Container to buffer N max elements

max_buffer.cpp

#include <iostream>
#include <string>
#include <algorithm>
template<class Key, class T>
class MaxBuffer
{
  typedef std::pair<Key, T> value_type;
  typedef typename std::vector<value_type>::iterator iterator;
  typedef typename std::vector<value_type>::const_iterator const_iterator;
  typedef typename std::vector<value_type>::reverse_iterator reverse_iterator;
  typedef typename std::vector<value_type>::const_reverse_iterator const_reverse_iterator;

public:
  MaxBuffer(const size_t& size) : v_() , size_(size)
  { v_.reserve(size); }

  bool update(const Key& k, const T& v)
  {
    auto cmp = [](const value_type& a, const value_type& b) {return a.first > b.first;};

    if (v_.size() < size_)
    {
      v_.push_back(std::make_pair(k,v));
      std::push_heap(v_.begin(), v_.end(), cmp);
      return true;
    }

    if (v_.front().first < k)
    {
      std::pop_heap(v_.begin(), v_.end(), cmp);
      v_.back() = std::make_pair(k,v);
      std::push_heap(v_.begin(), v_.end(), cmp);
      return true;
    }
    return false;
  }

  inline iterator begin() { return v_.begin(); }
  inline iterator end() { return v_.end(); }
  inline reverse_iterator rbegin() { return v_.rbegin(); }
  inline reverse_iterator rend() { return v_.rend(); }

  inline const_iterator begin() const { return v_.begin(); }
  inline const_iterator end() const{ return v_.end(); }
  inline const_reverse_iterator rbegin() const { return v_.rbegin(); }
  inline const_reverse_iterator rend() const { return v_.rend(); }

private:
  std::vector<value_type> v_;
  size_t size_;
};


template <class T>
void print(const T& v)
{
  std::cout << "Elements: ";
  for (const auto& e : v)
  {
    std::cout << "(" << e.first << "," << e.second << ") ";
  }
  std::cout << std::endl;
}

int main()
{
  MaxBuffer<float, std::string> b(3);
  b.update(-10,"a"); print(b);
  b.update(-2,"b"); print(b);
  b.update(-3,"c"); print(b);
  b.update(6,"e"); print(b);
  b.update(-1,"f"); print(b);
  b.update(-6,"e"); print(b);
}