libstdc++
stl_construct.h
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00001 // nonstandard construct and destroy functions -*- C++ -*-
00002 
00003 // Copyright (C) 2001-2019 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /*
00026  *
00027  * Copyright (c) 1994
00028  * Hewlett-Packard Company
00029  *
00030  * Permission to use, copy, modify, distribute and sell this software
00031  * and its documentation for any purpose is hereby granted without fee,
00032  * provided that the above copyright notice appear in all copies and
00033  * that both that copyright notice and this permission notice appear
00034  * in supporting documentation.  Hewlett-Packard Company makes no
00035  * representations about the suitability of this software for any
00036  * purpose.  It is provided "as is" without express or implied warranty.
00037  *
00038  *
00039  * Copyright (c) 1996,1997
00040  * Silicon Graphics Computer Systems, Inc.
00041  *
00042  * Permission to use, copy, modify, distribute and sell this software
00043  * and its documentation for any purpose is hereby granted without fee,
00044  * provided that the above copyright notice appear in all copies and
00045  * that both that copyright notice and this permission notice appear
00046  * in supporting documentation.  Silicon Graphics makes no
00047  * representations about the suitability of this software for any
00048  * purpose.  It is provided "as is" without express or implied warranty.
00049  */
00050 
00051 /** @file bits/stl_construct.h
00052  *  This is an internal header file, included by other library headers.
00053  *  Do not attempt to use it directly. @headername{memory}
00054  */
00055 
00056 #ifndef _STL_CONSTRUCT_H
00057 #define _STL_CONSTRUCT_H 1
00058 
00059 #include <new>
00060 #include <bits/move.h>
00061 #include <ext/alloc_traits.h>
00062 
00063 namespace std _GLIBCXX_VISIBILITY(default)
00064 {
00065 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00066 
00067   /**
00068    * Constructs an object in existing memory by invoking an allocated
00069    * object's constructor with an initializer.
00070    */
00071 #if __cplusplus >= 201103L
00072   template<typename _T1, typename... _Args>
00073     inline void
00074     _Construct(_T1* __p, _Args&&... __args)
00075     { ::new(static_cast<void*>(__p)) _T1(std::forward<_Args>(__args)...); }
00076 #else
00077   template<typename _T1, typename _T2>
00078     inline void
00079     _Construct(_T1* __p, const _T2& __value)
00080     {
00081       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00082       // 402. wrong new expression in [some_]allocator::construct
00083       ::new(static_cast<void*>(__p)) _T1(__value);
00084     }
00085 #endif
00086 
00087   template<typename _T1>
00088     inline void
00089     _Construct_novalue(_T1* __p)
00090     { ::new(static_cast<void*>(__p)) _T1; }
00091 
00092   /**
00093    * Destroy the object pointed to by a pointer type.
00094    */
00095   template<typename _Tp>
00096     inline void
00097     _Destroy(_Tp* __pointer)
00098     { __pointer->~_Tp(); }
00099 
00100   template<bool>
00101     struct _Destroy_aux
00102     {
00103       template<typename _ForwardIterator>
00104         static void
00105         __destroy(_ForwardIterator __first, _ForwardIterator __last)
00106         {
00107           for (; __first != __last; ++__first)
00108             std::_Destroy(std::__addressof(*__first));
00109         }
00110     };
00111 
00112   template<>
00113     struct _Destroy_aux<true>
00114     {
00115       template<typename _ForwardIterator>
00116         static void
00117         __destroy(_ForwardIterator, _ForwardIterator) { }
00118     };
00119 
00120   /**
00121    * Destroy a range of objects.  If the value_type of the object has
00122    * a trivial destructor, the compiler should optimize all of this
00123    * away, otherwise the objects' destructors must be invoked.
00124    */
00125   template<typename _ForwardIterator>
00126     inline void
00127     _Destroy(_ForwardIterator __first, _ForwardIterator __last)
00128     {
00129       typedef typename iterator_traits<_ForwardIterator>::value_type
00130                        _Value_type;
00131 #if __cplusplus >= 201103L
00132       // A deleted destructor is trivial, this ensures we reject such types:
00133       static_assert(is_destructible<_Value_type>::value,
00134                     "value type is destructible");
00135 #endif
00136       std::_Destroy_aux<__has_trivial_destructor(_Value_type)>::
00137         __destroy(__first, __last);
00138     }
00139 
00140   template<bool>
00141     struct _Destroy_n_aux
00142     {
00143       template<typename _ForwardIterator, typename _Size>
00144         static _ForwardIterator
00145         __destroy_n(_ForwardIterator __first, _Size __count)
00146         {
00147           for (; __count > 0; (void)++__first, --__count)
00148             std::_Destroy(std::__addressof(*__first));
00149           return __first;
00150         }
00151     };
00152 
00153   template<>
00154     struct _Destroy_n_aux<true>
00155     {
00156       template<typename _ForwardIterator, typename _Size>
00157         static _ForwardIterator
00158         __destroy_n(_ForwardIterator __first, _Size __count)
00159         {
00160           std::advance(__first, __count);
00161           return __first;
00162         }
00163     };
00164 
00165   /**
00166    * Destroy a range of objects.  If the value_type of the object has
00167    * a trivial destructor, the compiler should optimize all of this
00168    * away, otherwise the objects' destructors must be invoked.
00169    */
00170   template<typename _ForwardIterator, typename _Size>
00171     inline _ForwardIterator
00172     _Destroy_n(_ForwardIterator __first, _Size __count)
00173     {
00174       typedef typename iterator_traits<_ForwardIterator>::value_type
00175                        _Value_type;
00176 #if __cplusplus >= 201103L
00177       // A deleted destructor is trivial, this ensures we reject such types:
00178       static_assert(is_destructible<_Value_type>::value,
00179                     "value type is destructible");
00180 #endif
00181       return std::_Destroy_n_aux<__has_trivial_destructor(_Value_type)>::
00182         __destroy_n(__first, __count);
00183     }
00184 
00185   /**
00186    * Destroy a range of objects using the supplied allocator.  For
00187    * nondefault allocators we do not optimize away invocation of 
00188    * destroy() even if _Tp has a trivial destructor.
00189    */
00190 
00191   template<typename _ForwardIterator, typename _Allocator>
00192     void
00193     _Destroy(_ForwardIterator __first, _ForwardIterator __last,
00194              _Allocator& __alloc)
00195     {
00196       typedef __gnu_cxx::__alloc_traits<_Allocator> __traits;
00197       for (; __first != __last; ++__first)
00198         __traits::destroy(__alloc, std::__addressof(*__first));
00199     }
00200 
00201   template<typename _ForwardIterator, typename _Tp>
00202     inline void
00203     _Destroy(_ForwardIterator __first, _ForwardIterator __last,
00204              allocator<_Tp>&)
00205     {
00206       _Destroy(__first, __last);
00207     }
00208 
00209 #if __cplusplus > 201402L
00210   template <typename _Tp>
00211     inline void
00212     destroy_at(_Tp* __location)
00213     {
00214       std::_Destroy(__location);
00215     }
00216 
00217   template <typename _ForwardIterator>
00218     inline void
00219     destroy(_ForwardIterator __first, _ForwardIterator __last)
00220     {
00221       std::_Destroy(__first, __last);
00222     }
00223 
00224   template <typename _ForwardIterator, typename _Size>
00225     inline _ForwardIterator
00226     destroy_n(_ForwardIterator __first, _Size __count)
00227     {
00228       return std::_Destroy_n(__first, __count);
00229     }
00230 #endif
00231 
00232 _GLIBCXX_END_NAMESPACE_VERSION
00233 } // namespace std
00234 
00235 #endif /* _STL_CONSTRUCT_H */
00236