有没有类似于循环(循环)迭代器的东西？

Question

我想知道是否有某种迭代器可以迭代std :: string中的值,当它到达结尾时从头开始.换句话说,该对象将无限地迭代,一遍又一遍地吐出相同的值序列.

谢谢!

Answer 1

生成器功能可以是那样.Boost Iterator有一个迭代器适配器:

• http://www.boost.org/doc/libs/1_52_0/libs/utility/generator_iterator.htm

示例:http://coliru.stacked-crooked.com/a/267279405be9289d

#include <iostream>
#include <functional>
#include <algorithm>
#include <iterator>
#include <boost/generator_iterator.hpp>

int main()
{
  const std::string data = "hello";
  auto curr = data.end();

  std::function<char()> gen = [curr,data]() mutable -> char
  { 
      if (curr==data.end())
          curr = data.begin();
      return *curr++;
  };

  auto it = boost::make_generator_iterator(gen);
  std::copy_n(it, 35, std::ostream_iterator<char>(std::cout, ";"));
}