// Temporary buffer implementation -*- C++ -*- // Copyright (C) 2001-2020 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /* * * Copyright (c) 1994 * Hewlett-Packard Company * * Permission to use, copy, modify, distribute and sell this software * and its documentation for any purpose is hereby granted without fee, * provided that the above copyright notice appear in all copies and * that both that copyright notice and this permission notice appear * in supporting documentation. Hewlett-Packard Company makes no * representations about the suitability of this software for any * purpose. It is provided "as is" without express or implied warranty. * * * Copyright (c) 1996,1997 * Silicon Graphics Computer Systems, Inc. * * Permission to use, copy, modify, distribute and sell this software * and its documentation for any purpose is hereby granted without fee, * provided that the above copyright notice appear in all copies and * that both that copyright notice and this permission notice appear * in supporting documentation. Silicon Graphics makes no * representations about the suitability of this software for any * purpose. It is provided "as is" without express or implied warranty. */ /** @file bits/stl_tempbuf.h * This is an internal header file, included by other library headers. * Do not attempt to use it directly. @headername{memory} */ #ifndef _STL_TEMPBUF_H #define _STL_TEMPBUF_H 1 #include <bits/stl_algobase.h> #include <bits/stl_construct.h> namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION namespace __detail { template<typename _Tp> inline void __return_temporary_buffer(_Tp* __p, size_t __len __attribute__((__unused__))) { #if __cpp_sized_deallocation ::operator delete(__p, __len * sizeof(_Tp)); #else ::operator delete(__p); #endif } } /** * @brief Allocates a temporary buffer. * @param __len The number of objects of type Tp. * @return See full description. * * Reinventing the wheel, but this time with prettier spokes! * * This function tries to obtain storage for @c __len adjacent Tp * objects. The objects themselves are not constructed, of course. * A pair<> is returned containing <em>the buffer s address and * capacity (in the units of sizeof(_Tp)), or a pair of 0 values if * no storage can be obtained.</em> Note that the capacity obtained * may be less than that requested if the memory is unavailable; * you should compare len with the .second return value. * * Provides the nothrow exception guarantee. */ template<typename _Tp> pair<_Tp*, ptrdiff_t> get_temporary_buffer(ptrdiff_t __len) _GLIBCXX_NOEXCEPT { const ptrdiff_t __max = __gnu_cxx::__numeric_traits<ptrdiff_t>::__max / sizeof(_Tp); if (__len > __max) __len = __max; while (__len > 0) { _Tp* __tmp = static_cast<_Tp*>(::operator new(__len * sizeof(_Tp), std::nothrow)); if (__tmp != 0) return std::pair<_Tp*, ptrdiff_t>(__tmp, __len); __len /= 2; } return std::pair<_Tp*, ptrdiff_t>(static_cast<_Tp*>(0), 0); } /** * @brief The companion to get_temporary_buffer(). * @param __p A buffer previously allocated by get_temporary_buffer. * @return None. * * Frees the memory pointed to by __p. */ template<typename _Tp> inline void return_temporary_buffer(_Tp* __p) { ::operator delete(__p); } /** * This class is used in two places: stl_algo.h and ext/memory, * where it is wrapped as the temporary_buffer class. See * temporary_buffer docs for more notes. */ template<typename _ForwardIterator, typename _Tp> class _Temporary_buffer { // concept requirements __glibcxx_class_requires(_ForwardIterator, _ForwardIteratorConcept) public: typedef _Tp value_type; typedef value_type* pointer; typedef pointer iterator; typedef ptrdiff_t size_type; protected: size_type _M_original_len; size_type _M_len; pointer _M_buffer; public: /// As per Table mumble. size_type size() const { return _M_len; } /// Returns the size requested by the constructor; may be >size(). size_type requested_size() const { return _M_original_len; } /// As per Table mumble. iterator begin() { return _M_buffer; } /// As per Table mumble. iterator end() { return _M_buffer + _M_len; } /** * Constructs a temporary buffer of a size somewhere between * zero and the given length. */ _Temporary_buffer(_ForwardIterator __seed, size_type __original_len); ~_Temporary_buffer() { std::_Destroy(_M_buffer, _M_buffer + _M_len); std::__detail::__return_temporary_buffer(_M_buffer, _M_len); } private: // Disable copy constructor and assignment operator. _Temporary_buffer(const _Temporary_buffer&); void operator=(const _Temporary_buffer&); }; template<bool> struct __uninitialized_construct_buf_dispatch { template<typename _Pointer, typename _ForwardIterator> static void __ucr(_Pointer __first, _Pointer __last, _ForwardIterator __seed) { if (__first == __last) return; _Pointer __cur = __first; __try { std::_Construct(std::__addressof(*__first), _GLIBCXX_MOVE(*__seed)); _Pointer __prev = __cur; ++__cur; for(; __cur != __last; ++__cur, ++__prev) std::_Construct(std::__addressof(*__cur), _GLIBCXX_MOVE(*__prev)); *__seed = _GLIBCXX_MOVE(*__prev); } __catch(...) { std::_Destroy(__first, __cur); __throw_exception_again; } } }; template<> struct __uninitialized_construct_buf_dispatch<true> { template<typename _Pointer, typename _ForwardIterator> static void __ucr(_Pointer, _Pointer, _ForwardIterator) { } }; // Constructs objects in the range [first, last). // Note that while these new objects will take valid values, // their exact value is not defined. In particular they may // be 'moved from'. // // While *__seed may be altered during this algorithm, it will have // the same value when the algorithm finishes, unless one of the // constructions throws. // // Requirements: _Pointer::value_type(_Tp&&) is valid. template<typename _Pointer, typename _ForwardIterator> inline void __uninitialized_construct_buf(_Pointer __first, _Pointer __last, _ForwardIterator __seed) { typedef typename std::iterator_traits<_Pointer>::value_type _ValueType; std::__uninitialized_construct_buf_dispatch< __has_trivial_constructor(_ValueType)>:: __ucr(__first, __last, __seed); } template<typename _ForwardIterator, typename _Tp> _Temporary_buffer<_ForwardIterator, _Tp>:: _Temporary_buffer(_ForwardIterator __seed, size_type __original_len) : _M_original_len(__original_len), _M_len(0), _M_buffer(0) { std::pair<pointer, size_type> __p( std::get_temporary_buffer<value_type>(_M_original_len)); if (__p.first) { __try { std::__uninitialized_construct_buf(__p.first, __p.first + __p.second, __seed); _M_buffer = __p.first; _M_len = __p.second; } __catch(...) { std::__detail::__return_temporary_buffer(__p.first, __p.second); __throw_exception_again; } } } _GLIBCXX_END_NAMESPACE_VERSION } // namespace #endif /* _STL_TEMPBUF_H */