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
|
#include <string>
#include <vector>
#include <iterator>
#include <iostream>
#include <algorithm>
struct Data
{
using value_type = std::string;
struct iterator
{
using iterator_category = std::forward_iterator_tag;
using difference_type = std::ptrdiff_t;
using value_type = std::string;
using pointer = value_type const *;
using reference = value_type const &;
friend class Data;
friend bool operator==(iterator const &lhs, iterator const &rhs);
// or (see below):
// friend auto operator<=>(iterator const &lhs, iterator const &rhs);
private:
std::vector<std::string>::const_iterator d_iter;
public:
std::string const &operator*() const;
iterator &operator++();
iterator &operator--();
private:
iterator(std::vector<std::string>::const_iterator iter);
};
private:
static std::vector<std::string> s_data;
std::vector<std::string> d_data;
public:
void push_back(std::string const &txt);
iterator begin() const;
iterator end() const;
std::reverse_iterator<iterator> rbegin() const;
auto rend() const;
};
inline void Data::push_back(std::string const &txt)
{
std::cout << "pushing back: " << txt << '\n';
}
inline std::string const &Data::iterator::operator*() const
{
return *d_iter;
}
Data::iterator &Data::iterator::operator++()
{
++d_iter;
return *this;
}
Data::iterator &Data::iterator::operator--()
{
--d_iter;
return *this;
}
inline Data::iterator::iterator(std::vector<std::string>::const_iterator iter)
:
d_iter(iter)
{}
std::reverse_iterator<Data::iterator> Data::rbegin() const
{
return std::reverse_iterator(end());
}
auto Data::rend() const
{
return std::reverse_iterator(begin());
}
inline Data::iterator Data::begin() const
{
return s_data.cbegin();
}
inline Data::iterator Data::end() const
{
return s_data.cend();
}
inline bool operator==(Data::iterator const &lhs, Data::iterator const &rhs)
{
return lhs.d_iter == rhs.d_iter;
}
inline bool operator!=(Data::iterator const &lhs, Data::iterator const &rhs)
{
return not (lhs == rhs);
}
// or:
//inline auto operator<=>(Data::iterator const &lhs, Data::iterator const &rhs)
//{
// return lhs.d_iter <=> rhs.d_iter;
//}
std::vector<std::string> Data::s_data{
"alpha", "bravo", "charley", "delta", "echo"
};
using namespace std;
int main()
{
Data data;
for( string const &str: data)
cout << str << ' ';
cout << '\n';
copy(data.begin(), data.end(), ostream_iterator<string>(cout, ", "));
cout << '\n';
copy(data.rbegin(), data.rend(), ostream_iterator<string>(cout, ", "));
cout << '\n';
copy(data.begin(), data.end(), back_inserter(data));
}
|
