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/core/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.
key_value_pair()28 key_value_pair() { }
29
30 // Value-initializes the object held by m_value.
key_value_pair(const std::string & key)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.
key_value_pair(const std::string & key,const T & value)38 key_value_pair(const std::string& key, const T& value)
39 :
40 m_key(key), m_value(value)
41 {
42 }
43
get_value() const44 const T& get_value() const
45 {
46 return m_value;
47 }
48 };
49
50
51 // Tells whether the argument is value-initialized.
is_value_initialized(const int & arg)52 bool is_value_initialized(const int& arg)
53 {
54 return arg == 0;
55 }
56
57
58 // Tells whether the argument is value-initialized.
is_value_initialized(const std::string & arg)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
operator ==(const foo & lhs,const foo & rhs)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.
is_value_initialized(const foo & arg)76 bool is_value_initialized(const foo& arg)
77 {
78 return arg.data == 0;
79 }
80
81
82 template <class T>
test_key_value_pair(const T & magic_value)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.
main()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 }
117