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alloc_traits.h (__allocator_always_compares_equal): New trait, provide partial specializations for known allocators. 

2011-07-09  Jonathan Wakely  <jwakely.gcc@gmail.com>

	* include/ext/alloc_traits.h (__allocator_always_compares_equal): New
	trait, provide partial specializations for known allocators.
	(__alloc_traits::construct, __alloc_traits::destroy): Overload for
	non-standard pointer types.
	(__alloc_traits::_S_always_equal): New trait for use with noexcept.
	(__alloc_traits::_S_nothrow_move): Likewise.
	(__alloc_traits::_S_nothrow_swap): Likewise.

From-SVN: r176077
This commit is contained in:
Jonathan Wakely 2011-07-09 12:48:32 +00:00 committed by Jonathan Wakely
parent eece716393
commit d526242cd8
2 changed files with 89 additions and 4 deletions
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10
libstdc++-v3/ChangeLog
View File

@ -1,3 +1,13 @@
2011-07-09 Jonathan Wakely <jwakely.gcc@gmail.com>
* include/ext/alloc_traits.h (__allocator_always_compares_equal): New
trait, provide partial specializations for known allocators.
(__alloc_traits::construct, __alloc_traits::destroy): Overload for
non-standard pointer types.
(__alloc_traits::_S_always_equal): New trait for use with noexcept.
(__alloc_traits::_S_nothrow_move): Likewise.
(__alloc_traits::_S_nothrow_swap): Likewise.
2011-07-09 Jonathan Wakely <jwakely.gcc@gmail.com>
* include/ext/cast.h: Fix typo in include guard.

83
libstdc++-v3/include/ext/alloc_traits.h
View File

@ -37,14 +37,55 @@
# include <bits/allocator.h> // for __alloc_swap
#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename> struct allocator;
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @brief Uniform interface to C++98 and C++0x allocators.
* @ingroup allocators
*/
#ifdef __GXX_EXPERIMENTAL_CXX0X__
template<typename _Alloc>
struct __allocator_always_compares_equal
{ static const bool value = false; };
template<typename _Tp>
struct __allocator_always_compares_equal<std::allocator<_Tp>>
{ static const bool value = true; };
template<typename, typename> struct array_allocator;
template<typename _Tp, typename _Array>
struct __allocator_always_compares_equal<array_allocator<_Tp, _Array>>
{ static const bool value = true; };
template<typename> struct mt_allocator;
template<typename _Tp>
struct __allocator_always_compares_equal<mt_allocator<_Tp>>
{ static const bool value = true; };
template<typename> struct new_allocator;
template<typename _Tp>
struct __allocator_always_compares_equal<new_allocator<_Tp>>
{ static const bool value = true; };
template<typename> struct pool_allocator;
template<typename _Tp>
struct __allocator_always_compares_equal<pool_allocator<_Tp>>
{ static const bool value = true; };
#endif
/**
* @brief Uniform interface to C++98 and C++0x allocators.
* @ingroup allocators
*/
template<typename _Alloc>
struct __alloc_traits
#ifdef __GXX_EXPERIMENTAL_CXX0X__
@ -66,6 +107,27 @@ template<typename _Alloc>
using _Base_type::construct;
using _Base_type::destroy;
private:
template<typename _Ptr>
struct __is_custom_pointer
: std::integral_constant<bool, std::is_same<pointer, _Ptr>::value
&& !std::is_pointer<_Ptr>::value>
{ };
public:
template<typename _Ptr, typename... _Args>
static typename std::enable_if<__is_custom_pointer<_Ptr>::value>::type
construct(_Alloc& __a, _Ptr __p, _Args&&... __args)
{
_Base_type::construct(__a, std::addressof(*__p),
std::forward<_Args>(__args)...);
}
template<typename _Ptr>
static typename std::enable_if<__is_custom_pointer<_Ptr>::value>::type
destroy(_Alloc& __a, _Ptr __p)
{ _Base_type::destroy(__a, std::addressof(*__p)); }
static _Alloc _S_select_on_copy(const _Alloc& __a)
{ return _Base_type::select_on_container_copy_construction(__a); }
@ -81,6 +143,19 @@ template<typename _Alloc>
static constexpr bool _S_propagate_on_swap()
{ return _Base_type::propagate_on_container_swap::value; }
static constexpr bool _S_always_equal()
{ return __allocator_always_compares_equal<_Alloc>::value; }
static constexpr bool _S_nothrow_move()
{ return _S_propagate_on_move_assign() || _S_always_equal(); }
static constexpr bool _S_nothrow_swap()
{
using std::swap;
return !_S_propagate_on_swap()
|| noexcept(swap(std::declval<_Alloc&>(), std::declval<_Alloc&>()));
}
#else
typedef typename _Alloc::pointer pointer;