FastJet 3.0.0
|
00001 #ifndef __FASTJET_SHARED_PTR_HH__ 00002 #define __FASTJET_SHARED_PTR_HH__ 00003 00004 //STARTHEADER 00005 // $Id: SharedPtr.hh 2577 2011-09-13 15:11:38Z salam $ 00006 // 00007 // Copyright (c) 2005-2011, Matteo Cacciari, Gavin P. Salam and Gregory Soyez 00008 // 00009 //---------------------------------------------------------------------- 00010 // This file is part of FastJet. 00011 // 00012 // FastJet is free software; you can redistribute it and/or modify 00013 // it under the terms of the GNU General Public License as published by 00014 // the Free Software Foundation; either version 2 of the License, or 00015 // (at your option) any later version. 00016 // 00017 // The algorithms that underlie FastJet have required considerable 00018 // development and are described in hep-ph/0512210. If you use 00019 // FastJet as part of work towards a scientific publication, please 00020 // include a citation to the FastJet paper. 00021 // 00022 // FastJet is distributed in the hope that it will be useful, 00023 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00024 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00025 // GNU General Public License for more details. 00026 // 00027 // You should have received a copy of the GNU General Public License 00028 // along with FastJet. If not, see <http://www.gnu.org/licenses/>. 00029 //---------------------------------------------------------------------- 00030 //ENDHEADER 00031 00032 #include "fastjet/internal/base.hh" 00033 #include <cstdlib> // for NULL!!! 00034 00035 // for testing purposes, the following define makes it possible 00036 // for our SharedPtr simply to be derived from the STL TR1 one. 00037 // #define USETR1SHAREDPTR 00038 00039 #ifdef USETR1SHAREDPTR 00040 #include <tr1/memory> 00041 #endif // USETR1SHAREDPTR 00042 00043 FASTJET_BEGIN_NAMESPACE // defined in fastjet/internal/base.hh 00044 00045 #ifdef USETR1SHAREDPTR 00046 00047 /// @ingroup advanced_usage 00048 /// \class SharedPtr 00049 /// replaces our shared pointer with the TR1 one (for testing purpose) 00050 /// 00051 /// for testing purposes, it can be useful to replace our home-made 00052 /// SharedPtr with the standard library one. Having a class derived 00053 /// from the standard one is way of arranging for this to happen. 00054 /// 00055 /// The other way of working this is a template class with an 00056 /// internal typedef (http://bytes.com/topic/c/answers/60312-typedef-template) 00057 /// since templated typedefs don't work in standard C++ 00058 /// 00059 /// Note that some facilities that are present in the FastJet shared 00060 /// pointer (resetting use-count) are not handled by the TR1 shared 00061 /// pointer; and the FastJet SharedPtr has a different underlying data 00062 /// structure from the TR1 shared pointer, which prevents us from 00063 /// implementing some of TR1 features (notably assignment from shared 00064 /// pointers to a derived class). 00065 template<class T> 00066 class SharedPtr : public std::tr1::shared_ptr<T> { 00067 public: 00068 SharedPtr() : std::tr1::shared_ptr<T>() {} 00069 SharedPtr(T * t) : std::tr1::shared_ptr<T>(t) {} 00070 SharedPtr(const SharedPtr<T> & t) : std::tr1::shared_ptr<T>(t) {} 00071 // for some reason operator() doesn't get inherited 00072 inline operator bool() const {return (this->get()!=NULL);} 00073 /// return the pointer we're pointing to 00074 T* operator ()() const{ 00075 return this->get(); // automatically returns NULL when out-of-scope 00076 } 00077 }; 00078 00079 00080 #else // USETR1SHAREDPTR 00081 00082 /** 00083 * @ingroup advanced_usage 00084 * \class SharedPtr 00085 * an implementation of C++0x shared pointers (or boost's) 00086 * 00087 * this class implements a smart pointer, based on the shared+ptr 00088 * proposal. A description of shared_ptr can be found in Section 2.2.3 00089 * of the first C++ Technical Report (TR1) 00090 * http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1745.pdf 00091 * or, alternatively, on the Boost C++ library website at 00092 * http://www.boost.org/doc/libs/1_42_0/libs/smart_ptr/shared_ptr.htm 00093 * 00094 * Our implementation is compatible with both of these apart from a 00095 * series of members and functions that have not been implemented: 00096 * - conversion from weak and auto pointers 00097 * - support for deleters and allocators 00098 * - static, constant and dynamic casts 00099 * - constructor and assignment sharing ownership with a shared 00100 * pointer r but storing a different pointer than r (needed for the 00101 * previous item) 00102 * In the last 2 cases, their implementation would require storing two 00103 * pointers for every copies of the shared pointer, while our 00104 * implementation only needs one. We did not implement then since we 00105 * want to limit as much as possible memory and time consumption, and 00106 * can easily avoid (at least for our needs so far) the casts. 00107 * 00108 * We also add the possibility to force an update of the count. 00109 * 00110 * The class has been tested against the existing boost (v1.42) 00111 * implementation (for the parts that we have implemented). 00112 */ 00113 template<class T> 00114 class SharedPtr{ 00115 public: 00116 /// forward declaration of the counting container 00117 class __SharedCountingPtr; 00118 00119 /// default ctor 00120 SharedPtr() : _ptr(NULL){} 00121 00122 /// initialise with the main data 00123 /// \param t : the object we want a smart pointer to 00124 template<class Y> explicit SharedPtr(Y* ptr){ 00125 _ptr = new __SharedCountingPtr(ptr); 00126 } 00127 00128 /// overload the copy ctor so that it updates count 00129 /// \param share : the object we want to copy 00130 SharedPtr(SharedPtr const & share) : _ptr(share._get_container()){ 00131 if (_ptr!=NULL) (*_ptr)++; 00132 } 00133 // old version 00134 // SharedPtr(SharedPtr const & share) : _ptr(NULL){ 00135 // reset(share); 00136 // } 00137 00138 // will not work with the current structure 00139 // /// overload the copy ctor so that it updates count 00140 // /// \param share : the object we want to copy 00141 // template<class Y> SharedPtr(SharedPtr<Y> const & share) : _ptr(NULL){ 00142 // reset(share); 00143 // } 00144 00145 /// default dtor 00146 ~SharedPtr(){ 00147 // make sure the object has been allocated 00148 if (_ptr==NULL) return; 00149 00150 _decrease_count(); 00151 } 00152 00153 /// reset the pointer to default value (NULL) 00154 void reset(){ 00155 // // if we already are pointing to sth, be sure to decrease its count 00156 // if (_ptr!=NULL) _decrease_count(); 00157 // _ptr = NULL; 00158 SharedPtr().swap(*this); 00159 } 00160 00161 // will not work with the current structure 00162 /// reset from a pointer 00163 template<class Y> void reset(Y * ptr){ 00164 // // if we already are pointing to sth, be sure to decrease its count 00165 // if (_ptr!=NULL) _decrease_count(); 00166 // 00167 // _ptr = new __SharedCountingPtr(ptr); 00168 SharedPtr(ptr).swap(*this); 00169 } 00170 00171 // not part of the standard 00172 /// do a smart copy 00173 /// \param share : the object we want to copy 00174 /// Q? Do we need a non-template<Y> version as for the ctor and the assignment? 00175 template<class Y> void reset(SharedPtr<Y> const & share){ 00176 //void reset(SharedPtr const & share){ 00177 // if we already are pointing to sth, be sure to decrease its count 00178 if (_ptr!=NULL){ 00179 // in the specific case where we're having the same 00180 // share,reset() has actually no effect. However if *this is the 00181 // only instance still alive (implying share==*this) bringing 00182 // the count down to 0 and deleting the object will not have the 00183 // expected effect. So we just avoid that situation explicitly 00184 if (_ptr == share._get_container()) return; 00185 00186 _decrease_count(); 00187 } 00188 00189 // Watch out: if share is empty, construct an empty shared_ptr 00190 00191 // copy the container 00192 _ptr = share._get_container(); // Note: automatically set it to NULL if share is empty 00193 00194 if (_ptr!=NULL) 00195 (*_ptr)++; 00196 } 00197 00198 /// overload the = operator so that it updates count 00199 /// \param share : the object we want to copy 00200 SharedPtr& operator=(SharedPtr const & share){ 00201 reset(share); 00202 return *this; 00203 } 00204 00205 /// overload the = operator so that it updates count 00206 /// \param share : the object we want to copy 00207 template<class Y> SharedPtr& operator=(SharedPtr<Y> const & share){ 00208 reset(share); 00209 return *this; 00210 } 00211 00212 /// return the pointer we're pointing to 00213 T* operator ()() const{ 00214 if (_ptr==NULL) return NULL; 00215 return _ptr->get(); // automatically returns NULL when out-of-scope 00216 } 00217 00218 /// indirection, get a reference to the stored pointer 00219 /// 00220 /// !!! WATCH OUT 00221 /// It fails to check the requirement that the stored pointer must 00222 /// not be NULL!! So you need explicitly to check the validity in 00223 /// your code 00224 inline T& operator*() const{ 00225 return *(_ptr->get()); 00226 } 00227 00228 /// indirection, get the stored pointer 00229 /// 00230 /// !!! WATCH OUT 00231 /// It fails to check the requirement that the stored pointer must 00232 /// not be NULL!! So you need explicitly to check the validity in 00233 /// your code 00234 inline T* operator->() const{ 00235 if (_ptr==NULL) return NULL; 00236 return _ptr->get(); 00237 } 00238 00239 /// get the stored pointer 00240 inline T* get() const{ 00241 if (_ptr==NULL) return NULL; 00242 return _ptr->get(); 00243 } 00244 00245 /// check if the instance is unique 00246 inline bool unique() const{ 00247 return (use_count()==1); 00248 } 00249 00250 /// return the number of counts 00251 inline long use_count() const{ 00252 if (_ptr==NULL) return 0; 00253 return _ptr->use_count(); // automatically returns NULL when out-of-scope 00254 } 00255 00256 /// conversion to bool 00257 /// This will allow you to use the indirection nicely 00258 inline operator bool() const{ 00259 return (get()!=NULL); 00260 } 00261 00262 /// exchange the content of the two pointers 00263 inline void swap(SharedPtr & share){ 00264 __SharedCountingPtr* share_container = share._ptr; 00265 share._ptr = _ptr; 00266 _ptr = share_container; 00267 } 00268 00269 /// force the count to be set to a specified value 00270 /// \param count the value that we ned to reset to 00271 void set_count(const long & count){ 00272 if (_ptr==NULL) return; 00273 _ptr->set_count(count); 00274 } 00275 00276 /** 00277 * \if internal_doc 00278 * \class __SharedCountingPtr 00279 * A reference-counting pointer 00280 * 00281 * This is implemented as a container for that pointer together with 00282 * reference counting. 00283 * The pointer is deleted when the number of counts goes to 0; 00284 * \endif 00285 */ 00286 class __SharedCountingPtr{ 00287 public: 00288 /// default ctor 00289 __SharedCountingPtr() : _ptr(NULL), _count(0){} 00290 00291 /// ctor with initialisation 00292 template<class Y> explicit __SharedCountingPtr(Y* ptr) : _ptr(ptr), _count(1){} 00293 00294 /// default dtor 00295 ~__SharedCountingPtr(){ 00296 // force the deletion of the object we keep track of 00297 if (_ptr!=NULL){ delete _ptr;} 00298 } 00299 00300 /// return a pointer to the object 00301 inline T* get() const {return _ptr;} 00302 00303 /// return the count 00304 inline long use_count() const {return _count;} 00305 00306 /// postfix incrementation 00307 inline long operator++(int unused){return _count++;} 00308 00309 /// postfix decrementation 00310 inline long operator--(int unused){return _count--;} 00311 00312 /// prefix incrementation 00313 inline long operator++(){return ++_count;} 00314 00315 /// prefix decrementation 00316 inline long operator--(){return --_count;} 00317 00318 /// force the count to be set to a specified value 00319 /// \param count the value that we ned to reset to 00320 void set_count(const long & count){ 00321 _count = count; 00322 } 00323 00324 private: 00325 T *_ptr; ///< the pointer we're counting the references to 00326 long _count; ///< the number of references 00327 }; 00328 00329 private: 00330 /// return the common container 00331 inline __SharedCountingPtr* _get_container() const{ 00332 return _ptr; 00333 } 00334 00335 /// decrease the pointer count and support deletion 00336 /// Warning: we don't test that the pointer is allocated 00337 /// This can be dangerous if we have explicitly reset the 00338 /// count. Generally speaking, if the count goes negative 00339 /// after _ptr has been effectively deleted, this is going 00340 /// to lead to a segmentation fault. But, if in the course 00341 /// of the deletion of _ptr, the deletion of its pointer 00342 /// (_ptr::_ptr, i.e. the real data we're storing) makes 00343 /// the counts to become negative, this is going to pass 00344 /// smoothly. 00345 void _decrease_count(){ 00346 // decrease the count 00347 (*_ptr)--; 00348 00349 // if no one else is using it, free the allocated memory 00350 if (_ptr->use_count()==0) 00351 delete _ptr; // that automatically deletes the object itself 00352 } 00353 00354 // the real info 00355 __SharedCountingPtr *_ptr; 00356 }; 00357 00358 00359 /// comparison: equality 00360 template<class T,class U> 00361 inline bool operator==(SharedPtr<T> const & t, SharedPtr<U> const & u){ 00362 return t.get() == u.get(); 00363 } 00364 00365 /// comparison: difference 00366 template<class T,class U> 00367 inline bool operator!=(SharedPtr<T> const & t, SharedPtr<U> const & u){ 00368 return t.get() != u.get(); 00369 } 00370 00371 /// comparison: orgering 00372 template<class T,class U> 00373 inline bool operator<(SharedPtr<T> const & t, SharedPtr<U> const & u){ 00374 return t.get() < u.get(); 00375 } 00376 00377 /// swapping 00378 template<class T> 00379 inline void swap(SharedPtr<T> & a, SharedPtr<T> & b){ 00380 return a.swap(b); 00381 } 00382 00383 /// getting the pointer 00384 template<class T> 00385 inline T* get_pointer(SharedPtr<T> const & t){ 00386 return t.get(); 00387 } 00388 00389 #endif // USETR1SHAREDPTR 00390 00391 FASTJET_END_NAMESPACE // defined in fastjet/internal/base.hh 00392 00393 #endif // __FASTJET_SHARED_PTR_HH__