00001 // <memory> -*- C++ -*- 00002 00003 // Copyright (C) 2001, 2002, 2004 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 2, 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 // You should have received a copy of the GNU General Public License along 00017 // with this library; see the file COPYING. If not, write to the Free 00018 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, 00019 // USA. 00020 00021 // As a special exception, you may use this file as part of a free software 00022 // library without restriction. Specifically, if other files instantiate 00023 // templates or use macros or inline functions from this file, or you compile 00024 // this file and link it with other files to produce an executable, this 00025 // file does not by itself cause the resulting executable to be covered by 00026 // the GNU General Public License. This exception does not however 00027 // invalidate any other reasons why the executable file might be covered by 00028 // the GNU General Public License. 00029 00030 /* 00031 * Copyright (c) 1997-1999 00032 * Silicon Graphics Computer Systems, Inc. 00033 * 00034 * Permission to use, copy, modify, distribute and sell this software 00035 * and its documentation for any purpose is hereby granted without fee, 00036 * provided that the above copyright notice appear in all copies and 00037 * that both that copyright notice and this permission notice appear 00038 * in supporting documentation. Silicon Graphics makes no 00039 * representations about the suitability of this software for any 00040 * purpose. It is provided "as is" without express or implied warranty. 00041 * 00042 */ 00043 00044 /** @file 00045 * This is a Standard C++ Library header. 00046 */ 00047 00048 #ifndef _GLIBCXX_MEMORY 00049 #define _GLIBCXX_MEMORY 1 00050 00051 #pragma GCC system_header 00052 00053 #include <bits/stl_algobase.h> 00054 #include <bits/allocator.h> 00055 #include <bits/stl_construct.h> 00056 #include <bits/stl_iterator_base_types.h> //for iterator_traits 00057 #include <bits/stl_uninitialized.h> 00058 #include <bits/stl_raw_storage_iter.h> 00059 #include <debug/debug.h> 00060 #include <limits> 00061 00062 namespace std 00063 { 00064 /** 00065 * @if maint 00066 * This is a helper function. The unused second parameter exists to 00067 * permit the real get_temporary_buffer to use template parameter deduction. 00068 * 00069 * XXX This should perhaps use the pool. 00070 * @endif 00071 */ 00072 template<typename _Tp> 00073 pair<_Tp*, ptrdiff_t> 00074 __get_temporary_buffer(ptrdiff_t __len, _Tp*) 00075 { 00076 const ptrdiff_t __max = numeric_limits<ptrdiff_t>::max() / sizeof(_Tp); 00077 if (__len > __max) 00078 __len = __max; 00079 00080 while (__len > 0) 00081 { 00082 _Tp* __tmp = static_cast<_Tp*>(::operator new(__len * sizeof(_Tp), 00083 nothrow)); 00084 if (__tmp != 0) 00085 return pair<_Tp*, ptrdiff_t>(__tmp, __len); 00086 __len /= 2; 00087 } 00088 return pair<_Tp*, ptrdiff_t>(static_cast<_Tp*>(0), 0); 00089 } 00090 00091 /** 00092 * @brief Allocates a temporary buffer. 00093 * @param len The number of objects of type Tp. 00094 * @return See full description. 00095 * 00096 * Reinventing the wheel, but this time with prettier spokes! 00097 * 00098 * This function tries to obtain storage for @c len adjacent Tp 00099 * objects. The objects themselves are not constructed, of course. 00100 * A pair<> is returned containing "the buffer s address and 00101 * capacity (in the units of sizeof(Tp)), or a pair of 0 values if 00102 * no storage can be obtained." Note that the capacity obtained 00103 * may be less than that requested if the memory is unavailable; 00104 * you should compare len with the .second return value. 00105 * 00106 * Provides the nothrow exception guarantee. 00107 */ 00108 template<typename _Tp> 00109 inline pair<_Tp*, ptrdiff_t> 00110 get_temporary_buffer(ptrdiff_t __len) 00111 { return std::__get_temporary_buffer(__len, static_cast<_Tp*>(0)); } 00112 00113 /** 00114 * @brief The companion to get_temporary_buffer(). 00115 * @param p A buffer previously allocated by get_temporary_buffer. 00116 * @return None. 00117 * 00118 * Frees the memory pointed to by p. 00119 */ 00120 template<typename _Tp> 00121 void 00122 return_temporary_buffer(_Tp* __p) 00123 { ::operator delete(__p, nothrow); } 00124 00125 /** 00126 * A wrapper class to provide auto_ptr with reference semantics. 00127 * For example, an auto_ptr can be assigned (or constructed from) 00128 * the result of a function which returns an auto_ptr by value. 00129 * 00130 * All the auto_ptr_ref stuff should happen behind the scenes. 00131 */ 00132 template<typename _Tp1> 00133 struct auto_ptr_ref 00134 { 00135 _Tp1* _M_ptr; 00136 00137 explicit 00138 auto_ptr_ref(_Tp1* __p): _M_ptr(__p) { } 00139 }; 00140 00141 00142 /** 00143 * @brief A simple smart pointer providing strict ownership semantics. 00144 * 00145 * The Standard says: 00146 * <pre> 00147 * An @c auto_ptr owns the object it holds a pointer to. Copying 00148 * an @c auto_ptr copies the pointer and transfers ownership to the 00149 * destination. If more than one @c auto_ptr owns the same object 00150 * at the same time the behavior of the program is undefined. 00151 * 00152 * The uses of @c auto_ptr include providing temporary 00153 * exception-safety for dynamically allocated memory, passing 00154 * ownership of dynamically allocated memory to a function, and 00155 * returning dynamically allocated memory from a function. @c 00156 * auto_ptr does not meet the CopyConstructible and Assignable 00157 * requirements for Standard Library <a 00158 * href="tables.html#65">container</a> elements and thus 00159 * instantiating a Standard Library container with an @c auto_ptr 00160 * results in undefined behavior. 00161 * </pre> 00162 * Quoted from [20.4.5]/3. 00163 * 00164 * Good examples of what can and cannot be done with auto_ptr can 00165 * be found in the libstdc++ testsuite. 00166 * 00167 * @if maint 00168 * _GLIBCXX_RESOLVE_LIB_DEFECTS 00169 * 127. auto_ptr<> conversion issues 00170 * These resolutions have all been incorporated. 00171 * @endif 00172 */ 00173 template<typename _Tp> 00174 class auto_ptr 00175 { 00176 private: 00177 _Tp* _M_ptr; 00178 00179 public: 00180 /// The pointed-to type. 00181 typedef _Tp element_type; 00182 00183 /** 00184 * @brief An %auto_ptr is usually constructed from a raw pointer. 00185 * @param p A pointer (defaults to NULL). 00186 * 00187 * This object now @e owns the object pointed to by @a p. 00188 */ 00189 explicit 00190 auto_ptr(element_type* __p = 0) throw() : _M_ptr(__p) { } 00191 00192 /** 00193 * @brief An %auto_ptr can be constructed from another %auto_ptr. 00194 * @param a Another %auto_ptr of the same type. 00195 * 00196 * This object now @e owns the object previously owned by @a a, 00197 * which has given up ownsership. 00198 */ 00199 auto_ptr(auto_ptr& __a) throw() : _M_ptr(__a.release()) { } 00200 00201 /** 00202 * @brief An %auto_ptr can be constructed from another %auto_ptr. 00203 * @param a Another %auto_ptr of a different but related type. 00204 * 00205 * A pointer-to-Tp1 must be convertible to a 00206 * pointer-to-Tp/element_type. 00207 * 00208 * This object now @e owns the object previously owned by @a a, 00209 * which has given up ownsership. 00210 */ 00211 template<typename _Tp1> 00212 auto_ptr(auto_ptr<_Tp1>& __a) throw() : _M_ptr(__a.release()) { } 00213 00214 /** 00215 * @brief %auto_ptr assignment operator. 00216 * @param a Another %auto_ptr of the same type. 00217 * 00218 * This object now @e owns the object previously owned by @a a, 00219 * which has given up ownsership. The object that this one @e 00220 * used to own and track has been deleted. 00221 */ 00222 auto_ptr& 00223 operator=(auto_ptr& __a) throw() 00224 { 00225 reset(__a.release()); 00226 return *this; 00227 } 00228 00229 /** 00230 * @brief %auto_ptr assignment operator. 00231 * @param a Another %auto_ptr of a different but related type. 00232 * 00233 * A pointer-to-Tp1 must be convertible to a pointer-to-Tp/element_type. 00234 * 00235 * This object now @e owns the object previously owned by @a a, 00236 * which has given up ownsership. The object that this one @e 00237 * used to own and track has been deleted. 00238 */ 00239 template<typename _Tp1> 00240 auto_ptr& 00241 operator=(auto_ptr<_Tp1>& __a) throw() 00242 { 00243 reset(__a.release()); 00244 return *this; 00245 } 00246 00247 /** 00248 * When the %auto_ptr goes out of scope, the object it owns is 00249 * deleted. If it no longer owns anything (i.e., @c get() is 00250 * @c NULL), then this has no effect. 00251 * 00252 * @if maint 00253 * The C++ standard says there is supposed to be an empty throw 00254 * specification here, but omitting it is standard conforming. Its 00255 * presence can be detected only if _Tp::~_Tp() throws, but this is 00256 * prohibited. [17.4.3.6]/2 00257 * @endif 00258 */ 00259 ~auto_ptr() { delete _M_ptr; } 00260 00261 /** 00262 * @brief Smart pointer dereferencing. 00263 * 00264 * If this %auto_ptr no longer owns anything, then this 00265 * operation will crash. (For a smart pointer, "no longer owns 00266 * anything" is the same as being a null pointer, and you know 00267 * what happens when you dereference one of those...) 00268 */ 00269 element_type& 00270 operator*() const throw() 00271 { 00272 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); 00273 return *_M_ptr; 00274 } 00275 00276 /** 00277 * @brief Smart pointer dereferencing. 00278 * 00279 * This returns the pointer itself, which the language then will 00280 * automatically cause to be dereferenced. 00281 */ 00282 element_type* 00283 operator->() const throw() 00284 { 00285 _GLIBCXX_DEBUG_ASSERT(_M_ptr != 0); 00286 return _M_ptr; 00287 } 00288 00289 /** 00290 * @brief Bypassing the smart pointer. 00291 * @return The raw pointer being managed. 00292 * 00293 * You can get a copy of the pointer that this object owns, for 00294 * situations such as passing to a function which only accepts 00295 * a raw pointer. 00296 * 00297 * @note This %auto_ptr still owns the memory. 00298 */ 00299 element_type* 00300 get() const throw() { return _M_ptr; } 00301 00302 /** 00303 * @brief Bypassing the smart pointer. 00304 * @return The raw pointer being managed. 00305 * 00306 * You can get a copy of the pointer that this object owns, for 00307 * situations such as passing to a function which only accepts 00308 * a raw pointer. 00309 * 00310 * @note This %auto_ptr no longer owns the memory. When this object 00311 * goes out of scope, nothing will happen. 00312 */ 00313 element_type* 00314 release() throw() 00315 { 00316 element_type* __tmp = _M_ptr; 00317 _M_ptr = 0; 00318 return __tmp; 00319 } 00320 00321 /** 00322 * @brief Forcibly deletes the managed object. 00323 * @param p A pointer (defaults to NULL). 00324 * 00325 * This object now @e owns the object pointed to by @a p. The 00326 * previous object has been deleted. 00327 */ 00328 void 00329 reset(element_type* __p = 0) throw() 00330 { 00331 if (__p != _M_ptr) 00332 { 00333 delete _M_ptr; 00334 _M_ptr = __p; 00335 } 00336 } 00337 00338 /** 00339 * @brief Automatic conversions 00340 * 00341 * These operations convert an %auto_ptr into and from an auto_ptr_ref 00342 * automatically as needed. This allows constructs such as 00343 * @code 00344 * auto_ptr<Derived> func_returning_auto_ptr(.....); 00345 * ... 00346 * auto_ptr<Base> ptr = func_returning_auto_ptr(.....); 00347 * @endcode 00348 */ 00349 auto_ptr(auto_ptr_ref<element_type> __ref) throw() 00350 : _M_ptr(__ref._M_ptr) { } 00351 00352 auto_ptr& 00353 operator=(auto_ptr_ref<element_type> __ref) throw() 00354 { 00355 if (__ref._M_ptr != this->get()) 00356 { 00357 delete _M_ptr; 00358 _M_ptr = __ref._M_ptr; 00359 } 00360 return *this; 00361 } 00362 00363 template<typename _Tp1> 00364 operator auto_ptr_ref<_Tp1>() throw() 00365 { return auto_ptr_ref<_Tp1>(this->release()); } 00366 00367 template<typename _Tp1> 00368 operator auto_ptr<_Tp1>() throw() 00369 { return auto_ptr<_Tp1>(this->release()); } 00370 }; 00371 } // namespace std 00372 00373 #endif /* _GLIBCXX_MEMORY */