1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP___SSO_ALLOCATOR
11#define _LIBCPP___SSO_ALLOCATOR
12
13#include <__config>
14#include <type_traits>
15#include <new>
16
17#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
18#pragma GCC system_header
19#endif
20
21_LIBCPP_BEGIN_NAMESPACE_STD
22
23template <class _Tp, size_t _Np> class _LIBCPP_HIDDEN __sso_allocator;
24
25template <size_t _Np>
26class _LIBCPP_HIDDEN __sso_allocator<void, _Np>
27{
28public:
29 typedef const void* const_pointer;
30 typedef void value_type;
31};
32
33template <class _Tp, size_t _Np>
34class _LIBCPP_HIDDEN __sso_allocator
35{
36 typename aligned_storage<sizeof(_Tp) * _Np>::type buf_;
37 bool __allocated_;
38public:
39 typedef size_t size_type;
40 typedef _Tp* pointer;
41 typedef _Tp value_type;
42
43 _LIBCPP_INLINE_VISIBILITY __sso_allocator() throw() : __allocated_(false) {}
44 _LIBCPP_INLINE_VISIBILITY __sso_allocator(const __sso_allocator&) throw() : __allocated_(false) {}
45 template <class _Up> _LIBCPP_INLINE_VISIBILITY __sso_allocator(const __sso_allocator<_Up, _Np>&) throw()
46 : __allocated_(false) {}
47private:
48 __sso_allocator& operator=(const __sso_allocator&);
49public:
50 _LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, typename __sso_allocator<void, _Np>::const_pointer = 0)
51 {
52 if (!__allocated_ && __n <= _Np)
53 {
54 __allocated_ = true;
55 return (pointer)&buf_;
56 }
57 return static_cast<pointer>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)));
58 }
59 _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type __n)
60 {
61 if (__p == (pointer)&buf_)
62 __allocated_ = false;
63 else
64 _VSTD::__libcpp_deallocate(__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
65 }
66 _LIBCPP_INLINE_VISIBILITY size_type max_size() const throw() {return size_type(~0) / sizeof(_Tp);}
67
68 _LIBCPP_INLINE_VISIBILITY
69 bool operator==(__sso_allocator& __a) const {return &buf_ == &__a.buf_;}
70 _LIBCPP_INLINE_VISIBILITY
71 bool operator!=(__sso_allocator& __a) const {return &buf_ != &__a.buf_;}
72};
73
74_LIBCPP_END_NAMESPACE_STD
75
76#endif // _LIBCPP___SSO_ALLOCATOR
77