cxx/include/__sso_allocator

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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___SSO_ALLOCATOR
#define _LIBCPP___SSO_ALLOCATOR
#include <__config>
#include <type_traits>
#include <new>
#pragma GCC system_header
_LIBCPP_BEGIN_NAMESPACE_STD
template <class _Tp, size_t _N> class _LIBCPP_HIDDEN __sso_allocator;
template <size_t _N>
class _LIBCPP_HIDDEN __sso_allocator<void, _N>
{
public:
typedef const void* const_pointer;
typedef void value_type;
};
template <class _Tp, size_t _N>
class _LIBCPP_HIDDEN __sso_allocator
{
typename aligned_storage<sizeof(_Tp) * _N>::type buf_;
bool __allocated_;
public:
typedef size_t size_type;
typedef _Tp* pointer;
typedef _Tp value_type;
_LIBCPP_INLINE_VISIBILITY __sso_allocator() throw() : __allocated_(false) {}
_LIBCPP_INLINE_VISIBILITY __sso_allocator(const __sso_allocator&) throw() : __allocated_(false) {}
template <class _Up> _LIBCPP_INLINE_VISIBILITY __sso_allocator(const __sso_allocator<_Up, _N>&) throw()
: __allocated_(false) {}
private:
__sso_allocator& operator=(const __sso_allocator&);
public:
_LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, typename __sso_allocator<void, _N>::const_pointer = 0)
{
if (!__allocated_ && __n <= _N)
{
__allocated_ = true;
return (pointer)&buf_;
}
return static_cast<pointer>(::operator new(__n * sizeof(_Tp)));
}
_LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type)
{
if (__p == (pointer)&buf_)
__allocated_ = false;
else
::operator delete(__p);
}
_LIBCPP_INLINE_VISIBILITY size_type max_size() const throw() {return size_type(~0) / sizeof(_Tp);}
_LIBCPP_INLINE_VISIBILITY
bool operator==(__sso_allocator& __a) const {return &buf_ == &__a.buf_;}
_LIBCPP_INLINE_VISIBILITY
bool operator!=(__sso_allocator& __a) const {return &buf_ != &__a.buf_;}
};
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___SSO_ALLOCATOR