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