GEEKING

Base/include/rbx/make_shared.h

@@ -0,0 +1,171 @@
+#pragma once
+#include <boost/config.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/type_traits/type_with_alignment.hpp>
+#include <boost/type_traits/alignment_of.hpp>
+#include <cstddef>
+#include <new>
+
+// This is a copy of make_shared from boost 1.42.1
+// When we upgrade we can use boost directly
+// NOTE: 1.38.1 has an undocumented make_shared.hpp, but I don't know if it is 
+//       safe or not to use.
+namespace rbx
+{
+namespace detail
+{
+template< std::size_t N, std::size_t A > struct sp_aligned_storage
+{
+    union type
+    {
+        char data_[ N ];
+        typename boost::type_with_alignment< A >::type align_;
+    };
+};
+
+template< class T > class sp_ms_deleter
+{
+private:
+
+    typedef typename sp_aligned_storage< sizeof( T ), ::boost::alignment_of< T >::value >::type storage_type;
+
+    bool initialized_;
+    storage_type storage_;
+
+private:
+
+    void destroy()
+    {
+        if( initialized_ )
+        {
+            reinterpret_cast< T* >( storage_.data_ )->~T();
+            initialized_ = false;
+        }
+    }
+
+public:
+
+    sp_ms_deleter(): initialized_( false )
+    {
+    }
+
+    // optimization: do not copy storage_
+    sp_ms_deleter( sp_ms_deleter const & ): initialized_( false )
+    {
+    }
+
+    ~sp_ms_deleter()
+    {
+        destroy();
+    }
+
+    void operator()( T * )
+    {
+        destroy();
+    }
+
+    void * address()
+    {
+        return storage_.data_;
+    }
+
+    void set_initialized()
+    {
+        initialized_ = true;
+    }
+};
+
+#if defined( BOOST_HAS_RVALUE_REFS )
+template< class T > T&& sp_forward( T & t )
+{
+    return static_cast< T&& >( t );
+}
+#endif
+} // namespace detail
+
+// TODO: This implementation may not support shared_from_this properly. Upgrade to new boost, which implements this for us
+template< class T > boost::shared_ptr< T > make_shared()
+{
+    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), rbx::detail::sp_ms_deleter< T >() );
+
+    rbx::detail::sp_ms_deleter< T > * pd = boost::get_deleter< rbx::detail::sp_ms_deleter< T > >( pt );
+
+    void * pv = pd->address();
+
+    ::new( pv ) T();
+    pd->set_initialized();
+
+    T * pt2 = static_cast< T* >( pv );
+
+    return boost::shared_ptr< T >( pt, pt2 );
+}
+
+template< class T> boost::shared_ptr< T > make_shared(std::allocator<T> a)
+{
+    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), rbx::detail::sp_ms_deleter< T >(), a );
+
+    rbx::detail::sp_ms_deleter< T > * pd = boost::get_deleter< rbx::detail::sp_ms_deleter< T > >( pt );
+
+    void * pv = pd->address();
+
+    ::new( pv ) T();
+    pd->set_initialized();
+
+    T * pt2 = static_cast< T* >( pv );
+
+    return boost::shared_ptr< T >( pt, pt2 );
+}
+
+
+template< class T, class A1 >
+boost::shared_ptr< T > make_shared( A1 const & a1)
+{
+    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), rbx::detail::sp_ms_deleter< T >() );
+
+    rbx::detail::sp_ms_deleter< T > * pd = boost::get_deleter< rbx::detail::sp_ms_deleter< T > >( pt );
+
+    void * pv = pd->address();
+
+    ::new( pv ) T( a1 );
+    pd->set_initialized();
+
+    T * pt2 = static_cast< T* >( pv );
+
+    return boost::shared_ptr< T >( pt, pt2 );
+}
+
+template< class T, class A1, class A2 >
+boost::shared_ptr< T > make_shared( A1 const & a1, A2 const & a2 )
+{
+    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), rbx::detail::sp_ms_deleter< T >() );
+
+    rbx::detail::sp_ms_deleter< T > * pd = boost::get_deleter< rbx::detail::sp_ms_deleter< T > >( pt );
+
+    void * pv = pd->address();
+
+    ::new( pv ) T( a1, a2 );
+    pd->set_initialized();
+
+    T * pt2 = static_cast< T* >( pv );
+
+    return boost::shared_ptr< T >( pt, pt2 );
+}
+
+template< class T, class A1, class A2, class A3 >
+boost::shared_ptr< T > make_shared( A1 const & a1, A2 const & a2, A3 const & a3 )
+{
+    boost::shared_ptr< T > pt( static_cast< T* >( 0 ), rbx::detail::sp_ms_deleter< T >() );
+
+    rbx::detail::sp_ms_deleter< T > * pd = boost::get_deleter< rbx::detail::sp_ms_deleter< T > >( pt );
+
+    void * pv = pd->address();
+
+    ::new( pv ) T( a1, a2, a3 );
+    pd->set_initialized();
+
+    T * pt2 = static_cast< T* >( pv );
+
+    return boost::shared_ptr< T >( pt, pt2 );
+}
+
+}