Function sort_comp

3rd/lua-5.4.3/src/ltablib.c:274–287

** Return true iff value at stack index 'a' is less than the value at ** index 'b' (according to the order of the sort). */

** index 'b' (according to the order of the sort).
*/
static int sort_comp (lua_State *L, int a, int b) {
  if (lua_isnil(L, 2))  /* no function? */
    return lua_compare(L, a, b, LUA_OPLT);  /* a < b */
  else {  /* function */
    int res;
    lua_pushvalue(L, 2);    /* push function */
    lua_pushvalue(L, a-1);  /* -1 to compensate function */
    lua_pushvalue(L, b-2);  /* -2 to compensate function and 'a' */
    lua_call(L, 2, 1);      /* call function */
    res = lua_toboolean(L, -1);  /* get result */
    lua_pop(L, 1);          /* pop result */
    return res;
  }
}


/*