testtypedef.cxx

一个著名的SIP协议栈

#include <cassert>
#include <iostream>

using namespace std;

namespace resip
{

template <class P>
class IntrusiveListElement
{
   public:
      IntrusiveListElement() 
         : mNext(0),
           mPrev(0)
      {}

      virtual ~IntrusiveListElement() 
      {
         remove();
      }

      // make this element an empty list
      static P makeList(P elem)
      {
         assert(!elem->IntrusiveListElement::mNext);

         elem->IntrusiveListElement::mPrev = elem;
         elem->IntrusiveListElement::mNext = elem;

         return elem;
      }

      bool empty() const
      {
         assert(mPrev);
         assert(mNext);

         return mNext == static_cast<P>(const_cast<IntrusiveListElement<P>*>(this));
      }

      // .dlb. add reverse_iterator?

      class iterator
      {
         public:
            explicit iterator(const P start)
               : mPos(start)
            {}

            iterator& operator=(const iterator& rhs)
            {
               mPos = rhs.mPos;
               return *this;
            }

            iterator& operator++()
            {
               mPos = mPos->IntrusiveListElement::mNext;
               return *this;
            }

            bool operator==(const iterator& rhs)
            {
               return mPos == rhs.mPos;
            }

            bool operator!=(const iterator& rhs)
            {
               return mPos != rhs.mPos;
            }

            P operator*()
            {
               return mPos;
            }

         private:
            P mPos;
      };

      iterator begin()
      {
         assert(mPrev);
         assert(mNext);
         return iterator(mNext);
      }

      iterator end()
      {
         assert(mPrev);
         assert(mNext);
         return iterator(static_cast<P>(this));
      }

      friend class iterator;

      // pushing an element onto the same list twice is undefined
      void push_front(P elem)
      {
         assert(mPrev);
         assert(mNext);

         elem->IntrusiveListElement::mNext = mNext;
         elem->IntrusiveListElement::mPrev = static_cast<P>(this);
         
         elem->IntrusiveListElement::mNext->IntrusiveListElement::mPrev = elem;
         elem->IntrusiveListElement::mPrev->IntrusiveListElement::mNext = elem;
      }

      // putting an element onto the same list twice is undefined
      void push_back(P elem)
      {
         assert(mPrev);
         assert(mNext);

         elem->IntrusiveListElement::mPrev = mPrev;
         elem->IntrusiveListElement::mNext = static_cast<P>(this);
         
         elem->IntrusiveListElement::mPrev->IntrusiveListElement::mNext = elem;
         elem->IntrusiveListElement::mNext->IntrusiveListElement::mPrev = elem;
      }

      void remove()
      {
         if (mNext)
         {
            // prev  -> this -> next
            //       <-      <-
            //
            // prev -> next
            //      <-
            mNext->IntrusiveListElement::mPrev = mPrev;
            mPrev->IntrusiveListElement::mNext = mNext;
         }

         mNext = 0;
         mPrev = 0;
      }

   protected:
      mutable P mNext;
      mutable P mPrev;
};

template <class P>
class IntrusiveListElement1
{
   public:
      IntrusiveListElement1() 
         : mNext(0),
           mPrev(0)
      {}

      virtual ~IntrusiveListElement1() 
      {
         remove();
      }

      // make this element an empty list
      static P makeList(P elem)
      {
         assert(!elem->IntrusiveListElement1::mNext);

         elem->IntrusiveListElement1::mPrev = elem;
         elem->IntrusiveListElement1::mNext = elem;

         return elem;
      }

      bool empty() const
      {
         assert(mPrev);
         assert(mNext);

         return mNext == static_cast<P>(const_cast<IntrusiveListElement1<P>*>(this));
      }

      // .dlb. add reverse_iterator?

      class iterator
      {
         public:
            explicit iterator(const P start)
               : mPos(start)
            {}

            iterator& operator=(const iterator& rhs)
            {
               mPos = rhs.mPos;
               return *this;
            }

            iterator& operator++()
            {
               mPos = mPos->IntrusiveListElement1::mNext;
               return *this;
            }

            bool operator==(const iterator& rhs)
            {
               return mPos == rhs.mPos;
            }

            bool operator!=(const iterator& rhs)
            {
               return mPos != rhs.mPos;
            }

            P operator*()
            {
               return mPos;
            }

         private:
            P mPos;
      };

      iterator begin()
      {
         assert(mPrev);
         assert(mNext);
         return iterator(mNext);
      }

      iterator end()
      {
         assert(mPrev);
         assert(mNext);
         return iterator(static_cast<P>(this));
      }

      friend class iterator;

      // pushing an element onto the same list twice is undefined
      void push_front(P elem)
      {
         assert(mPrev);
         assert(mNext);

         elem->IntrusiveListElement1::mNext = mNext;
         elem->IntrusiveListElement1::mPrev = static_cast<P>(this);
         
         elem->IntrusiveListElement1::mNext->IntrusiveListElement1::mPrev = elem;
         elem->IntrusiveListElement1::mPrev->IntrusiveListElement1::mNext = elem;
      }

      // putting an element onto the same list twice is undefined
      void push_back(P elem)
      {
         assert(mPrev);
         assert(mNext);

         elem->IntrusiveListElement1::mPrev = mPrev;
         elem->IntrusiveListElement1::mNext = static_cast<P>(this);
         
         elem->IntrusiveListElement1::mPrev->IntrusiveListElement1::mNext = elem;
         elem->IntrusiveListElement1::mNext->IntrusiveListElement1::mPrev = elem;
      }

      void remove()
      {
         if (mNext)
         {
            // prev  -> this -> next
            //       <-      <-
            //
            // prev -> next
            //      <-
            mNext->IntrusiveListElement1::mPrev = mPrev;
            mPrev->IntrusiveListElement1::mNext = mNext;
         }

         mNext = 0;
         mPrev = 0;
      }

   protected:
      mutable P mNext;
      mutable P mPrev;
};

template <class P>
class IntrusiveListElement2
{
   public:
      IntrusiveListElement2() 
         : mNext(0),
           mPrev(0)
      {}

      virtual ~IntrusiveListElement2() 
      {
         remove();
      }

      // make this element an empty list
      static P makeList(P elem)
      {
         assert(!elem->IntrusiveListElement2::mNext);

         elem->IntrusiveListElement2::mPrev = elem;
         elem->IntrusiveListElement2::mNext = elem;

         return elem;
      }

      bool empty() const
      {
         assert(mPrev);
         assert(mNext);

         return mNext == static_cast<P>(const_cast<IntrusiveListElement2<P>*>(this));
      }

      // .dlb. add reverse_iterator?

      class iterator
      {
         public:
            explicit iterator(const P start)
               : mPos(start)
            {}

            iterator& operator=(const iterator& rhs)
            {
               mPos = rhs.mPos;
               return *this;
            }

            iterator& operator++()
            {
               mPos = mPos->IntrusiveListElement2::mNext;
               return *this;
            }

            bool operator==(const iterator& rhs)
            {
               return mPos == rhs.mPos;
            }

            bool operator!=(const iterator& rhs)
            {
               return mPos != rhs.mPos;
            }

            P operator*()
            {
               return mPos;
            }

         private:
            P mPos;
      };

      iterator begin()
      {
         assert(mPrev);
         assert(mNext);
         return iterator(mNext);
      }

      iterator end()