http://kmlinux.fjfi.cvut.cz/~culik/zpro/tree

<code C++>
#ifndef TREE_H
#define TREE_H

#include <string>
using std::string;

class Node
{
private:
    Node*up;
    Node*next;
    Node*prev;
    Node*first;
    Node*last;

    void link (Node*a,Node*b, Node*c); //b novy prvek

public:  
    string name;
    Node*getUp(){return up;}
    Node*getNext(){return next;}
    Node*getPrev(){return prev;}
    Node*getFirst(){return first;}
    Node*getLast(){return last;}

    void linkNext (Node*p);
    void linkPrev (Node*p);
    void linkFirst (Node*p);
    void linkLast (Node*p);

    void unlink ();

    void print (int level = 1);

    Node(string name0=""):
        up(nullptr),next(nullptr), prev(nullptr), first(nullptr), last(nullptr), name(name0) {}
    ~Node();
};

#endif // TREE_H
</code>

<code C++>
#include "tree.h"
#include <cassert>
#include <iostream>

using namespace std;

void Node::link(Node *a, Node *b, Node *c)
{
    // #include <cassert>
    assert (this != nullptr); //nemelo by se stat, ale pro jistotu

    assert (b != nullptr);

    assert (b->up == nullptr);
    b->up = this;

    assert (a == nullptr || a->up == this);
    assert (c == nullptr || c->up == this);

    b->prev = a;
    b->next = c;

    if (a != nullptr)
       a->next = b;
    else
       first = b;

    if (c != nullptr)
       c->prev = b;
    else
       last = b;
}

void Node::linkFirst(Node *p)
{
    assert(this != nullptr);
    link (nullptr, p, first);
}

void Node::linkLast(Node *p)
{
    assert(this != nullptr);
    link (last, p, nullptr);
}

void Node::linkPrev(Node *p)
{
    assert(this != nullptr);
    assert (up!=nullptr);
    up->link (prev, p, this);
}

void Node::linkNext(Node *p)
{
    assert(this != nullptr);
    assert (up!=nullptr);
    up->link (this, p, next);
}

void Node::unlink()
{
    assert (this != nullptr);
    assert (up != nullptr);

    Node * a = prev;
    Node * c = next;

    if (a != nullptr)
       a->next = c; // mame predchudce, muzeme propojit
    else
       up->first = c; // nemame predchudce, naslednik se stava prvnim

    if (c != nullptr)
       c->prev = a;
    else
       up->last = a;

    up = nullptr;
    prev = nullptr;
    next = nullptr;
}

Node::~Node()
{
    cout << "Mažu " << name << endl;
    if (up != nullptr)
        unlink();

    Node * p = first;
    while (p != nullptr)
    {
        Node * t = p->next;
        delete p;
        p = t;
    }

}

void Node::print (int level)
{
   cout << string (level*4,' ') << name <<   endl;

   if (first != nullptr)
   {
      cout << string (level*4 + 2, ' ') << "[" << endl;

      Node * p = first;
      while (p != nullptr)
      {
          p->print (level + 1);
          p = p->next;
      }

      cout << string (level*4 + 2,' ') << "]" << endl;
   }
}


</code>