lib/nodemove.cpp

The following code example is taken from the book
C++17 - The Complete Guide by Nicolai M. Josuttis, Leanpub, 2017
The code is licensed under a Creative Commons Attribution 4.0 International License.

---

// raw code

#include <iostream>
#include <string>
#include <map>

template<typename T1, typename T2>
void print(const T1& coll1, const T2& coll2)
{
  std::cout << "values:\n";
  for (const auto& [key, value] : coll1) {
    std::cout << "  [" << key << ":" << value << "]";
  }
  std::cout << '\n';
  for (const auto& [key, value] : coll2) {
    std::cout << "  [" << key << ":" << value << "]";
  }
  std::cout << '\n';
}

int main()
{
  std::multimap<double, std::string> src {{1.1, "one"},
                                          {2.2, "two"},
                                          {3.3, "three"}};
  std::map<double, std::string> dst {{3.3, "old data"}};

  print(src, dst);

  // move some elements from multimap src to map dst:
  dst.insert(src.extract(src.find(1.1)));  // splice using an iterator
  dst.insert(src.extract(2.2));            // splice using the key

  print(src, dst);
}