| // Copyright 2010, Niels Dekker. |
| // |
| // Distributed under the Boost Software License, Version 1.0. (See |
| // accompanying file LICENSE_1_0.txt or copy at |
| // http://www.boost.org/LICENSE_1_0.txt) |
| // |
| // Test program for boost::initialized<T>. |
| // |
| // 2 May 2010 (Created) Niels Dekker |
| |
| #include <boost/utility/value_init.hpp> |
| #include <boost/detail/lightweight_test.hpp> |
| |
| #include <string> |
| |
| namespace |
| { |
| // Typical use case for boost::initialized<T>: A generic class that |
| // holds a value of type T, which must be initialized by either |
| // value-initialization or direct-initialization. |
| template <class T> class key_value_pair |
| { |
| std::string m_key; |
| boost::initialized<T> m_value; |
| public: |
| |
| // Value-initializes the object held by m_value. |
| key_value_pair() { } |
| |
| // Value-initializes the object held by m_value. |
| explicit key_value_pair(const std::string& key) |
| : |
| m_key(key) |
| { |
| } |
| |
| // Direct-initializes the object held by m_value. |
| key_value_pair(const std::string& key, const T& value) |
| : |
| m_key(key), m_value(value) |
| { |
| } |
| |
| const T& get_value() const |
| { |
| return m_value; |
| } |
| }; |
| |
| |
| // Tells whether the argument is value-initialized. |
| bool is_value_initialized(const int& arg) |
| { |
| return arg == 0; |
| } |
| |
| |
| // Tells whether the argument is value-initialized. |
| bool is_value_initialized(const std::string& arg) |
| { |
| return arg.empty(); |
| } |
| |
| struct foo |
| { |
| int data; |
| }; |
| |
| bool operator==(const foo& lhs, const foo& rhs) |
| { |
| return lhs.data == rhs.data; |
| } |
| |
| |
| // Tells whether the argument is value-initialized. |
| bool is_value_initialized(const foo& arg) |
| { |
| return arg.data == 0; |
| } |
| |
| |
| template <class T> |
| void test_key_value_pair(const T& magic_value) |
| { |
| // The value component of a default key_value_pair must be value-initialized. |
| key_value_pair<T> default_key_value_pair; |
| BOOST_TEST( is_value_initialized(default_key_value_pair.get_value() ) ); |
| |
| // The value component of a key_value_pair that only has its key explicitly specified |
| // must also be value-initialized. |
| BOOST_TEST( is_value_initialized(key_value_pair<T>("key").get_value()) ); |
| |
| // However, the value component of the following key_value_pair must be |
| // "magic_value", as it must be direct-initialized. |
| BOOST_TEST( key_value_pair<T>("key", magic_value).get_value() == magic_value ); |
| } |
| } |
| |
| |
| // Tests boost::initialize for a fundamental type, a type with a |
| // user-defined constructor, and a user-defined type without |
| // a user-defined constructor. |
| int main() |
| { |
| |
| const int magic_number = 42; |
| test_key_value_pair(magic_number); |
| |
| const std::string magic_string = "magic value"; |
| test_key_value_pair(magic_string); |
| |
| const foo magic_foo = { 42 }; |
| test_key_value_pair(magic_foo); |
| |
| return boost::report_errors(); |
| } |