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// Copyright (C) 2019 T. Zachary Laine
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#include <boost/stl_interfaces/iterator_interface.hpp>
#include <algorithm>
#include <array>
#include <iostream>
#include <cassert>
//[ node_defn
template<typename T>
struct node
{
T value_;
node * next_; // == nullptr in the tail node
};
//]
//[ node_iterator_class_head
template<typename T>
struct node_iterator
: boost::stl_interfaces::iterator_interface<
#if !BOOST_STL_INTERFACES_USE_DEDUCED_THIS
node_iterator<T>,
#endif
std::forward_iterator_tag, T>
//]
{
//[ node_iterator_ctors
constexpr node_iterator() noexcept : it_(nullptr) {}
constexpr node_iterator(node<T> * it) noexcept : it_(it) {}
//]
//[ node_iterator_user_ops
constexpr T & operator*() const noexcept { return it_->value_; }
constexpr node_iterator & operator++() noexcept
{
it_ = it_->next_;
return *this;
}
friend constexpr bool
operator==(node_iterator lhs, node_iterator rhs) noexcept
{
return lhs.it_ == rhs.it_;
}
//]
//[ node_iterator_using_declaration
using base_type = boost::stl_interfaces::iterator_interface<
#if !BOOST_STL_INTERFACES_USE_DEDUCED_THIS
node_iterator<T>,
#endif
std::forward_iterator_tag, T>;
using base_type::operator++;
//]
private:
node<T> * it_;
};
//[ node_iterator_concept_check Equivalent to
// static_assert(std::forward_iterator<node_iterator>, ""), or nothing in
// C++17 and earlier.
BOOST_STL_INTERFACES_STATIC_ASSERT_CONCEPT(
node_iterator<int>, std::forward_iterator)
//]
int main()
{
std::array<node<int>, 5> nodes;
std::generate(nodes.begin(), nodes.end(), [] {
static int i = 0;
return node<int>{i++};
});
std::adjacent_find(
nodes.begin(), nodes.end(), [](node<int> & a, node<int> & b) {
a.next_ = &b;
return false;
});
nodes.back().next_ = nullptr;
//[ node_iterator_usage
node_iterator<int> const first(&nodes[0]);
node_iterator<int> const last;
for (auto it = first; it != last; it++) {
std::cout << *it << " "; // Prints 0 1 2 3 4
}
std::cout << "\n";
//]
}
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