forked from OSchip/llvm-project
78 lines
2.4 KiB
C++
78 lines
2.4 KiB
C++
// -*- C++ -*-
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef _LIBCPP___SSO_ALLOCATOR
|
|
#define _LIBCPP___SSO_ALLOCATOR
|
|
|
|
#include <__config>
|
|
#include <memory>
|
|
#include <new>
|
|
#include <type_traits>
|
|
|
|
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
|
|
#pragma GCC system_header
|
|
#endif
|
|
|
|
_LIBCPP_BEGIN_NAMESPACE_STD
|
|
|
|
template <class _Tp, size_t _Np> class _LIBCPP_HIDDEN __sso_allocator;
|
|
|
|
template <size_t _Np>
|
|
class _LIBCPP_HIDDEN __sso_allocator<void, _Np>
|
|
{
|
|
public:
|
|
typedef const void* const_pointer;
|
|
typedef void value_type;
|
|
};
|
|
|
|
template <class _Tp, size_t _Np>
|
|
class _LIBCPP_HIDDEN __sso_allocator
|
|
{
|
|
typename aligned_storage<sizeof(_Tp) * _Np>::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, _Np>&) throw()
|
|
: __allocated_(false) {}
|
|
private:
|
|
__sso_allocator& operator=(const __sso_allocator&);
|
|
public:
|
|
_LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, typename __sso_allocator<void, _Np>::const_pointer = nullptr)
|
|
{
|
|
if (!__allocated_ && __n <= _Np)
|
|
{
|
|
__allocated_ = true;
|
|
return (pointer)&buf_;
|
|
}
|
|
return allocator<_Tp>().allocate(__n);
|
|
}
|
|
_LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type __n)
|
|
{
|
|
if (__p == (pointer)&buf_)
|
|
__allocated_ = false;
|
|
else
|
|
allocator<_Tp>().deallocate(__p, __n);
|
|
}
|
|
_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
|