lapi.hpp

/*
** $Id: lapi.h,v 2.7 2009/11/27 15:37:59 roberto Exp $
** Auxiliary functions from Lua API
** See Copyright Notice in lua.h
*/

#ifndef lapi_h
#define lapi_h

/* value at a non-valid index */
#define NONVALIDVALUE		cast(TValue *, luaO_nilobject)

/* test for pseudo index */
#define ispseudo(i)		((i) <= LUA_REGISTRYINDEX)

#include "llimits.hpp"
#include "lstate.hpp"

#define api_incr_top(L)   {L->top++; api_check(L, L->top <= L->ci->top, \
				"stack overflow");}

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

#define api_checknelems(L,n)	api_check(L, (n) < (L->top - L->ci->func), \
				  "not enough elements in the stack")


inline TValue *index2addr (lua_State *L, int idx) {
  CallInfo *ci = L->ci;
  if (idx > 0) {
    TValue *o = ci->func + idx;
    api_check(L, idx <= ci->top - (ci->func + 1), "unacceptable index");
    if (o >= L->top) return NONVALIDVALUE;
    else return o;
  }
  else if (!ispseudo(idx)) {  /* negative index */
    api_check(L, idx != 0 && -idx <= L->top - (ci->func + 1), "invalid index");
    return L->top + idx;
  }
  else if (idx == LUA_REGISTRYINDEX)
    return &G(L)->l_registry;
  else {  /* upvalues */
    idx = LUA_REGISTRYINDEX - idx;
    api_check(L, idx <= MAXUPVAL + 1, "upvalue index too large");
    if (ttislcf(ci->func))  /* light C function? */
      return NONVALIDVALUE;  /* it has no upvalues */
    else {
      CClosure *func = clCvalue(ci->func);
      return (idx <= func->nupvalues) ? &func->upvalue[idx-1] : NONVALIDVALUE;
    }
  }
}

#endif