Function luaD_pretailcall

xrepo/packages/l/lua/port/lua/src/ldo.c:520–554

** Prepare a function for a tail call, building its call info on top ** of the current call info. 'narg1' is the number of arguments plus 1 ** (so that it includes the function itself). Return the number of ** results, if it was a C function, or -1 for a Lua function. */

** results, if it was a C function, or -1 for a Lua function.
*/
int luaD_pretailcall (lua_State *L, CallInfo *ci, StkId func,
                                    int narg1, int delta) {
 retry:
  switch (ttypetag(s2v(func))) {
    case LUA_VCCL:  /* C closure */
      return precallC(L, func, LUA_MULTRET, clCvalue(s2v(func))->f);
    case LUA_VLCF:  /* light C function */
      return precallC(L, func, LUA_MULTRET, fvalue(s2v(func)));
    case LUA_VLCL: {  /* Lua function */
      Proto *p = clLvalue(s2v(func))->p;
      int fsize = p->maxstacksize;  /* frame size */
      int nfixparams = p->numparams;
      int i;
      checkstackGCp(L, fsize - delta, func);
      ci->func -= delta;  /* restore 'func' (if vararg) */
      for (i = 0; i < narg1; i++)  /* move down function and arguments */
        setobjs2s(L, ci->func + i, func + i);
      func = ci->func;  /* moved-down function */
      for (; narg1 <= nfixparams; narg1++)
        setnilvalue(s2v(func + narg1));  /* complete missing arguments */
      ci->top = func + 1 + fsize;  /* top for new function */
      lua_assert(ci->top <= L->stack_last);
      ci->u.l.savedpc = p->code;  /* starting point */
      ci->callstatus |= CIST_TAIL;
      L->top = func + narg1;  /* set top */
      return -1;
    }
    default: {  /* not a function */
      func = luaD_tryfuncTM(L, func);  /* try to get '__call' metamethod */
      /* return luaD_pretailcall(L, ci, func, narg1 + 1, delta); */
      narg1++;
      goto retry;  /* try again */
    }
  }
}


/*