| // (C) Copyright 2002-2008, Fernando Luis Cacciola Carballal. |
| // |
| // 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) |
| // |
| // 21 Ago 2002 (Created) Fernando Cacciola |
| // 24 Dec 2007 (Refactored and worked around various compiler bugs) Fernando Cacciola, Niels Dekker |
| // 23 May 2008 (Fixed operator= const issue, added initialized_value) Niels Dekker, Fernando Cacciola |
| // 21 Ago 2008 (Added swap) Niels Dekker, Fernando Cacciola |
| // 20 Feb 2009 (Fixed logical const-ness issues) Niels Dekker, Fernando Cacciola |
| // 03 Apr 2010 (Added initialized<T>, suggested by Jeffrey Hellrung, fixing #3472) Niels Dekker |
| // 30 May 2010 (Made memset call conditional, fixing #3869) Niels Dekker |
| // |
| #ifndef BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP |
| #define BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP |
| |
| // Note: The implementation of boost::value_initialized had to deal with the |
| // fact that various compilers haven't fully implemented value-initialization. |
| // The constructor of boost::value_initialized<T> works around these compiler |
| // issues, by clearing the bytes of T, before constructing the T object it |
| // contains. More details on these issues are at libs/utility/value_init.htm |
| |
| #include <boost/aligned_storage.hpp> |
| #include <boost/config.hpp> // For BOOST_NO_COMPLETE_VALUE_INITIALIZATION. |
| #include <boost/detail/workaround.hpp> |
| #include <boost/static_assert.hpp> |
| #include <boost/type_traits/cv_traits.hpp> |
| #include <boost/type_traits/alignment_of.hpp> |
| #include <boost/swap.hpp> |
| #include <cstring> |
| #include <new> |
| |
| #ifdef BOOST_MSVC |
| #pragma warning(push) |
| // It is safe to ignore the following warning from MSVC 7.1 or higher: |
| // "warning C4351: new behavior: elements of array will be default initialized" |
| #pragma warning(disable: 4351) |
| // It is safe to ignore the following MSVC warning, which may pop up when T is |
| // a const type: "warning C4512: assignment operator could not be generated". |
| #pragma warning(disable: 4512) |
| #endif |
| |
| #ifdef BOOST_NO_COMPLETE_VALUE_INITIALIZATION |
| // Implementation detail: The macro BOOST_DETAIL_VALUE_INIT_WORKAROUND_SUGGESTED |
| // suggests that a workaround should be applied, because of compiler issues |
| // regarding value-initialization. |
| #define BOOST_DETAIL_VALUE_INIT_WORKAROUND_SUGGESTED |
| #endif |
| |
| // Implementation detail: The macro BOOST_DETAIL_VALUE_INIT_WORKAROUND |
| // switches the value-initialization workaround either on or off. |
| #ifndef BOOST_DETAIL_VALUE_INIT_WORKAROUND |
| #ifdef BOOST_DETAIL_VALUE_INIT_WORKAROUND_SUGGESTED |
| #define BOOST_DETAIL_VALUE_INIT_WORKAROUND 1 |
| #else |
| #define BOOST_DETAIL_VALUE_INIT_WORKAROUND 0 |
| #endif |
| #endif |
| |
| namespace boost { |
| |
| template<class T> |
| class initialized |
| { |
| private : |
| struct wrapper |
| { |
| #if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x592)) |
| typename |
| #endif |
| remove_const<T>::type data; |
| |
| BOOST_GPU_ENABLED |
| wrapper() |
| : |
| data() |
| { |
| } |
| |
| BOOST_GPU_ENABLED |
| wrapper(T const & arg) |
| : |
| data(arg) |
| { |
| } |
| }; |
| |
| mutable |
| #if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x592)) |
| typename |
| #endif |
| aligned_storage<sizeof(wrapper), alignment_of<wrapper>::value>::type x; |
| |
| BOOST_GPU_ENABLED |
| wrapper * wrapper_address() const |
| { |
| return static_cast<wrapper *>( static_cast<void*>(&x)); |
| } |
| |
| public : |
| |
| BOOST_GPU_ENABLED |
| initialized() |
| { |
| #if BOOST_DETAIL_VALUE_INIT_WORKAROUND |
| std::memset(&x, 0, sizeof(x)); |
| #endif |
| new (wrapper_address()) wrapper(); |
| } |
| |
| BOOST_GPU_ENABLED |
| initialized(initialized const & arg) |
| { |
| new (wrapper_address()) wrapper( static_cast<wrapper const &>(*(arg.wrapper_address()))); |
| } |
| |
| BOOST_GPU_ENABLED |
| explicit initialized(T const & arg) |
| { |
| new (wrapper_address()) wrapper(arg); |
| } |
| |
| BOOST_GPU_ENABLED |
| initialized & operator=(initialized const & arg) |
| { |
| // Assignment is only allowed when T is non-const. |
| BOOST_STATIC_ASSERT( ! is_const<T>::value ); |
| *wrapper_address() = static_cast<wrapper const &>(*(arg.wrapper_address())); |
| return *this; |
| } |
| |
| BOOST_GPU_ENABLED |
| ~initialized() |
| { |
| wrapper_address()->wrapper::~wrapper(); |
| } |
| |
| BOOST_GPU_ENABLED |
| T const & data() const |
| { |
| return wrapper_address()->data; |
| } |
| |
| BOOST_GPU_ENABLED |
| T& data() |
| { |
| return wrapper_address()->data; |
| } |
| |
| BOOST_GPU_ENABLED |
| void swap(initialized & arg) |
| { |
| ::boost::swap( this->data(), arg.data() ); |
| } |
| |
| BOOST_GPU_ENABLED |
| operator T const &() const |
| { |
| return wrapper_address()->data; |
| } |
| |
| BOOST_GPU_ENABLED |
| operator T&() |
| { |
| return wrapper_address()->data; |
| } |
| |
| } ; |
| |
| template<class T> |
| BOOST_GPU_ENABLED |
| T const& get ( initialized<T> const& x ) |
| { |
| return x.data() ; |
| } |
| |
| template<class T> |
| BOOST_GPU_ENABLED |
| T& get ( initialized<T>& x ) |
| { |
| return x.data() ; |
| } |
| |
| template<class T> |
| BOOST_GPU_ENABLED |
| void swap ( initialized<T> & lhs, initialized<T> & rhs ) |
| { |
| lhs.swap(rhs) ; |
| } |
| |
| template<class T> |
| class value_initialized |
| { |
| private : |
| |
| // initialized<T> does value-initialization by default. |
| initialized<T> m_data; |
| |
| public : |
| |
| BOOST_GPU_ENABLED |
| value_initialized() |
| : |
| m_data() |
| { } |
| |
| BOOST_GPU_ENABLED |
| T const & data() const |
| { |
| return m_data.data(); |
| } |
| |
| BOOST_GPU_ENABLED |
| T& data() |
| { |
| return m_data.data(); |
| } |
| |
| BOOST_GPU_ENABLED |
| void swap(value_initialized & arg) |
| { |
| m_data.swap(arg.m_data); |
| } |
| |
| BOOST_GPU_ENABLED |
| operator T const &() const |
| { |
| return m_data; |
| } |
| |
| BOOST_GPU_ENABLED |
| operator T&() |
| { |
| return m_data; |
| } |
| } ; |
| |
| |
| template<class T> |
| BOOST_GPU_ENABLED |
| T const& get ( value_initialized<T> const& x ) |
| { |
| return x.data() ; |
| } |
| |
| template<class T> |
| BOOST_GPU_ENABLED |
| T& get ( value_initialized<T>& x ) |
| { |
| return x.data() ; |
| } |
| |
| template<class T> |
| BOOST_GPU_ENABLED |
| void swap ( value_initialized<T> & lhs, value_initialized<T> & rhs ) |
| { |
| lhs.swap(rhs) ; |
| } |
| |
| |
| class initialized_value_t |
| { |
| public : |
| |
| template <class T> BOOST_GPU_ENABLED operator T() const |
| { |
| return initialized<T>().data(); |
| } |
| }; |
| |
| initialized_value_t const initialized_value = {} ; |
| |
| |
| } // namespace boost |
| |
| #ifdef BOOST_MSVC |
| #pragma warning(pop) |
| #endif |
| |
| #endif |