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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_number); | |
108 | ||
109 | const std::string magic_string = "magic value"; | |
110 | test_key_value_pair(magic_string); | |
111 | ||
112 | const foo magic_foo = { 42 }; | |
113 | test_key_value_pair(magic_foo); | |
114 | ||
115 | return boost::report_errors(); | |
116 | } |