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C++ custom container with reverse iterator example
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| #include <algorithm> | |
| #include <cstdlib> | |
| #include <vector> | |
| #include <iostream> | |
| #include <iterator> | |
| struct someStruct { | |
| double m_d; | |
| int m_i; | |
| }; | |
| template<typename T> //, class _Alloc = allocator<T> > | |
| class list2 { | |
| public: | |
| std::vector<T> _data; | |
| using value_type = T; | |
| using reference = T&; | |
| using const_reference = const T&; | |
| using iterator = T*; | |
| using const_iterator = const T*; | |
| using reverse_iterator = std::reverse_iterator<iterator>; | |
| using const_reverse_iterator = std::reverse_iterator<const_iterator>; | |
| list2(const list2<T> &l) { _data = l._data; } | |
| list2(std::initializer_list<T> l) { | |
| for (const auto &elem : l) | |
| _data.push_back(elem); | |
| } | |
| void push_back(const T& elem) { _data.push_back(elem); } | |
| ~list2() { _data.clear(); } | |
| reverse_iterator rbegin() { | |
| return reverse_iterator(end()); | |
| } | |
| const_reverse_iterator crbegin() const { | |
| return const_reverse_iterator(cend()); | |
| } | |
| reverse_iterator rend() { | |
| return reverse_iterator(begin()); | |
| } | |
| const_reverse_iterator crend() const { | |
| return const_reverse_iterator(cbegin()); | |
| } | |
| iterator begin() { return _data.data(); } | |
| const_iterator cbegin() const { return _data.data(); } | |
| iterator end() { return _data.data() + _data.size(); } | |
| const_iterator cend() const { return _data.data() + _data.size(); } | |
| }; | |
| // ------------------------------------------------------------------- | |
| // --- Reversed iterable | |
| template <typename T> | |
| struct reversion_wrapper { T& iterable; }; | |
| template <typename T> | |
| auto begin (reversion_wrapper<T> w) { return std::rbegin(w.iterable); } | |
| template <typename T> | |
| auto end (reversion_wrapper<T> w) { return std::rend(w.iterable); } | |
| template <typename T> | |
| reversion_wrapper<T> reverse (T&& iterable) { return { iterable }; } | |
| int main () | |
| { | |
| list2<double> lst_vec{1.1, 1, 2.2, 2}; | |
| list2<someStruct> lst{{1.1, 1}, {2.2, 2}, {3.3, 3}}; | |
| std::vector<double> vect{1.1, 1, 2.2, 2}; | |
| for (auto num : reverse(lst_vec)) { | |
| std::cout << num << " "; | |
| } | |
| std::cout << "\n"; | |
| for (auto num : lst) { | |
| std::cout << num.m_d << " " << num.m_i << " "; | |
| } | |
| std::cout << "\n"; | |
| for (auto num : reverse(lst)) { | |
| std::cout << num.m_d << " " << num.m_i << " "; | |
| } | |
| std::cout << "\n"; | |
| for (auto num : reverse(vect)) { | |
| std::cout << num << " "; | |
| } | |
| std::cout << "\n"; | |
| return 0; | |
| } |
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