1 // -*- C++ -*- 2 //===----------------------------------------------------------------------===// 3 // 4 // The LLVM Compiler Infrastructure 5 // 6 // This file is dual licensed under the MIT and the University of Illinois Open 7 // Source Licenses. See LICENSE.TXT for details. 8 // 9 //===----------------------------------------------------------------------===// 10 11 #ifndef _LIBCPP___SSO_ALLOCATOR 12 #define _LIBCPP___SSO_ALLOCATOR 13 14 #include <__config> 15 #include <type_traits> 16 #include <new> 17 18 #include <__undef___deallocate> 19 20 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 21 #pragma GCC system_header 22 #endif 23 24 _LIBCPP_BEGIN_NAMESPACE_STD 25 26 template <class _Tp, size_t _Np> class _LIBCPP_HIDDEN __sso_allocator; 27 28 template <size_t _Np> 29 class _LIBCPP_HIDDEN __sso_allocator<void, _Np> 30 { 31 public: 32 typedef const void* const_pointer; 33 typedef void value_type; 34 }; 35 36 template <class _Tp, size_t _Np> 37 class _LIBCPP_HIDDEN __sso_allocator 38 { 39 typename aligned_storage<sizeof(_Tp) * _Np>::type buf_; 40 bool __allocated_; 41 public: 42 typedef size_t size_type; 43 typedef _Tp* pointer; 44 typedef _Tp value_type; 45 46 _LIBCPP_INLINE_VISIBILITY __sso_allocator() throw() : __allocated_(false) {} 47 _LIBCPP_INLINE_VISIBILITY __sso_allocator(const __sso_allocator&) throw() : __allocated_(false) {} 48 template <class _Up> _LIBCPP_INLINE_VISIBILITY __sso_allocator(const __sso_allocator<_Up, _Np>&) throw() 49 : __allocated_(false) {} 50 private: 51 __sso_allocator& operator=(const __sso_allocator&); 52 public: 53 _LIBCPP_INLINE_VISIBILITY pointer allocate(size_type __n, typename __sso_allocator<void, _Np>::const_pointer = 0) 54 { 55 if (!__allocated_ && __n <= _Np) 56 { 57 __allocated_ = true; 58 return (pointer)&buf_; 59 } 60 return static_cast<pointer>(_VSTD::__allocate(__n * sizeof(_Tp))); 61 } 62 _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type) 63 { 64 if (__p == (pointer)&buf_) 65 __allocated_ = false; 66 else 67 _VSTD::__deallocate(__p); 68 } 69 _LIBCPP_INLINE_VISIBILITY size_type max_size() const throw() {return size_type(~0) / sizeof(_Tp);} 70 71 _LIBCPP_INLINE_VISIBILITY 72 bool operator==(__sso_allocator& __a) const {return &buf_ == &__a.buf_;} 73 _LIBCPP_INLINE_VISIBILITY 74 bool operator!=(__sso_allocator& __a) const {return &buf_ != &__a.buf_;} 75 }; 76 77 _LIBCPP_END_NAMESPACE_STD 78 79 #endif // _LIBCPP___SSO_ALLOCATOR 80
