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value_init now uses aligned_storage::address(), instead of "&x", as recommended by Fernando Cacciola (by mail)

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[SVN r42277]
This commit is contained in:
Niels Dekker 2007-12-24 20:42:16 +00:00
parent c1fd670480
commit ac1567b3fc
1 changed files with 7 additions and 17 deletions
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24
include/boost/utility/value_init.hpp
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@ -5,9 +5,7 @@
// http://www.boost.org/LICENSE_1_0.txt) // http://www.boost.org/LICENSE_1_0.txt)
// //
// 21 Ago 2002 (Created) Fernando Cacciola // 21 Ago 2002 (Created) Fernando Cacciola
// 07 Set 2007 (Worked around MSVC++ bug) Fernando Cacciola, Niels Dekker // 24 Dec 2007 (Refactored and worked around various compiler bugs) Fernando Cacciola, Niels Dekker
// 16 Nov 2007 (Refactoring: removed private base classes) Fernando Cacciola, Niels Dekker
// 09 Dec 2007 (Worked around various compiler bugs) Fernando Cacciola, Niels Dekker
// //
#ifndef BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP #ifndef BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
#define BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP #define BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
@ -30,7 +28,6 @@
// clearing the bytes of T, before constructing the T object it contains. // clearing the bytes of T, before constructing the T object it contains.
#include <boost/aligned_storage.hpp> #include <boost/aligned_storage.hpp>
#include <boost/detail/select_type.hpp>
#include <boost/detail/workaround.hpp> #include <boost/detail/workaround.hpp>
#include <boost/type_traits/cv_traits.hpp> #include <boost/type_traits/cv_traits.hpp>
#include <boost/type_traits/alignment_of.hpp> #include <boost/type_traits/alignment_of.hpp>
@ -51,17 +48,13 @@ class value_initialized
remove_const<T>::type data; remove_const<T>::type data;
}; };
mutable mutable aligned_storage<sizeof(wrapper), alignment_of<wrapper>::value> x;
#if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x592))
typename
#endif
::boost::aligned_storage<sizeof(wrapper), ::boost::alignment_of<wrapper>::value>::type x;
public : public :
value_initialized() value_initialized()
{ {
std::memset(&x, 0, sizeof(x)); std::memset(x.address(), 0, sizeof(x));
#ifdef BOOST_MSVC #ifdef BOOST_MSVC
#pragma warning(push) #pragma warning(push)
#if _MSC_VER >= 1310 #if _MSC_VER >= 1310
@ -71,7 +64,7 @@ class value_initialized
#pragma warning(disable: 4345) #pragma warning(disable: 4345)
#endif #endif
#endif #endif
new (&x) wrapper(); new (x.address()) wrapper();
#ifdef BOOST_MSVC #ifdef BOOST_MSVC
#pragma warning(pop) #pragma warning(pop)
#endif #endif
@ -79,8 +72,7 @@ class value_initialized
value_initialized(value_initialized const & arg) value_initialized(value_initialized const & arg)
{ {
void const * const ptr = &(arg.x); new (x.address()) wrapper( *static_cast<wrapper const *>(arg.x.address()) );
new (&x) wrapper( *static_cast<wrapper const *>(ptr) );
} }
value_initialized & operator=(value_initialized const & arg) value_initialized & operator=(value_initialized const & arg)
@ -93,14 +85,12 @@ class value_initialized
~value_initialized() ~value_initialized()
{ {
void * const ptr = &x; static_cast<wrapper *>(x.address())->wrapper::~wrapper();
static_cast<wrapper *>(ptr)->wrapper::~wrapper();
} }
T& data() const T& data() const
{ {
void * const ptr = &x; return static_cast<wrapper *>(x.address())->data;
return static_cast<wrapper *>(ptr)->data;
} }
operator T&() const { return this->data(); } operator T&() const { return this->data(); }