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Diffstat (limited to 'mmc_updater/depends/win32cpp/shared_ptr.h')
| -rw-r--r-- | mmc_updater/depends/win32cpp/shared_ptr.h | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/mmc_updater/depends/win32cpp/shared_ptr.h b/mmc_updater/depends/win32cpp/shared_ptr.h new file mode 100644 index 00000000..0d2f8b0c --- /dev/null +++ b/mmc_updater/depends/win32cpp/shared_ptr.h @@ -0,0 +1,199 @@ +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF +// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED +// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A +// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT +// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR +// ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN +// ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE +// OR OTHER DEALINGS IN THE SOFTWARE. +// +// This software was developed from code available in the public domain +// and has no copyright. + + +// About Shared_Ptr: +// Shared_Ptr wraps a reference-counted smart pointer around a dynamically +// allocated object. Unlike auto_ptr, the Shared_Ptr can be used as a smart +// pointer for objects stored in containers like std::vector. Do not use +// Shared_Ptr (or shared_ptr or auto_ptr) for dynamically allocated arrays. +// See below for advice on how to wrap dynamically allocated arrays in a +// vector. +// +// The next standard of C++ will also contain a shared_ptr. Some modern +// compilers already have a shared_ptr available as std::tr1::shared_ptr. If +// your compiler already provides a shared_ptr, or if you have Boost, you +// should use that smart pointer instead. This class has been provided for +// those users who don't have easy access to an "official" shared_ptr. +// Note that this class is "Shared_Ptr", a slightly different name to the +// future "shared_ptr" to avoid naming conflicts. + +// Advantages of Shared_Ptr (or shared_ptr where available): +// - Shared_Ptr can be safely copied. This makes then suitable for containers. +// - Shared_Ptr automatically calls delete for the wrapped pointer when +// its last copy goes out of scope. +// - Shared_Ptr simplifies exception safety. +// +// Without smart pointers, it can be quite challenging to ensure that every +// dynamically allocated pointer (i.e. use of new) is deleted in the event of +// all possible exceptions. In addition to the exceptions we throw ourselves, +// "new" itself will throw an exception it it fails, as does the STL (Standard +// Template Library which includes vector and string). Without smart pointers +// we often need to resort to additional try/catch blocks simply to avoid +// memory leaks when exceptions occur. + +// Examples: +// Shared_Ptr<CWnd> w1(new CWnd); +// or +// Shared_Ptr<CWnd> w1 = new CWnd; +// or +// typedef Shared_Ptr<CWnd> CWndPtr; +// CWndPtr w1 = new CWnd; +// or +// typedef Shared_Ptr<CWnd> CWndPtr; +// CWndPtr w1(new CWnd); +// +// And with a vector +// typedef Shared_Ptr<CWnd> CWndPtr; +// std::vector<CWndPtr> MyVector; +// MyVector.push_back(new CWnd); +// or +// typedef Shared_Ptr<CWnd> CWndPtr; +// CWnd* pWnd = new CWnd; +// std::vector<CWndPtr> MyVector; +// MyVector.push_back(pWnd); +// + +// How to handle dynamically allocated arrays: +// While we could create a smart pointer for arrays, we don't need to because +// std::vector already handles this for us. Consider the following example: +// int nLength = ::GetWindowTextLength(m_hWnd); +// pTChar = new TCHAR[nLength+1]; +// memset(pTChar, 0, (nLength+1)*sizeof(TCHAR)); +// ::GetWindowText(m_hWnd, m_pTChar, nLength+1); +// .... +// delete[] pTChar; +// +// This can be improved by using a vector instead of an array +// int nLength = ::GetWindowTextLength(m_hWnd); +// std::vector<TCHAR> vTChar( nLength+1, _T('\0') ); +// TCHAR* pTCharArray = &vTChar.front(); +// ::GetWindowText(m_hWnd, pTCharArray, nLength+1); +// +// This works because the memory in a vector is always contiguous. Note that +// this is NOT always true of std::string. + + +// Summing up: +// In my opinion, "naked" pointers for dynamically created objects should be +// avoided in modern C++ code. That's to say that calls to "new" should be +// wrapped in some sort of smart pointer wherever possible. This eliminates +// the possibility of memory leaks (particularly in the event of exceptions). +// It also elminiates the need for delete in user's code. + +#ifndef _WIN32XX_SHARED_PTR_ +#define _WIN32XX_SHARED_PTR_ + +namespace Win32xx +{ + + template <class T1> + class Shared_Ptr + { + public: + Shared_Ptr() : m_ptr(NULL), m_count(NULL) { } + Shared_Ptr(T1 * p) : m_ptr(p), m_count(NULL) + { + try + { + if (m_ptr) m_count = new long(0); + inc_ref(); + } + // catch the unlikely event of 'new long(0)' throwing an exception + catch (const std::bad_alloc&) + { + delete m_ptr; + throw; + } + } + Shared_Ptr(const Shared_Ptr& rhs) : m_ptr(rhs.m_ptr), m_count(rhs.m_count) { inc_ref(); } + ~Shared_Ptr() + { + if(m_count && 0 == dec_ref()) + { + // Note: This code doesn't handle a pointer to an array. + // We would need delete[] m_ptr to handle that. + delete m_ptr; + delete m_count; + } + } + + T1* get() const { return m_ptr; } + long use_count() const { return m_count? *m_count : 0; } + bool unique() const { return (m_count && (*m_count == 1)); } + + void swap(Shared_Ptr& rhs) + { + std::swap(m_ptr, rhs.m_ptr); + std::swap(m_count, rhs.m_count); + } + + Shared_Ptr& operator=(const Shared_Ptr& rhs) + { + Shared_Ptr tmp(rhs); + this->swap(tmp); + return *this; + } + + T1* operator->() const + { + assert(m_ptr); + return m_ptr; + } + + T1& operator*() const + { + assert (m_ptr); + return *m_ptr; + } + + bool operator== (const Shared_Ptr& rhs) const + { + return ( *m_ptr == *rhs.m_ptr); + } + + bool operator!= (const Shared_Ptr& rhs) const + { + return ( *m_ptr != *rhs.m_ptr); + } + + bool operator< (const Shared_Ptr& rhs) const + { + return ( *m_ptr < *rhs.m_ptr ); + } + + bool operator> (const Shared_Ptr& rhs) const + { + return ( *m_ptr > *rhs.m_ptr ); + } + + private: + void inc_ref() + { + if(m_count) + InterlockedIncrement(m_count); + } + + int dec_ref() + { + assert (m_count); + return InterlockedDecrement(m_count); + } + + T1* m_ptr; + long* m_count; + }; + +} + +#endif // _WIN32XX_SHARED_PTR_ |