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