使用C++实现Range序列生成器的示例代码

namespace Range
{
  template<typename value_t>
  class RangeImpl
  {
    class Iterator;
  public:
    RangeImpl(value_t begin, value_t end, value_t step = 1) :m_begin(begin), m_end(end), m_step(step)
    {
      if (step>0 && m_begin >= m_end)
        throw std::logic_error("end must greater than begin.");
      else if (step<0 && m_begin <= m_end)
        throw std::logic_error("end must less than begin.");

      m_step_end = (m_end - m_begin) / m_step;
      if (m_begin + m_step_end*m_step != m_end)
      {
        m_step_end++;
      }
    }

    Iterator begin()
    {
      return Iterator(0, *this);
    }

    Iterator end()
    {
      return Iterator(m_step_end, *this);
    }

    value_t operator[](int s)
    {
      return m_begin + s*m_step;
    }

    int size()
    {
      return m_step_end;
    }

  private:
    value_t m_begin;
    value_t m_end;
    value_t m_step;
    int m_step_end;

    class Iterator
    {
    public:
      Iterator(int start, RangeImpl& range) : m_current_step(start), m_range(range)
      {
        m_current_value = m_range.m_begin + m_current_step*m_range.m_step;
      }

      value_t operator*() { return m_current_value; }

      const Iterator* operator++()
      {
        m_current_value += m_range.m_step;
        m_current_step++;
        return this;
      }

      bool operator==(const Iterator& other)
      {
        return m_current_step == other.m_current_step;
      }

      bool operator!=(const Iterator& other)
      {
        return m_current_step != other.m_current_step;
      }

      const Iterator* operator--()
      {
        m_current_value -= m_range.m_step;
        m_current_step--;
        return this;
      }

    private:
      value_t m_current_value;
      int m_current_step;
      RangeImpl& m_range;
    };
  };

  template<typename T, typename V>
  auto Range(T begin, T end, V stepsize)->RangeImpl<decltype(begin + end + stepsize)>
  {
    return RangeImpl<decltype(begin + end + stepsize)>(begin, end, stepsize);
  }

  template<typename T>
  RangeImpl<T> Range(T begin, T end)
  {
    return RangeImpl<T>(begin, end, 1);
  }

  template<typename T>
  RangeImpl<T> Range(T end)
  {
    return RangeImpl<T>(T(), end, 1);
  }
}

#include <iostream>
#include "Range.hpp"

using namespace std;

int main(int argc, char* argv[])
{
  for (int i : Range::Range(15))
  {
    std::cout << i << std::endl;
  }

  for (int i : Range::Range(2, 6))
  {
    std::cout << i << std::endl;
  }

  for (float i : Range::Range(10.5, 15.5))
  {
    std::cout << i << std::endl;
  }

  for (int i : Range::Range(35, 27, -1))
  {
    std::cout << i << std::endl;
  }

  for (float i : Range::Range(2, 8, 0.5))
  {
    std::cout << i << std::endl;
  }

  for (auto i : Range::Range(8, 7, -0.1))
  {
    std::cout << i << std::endl;
  }

  for (auto i : Range::Range('a', 'z'))
  {
    std::cout << i << std::endl;
  }
  
  std::system("pause");
  return 0;
}