// file      : odb/traits.hxx
// author    : Boris Kolpackov <boris@codesynthesis.com>
// copyright : Copyright (c) 2009-2010 Code Synthesis Tools CC
// license   : GNU GPL v2; see accompanying LICENSE file

#ifndef ODB_TRAITS_HXX
#define ODB_TRAITS_HXX

#include <odb/forward.hxx>
#include <odb/buffer.hxx>
#include <odb/shared-ptr.hxx>
#include <odb/pointer-traits.hxx>

namespace odb
{
  enum id_source
  {
    ids_assigned /* Assigned by the application. */
  };

  // template <typename T>
  // class access::object_traits;
  //
  // Specializations should inherit from object_memory, object_factory
  // and define the following members:
  //
  // id_type               - object id (primary key) type
  // id_source             - object id (primary key) source
  // id_type id (const T&) - get object id
  //
  // void persist (database&, T&)
  // void store (database&, T&)
  // void erase (database&, const id_type&)
  // pointer_type find (database&, const id_type&)
  // bool find (database&, const id_type&, T&)
  //
  //

  template <typename T>
  class access::object_memory
  {
  public:
    typedef T* pointer_type;
  };

  template <typename T>
  class access::object_factory
  {
  public:
    static typename object_memory<T>::pointer_type
    create ()
    {
      // By default use pointer-specific construction.
      //
      return
        pointer_factory<typename object_memory<T>::pointer_type>::create ();
    }
  };

  template <typename P>
  class access::pointer_factory
  {
  public:
    typedef typename pointer_traits<P>::type object_type;

    static P
    create ()
    {
      void* v (pointer_traits<P>::allocate (sizeof (object_type)));
      guard g (v);
      P p (new (v) object_type);
      g.release ();
      return p;
    }
  private:
    struct guard
    {
      guard (void* p): p_ (p) {}
      ~guard () {if (p_) pointer_traits<P>::free (p_);}
      void release () {p_ = 0;}
      void* p_;
    };
  };

  template <typename T>
  struct object_traits: access::object_traits<T>
  {
    typedef
    pointer_traits<typename access::object_traits<T>::pointer_type>
    pointer_ops;
  };

  template <typename V>
  class value_traits
  {
  public:
    typedef V value_type;

    template <typename I>
    static void
    set_value (value_type& v, I i, bool is_null)
    {
      if (!is_null)
        v = value_type (i);
      else
        v = value_type ();
    }

    template <typename I>
    static void
    set_image (I& i, bool& is_null, value_type v)
    {
      is_null = false;
      i = I (v);
    }
  };
}

#endif // ODB_TRAITS_HXX