#ifndef DATA_STRUCTURES
#define DATA_STRUCTURES

//Constants.
const int
    SINGLE = 0,
    DOUBLE = 1,

    LINEAR = 0,
    CIRCULAR = 2,

    NONE = 0,
    FRONT = 1,
    BACK = 2;

class node
{
    private:
        int* value;
        int* before, after;

    public:
        int Read();
        bool Write(int);

        int* Before();
        int* After();

        bool SetBefore();
        bool SetAfter();
};

class data_structure_archetype
{
    private:
        int bound;

    public:
        int Size();
        bool IsEmpty();
        bool CanAdd(int);
        bool SetBound(int);
};

class linked_list
{
    private:
        int link;
        int* first_node, last_node;

        void make_links(node, node, node);

    public:
        int* Get(int, bool);
        int* Index(int, bool);
        bool Add(int);
        bool Insert(int, int);
        bool Cut(int, int);
        bool Remove(int);
        bool Swap(int, int);
        bool Empty();
        int* Merge(linked_list, bool);
        bool Find(int);
        int* Copy(int, int, bool, bool);
};

class singly_linked {};
class linearly_linked {};
class doubly_linked {};
class circularly_linked {};
class doubly_circularly_linked {};

class deque
{
    private:
        int input_restriction;
        int output_restriction;

        int* front_node, back_node;

    public:
        int* PushBack(bool);
        int* PushFront(bool);
        int* PopBack(bool);
        int* PopFront(bool);

        int* Examine(int, bool);
        int* Front(bool);
        int* Back(bool);

        bool SetInputRestriction(bool, bool);
        bool SetOutputRestriction(bool, bool);
};

class stack
{
    private:
        int* top_node;

    public:
        int* Push(bool);
        int* Pop(bool);

        int* Top(bool);
};

class queue
{
    private:
        int front_node, back_node;

    public:
        int* Push(bool);
        int* Pop(bool);

        int* Front(bool);
};

#endif

#include <iostream>

using namespace std;

#include "Structures.cpp"
#include "header.h"

int main()
{
    cout << "Hello world!" << endl;
    return 0;
}

#include "header.h"

//Implementation of the node class.

int *before, *after;