pBendan

  1 /*
  2  * Copyright (c) 1997-1999
  3  * Silicon Graphics Computer Systems, Inc.
  4  *
  5  * Permission to use, copy, modify, distribute and sell this software
  6  * and its documentation for any purpose is hereby granted without fee,
  7  * provided that the above copyright notice appear in all copies and
  8  * that both that copyright notice and this permission notice appear
  9  * in supporting documentation.  Silicon Graphics makes no
 10  * representations about the suitability of this software for any
 11  * purpose.  It is provided "as is" without express or implied warranty.
 12  *
 13  */
 14 
 15 #ifndef __SGI_STL_MEMORY
 16 #define __SGI_STL_MEMORY
 17 
 18 #include <stl_algobase.h>
 19 #include <stl_alloc.h>
 20 #include <stl_construct.h>
 21 #include <stl_tempbuf.h>
 22 #include <stl_uninitialized.h>
 23 #include <stl_raw_storage_iter.h>
 24 
 25 
 26 __STL_BEGIN_NAMESPACE
 27 
 28 #if defined(__SGI_STL_USE_AUTO_PTR_CONVERSIONS) && \
 29     defined(__STL_MEMBER_TEMPLATES)
 30 
 31 template<class _Tp1> struct auto_ptr_ref {
 32   _Tp1* _M_ptr;
 33   auto_ptr_ref(_Tp1* __p) : _M_ptr(__p) {}
 34 };
 35 
 36 #endif
 37 
 38 template <class _Tp> class auto_ptr {
 39 private:
 40   _Tp* _M_ptr;  // 維護一個類型指針
 41 
 42 public:
 43   typedef _Tp element_type;
 44 
 45    // 構造函數，初始化所維護的指針 
 46   explicit auto_ptr(_Tp* __p = 0) __STL_NOTHROW : _M_ptr(__p) {}
 47 
 48   // 拷貝構造函數，轉移控制權，將__a維護的指針轉交給當前對象來維護；
 49   auto_ptr(auto_ptr& __a) __STL_NOTHROW : _M_ptr(__a.release()) {}
 50 
 51 #ifdef __STL_MEMBER_TEMPLATES
 52   template <class _Tp1> auto_ptr(auto_ptr<_Tp1>& __a) __STL_NOTHROW
 53     : _M_ptr(__a.release()) {}
 54 #endif /* __STL_MEMBER_TEMPLATES */
 55 
 56   // 賦值構造函數，重新設定控制權
 57   auto_ptr& operator=(auto_ptr& __a) __STL_NOTHROW {
 58     if (&__a != this) {
 59       delete _M_ptr; // 解除當前控制權，將所維護的指針所指向的對象析構掉。
 60       _M_ptr = __a.release(); // 重新設定控制權，將__a維護的指針轉交給當前對象來維護。
 61     }
 62     return *this;
 63   }
 64 
 65 #ifdef __STL_MEMBER_TEMPLATES
 66   template <class _Tp1>
 67   auto_ptr& operator=(auto_ptr<_Tp1>& __a) __STL_NOTHROW {
 68     if (__a.get() != this->get()) {
 69       delete _M_ptr;
 70       _M_ptr = __a.release();
 71     }
 72     return *this;
 73   }
 74 #endif /* __STL_MEMBER_TEMPLATES */
 75 
 76   // Note: The C++ standard says there is supposed to be an empty throw
 77   // specification here, but omitting it is standard conforming.  Its 
 78   // presence can be detected only if _Tp::~_Tp() throws, but (17.4.3.6/2)
 79   // this is prohibited.
 80   ~auto_ptr() { delete _M_ptr; } // 析構函數，釋放所維護指針指向的資源
 81 
 82   _Tp& operator*() const __STL_NOTHROW {
 83     return *_M_ptr; // 重載*操作符，返回對象引用
 84   }
 85   _Tp* operator->() const __STL_NOTHROW {
 86     return _M_ptr; // 重載->操作符，返回對象地址
 87   }
 88   _Tp* get() const __STL_NOTHROW {
 89     return _M_ptr; // 獲取所維護指針
 90   }
 91   _Tp* release() __STL_NOTHROW {
 92     _Tp* __tmp = _M_ptr;
 93     _M_ptr = 0; // 轉移控制權，當前對象不再維護任何指針
 94     return __tmp; // 讓出控制權
 95   }
 96   // 重新設定控制權，如果以默認值調用，則釋放對象，結束控制權
 97   void reset(_Tp* __p = 0) __STL_NOTHROW {
 98     if (__p != _M_ptr) {
 99       delete _M_ptr;
100       _M_ptr = __p;
101     }
102   }
103 
104   // According to the C++ standard, these conversions are required.  Most
105   // present-day compilers, however, do not enforce that requirement---and, 
106   // in fact, most present-day compilers do not support the language 
107   // features that these conversions rely on.
108   
109 #if defined(__SGI_STL_USE_AUTO_PTR_CONVERSIONS) && \
110     defined(__STL_MEMBER_TEMPLATES)
111 
112 public:
113   auto_ptr(auto_ptr_ref<_Tp> __ref) __STL_NOTHROW
114     : _M_ptr(__ref._M_ptr) {}
115 
116   auto_ptr& operator=(auto_ptr_ref<_Tp> __ref) __STL_NOTHROW {
117     if (__ref._M_ptr != this->get()) {
118       delete _M_ptr;
119       _M_ptr = __ref._M_ptr;
120     }
121     return *this;
122   }
123 
124   template <class _Tp1> operator auto_ptr_ref<_Tp1>() __STL_NOTHROW 
125     { return auto_ptr_ref<_Tp1>(this->release()); }
126   template <class _Tp1> operator auto_ptr<_Tp1>() __STL_NOTHROW
127     { return auto_ptr<_Tp1>(this->release()); }
128 
129 #endif /* auto ptr conversions && member templates */
130 };
131 
132 __STL_END_NAMESPACE
133 
134 #endif /* __SGI_STL_MEMORY */
135 
136 
137 // Local Variables:
138 // mode:C++
139 // End: