372 lines
11 KiB
C++
372 lines
11 KiB
C++
// <memory> -*- C++ -*-
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// Copyright (C) 2001, 2002 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 2, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING. If not, write to the Free
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// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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// USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline functions from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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/*
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* Copyright (c) 1997-1999
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* Silicon Graphics Computer Systems, Inc.
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Silicon Graphics makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*
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*/
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/** @file memory
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* This is a Standard C++ Library header. You should @c #include this header
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* in your programs, rather than any of the "st[dl]_*.h" implementation files.
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*/
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#ifndef _CPP_MEMORY
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#define _CPP_MEMORY 1
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#pragma GCC system_header
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#include <bits/stl_algobase.h>
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#include <bits/stl_alloc.h>
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#include <bits/stl_construct.h>
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#include <bits/stl_iterator_base_types.h> //for iterator_traits
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#include <bits/stl_uninitialized.h>
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#include <bits/stl_raw_storage_iter.h>
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// Since this entire file is within namespace std, there's no reason to
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// waste two spaces along the left column. Thus the leading indentation is
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// slightly violated from here on.
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namespace std
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{
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/**
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* @if maint
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* This is a helper function. The unused second parameter exists to
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* permit the real get_temporary_buffer to use template parameter deduction.
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*
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* XXX This should perhaps use the pool.
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* @endif
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*/
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template <typename _Tp>
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pair<_Tp*, ptrdiff_t>
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__get_temporary_buffer(ptrdiff_t __len, _Tp*)
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{
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if (__len > ptrdiff_t(INT_MAX / sizeof(_Tp)))
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__len = INT_MAX / sizeof(_Tp);
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while (__len > 0) {
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_Tp* __tmp = (_Tp*) std::malloc((std::size_t)__len * sizeof(_Tp));
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if (__tmp != 0)
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return pair<_Tp*, ptrdiff_t>(__tmp, __len);
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__len /= 2;
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}
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return pair<_Tp*, ptrdiff_t>((_Tp*)0, 0);
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}
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/**
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* @brief This is a mostly-useless wrapper around malloc().
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* @param len The number of objects of type Tp.
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* @return See full description.
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*
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* Reinventing the wheel, but this time with prettier spokes!
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*
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* This function tries to obtain storage for @c len adjacent Tp objects.
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* The objects themselves are not constructed, of course. A pair<> is
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* returned containing "the buffer s address and capacity (in the units of
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* sizeof(Tp)), or a pair of 0 values if no storage can be obtained."
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* Note that the capacity obtained may be less than that requested if the
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* memory is unavailable; you should compare len with the .second return
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* value.
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*/
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template<typename _Tp>
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inline pair<_Tp*,ptrdiff_t>
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get_temporary_buffer(ptrdiff_t __len)
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{
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return __get_temporary_buffer(__len, (_Tp*) 0);
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}
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/**
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* @brief The companion to get_temporary_buffer().
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* @param p A buffer previously allocated by get_temporary_buffer.
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* @return None.
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*
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* Frees the memory pointed to by p.
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*/
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template<typename _Tp>
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void
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return_temporary_buffer(_Tp* __p)
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{
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std::free(__p);
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}
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/**
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* A wrapper class to provide auto_ptr with reference semantics. For
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* example, an auto_ptr can be assigned (or constructed from) the result of
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* a function which returns an auto_ptr by value.
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*
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* All the auto_ptr_ref stuff should happen behind the scenes.
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*/
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template<typename _Tp1>
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struct auto_ptr_ref
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{
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_Tp1* _M_ptr;
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explicit
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auto_ptr_ref(_Tp1* __p)
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: _M_ptr(__p) {}
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};
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/**
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* @brief A simple smart pointer providing strict ownership semantics.
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*
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* The Standard says:
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* <pre>
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* An @c auto_ptr owns the object it holds a pointer to. Copying an
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* @c auto_ptr copies the pointer and transfers ownership to the destination.
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* If more than one @c auto_ptr owns the same object at the same time the
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* behavior of the program is undefined.
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*
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* The uses of @c auto_ptr include providing temporary exception-safety for
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* dynamically allocated memory, passing ownership of dynamically allocated
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* memory to a function, and returning dynamically allocated memory from a
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* function. @c auto_ptr does not meet the CopyConstructible and Assignable
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* requirements for Standard Library <a href="tables.html#65">container</a>
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* elements and thus instantiating a Standard Library container with an
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* @c auto_ptr results in undefined behavior.
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* </pre>
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* Quoted from [20.4.5]/3.
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*
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* Good examples of what can and cannot be done with auto_ptr can be found
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* in the libstdc++ testsuite.
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*
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* @if maint
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* _GLIBCPP_RESOLVE_LIB_DEFECTS
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* 127. auto_ptr<> conversion issues
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* These resolutions have all been incorporated.
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* @endif
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*/
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template<typename _Tp>
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class auto_ptr
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{
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private:
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_Tp* _M_ptr;
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public:
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/// The pointed-to type.
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typedef _Tp element_type;
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/**
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* @brief An %auto_ptr is usually constructed from a raw pointer.
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* @param p A pointer (defaults to NULL).
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*
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* This object now @e owns the object pointed to by @a p.
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*/
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explicit
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auto_ptr(element_type* __p = 0) throw()
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: _M_ptr(__p) { }
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/**
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* @brief An %auto_ptr can be constructed from another %auto_ptr.
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* @param a Another %auto_ptr of the same type.
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*
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* This object now @e owns the object previously owned by @a a, which has
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* given up ownsership.
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*/
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auto_ptr(auto_ptr& __a) throw()
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: _M_ptr(__a.release()) { }
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/**
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* @brief An %auto_ptr can be constructed from another %auto_ptr.
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* @param a Another %auto_ptr of a different but related type.
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*
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* A pointer-to-Tp1 must be convertible to a pointer-to-Tp/element_type.
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*
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* This object now @e owns the object previously owned by @a a, which has
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* given up ownsership.
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*/
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template<typename _Tp1>
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auto_ptr(auto_ptr<_Tp1>& __a) throw()
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: _M_ptr(__a.release()) { }
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/**
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* @brief %auto_ptr assignment operator.
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* @param a Another %auto_ptr of the same type.
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*
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* This object now @e owns the object previously owned by @a a, which has
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* given up ownsership. The object that this one @e used to own and
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* track has been deleted.
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*/
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auto_ptr&
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operator=(auto_ptr& __a) throw()
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{
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reset(__a.release());
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return *this;
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}
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/**
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* @brief %auto_ptr assignment operator.
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* @param a Another %auto_ptr of a different but related type.
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*
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* A pointer-to-Tp1 must be convertible to a pointer-to-Tp/element_type.
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*
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* This object now @e owns the object previously owned by @a a, which has
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* given up ownsership. The object that this one @e used to own and
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* track has been deleted.
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*/
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template <typename _Tp1>
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auto_ptr&
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operator=(auto_ptr<_Tp1>& __a) throw()
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{
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reset(__a.release());
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return *this;
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}
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/**
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* When the %auto_ptr goes out of scope, the object it owns is deleted.
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* If it no longer owns anything (i.e., @c get() is @c NULL), then this
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* has no effect.
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*
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* @if maint
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* The C++ standard says there is supposed to be an empty throw
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* specification here, but omitting it is standard conforming. Its
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* presence can be detected only if _Tp::~_Tp() throws, but this is
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* prohibited. [17.4.3.6]/2
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* @end maint
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*/
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~auto_ptr() { delete _M_ptr; }
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/**
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* @brief Smart pointer dereferencing.
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*
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* If this %auto_ptr no longer owns anything, then this operation will
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* crash. (For a smart pointer, "no longer owns anything" is the same as
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* being a null pointer, and you know what happens when you dereference
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* one of those...)
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*/
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element_type&
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operator*() const throw() { return *_M_ptr; }
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/**
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* @brief Smart pointer dereferencing.
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*
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* This returns the pointer itself, which the language then will
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* automatically cause to be dereferenced.
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*/
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element_type*
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operator->() const throw() { return _M_ptr; }
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/**
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* @brief Bypassing the smart pointer.
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* @return The raw pointer being managed.
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*
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* You can get a copy of the pointer that this object owns, for
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* situations such as passing to a function which only accepts a raw
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* pointer.
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*
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* @note This %auto_ptr still owns the memory.
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*/
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element_type*
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get() const throw() { return _M_ptr; }
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/**
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* @brief Bypassing the smart pointer.
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* @return The raw pointer being managed.
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*
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* You can get a copy of the pointer that this object owns, for
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* situations such as passing to a function which only accepts a raw
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* pointer.
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*
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* @note This %auto_ptr no longer owns the memory. When this object
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* goes out of scope, nothing will happen.
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*/
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element_type*
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release() throw()
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{
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element_type* __tmp = _M_ptr;
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_M_ptr = 0;
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return __tmp;
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}
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/**
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* @brief Forcibly deletes the managed object.
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* @param p A pointer (defaults to NULL).
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*
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* This object now @e owns the object pointed to by @a p. The previous
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* object has been deleted.
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*/
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void
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reset(element_type* __p = 0) throw()
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{
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if (__p != _M_ptr)
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{
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delete _M_ptr;
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_M_ptr = __p;
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}
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}
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/** @{
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* @brief Automatic conversions
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*
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* These operations convert an %auto_ptr into and from an auto_ptr_ref
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* automatically as needed. This allows constructs such as
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* @code
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* auto_ptr<Derived> func_returning_auto_ptr(.....);
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* ...
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* auto_ptr<Base> ptr = func_returning_auto_ptr(.....);
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* @endcode
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*/
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auto_ptr(auto_ptr_ref<element_type> __ref) throw()
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: _M_ptr(__ref._M_ptr) {}
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auto_ptr&
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operator=(auto_ptr_ref<element_type> __ref) throw()
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{
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if (__ref._M_ptr != this->get())
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{
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delete _M_ptr;
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_M_ptr = __ref._M_ptr;
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}
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return *this;
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}
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template<typename _Tp1>
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operator auto_ptr_ref<_Tp1>() throw()
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{ return auto_ptr_ref<_Tp1>(this->release()); }
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template<typename _Tp1>
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operator auto_ptr<_Tp1>() throw()
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{ return auto_ptr<_Tp1>(this->release()); }
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/** @} */
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};
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} // namespace std
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#endif /* _CPP_MEMORY */
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