boost_iterator_facade.cpp

#include <algorithm>
#include <iostream>
#include <string>
using namespace std;

#include <boost/iterator/iterator_facade.hpp>

// Single linked list node
struct Node {
  string value;
  Node *next = nullptr;

  explicit Node(const string &value) : value(value) {}

  Node(const string &value, Node *const parent) : value(value) {
    parent->next = this;
  }
};

// Linked List iterator based on boost::iterator_facade.
// Requires implementation of: increment(), equal(), and dereference() methods.
struct ListIterator
    : boost::iterator_facade<ListIterator, Node, boost::forward_traversal_tag> {

  Node *current = nullptr;

  ListIterator() {}

  explicit ListIterator(Node *const current) : current(current) {}

private:
  friend class boost::iterator_core_access;

  void increment() { current = current->next; }

  bool equal(const ListIterator &other) const {
    return other.current == current;
  };

  Node &dereference() const { return *current; }
};

int main() {
  Node alpha{"alpha"};
  Node beta{"beta", &alpha};
  Node gamma{"gamma", &beta};

  for_each(ListIterator{&alpha}, ListIterator{},
           [](const Node &n) { cout << n.value << endl; });

  return 0;
}