| // Copyright Daniel Wallin 2006. |
| // 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) |
| |
| // |
| // 2009.10.21 TDS remove depenency on boost::python::detail::referent_storage |
| // |
| #ifndef BOOST_PARAMETER_MAYBE_091021_HPP |
| #define BOOST_PARAMETER_MAYBE_091021_HPP |
| |
| namespace boost { namespace parameter { namespace aux { |
| |
| template <typename T> |
| struct referent_size; |
| }}} // namespace boost::parameter::aux |
| |
| #include <boost/parameter/config.hpp> |
| |
| namespace boost { namespace parameter { namespace aux { |
| |
| template <typename T> |
| struct referent_size<T&> |
| { |
| BOOST_STATIC_CONSTANT(::std::size_t, value = sizeof(T)); |
| }; |
| }}} // namespace boost::parameter::aux |
| |
| #include <boost/type_traits/aligned_storage.hpp> |
| |
| namespace boost { namespace parameter { namespace aux { |
| |
| // A metafunction returning a POD type which can store U, where T == U&. |
| // If T is not a reference type, returns a POD which can store T. |
| template <typename T> |
| struct referent_storage |
| : ::boost::aligned_storage< |
| ::boost::parameter::aux::referent_size<T>::value |
| > |
| { |
| }; |
| }}} // namespace boost::parameter::aux |
| |
| #include <boost/parameter/aux_/is_maybe.hpp> |
| #include <boost/optional/optional.hpp> |
| |
| #if defined(BOOST_PARAMETER_CAN_USE_MP11) |
| #include <type_traits> |
| #else // !defined(BOOST_PARAMETER_CAN_USE_MP11) |
| #include <boost/type_traits/add_lvalue_reference.hpp> |
| #include <boost/type_traits/remove_cv.hpp> |
| #if !BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564)) |
| #include <boost/type_traits/add_const.hpp> |
| #endif |
| #endif // BOOST_PARAMETER_CAN_USE_MP11 |
| |
| namespace boost { namespace parameter { namespace aux { |
| |
| template <typename T> |
| struct maybe : ::boost::parameter::aux::maybe_base |
| { |
| #if defined(BOOST_PARAMETER_CAN_USE_MP11) |
| typedef typename ::std::add_lvalue_reference< |
| typename ::std::add_const<T>::type |
| #else // !defined(BOOST_PARAMETER_CAN_USE_MP11) |
| typedef typename ::boost::add_lvalue_reference< |
| #if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564)) |
| T const |
| #else |
| typename ::boost::add_const<T>::type |
| #endif |
| #endif // BOOST_PARAMETER_CAN_USE_MP11 |
| >::type reference; |
| |
| #if defined(BOOST_PARAMETER_CAN_USE_MP11) |
| typedef typename ::std::remove_cv< |
| typename ::std::remove_reference<reference>::type |
| #else |
| typedef typename ::boost::remove_cv< |
| BOOST_DEDUCED_TYPENAME ::boost::remove_reference<reference>::type |
| #endif |
| >::type non_cv_value; |
| |
| inline explicit maybe(T value_) : value(value_), constructed(false) |
| { |
| } |
| |
| inline maybe() : value(), constructed(false) |
| { |
| } |
| |
| ~maybe() |
| { |
| if (this->constructed) |
| { |
| this->destroy(); |
| } |
| } |
| |
| inline reference construct(reference value_) const |
| { |
| return value_; |
| } |
| |
| template <typename U> |
| reference construct2(U const& value_) const |
| { |
| new (this->m_storage.address()) non_cv_value(value_); |
| this->constructed = true; |
| return *reinterpret_cast<non_cv_value*>( |
| this->m_storage.address() |
| ); |
| } |
| |
| template <typename U> |
| inline reference construct(U const& value_) const |
| { |
| return this->construct2(value_); |
| } |
| |
| void destroy() |
| { |
| reinterpret_cast<non_cv_value*>( |
| this->m_storage.address() |
| )->~non_cv_value(); |
| } |
| |
| typedef reference( |
| ::boost::parameter::aux::maybe<T>::*safe_bool |
| )() const; |
| |
| inline operator safe_bool() const |
| { |
| return this->value ? &::boost::parameter::aux::maybe<T>::get : 0; |
| } |
| |
| inline reference get() const |
| { |
| return this->value.get(); |
| } |
| |
| private: |
| ::boost::optional<T> value; |
| mutable bool constructed; |
| mutable typename ::boost::parameter::aux |
| ::referent_storage<reference>::type m_storage; |
| }; |
| }}} // namespace boost::parameter::aux |
| |
| #endif // include guard |
| |