader, data);
  status = luaD_protectedparser(L, &z, chunkname);
  lua_unlock(L);
  return status;
}


LUA_API int lua_dump (lua_State *L, lua_Writer writer, void *data) {
  int status;
  TValue *o;
  lua_lock(L);
  api_checknelems(L, 1);
  o = L->top - 1;
  if (isLfunction(o))
    status = luaU_dump(L, clvalue(o)->l.p, writer, data, 0);
  else
    status = 1;
  lua_unlock(L);
  return status;
}


LUA_API int  lua_status (lua_State *L) {
  return L->status;
}


/*
** Garbage-collection function
*/

LUA_API int lua_gc (lua_State *L, int what, int data) {
  int res = 0;
  global_State *g;
  lua_lock(L);
  g = G(L);
  switch (what) {
    case LUA_GCSTOP: {
      g->GCthreshold = MAX_LUMEM;
      break;
    }
    case LUA_GCRESTART: {
      g->GCthreshold = g->totalbytes;
      break;
    }
    case LUA_GCCOLLECT: {
      luaC_fullgc(L);
      break;
    }
    case LUA_GCCOUNT: {
      /* GC values are expressed in Kbytes: #bytes/2^10 */
      res = cast_int(g->totalbytes >> 10);
      break;
    }
    case LUA_GCCOUNTB: {
      res = cast_int(g->totalbytes & 0x3ff);
      break;
    }
    case LUA_GCSTEP: {
      lu_mem a = (cast(lu_mem, data) << 10);
      if (a <= g->totalbytes)
        g->GCthreshold = g->totalbytes - a;
      else
        g->GCthreshold = 0;
      while (g->GCthreshold <= g->totalbytes)
        luaC_step(L);
      if (g->gcstate == GCSpause)  /* end of cycle? */
        res = 1;  /* signal it */
      break;
    }
    case LUA_GCSETPAUSE: {
      res = g->gcpause;
      g->gcpause = data;
      break;
    }
    case LUA_GCSETSTEPMUL: {
      res = g->gcstepmul;
      g->gcstepmul = data;
      break;
    }
    default: res = -1;  /* invalid option */
  }
  lua_unlock(L);
  return res;
}



/*
** miscellaneous functions
*/


LUA_API int lua_error (lua_State *L) {
  lua_lock(L);
  api_checknelems(L, 1);
  luaG_errormsg(L);
  lua_unlock(L);
  return 0;  /* to avoid warnings */
}


LUA_API int lua_next (lua_State *L, int idx) {
  StkId t;
  int more;
  lua_lock(L);
  t = index2adr(L, idx);
  api_check(L, ttistable(t));
  more = luaH_next(L, hvalue(t), L->top - 1);
  if (more) {
    api_incr_top(L);
  }
  else  /* no more elements */
    L->top -= 1;  /* remove key */
  lua_unlock(L);
  return more;
}


LUA_API void lua_concat (lua_State *L, int n) {
  lua_lock(L);
  api_checknelems(L, n);
  if (n >= 2) {
    luaC_checkGC(L);
    luaV_concat(L, n, cast_int(L->top - L->base) - 1);
    L->top -= (n-1);
  }
  else if (n == 0) {  /* push empty string */
    setsvalue2s(L, L->top, luaS_newlstr(L, "", 0));
    api_incr_top(L);
  }
  /* else n == 1; nothing to do */
  lua_unlock(L);
}


LUA_API lua_Alloc lua_getallocf (lua_State *L, void **ud) {
  lua_Alloc f;
  lua_lock(L);
  if (ud) *ud = G(L)->ud;
  f = G(L)->frealloc;
  lua_unlock(L);
  return f;
}


LUA_API void lua_setallocf (lua_State *L, lua_Alloc f, void *ud) {
  lua_lock(L);
  G(L)->ud = ud;
  G(L)->frealloc = f;
  lua_unlock(L);
}


LUA_API void *lua_newuserdata (lua_State *L, size_t size) {
  Udata *u;
  lua_lock(L);
  luaC_checkGC(L);
  u = luaS_newudata(L, size, getcurrenv(L));
  setuvalue(L, L->top, u);
  api_incr_top(L);
  lua_unlock(L);
  return u + 1;
}




static const char *aux_upvalue (StkId fi, int n, TValue **val) {
  Closure *f;
  if (!ttisfunction(fi)) return NULL;
  f = clvalue(fi);
  if (f->c.isC) {
    if (!(1 <= n && n <= f->c.nupvalues)) return NULL;
    *val = &f->c.upvalue[n-1];
    return "";
  }
  else {
    Proto *p = f->l.p;
    if (!(1 <= n && n <= p->sizeupvalues)) return NULL;
    *val = f->l.upvals[n-1]->v;
    return getstr(p->upvalues[n-1]);
  }
}


LUA_API const char *lua_getupvalue (lua_State *L, int funcindex, int n) {
  const char *name;
  TValue *val;
  lua_lock(L);
  name = aux_upvalue(index2adr(L, funcindex), n, &val);
  if (name) {
    setobj2s(L, L->top, val);
    api_incr_top(L);
  }
  lua_unlock(L);
  return name;
}


LUA_API const char *lua_setupvalue (lua_State *L, int funcindex, int n) {
  const char *name;
  TValue *val;
  StkId fi;
  lua_lock(L);
  fi = index2adr(L, funcindex);
  api_checknelems(L, 1);
  name = aux_upvalue(fi, n, &val);
  if (name) {
    L->top--;
    setobj(L, val, L->top);
    luaC_barrier(L, clvalue(fi), L->top);
  }
  lua_unlock(L);
  return name;
}