1fe6060f1SDimitry Andric // -*- C++ -*- 2fe6060f1SDimitry Andric //===----------------------------------------------------------------------===// 3fe6060f1SDimitry Andric // 4fe6060f1SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5fe6060f1SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 6fe6060f1SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7fe6060f1SDimitry Andric // 8fe6060f1SDimitry Andric //===----------------------------------------------------------------------===// 9fe6060f1SDimitry Andric 10fe6060f1SDimitry Andric #ifndef _LIBCPP_SSO_ALLOCATOR_H 11fe6060f1SDimitry Andric #define _LIBCPP_SSO_ALLOCATOR_H 12fe6060f1SDimitry Andric 13fe6060f1SDimitry Andric #include <__config> 145f757f3fSDimitry Andric #include <cstddef> 15fe6060f1SDimitry Andric #include <memory> 16fe6060f1SDimitry Andric #include <new> 17fe6060f1SDimitry Andric #include <type_traits> 18fe6060f1SDimitry Andric 19fe6060f1SDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 20fe6060f1SDimitry Andric # pragma GCC system_header 21fe6060f1SDimitry Andric #endif 22fe6060f1SDimitry Andric 23fe6060f1SDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 24fe6060f1SDimitry Andric 25*cb14a3feSDimitry Andric template <class _Tp, size_t _Np> 26*cb14a3feSDimitry Andric class _LIBCPP_HIDDEN __sso_allocator; 27fe6060f1SDimitry Andric 28fe6060f1SDimitry Andric template <size_t _Np> 29*cb14a3feSDimitry Andric class _LIBCPP_HIDDEN __sso_allocator<void, _Np> { 30fe6060f1SDimitry Andric public: 31fe6060f1SDimitry Andric typedef const void* const_pointer; 32fe6060f1SDimitry Andric typedef void value_type; 33fe6060f1SDimitry Andric }; 34fe6060f1SDimitry Andric 35fe6060f1SDimitry Andric template <class _Tp, size_t _Np> 36*cb14a3feSDimitry Andric class _LIBCPP_HIDDEN __sso_allocator { 375f757f3fSDimitry Andric alignas(_Tp) std::byte buf_[sizeof(_Tp) * _Np]; 38fe6060f1SDimitry Andric bool __allocated_; 39*cb14a3feSDimitry Andric 40fe6060f1SDimitry Andric public: 41fe6060f1SDimitry Andric typedef size_t size_type; 42fe6060f1SDimitry Andric typedef _Tp* pointer; 43fe6060f1SDimitry Andric typedef _Tp value_type; 44fe6060f1SDimitry Andric 4561cfbce3SDimitry Andric template <class U> 4661cfbce3SDimitry Andric struct rebind { 4761cfbce3SDimitry Andric using other = __sso_allocator<U, _Np>; 4861cfbce3SDimitry Andric }; 4961cfbce3SDimitry Andric 505f757f3fSDimitry Andric _LIBCPP_HIDE_FROM_ABI __sso_allocator() throw() : __allocated_(false) {} 515f757f3fSDimitry Andric _LIBCPP_HIDE_FROM_ABI __sso_allocator(const __sso_allocator&) throw() : __allocated_(false) {} 52*cb14a3feSDimitry Andric template <class _Up> 53*cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI __sso_allocator(const __sso_allocator<_Up, _Np>&) throw() : __allocated_(false) {} 54*cb14a3feSDimitry Andric 55fe6060f1SDimitry Andric private: 56fe6060f1SDimitry Andric __sso_allocator& operator=(const __sso_allocator&); 57*cb14a3feSDimitry Andric 58fe6060f1SDimitry Andric public: 59*cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI pointer allocate(size_type __n, typename __sso_allocator<void, _Np>::const_pointer = nullptr) { 60*cb14a3feSDimitry Andric if (!__allocated_ && __n <= _Np) { 61fe6060f1SDimitry Andric __allocated_ = true; 62fe6060f1SDimitry Andric return (pointer)&buf_; 63fe6060f1SDimitry Andric } 64fe6060f1SDimitry Andric return allocator<_Tp>().allocate(__n); 65fe6060f1SDimitry Andric } 66*cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI void deallocate(pointer __p, size_type __n) { 67fe6060f1SDimitry Andric if (__p == (pointer)&buf_) 68fe6060f1SDimitry Andric __allocated_ = false; 69fe6060f1SDimitry Andric else 70fe6060f1SDimitry Andric allocator<_Tp>().deallocate(__p, __n); 71fe6060f1SDimitry Andric } 725f757f3fSDimitry Andric _LIBCPP_HIDE_FROM_ABI size_type max_size() const throw() { return size_type(~0) / sizeof(_Tp); } 73fe6060f1SDimitry Andric 74*cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI bool operator==(const __sso_allocator& __a) const { return &buf_ == &__a.buf_; } 75*cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI bool operator!=(const __sso_allocator& __a) const { return &buf_ != &__a.buf_; } 76fe6060f1SDimitry Andric }; 77fe6060f1SDimitry Andric 78fe6060f1SDimitry Andric _LIBCPP_END_NAMESPACE_STD 79fe6060f1SDimitry Andric 80fe6060f1SDimitry Andric #endif // _LIBCPP_SSO_ALLOCATOR_H 81