Example Remove IF

remove_if.cpp

// vim: ts=2 sw=2 et
#include <cassert>
#include <algorithm>
#include <vector>

#include <iostream>

template <typename Container, typename Predicate>
void
RemoveIf(Container& container, Predicate predicate)
{
  auto head = std::begin(container);
  auto tail = std::end(container);
  auto good = head;

  while (head != tail) {
    if (predicate(*head)) {
      std::iter_swap(good, head);
      std::advance(good, 1);
    }
    std::advance(head, 1);
  }

  container.resize(
      std::distance(std::begin(container), good));
}


template <typename _Tp>
void
Print(_Tp data)
{
  for (const auto& elem: data) {
    std::cerr << elem << "\n";
  }
}

int
main()
{
  // {
  std::vector<int> D;

  size_t i = 0;
  std::generate_n(std::back_inserter(D), 26, [&](){return ++i;});
  // }

  {
    auto test2 = D;
    RemoveIf(test2, [](int d) { return d % 2 == 0; });
    assert(test2.size() == D.size() / 2);
  }

  {
    auto test3 = D;
    RemoveIf(test3, [](int d) { return d % 3 == 0; });
    assert(test3.size() == D.size() / 3);
  }
}