Chris@16: // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
Chris@16: // (C) Copyright 2005-2007 Jonathan Turkanis
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
Chris@16: 
Chris@16: // See http://www.boost.org/libs/iostreams for documentation.
Chris@16: 
Chris@16: // Recent changes to Boost.Optional involving assigment broke Boost.Iostreams,
Chris@16: // in a way which could be remedied only by relying on the deprecated reset
Chris@16: // functions; with VC6, even reset didn't work. Until this problem is 
Chris@16: // understood, Iostreams will use a private version of optional with a smart 
Chris@16: // pointer interface.
Chris@16: 
Chris@16: #ifndef BOOST_IOSTREAMS_DETAIL_OPTIONAL_HPP_INCLUDED
Chris@16: #define BOOST_IOSTREAMS_DETAIL_OPTIONAL_HPP_INCLUDED
Chris@16: 
Chris@16: #if defined(_MSC_VER) && (_MSC_VER >= 1020)
Chris@16: # pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/assert.hpp>
Chris@16: #include <boost/mpl/int.hpp>
Chris@16: #include <boost/type_traits/aligned_storage.hpp>
Chris@16: #include <boost/type_traits/alignment_of.hpp>
Chris@16: 
Chris@16: namespace boost { namespace iostreams { namespace detail {
Chris@16: 
Chris@16: // Taken from <boost/optional.hpp>.
Chris@16: template<class T>
Chris@16: class aligned_storage
Chris@16: {
Chris@16:     // Borland ICEs if unnamed unions are used for this!
Chris@16:     union dummy_u
Chris@16:     {
Chris@16:         char data[ sizeof(T) ];
Chris@16:         BOOST_DEDUCED_TYPENAME type_with_alignment<
Chris@16:           ::boost::alignment_of<T>::value >::type aligner_;
Chris@16:     } dummy_ ;
Chris@16: 
Chris@16:   public:
Chris@16: 
Chris@16:     void const* address() const { return &dummy_.data[0]; }
Chris@16:     void      * address()       { return &dummy_.data[0]; }
Chris@16: };
Chris@16: 
Chris@16: template<typename T>
Chris@16: class optional {
Chris@16: public:
Chris@16:     typedef T element_type;
Chris@16:     optional() : initialized_(false) { }
Chris@16:     optional(const T& t) : initialized_(false) { reset(t); }
Chris@16:     ~optional() { reset(); }
Chris@16:     T& operator*() 
Chris@16:     { 
Chris@16:         BOOST_ASSERT(initialized_);
Chris@16:         return *static_cast<T*>(address()); 
Chris@16:     }
Chris@16:     const T& operator*() const
Chris@16:     { 
Chris@16:         BOOST_ASSERT(initialized_);
Chris@16:         return *static_cast<const T*>(address()); 
Chris@16:     }
Chris@16:     T* operator->() 
Chris@16:     { 
Chris@16:         BOOST_ASSERT(initialized_);
Chris@16:         return static_cast<T*>(address()); 
Chris@16:     }
Chris@16:     const T* operator->() const
Chris@16:     { 
Chris@16:         BOOST_ASSERT(initialized_);
Chris@16:         return static_cast<const T*>(address()); 
Chris@16:     }
Chris@16:     T* get() 
Chris@16:     { 
Chris@16:         BOOST_ASSERT(initialized_);
Chris@16:         return static_cast<T*>(address()); 
Chris@16:     }
Chris@16:     const T* get() const
Chris@16:     { 
Chris@16:         BOOST_ASSERT(initialized_);
Chris@16:         return static_cast<const T*>(address()); 
Chris@16:     }
Chris@16:     void reset() 
Chris@16:     {
Chris@16:         if (initialized_) { 
Chris@16:         #if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564)) || \
Chris@16:             BOOST_WORKAROUND(__IBMCPP__, BOOST_TESTED_AT(600)) \
Chris@16:             /**/
Chris@16:             T* t = static_cast<T*>(address());
Chris@16:             t->~T();
Chris@16:         #else
Chris@16:             static_cast<T*>(address())->T::~T();
Chris@16:         #endif
Chris@16:             initialized_ = false;
Chris@16:         }
Chris@16:     }
Chris@16:     void reset(const T& t) 
Chris@16:     {
Chris@16:         reset();
Chris@16:         new (address()) T(t); 
Chris@16:         initialized_ = true;
Chris@16:     }
Chris@16: private:
Chris@16:     optional(const optional&);
Chris@16:     optional& operator=(const optional&);
Chris@16:     void* address() { return &storage_; }
Chris@16:     const void* address() const { return &storage_; }
Chris@16:     aligned_storage<T>  storage_;
Chris@16:     bool                initialized_;
Chris@16: };
Chris@16: 
Chris@16: } } } // End namespaces detail, iostreams, boost.
Chris@16: 
Chris@16: #endif // #ifndef BOOST_IOSTREAMS_DETAIL_OPTIONAL_HPP_INCLUDED