// Copyright Daniel Wallin 2006.
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// Distributed under the Boost Software License, Version 1.0.
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// (See 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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// 2009.10.21 TDS remove depenency on boost::python::detail::referent_storage
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//
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#ifndef BOOST_PARAMETER_MAYBE_091021_HPP
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#define BOOST_PARAMETER_MAYBE_091021_HPP
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namespace boost { namespace parameter { namespace aux {
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template <typename T>
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struct referent_size;
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}}} // namespace boost::parameter::aux
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#include <boost/parameter/config.hpp>
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namespace boost { namespace parameter { namespace aux {
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template <typename T>
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struct referent_size<T&>
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{
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BOOST_STATIC_CONSTANT(::std::size_t, value = sizeof(T));
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};
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}}} // namespace boost::parameter::aux
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#include <boost/type_traits/aligned_storage.hpp>
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namespace boost { namespace parameter { namespace aux {
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// A metafunction returning a POD type which can store U, where T == U&.
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// If T is not a reference type, returns a POD which can store T.
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template <typename T>
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struct referent_storage
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: ::boost::aligned_storage<
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::boost::parameter::aux::referent_size<T>::value
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>
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{
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};
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}}} // namespace boost::parameter::aux
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#include <boost/parameter/aux_/is_maybe.hpp>
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#include <boost/optional/optional.hpp>
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#if defined(BOOST_PARAMETER_CAN_USE_MP11)
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#include <type_traits>
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#else // !defined(BOOST_PARAMETER_CAN_USE_MP11)
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#include <boost/type_traits/add_lvalue_reference.hpp>
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#include <boost/type_traits/remove_cv.hpp>
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#if !BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
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#include <boost/type_traits/add_const.hpp>
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#endif
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#endif // BOOST_PARAMETER_CAN_USE_MP11
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namespace boost { namespace parameter { namespace aux {
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template <typename T>
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struct maybe : ::boost::parameter::aux::maybe_base
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{
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#if defined(BOOST_PARAMETER_CAN_USE_MP11)
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typedef typename ::std::add_lvalue_reference<
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typename ::std::add_const<T>::type
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#else // !defined(BOOST_PARAMETER_CAN_USE_MP11)
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typedef typename ::boost::add_lvalue_reference<
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#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x564))
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T const
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#else
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typename ::boost::add_const<T>::type
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#endif
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#endif // BOOST_PARAMETER_CAN_USE_MP11
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>::type reference;
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#if defined(BOOST_PARAMETER_CAN_USE_MP11)
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typedef typename ::std::remove_cv<
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typename ::std::remove_reference<reference>::type
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#else
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typedef typename ::boost::remove_cv<
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BOOST_DEDUCED_TYPENAME ::boost::remove_reference<reference>::type
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#endif
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>::type non_cv_value;
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inline explicit maybe(T value_) : value(value_), constructed(false)
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{
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}
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inline maybe() : value(), constructed(false)
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{
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}
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~maybe()
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{
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if (this->constructed)
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{
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this->destroy();
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}
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}
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inline reference construct(reference value_) const
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{
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return value_;
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}
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template <typename U>
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reference construct2(U const& value_) const
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{
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new (this->m_storage.address()) non_cv_value(value_);
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this->constructed = true;
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return *reinterpret_cast<non_cv_value*>(
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this->m_storage.address()
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);
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}
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template <typename U>
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inline reference construct(U const& value_) const
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{
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return this->construct2(value_);
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}
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void destroy()
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{
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reinterpret_cast<non_cv_value*>(
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this->m_storage.address()
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)->~non_cv_value();
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}
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typedef reference(
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::boost::parameter::aux::maybe<T>::*safe_bool
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)() const;
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inline operator safe_bool() const
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{
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return this->value ? &::boost::parameter::aux::maybe<T>::get : 0;
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}
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inline reference get() const
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{
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return this->value.get();
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}
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private:
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::boost::optional<T> value;
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mutable bool constructed;
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mutable typename ::boost::parameter::aux
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::referent_storage<reference>::type m_storage;
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};
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}}} // namespace boost::parameter::aux
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#endif // include guard
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