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// file : odb/polymorphic-object-result.hxx
// copyright : Copyright (c) 2009-2013 Code Synthesis Tools CC
// license : GNU GPL v2; see accompanying LICENSE file
#ifndef ODB_POLYMORPHIC_OBJECT_RESULT_HXX
#define ODB_POLYMORPHIC_OBJECT_RESULT_HXX
#include <odb/pre.hxx>
#include <cstddef> // std::size_t
#include <utility> // std::move
#include <odb/forward.hxx>
#include <odb/traits.hxx>
#include <odb/result.hxx>
#include <odb/object-result.hxx>
#include <odb/pointer-traits.hxx>
#include <odb/details/config.hxx> // ODB_CXX11
namespace odb
{
// Implementation for polymorphic objects with object id.
//
template <typename T>
class polymorphic_object_result_impl: public result_impl
{
protected:
// In result_impl, T is always non-const and the same as object_type.
//
typedef T object_type;
typedef odb::object_traits<object_type> object_traits;
typedef typename object_traits::id_type id_type;
typedef typename object_traits::pointer_type pointer_type;
typedef odb::pointer_traits<pointer_type> pointer_traits;
typedef typename object_traits::root_type root_type;
typedef odb::object_traits<root_type> root_traits;
typedef typename root_traits::discriminator_type discriminator_type;
friend class result<T>;
friend class result<const T>;
friend class result_iterator<T, class_object>;
friend class result_iterator<const T, class_object>;
friend class object_result_iterator<T, id_type, true>;
friend class object_result_iterator<const T, id_type, true>;
protected:
polymorphic_object_result_impl (odb::connection& conn)
: result_impl (conn), begin_ (true), end_ (false), current_ ()
{
}
// To make this work with all kinds of pointers (raw, std::auto_ptr,
// shared), we need to make sure we don't make any copies of the
// pointer on the return path.
//
pointer_type&
current ()
{
if (pointer_traits::null_ptr (current_) && !end_)
load ();
return current_;
}
void
release ()
{
current_ = pointer_type ();
guard_.release ();
}
void
begin ()
{
if (begin_)
{
next ();
begin_ = false;
}
}
bool
end () const
{
return end_;
}
protected:
// The fetch argument is a hint to the implementation. If it is
// false then it means load_id() was already called (and presumably
// fetched the data into the object image) and the object image
// is still valid (so the implementation doesn't need to fetch
// the data again).
//
// The load() signature differs from the non-polymorphic cases in
// that we pass a pointer to object instead of a reference. The
// object is only passed if the user requests loading into an
// existing instance. Otherwise, we pass NULL and load() is
// responsible for creating the object of a correct dynamic
// type and managing the object cache insertion.
//
virtual void
load (object_type*, bool fetch = true) = 0;
virtual id_type
load_id () = 0;
virtual discriminator_type
load_discriminator () = 0;
virtual void
next () = 0;
virtual void
cache () = 0;
virtual std::size_t
size () = 0;
protected:
#ifdef ODB_CXX11
void
current (pointer_type& p, bool guard = true)
{
current_ = std::move (p);
if (guard)
guard_.reset (current_);
else
guard_.reset ();
}
void
current (pointer_type&& p, bool guard = true)
{
current (p, guard);
}
#else
void
current (pointer_type p, bool guard = true)
{
current_ = p;
if (guard)
guard_.reset (current_);
else
guard_.reset ();
}
#endif
bool begin_;
bool end_;
private:
void
load ();
private:
pointer_type current_;
typename pointer_traits::guard guard_;
};
template <typename T, typename ID>
class object_result_iterator<T, ID, true>
{
public:
// T can be const T while object_type is always non-const.
//
typedef typename object_traits<T>::object_type object_type;
typedef typename object_traits<T>::id_type id_type;
typedef typename object_traits<T>::root_type root_type;
typedef typename object_traits<root_type>::discriminator_type
discriminator_type;
typedef polymorphic_object_result_impl<object_type> result_impl_type;
public:
object_result_iterator (result_impl_type* res)
: res_ (res)
{
}
public:
typename object_traits<T>::pointer_type
load ()
{
typename object_traits<T>::pointer_type r (res_->current ());
res_->release ();
return r;
}
void
load (object_type&);
id_type
id ()
{
return res_->load_id ();
}
discriminator_type
discriminator ()
{
return res_->load_discriminator ();
}
protected:
result_impl_type* res_;
};
}
#include <odb/polymorphic-object-result.txx>
#include <odb/post.hxx>
#endif // ODB_POLYMORPHIC_OBJECT_RESULT_HXX
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