1 | // Copyright 2010, Niels Dekker. |
2 | // |
3 | // Distributed under the Boost Software License, Version 1.0. (See |
4 | // accompanying file LICENSE_1_0.txt or copy at |
5 | // http://www.boost.org/LICENSE_1_0.txt) |
6 | // |
7 | // Test program for boost::initialized<T>. |
8 | // |
9 | // 2 May 2010 (Created) Niels Dekker |
10 | |
11 | #include <boost/utility/value_init.hpp> |
12 | #include <boost/detail/lightweight_test.hpp> |
13 | |
14 | #include <string> |
15 | |
16 | namespace |
17 | { |
18 | // Typical use case for boost::initialized<T>: A generic class that |
19 | // holds a value of type T, which must be initialized by either |
20 | // value-initialization or direct-initialization. |
21 | template <class T> class key_value_pair |
22 | { |
23 | std::string m_key; |
24 | boost::initialized<T> m_value; |
25 | public: |
26 | |
27 | // Value-initializes the object held by m_value. |
28 | key_value_pair() { } |
29 | |
30 | // Value-initializes the object held by m_value. |
31 | explicit key_value_pair(const std::string& key) |
32 | : |
33 | m_key(key) |
34 | { |
35 | } |
36 | |
37 | // Direct-initializes the object held by m_value. |
38 | key_value_pair(const std::string& key, const T& value) |
39 | : |
40 | m_key(key), m_value(value) |
41 | { |
42 | } |
43 | |
44 | const T& get_value() const |
45 | { |
46 | return m_value; |
47 | } |
48 | }; |
49 | |
50 | |
51 | // Tells whether the argument is value-initialized. |
52 | bool is_value_initialized(const int& arg) |
53 | { |
54 | return arg == 0; |
55 | } |
56 | |
57 | |
58 | // Tells whether the argument is value-initialized. |
59 | bool is_value_initialized(const std::string& arg) |
60 | { |
61 | return arg.empty(); |
62 | } |
63 | |
64 | struct foo |
65 | { |
66 | int data; |
67 | }; |
68 | |
69 | bool operator==(const foo& lhs, const foo& rhs) |
70 | { |
71 | return lhs.data == rhs.data; |
72 | } |
73 | |
74 | |
75 | // Tells whether the argument is value-initialized. |
76 | bool is_value_initialized(const foo& arg) |
77 | { |
78 | return arg.data == 0; |
79 | } |
80 | |
81 | |
82 | template <class T> |
83 | void test_key_value_pair(const T& magic_value) |
84 | { |
85 | // The value component of a default key_value_pair must be value-initialized. |
86 | key_value_pair<T> default_key_value_pair; |
87 | BOOST_TEST( is_value_initialized(default_key_value_pair.get_value() ) ); |
88 | |
89 | // The value component of a key_value_pair that only has its key explicitly specified |
90 | // must also be value-initialized. |
91 | BOOST_TEST( is_value_initialized(key_value_pair<T>("key" ).get_value()) ); |
92 | |
93 | // However, the value component of the following key_value_pair must be |
94 | // "magic_value", as it must be direct-initialized. |
95 | BOOST_TEST( key_value_pair<T>("key" , magic_value).get_value() == magic_value ); |
96 | } |
97 | } |
98 | |
99 | |
100 | // Tests boost::initialize for a fundamental type, a type with a |
101 | // user-defined constructor, and a user-defined type without |
102 | // a user-defined constructor. |
103 | int main() |
104 | { |
105 | |
106 | const int magic_number = 42; |
107 | test_key_value_pair(magic_value: magic_number); |
108 | |
109 | const std::string magic_string = "magic value" ; |
110 | test_key_value_pair(magic_value: magic_string); |
111 | |
112 | const foo magic_foo = { .data: 42 }; |
113 | test_key_value_pair(magic_value: magic_foo); |
114 | |
115 | return boost::report_errors(); |
116 | } |
117 | |