src/reverse_iterator.h

   1 // Taken from https://gist.github.com/arvidsson/7231973
   2
   3 #ifndef BITCOIN_REVERSE_ITERATOR_H
   4 #define BITCOIN_REVERSE_ITERATOR_H
   5
   6 /**
   7  * Template used for reverse iteration in C++11 range-based for loops.
   8  *
   9  *   std::vector<int> v = {1, 2, 3, 4, 5};
  10  *   for (auto x : reverse_iterate(v))
  11  *       std::cout << x << " ";
  12  */
  13
  14 template <typename T>
  15 class reverse_range
  16 {
  17     T &m_x;
  18
  19 public:
  20     explicit reverse_range(T &x) : m_x(x) {}
  21
  22     auto begin() const -> decltype(this->m_x.rbegin())
  23     {
  24         return m_x.rbegin();
  25     }
  26
  27     auto end() const -> decltype(this->m_x.rend())
  28     {
  29         return m_x.rend();
  30     }
  31 };
  32
  33 template <typename T>
  34 reverse_range<T> reverse_iterate(T &x)
  35 {
  36     return reverse_range<T>(x);
  37 }
  38
  39 #endif // BITCOIN_REVERSE_ITERATOR_H