fork download
copy 
  1. #include <iostream>
  2. #include <utility>
  3.  
  4.  
  5. template<typename T>
  6. class list {
  7.  
  8.    struct list_node;
  9.    struct list_node_base;
  10.  
  11.  
  12. public:
  13.    void reverse() {
  14.    	  std::swap(head.prev, head.next);
  15.    	  for (list_node_base * p = head.prev; p != &head; p = p->prev) {
  16.    	     std::swap(p->prev, p->next);
  17.    	  }
  18.    }
  19.  
  20.    bool empty() const {
  21.       return &head == head.next;
  22.    }
  23.  
  24.    void push_back(T const& value) {
  25.       head.insert_before(new list_node(value));
  26.    } 
  27.  
  28.    template<typename F>
  29.    void apply(F f) const {
  30.       for (list_node_base * p = head.next; p != &head; p = p->next) {
  31.          f(p->get_data());
  32.       }
  33.    }
  34.  
  35.    ~list() {
  36.       while (!empty()) {
  37.          head.next->erase();
  38.       }
  39.    }
  40.  
  41.  
  42. private:
  43.    struct list_node_base {
  44.  
  45.       list_node_base() : prev(this), next(this) {}
  46.  
  47.       void insert_before(list_node_base * const what) {
  48.          prev->next = what;
  49.          what->prev = prev;
  50.  
  51.          this->prev = what;
  52.          what->next = this;
  53.       }
  54.  
  55.       void erase() {
  56.          prev->next = next;
  57.          next->prev = prev;
  58.  
  59.          delete static_cast<list_node *>(this);
  60.       }
  61.  
  62.       T & get_data() {
  63.          return static_cast<list_node *>(this)->data;
  64.       }
  65.       T const& get_data() const {
  66.          return static_cast<list_node const*>(this)->data;
  67.       }
  68.  
  69.       list_node_base * prev;
  70.       list_node_base * next;
  71.    };
  72.  
  73.    struct list_node : list_node_base {
  74.  
  75.       list_node(T const& data) : data(data) {}
  76.  
  77.       T data;
  78.    };
  79.  
  80.    list_node_base head;
  81. };
  82.  
  83.  
  84. int main() {
  85.    list<int> instance;
  86.  
  87.    for (int i = 0; i != 5; ++i) {
  88.       instance.push_back(i);
  89.    }
  90.  
  91.    auto const printer = [](int const value) {
  92.       std::cout << value << ' ';
  93.    };
  94.  
  95.    instance.apply(printer);
  96.    std::cout << std::endl;
  97.  
  98.    instance.reverse();
  99.  
  100.    instance.apply(printer);
  101.    std::cout << std::endl;
  102. }
Success #stdin #stdout 0s 3472KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
0 1 2 3 4 
4 3 2 1 0
https://ideone.com/GBZvde
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!