/*
    Copyright (c) 2010 Volker Krause <vkrause@kde.org>

    This library is free software; you can redistribute it and/or modify it
    under the terms of the GNU Library General Public License as published by
    the Free Software Foundation; either version 2 of the License, or (at your
    option) any later version.

    This library is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
    License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to the
    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
    02110-1301, USA.
*/

#ifndef AKONADI_SHAREDVALUEPOOL_P_H
#define AKONADI_SHAREDVALUEPOOL_P_H

#include <boost/utility/enable_if.hpp>
#include <algorithm>

namespace Akonadi {
namespace Internal {

/*template <typename T> class container_traits
{
  private:
    typedef char sizeOne;
    typedef struct { char a[2]; } sizeTwo;
    template <typename C> static sizeOne testForKeyType( typename C::key_type const* );
    template <typename C> static sizeTwo testForKeyType( ... );
  public:
    enum { isAssociative = sizeof( container_traits<T>::testForKeyType<T>( 0 ) ) == 1 };
};*/

/**
 * Pool of implicitly shared values, use for optimizing memory use
 * when having a large amount of copies from a small set of different values.
 */
template <typename T, template <typename> class Container>
class SharedValuePool
{
  public:
    /** Returns the shared value equal to @p value .*/
    /*template <typename C> 
    typename boost::enable_if_c<container_traits<Container<C> >::isAssociative, C>::type sharedValue( const C &value, const int* = 0 )
    {
      typename Container<T>::const_iterator it = m_pool.constFind( value );
      if ( it != m_pool.constEnd() )
        return *it;
      m_pool.insert( value );
      return value;
    }

    template <typename C>
    typename boost::disable_if_c<container_traits<Container<C> >::isAssociative, C>::type sharedValue( const C &value )*/
    T sharedValue( const T &value )
    {
      // for small pool sizes this is actually faster than using lower_bound and a sorted vector
      typename Container<T>::const_iterator it = std::find( m_pool.constBegin(), m_pool.constEnd(), value );
      if ( it != m_pool.constEnd() )
        return *it;
      m_pool.push_back( value );
      return value;
    }

  private:
    Container<T> m_pool;
};

}
}

#endif
