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 #ifndef PHOOL_PHPOINTERLIST_H
 #define PHOOL_PHPOINTERLIST_H
 
 //  Purpose: a template list of pointers
 //
 //  Description:
 //       - The items are held internally as an array of type T.
 //       - The list is initialized with a maximum size of 2
 //         per default, or with the number given as constructor
 //         argument.
 //       - If this size is exceeded in the append() function,
 //         the array is allocated anew with double size and the
 //         old list is copied into this new one.
 //       - clear() sets the number of items to zero.
 //       - clearAndDestroy() does the same AND deletes all items.
 //       - The [] operator always performs a bound-check.
 //       - removeLast() returns the pointer to the last item in the
 //         array and decrements size by one.
 //       - removeAt(i) returns the pointer at position i and rearranges
 //         the internal list. This can cost PERFORMANCE in your application.
 //       - The output operator '<<' is overloaded for this class.
 //         Therefore class T for which the PHPointerList is insantiated must
 //         also have an overloaded output operator.
 //
 //  Author: Matthias Messer
 
 #include <iostream>
 
 template <class T>
 class PHPointerList
 {
  public:
   explicit PHPointerList(size_t = 2);
   PHPointerList(const PHPointerList<T>&);
   PHPointerList<T>& operator=(const PHPointerList<T>&);
   virtual ~PHPointerList();
 
  public:
   T* operator[](size_t) const;
   void clear();
   void clearAndDestroy();
   size_t length() const;
   T* removeLast();
   T* removeAt(size_t);
   bool append(T*);
   bool insertAt(T*, size_t);
 
  private:
   bool grow(size_t = 0);
 
  private:
   T** items;
   size_t maxNItems;
   size_t nItems;
 };
 
 // Implementation of member functions
 template <class T>
 PHPointerList<T>::PHPointerList(size_t initialSize)
 {
   maxNItems = initialSize;
   items = new T*[maxNItems];
   nItems = 0;
 }
 
 template <class T>
 PHPointerList<T>::PHPointerList(const PHPointerList<T>& l)
 {
   *this = l;
 }
 
 template <class T>
 PHPointerList<T>&
 PHPointerList<T>::operator=(const PHPointerList<T>& l)
 {
   if (this != &l)
   {
     maxNItems = l.maxNItems;
     if (maxNItems > 0)
     {
       grow(l.maxNItems);
     }
     else
     {
       items = nullptr;
     }
     nItems = l.length();
     for (size_t i = 0; i < nItems; ++i)
     {
       items[i] = l[i];
     }
   }
   return *this;
 }
 
 template <class T>
 PHPointerList<T>::~PHPointerList()
 {
   // This deletes the internal list of pointers and NOT the actual objects.
   delete[] items;
 }
 
 template <class T>
 bool PHPointerList<T>::grow(size_t newSize)
 {
   if (newSize == 0)
   {
     newSize = maxNItems * 2;
   }
   T** buffer = items;
   items = new T*[newSize];
   if (items)
   {
     for (size_t i = 0; i < maxNItems; ++i)
     {
       items[i] = buffer[i];
     }
     delete[] buffer;
     maxNItems = newSize;
   }
   else
   {
     std::cout << "PHPointerList<T>::grow: Out of memory?" << std::endl;
     return false;
   }
 
   return true;
 }
 
 template <class T>
 inline T* PHPointerList<T>::operator[](size_t i) const
 {
   if (i < nItems)
   {
     return items[i];
   }
   else
   {
     std::cout << "PHPointerList<T>::operator[]: nItems exceeded" << std::endl;
     return 0;
   }
 }
 
 template <class T>
 inline bool
 PHPointerList<T>::append(T* item)
 {
   if (nItems < maxNItems)
   {
     items[nItems] = item;
     ++nItems;
     return true;
   }
   else
   {
     if (grow())
     {
       items[nItems] = item;
       ++nItems;
       return true;
     }
     else
     {
       std::cout << "PHPointerList<T>::append: max nItems exceeded" << std::endl;
       return false;
     }
   }
 }
 
 template <class T>
 inline bool
 PHPointerList<T>::insertAt(T* item, size_t pos)
 {
   // This function inserts item at pos in the internal list
   if (pos > nItems)
   {
     std::cout << "PHPointerList<T>::insertAt: insert beyond nItems" << std::endl;
     return false;
   }
 
   // Append is used here as a convenient way to let the list grow, if necessary.
   append(item);
 
   // Now all items are shifted upwards in the list by one, starting at pos.
   for (size_t i = nItems; i > pos; --i)
   {
     items[i] = items[i - 1];
   }
 
   items[pos] = item;
 
   return true;
 }
 
 template <class T>
 inline void
 PHPointerList<T>::clear()
 {
   nItems = 0;
   items[nItems] = 0;
 }
 
 template <class T>
 inline void
 PHPointerList<T>::clearAndDestroy()
 {
   for (size_t i = 0; i < nItems; ++i)
   {
     delete items[i];
   }
   nItems = 0;
   items[nItems] = 0;
 }
 
 template <class T>
 inline size_t
 PHPointerList<T>::length() const
 {
   return nItems;
 }
 
 template <class T>
 inline T*
 PHPointerList<T>::removeLast()
 {
   if (nItems > 0)
   {
     return items[nItems--];
   }
   else
   {
     std::cout << "PHPointerList<T>::removeLast: no items in list" << std::endl;
     return 0;
   }
 }
 
 template <class T>
 inline T*
 PHPointerList<T>::removeAt(size_t i)
 {
   if (i > nItems)
   {
     return 0;
   }
 
   T* item = items[i];
 
   for (size_t j = i; j < nItems - 1; ++j)
   {
     items[j] = items[j + 1];
   }
   --nItems;
 
   return item;
 }
 
 // Implementation of external functions.
 template <class T>
 std::ostream&
 operator<<(std::ostream& stream, const PHPointerList<T>& thislist)
 {
   for (size_t i = 0; i < thislist.length(); ++i)
   {
     stream << *(thislist[i]) << std::endl;
   }
 
   return stream;
 }
 
 #endif

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