Function forlimit

third-party/lua-5.4.6/src/lvm.c:178–196

** Try to convert a 'for' limit to an integer, preserving the semantics ** of the loop. Return true if the loop must not run; otherwise, '*p' ** gets the integer limit. ** (The following explanation assumes a positive step; it is valid for ** negative steps mutatis mutandis.) ** If the limit is an integer or can be converted to an integer, ** rounding down, that is the limit. ** Otherwise, check w

** an initial value equal to LUA_MININTEGER.)
*/
static int forlimit (lua_State *L, lua_Integer init, const TValue *lim,
                                   lua_Integer *p, lua_Integer step) {
  if (!luaV_tointeger(lim, p, (step < 0 ? F2Iceil : F2Ifloor))) {
    /* not coercible to in integer */
    lua_Number flim;  /* try to convert to float */
    if (!tonumber(lim, &flim)) /* cannot convert to float? */
      luaG_forerror(L, lim, "limit");
    /* else 'flim' is a float out of integer bounds */
    if (luai_numlt(0, flim)) {  /* if it is positive, it is too large */
      if (step < 0) return 1;  /* initial value must be less than it */
      *p = LUA_MAXINTEGER;  /* truncate */
    }
    else {  /* it is less than min integer */
      if (step > 0) return 1;  /* initial value must be greater than it */
      *p = LUA_MININTEGER;  /* truncate */
    }
  }
  return (step > 0 ? init > *p : init < *p);  /* not to run? */
}


/*