检查迭代器的类型是否为reverse_iterator [英] Check if iterator's type is reverse_iterator

问题描述

有没有办法检查迭代器是否作为arg传递给fnc是reverse_iterator？我可以使用任何迭代器特征函数吗？

Is there a way to check if iterator passed as arg to fnc is reverse_iterator? Are there any iterator traits function I could use?

推荐答案

使用部分特化来编写它是微不足道的：

It's trivial to write with a partial specialization:

#include <iterator>
#include <type_traits>

template<typename Iter>
  struct is_reverse_iterator
  : std::false_type { };

template<typename Iter>
  struct is_reverse_iterator<std::reverse_iterator<Iter>>
  : std::true_type { };

虽然如下所述，但这并不能解决（恕我直言）不可能的情况 - 反向迭代器。在Bathsheba的答案中稍微不那么简单的版本正确地处理了这个案例。

Although as pointed out below, this doesn't handle the (IMHO unlikely) case of a "reverse-reverse" iterator. The slightly less trivial version in Bathsheba's answer handles that case correctly.

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