如何从 std::map 过滤项目？ [复制]

我大致有以下代码。这可以变得更好或更高效吗？也许使用std::remove_if？您可以在遍历地图时从地图上删除项目吗？我们可以避免使用临时地图吗？

typedef std::map<Action, What> Actions;
static Actions _actions;

bool expired(const Actions::value_type &action)
{
  return <something>;
}

void bar(const Actions::value_type &action)
{
  // do some stuff
}

void foo()
{
  // loop the actions finding expired items
  Actions actions;
  BOOST_FOREACH(Actions::value_type &action, _actions)
  {
    if (expired(action))
      bar(action);
    else
      actions[action.first]=action.second;
    }
  }
  actions.swap(_actions);
}

马克勒索算法的变体，但不需要临时。

for(Actions::iterator it = _actions.begin();it != _actions.end();)
{
    if (expired(*it))
    {
        bar(*it);
        _actions.erase(it++);  // Note the post increment here.
                               // This increments 'it' and returns a copy of
                               // the original 'it' to be used by erase()
    }
    else
    {
        ++it;  // Use Pre-Increment here as it is more effecient
               // Because no copy of it is required.
    }
}