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// file : odb/cache-traits.hxx
// copyright : Copyright (c) 2009-2012 Code Synthesis Tools CC
// license : GNU GPL v2; see accompanying LICENSE file
#ifndef ODB_CACHE_TRAITS_HXX
#define ODB_CACHE_TRAITS_HXX
#include <odb/pre.hxx>
#include <odb/traits.hxx>
#include <odb/forward.hxx>
#include <odb/session.hxx>
#include <odb/pointer-traits.hxx>
#include <odb/no-op-cache-traits.hxx>
namespace odb
{
// pointer_cache_traits
//
// Caching traits for objects passed by pointer. P should be the canonical
// pointer (non-const).
//
template <typename P, typename S, pointer_kind pk>
struct pointer_cache_traits_impl
{
typedef P pointer_type;
typedef S session_type;
typedef odb::pointer_traits<pointer_type> pointer_traits;
typedef typename pointer_traits::element_type object_type;
typedef typename object_traits<object_type>::id_type id_type;
struct position_type
{
typedef typename session_type::template position<object_type> base_type;
position_type (): empty_ (true) {}
position_type (const base_type& pos): empty_ (false), pos_ (pos) {}
bool empty_;
base_type pos_;
};
struct insert_guard
{
insert_guard () {}
insert_guard (const position_type& pos): pos_ (pos) {}
~insert_guard () {erase (pos_);}
const position_type&
position () const {return pos_;}
void
release () {pos_.empty_ = true;}
// Note: doesn't call erase() on the old position (assumes empty).
//
void
reset (const position_type& pos) {pos_ = pos;}
private:
position_type pos_;
};
// We need the insert() overload with explicit id to handle self-
// references. In such cases the object is not yet loaded and the
// id member does not contain the correct id.
//
// Qualify the database type to resolve a phony ambiguity in VC 10.
//
static position_type
insert (odb::database& db, const id_type& id, const pointer_type& p)
{
if (session_type::has_current ())
return session_type::current ().template insert<object_type> (
db, id, p);
else
return position_type ();
}
static position_type
insert (odb::database& db, const pointer_type& p)
{
const id_type& id (
object_traits<object_type>::id (
pointer_traits::get_ref (p)));
return insert (db, id, p);
}
static pointer_type
find (odb::database& db, const id_type& id)
{
if (session_type::has_current ())
return session_type::current ().template find<object_type> (db, id);
else
return pointer_type ();
}
static void
erase (odb::database& db, const id_type& id)
{
if (session_type::has_current ())
session_type::current ().template erase<object_type> (db, id);
}
static void
erase (const position_type& p)
{
if (!p.empty_)
session_type::current ().template erase<object_type> (p.pos_);
}
};
// Unique pointers don't work with the object cache.
//
template <typename P, typename S>
struct pointer_cache_traits_impl<P, S, pk_unique>:
no_op_pointer_cache_traits<P> {};
template <typename P, typename S>
struct pointer_cache_traits:
pointer_cache_traits_impl<P, S, pointer_traits<P>::kind> {};
// reference_cache_traits
//
// Caching traits for objects passed by reference. T should be the
// canonical object type (non-const). Only if the object pointer
// kind is raw do we add the object to the session.
//
template <typename T, typename S, pointer_kind pk>
struct reference_cache_traits_impl: no_op_reference_cache_traits<T> {};
template <typename T, typename S>
struct reference_cache_traits_impl<T, S, pk_raw>
{
typedef T object_type;
typedef typename object_traits<object_type>::pointer_type pointer_type;
typedef typename object_traits<object_type>::id_type id_type;
typedef pointer_cache_traits<pointer_type, S> pointer_traits;
typedef typename pointer_traits::position_type position_type;
typedef typename pointer_traits::insert_guard insert_guard;
static position_type
insert (odb::database& db, const id_type& id, object_type& obj)
{
pointer_type p (&obj);
return pointer_traits::insert (db, id, p);
}
static position_type
insert (odb::database& db, object_type& obj)
{
pointer_type p (&obj);
return pointer_traits::insert (db, p);
}
};
template <typename T, typename S>
struct reference_cache_traits:
reference_cache_traits_impl<
T, S, pointer_traits<typename object_traits<T>::pointer_type>::kind> {};
}
#include <odb/post.hxx>
#endif // ODB_CACHE_TRAITS_HXX
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