shared source/vb/language/shared/iiterator.h

   1 //-------------------------------------------------------------------------------------------------
   2 //
   3 //  Copyright (c) Microsoft Corporation.  All rights reserved.
   4 //
   5 //-------------------------------------------------------------------------------------------------
   6
   7 #pragma once
   8
   9
  10 template <class T>
  11 class IIterator : public virtual IConstIterator<T>
  12 {
  13 public:
  14     virtual
  15     ~IIterator()
  16     {
  17     }
  18
  19     virtual
  20     void Remove() = 0;
  21 };
  22
  23 template <class T>
  24 class Iterator : public virtual IIterator<T>
  25 {
  26 public:
  27     Iterator()
  28     {
  29     }
  30
  31     explicit Iterator(RefCountedPtr<IIterator<T> > spIterator)
  32         : m_spIterator(spIterator)
  33     {
  34
  35     }
  36
  37     template <class U>
  38     Iterator(const U& it)
  39     {
  40         m_spIterator.Attach(new (zeromemory) U(it));
  41     }
  42
  43     virtual __override
  44     bool MoveNext()
  45     {
  46         if ( m_spIterator )
  47         {
  48             return m_spIterator->MoveNext();
  49         }
  50         else
  51         {
  52             // NULL is used to represent an empty iterator
  53             return false;
  54         }
  55     }
  56
  57     virtual __override
  58     T Current()
  59     {
  60         ThrowIfFalse2(m_spIterator, "Current called on an empty iterator");
  61         return m_spIterator->Current();
  62     }
  63
  64     virtual __override
  65     void Remove()
  66     {
  67         ThrowIfFalse2(m_spIterator, "Remove called on an empty iterator");
  68         m_spIterator->Remove();
  69     }
  70
  71 private:
  72     // Allow default copy constructor and assignment operators to
  73     // be generated because RefCountedPtr is copy safe
  74     RefCountedPtr<IIterator<T> > m_spIterator;
  75 };
  76