OW_Enumeration.hpp

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#ifndef OW_ENUMERATION_HPP_INCLUDE_GUARD_
#define OW_ENUMERATION_HPP_INCLUDE_GUARD_
#include "OW_config.h"
#include "OW_TempFileEnumerationImplBase.hpp"
#include "OW_IntrusiveReference.hpp"

#include <iterator> // for the iterator tags

namespace OW_NAMESPACE
{

template <class T>
class TempFileEnumerationImpl : public TempFileEnumerationImplBase
{
public:
   TempFileEnumerationImpl()
   {
   }
   TempFileEnumerationImpl(String const& filename)
   : TempFileEnumerationImplBase(filename)
   {
   }
   virtual ~TempFileEnumerationImpl()
   {
   }
   void nextElement(T& out)
   {
      throwIfEmpty();
      out.readObject(m_Data);
      --m_size;
   }
   T nextElement()
   {
      throwIfEmpty();
      T retval;
      retval.readObject(m_Data);
      --m_size;
      return retval;
   }
   void addElement( const T& arg )
   {
      arg.writeObject(m_Data);
      ++m_size;
   }
private:
   // Prevent copying or assignment
   TempFileEnumerationImpl( const TempFileEnumerationImpl<T>& );
   TempFileEnumerationImpl<T>& operator=( const TempFileEnumerationImpl<T>& );
};

template <class T>
class Enumeration
{
public:
   Enumeration()
   : m_impl( new TempFileEnumerationImpl<T> )
   {
   }
   // Build an enumeration out of the file referenced by filename
   Enumeration(String const& filename)
   : m_impl( new TempFileEnumerationImpl<T>(filename) )
   {
   }
   bool hasMoreElements() const
   {
      return m_impl->hasMoreElements();
   }
   void nextElement(T& arg)
   {
      m_impl->nextElement(arg);
   }
   T nextElement()
   {
      return m_impl->nextElement();
   }
   size_t numberOfElements() const
   {
      return m_impl->numberOfElements();
   }
   void addElement(const T& arg)
   {
      m_impl->addElement(arg);
   }
   void clear()
   {
      m_impl->clear();
   }
   // Returns the filename of the file that contains the enumeration data.
   // After this call, the enumeration will not contain any items.
   String releaseFile()
   {
      return m_impl->releaseFile();
   }
   bool usingTempFile() const
   {
      return m_impl->usingTempFile();
   }
private:
   IntrusiveReference< TempFileEnumerationImpl<T> > m_impl;
};

template <class T>
class Enumeration_input_iterator
{
public:
   typedef Enumeration<T> enumeration_type;
   typedef std::input_iterator_tag iterator_category;
   typedef T value_type;
   typedef const T* pointer;
   typedef const T& reference;
   typedef ptrdiff_t difference_type;
   Enumeration_input_iterator() : m_enumeration(0), m_ok(false)
   {
   }
   Enumeration_input_iterator(enumeration_type& e) : m_enumeration(&e)
   {
      m_read();
   }

   // compiler generated copy ctor is what we want.
   // compiler generated copy-assignment operator= is what we want.

   reference operator*() const
   {
      return m_value;
   }
   pointer operator->() const
   {
      return &(operator*());
   }
   Enumeration_input_iterator& operator++()
   {
      m_read();
      return *this;
   }
   Enumeration_input_iterator operator++(int)
   {
      Enumeration_input_iterator tmp = *this;
      m_read();
      return tmp;
   }
   bool m_equal(const Enumeration_input_iterator& x) const
   {
      return(m_ok == x.m_ok) && (!m_ok || m_enumeration == x.m_enumeration);
   }
private:
   enumeration_type* m_enumeration;
   T m_value;
   bool m_ok;
   void m_read()
   {
      m_ok = (m_enumeration && m_enumeration->hasMoreElements()) ? true : false;
      if (m_ok)
      {
         m_enumeration->nextElement(m_value);
      }
   }
};

template <class T>
inline bool
operator==(const Enumeration_input_iterator<T>& x,
   const Enumeration_input_iterator<T>& y)
{
   return x.m_equal(y);
}

template <class T>
inline bool
operator!=(const Enumeration_input_iterator<T>& x,
   const Enumeration_input_iterator<T>& y)
{
   return !x.m_equal(y);
}

template <class T>
class Enumeration_insert_iterator
{
public:
   typedef Enumeration<T> enumeration_type;
   typedef std::output_iterator_tag            iterator_category;
   typedef void                           value_type;
   typedef void                           difference_type;
   typedef void                           pointer;
   typedef void                           reference;
   Enumeration_insert_iterator(enumeration_type& e) : m_enumeration(&e)
   {
   }
   Enumeration_insert_iterator<T>& operator=(const T& value)
   {
      m_enumeration->addElement(value);
      return *this;
   }
   Enumeration_insert_iterator<T>& operator*()
   {
      return *this;
   }
   Enumeration_insert_iterator<T>& operator++()
   {
      return *this;
   }
   Enumeration_insert_iterator<T>& operator++(int)
   {
      return *this;
   }
private:
   enumeration_type* m_enumeration;
};

template <class Container>
inline Enumeration_insert_iterator<Container> Enumeration_inserter(Enumeration<Container>& x)
{
   return Enumeration_insert_iterator<Container>(x);
}

} // end namespace OW_NAMESPACE

#endif

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