Function tryfuncTM

third-party/lua-5.5.0/src/ldo.c:523–536

** Check whether 'func' has a '__call' metafield. If so, put it in the ** stack, below original 'func', so that 'luaD_precall' can call it. ** Raise an error if there is no '__call' metafield. ** Bits CIST_CCMT in status count how many _call metamethods were ** invoked and how many corresponding extra arguments were pushed. ** (This count will be saved in the 'callstatus' of the call). ** Raise a

**  Raise an error if this counter overflows.
*/
static unsigned tryfuncTM (lua_State *L, StkId func, unsigned status) {
  const TValue *tm;
  StkId p;
  tm = luaT_gettmbyobj(L, s2v(func), TM_CALL);
  if (l_unlikely(ttisnil(tm)))  /* no metamethod? */
    luaG_callerror(L, s2v(func));
  for (p = L->top.p; p > func; p--)  /* open space for metamethod */
    setobjs2s(L, p, p-1);
  L->top.p++;  /* stack space pre-allocated by the caller */
  setobj2s(L, func, tm);  /* metamethod is the new function to be called */
  if ((status & MAX_CCMT) == MAX_CCMT)  /* is counter full? */
    luaG_runerror(L, "'__call' chain too long");
  return status + (1u << CIST_CCMT);  /* increment counter */
}


/* Generic case for 'moveresult' */