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158 lines
3.2 KiB
C++
158 lines
3.2 KiB
C++
// (C) Copyright 2002-2007, Fernando Luis Cacciola Carballal.
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// 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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// 21 Ago 2002 (Created) Fernando Cacciola
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// 07 Set 2007 (Worked around MSVC++ bug) Fernando Cacciola, Niels Dekker
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//
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#ifndef BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
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#define BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
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#include <boost/detail/select_type.hpp>
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#include <boost/type_traits/cv_traits.hpp>
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#include <boost/detail/workaround.hpp>
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#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1500) )
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// Microsoft Visual C++ does not correctly support value initialization, as reported by
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// Pavel Kuznetsov (MetaCommunications Engineering), 7/28/2005, Feedback ID 100744,
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// Feedback Title: Value-initialization in new-expression
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// https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=100744
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// The report was closed at 11/14/2006, and its status was set to "Closed (Won't Fix)".
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// Luckily, even in the presence of this compiler bug, boost::value_initialized will still
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// do its job correctly, when using the following workaround:
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#define BOOST_UTILITY_VALUE_INIT_WORKAROUND
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#endif
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#ifdef BOOST_UTILITY_VALUE_INIT_WORKAROUND
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#include <boost/aligned_storage.hpp>
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#include <boost/type_traits/alignment_of.hpp>
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#include <cstring>
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#include <new>
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namespace boost {
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namespace vinit_detail {
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template<class T>
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class const_T_base
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{
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protected :
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const_T_base()
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{
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std::memset(&x, 0, sizeof(x));
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new (&x) T();
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}
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~const_T_base() { get().T::~T(); }
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T & get() const
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{
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void const * ptr = &x;
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return *static_cast<T*>(ptr);
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}
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private :
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typename ::boost::aligned_storage<sizeof(T), ::boost::alignment_of<T>::value>::type x;
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} ;
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template<class T>
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class non_const_T_base
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{
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protected :
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non_const_T_base()
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{
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std::memset(&x, 0, sizeof(x));
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new (&x) T();
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}
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~non_const_T_base() { get().T::~T(); }
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T & get() const
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{
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void * ptr = &x;
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return *static_cast<T*>(ptr);
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}
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private :
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mutable typename ::boost::aligned_storage<sizeof(T), ::boost::alignment_of<T>::value>::type x;
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} ;
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#else
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namespace boost {
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namespace vinit_detail {
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template<class T>
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class const_T_base
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{
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protected :
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const_T_base() : x() {}
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T & get() const { return x; }
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private :
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T x ;
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} ;
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template<class T>
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class non_const_T_base
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{
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protected :
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non_const_T_base() : x() {}
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T & get() const { return x; }
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private :
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mutable T x ;
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} ;
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#endif
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template<class T>
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struct select_base
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{
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typedef
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#if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))
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typename
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#endif
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::boost::detail::if_true< ::boost::is_const<T>::value >
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::template then< const_T_base<T>, non_const_T_base<T> >::type type ;
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} ;
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} // namespace vinit_detail
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template<class T>
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class value_initialized : private vinit_detail::select_base<T>::type
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{
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public :
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value_initialized() {}
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operator T&() const { return this->get(); }
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T& data() const { return this->get(); }
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} ;
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template<class T>
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T const& get ( value_initialized<T> const& x )
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{
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return x.data() ;
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}
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template<class T>
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T& get ( value_initialized<T>& x )
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{
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return x.data() ;
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}
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} // namespace boost
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#endif
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