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// 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();
}
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