shared source/vb/language/shared/guardbase.h

   1 //-------------------------------------------------------------------------------------------------
   2 //
   3 //  Copyright (c) Microsoft Corporation.  All rights reserved.
   4 //
   5 //  Misc templates that make exception guarantees.
   6 //
   7 //-------------------------------------------------------------------------------------------------
   8
   9 class GuardBase
  10 {
  11 protected:
  12     GuardBase() : m_enabled(true), m_hasRun(false)
  13     {
  14     }
  15
  16     virtual void DoAction() = 0;
  17
  18 public:
  19
  20     void RunAction()
  21     {
  22         if ( m_enabled && !m_hasRun )
  23         {
  24             m_hasRun = true;
  25             DoAction();
  26         }
  27     }
  28
  29     bool IsEnabled() const
  30     {
  31         return m_enabled;
  32     }
  33
  34     void SetIsEnabled(bool enabled)
  35     {
  36         m_enabled = enabled;
  37     }
  38
  39 private:
  40     // Not copy safe
  41     GuardBase(const GuardBase&);
  42     GuardBase& operator=(const GuardBase&);
  43
  44     bool m_enabled;
  45     bool m_hasRun;
  46 };
  47
  48 template <typename T>
  49 class ClearPointerGuard : public GuardBase
  50 {
  51 public:
  52     ClearPointerGuard(T*& ptr) : m_ptr(ptr)
  53     {
  54     }
  55
  56     ~ClearPointerGuard()
  57     {
  58         RunAction();
  59     }
  60
  61 protected:
  62     virtual __override
  63     void DoAction()
  64     {
  65         m_ptr = NULL;
  66     }
  67
  68 private:
  69     T*& m_ptr;
  70 };