Iterator

0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156

#include <iostream>

template <class node, class T>
class iterator
{
public:

    iterator(node* n)
    : node_ptr(n)
    {
    }

    T* operator * ()
    {
        return node_ptr->get();
    }

    T* operator -> ()
    {
        return node_ptr->get();
    }

    void operator ++ ()
    {
        node_ptr = node_ptr->next();
    }

    iterator operator ++ (int)
    {
        iterator iter(*this);
        ++(*this);
        return iter;
    }

    bool operator == (iterator const& i)
    {
        return node_ptr == i.node_ptr;
    }

    bool operator != (iterator const& i)
    {
        return !(*this == i);
    }

private:

    node* node_ptr;
};

template <class T>
class list_node
{
public:

    list_node(T const& t)
    : object(t)
    , next_node(0)
    {
        
    }

    ~list_node()
    {
        delete next_node;
    }

    void push_back(T const& t)
    {
        if(next_node)
        {
            next_node->push_back(t);
        }
        else
        {
            next_node = new list_node(t);
        }
    }

    list_node* next()
    {
        return next_node;
    }

    T* get()
    {
        return &object;
    }

private:

    T object;
    list_node* next_node;
};

template <class T>
class list
{
public:

    typedef list_node<T> node;

    typedef iterator<node, T> iterator;

    list()
    : root(0)
    {
    }

    ~list()
    {
        delete root;
    }

    void push_back(T const& t)
    {
        if(root)
        {
            root->push_back(t);
        }
        else
        {
            root = new node(t);
        }
    }

    iterator begin()
    {
        return iterator(root);
    }

    iterator end()
    {
        return iterator(0);
    }

private:

    node* root;
};

int main()
{
    typedef list<std::string> string_container;
    string_container orders;

    orders.push_back("First");
    orders.push_back("Second");
    orders.push_back("Third");
    orders.push_back("Fourth");

    for(string_container::iterator it = orders.begin(); it != orders.end(); ++it)
    {
        std::cout << it->c_str() << std::endl;
    }

    return 0;
}