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/* /////////////////////////////////////////////////////////////////////////
* File: comstl/util/acyclic_connector.hpp
*
* Purpose: A component for relating two COM objects without cycles.
*
* Created: 25th March 2006
* Updated: 10th August 2009
*
* Home: http://stlsoft.org/
*
* Copyright (c) 2006-2009, Matthew Wilson and Synesis Software
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name(s) of Matthew Wilson and Synesis Software nor the names of
* any contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* ////////////////////////////////////////////////////////////////////// */
/** \file comstl/util/acyclic_connector.hpp
*
* \brief [C++ only; requires COM] Definition of the
* comstl::acyclic_connector class template
* (\ref group__library__utility__com "COM Utility" Library).
*/
#ifndef COMSTL_INCL_COMSTL_UTIL_HPP_ACYCLIC_CONNECTOR
#define COMSTL_INCL_COMSTL_UTIL_HPP_ACYCLIC_CONNECTOR
#ifndef STLSOFT_DOCUMENTATION_SKIP_SECTION
# define COMSTL_VER_COMSTL_UTIL_HPP_ACYCLIC_CONNECTOR_MAJOR 1
# define COMSTL_VER_COMSTL_UTIL_HPP_ACYCLIC_CONNECTOR_MINOR 2
# define COMSTL_VER_COMSTL_UTIL_HPP_ACYCLIC_CONNECTOR_REVISION 7
# define COMSTL_VER_COMSTL_UTIL_HPP_ACYCLIC_CONNECTOR_EDIT 21
#endif /* !STLSOFT_DOCUMENTATION_SKIP_SECTION */
/* /////////////////////////////////////////////////////////////////////////
* Includes
*/
#ifndef COMSTL_INCL_COMSTL_H_COMSTL
# include <comstl/comstl.h>
#endif /* !COMSTL_INCL_COMSTL_H_COMSTL */
#ifndef COMSTL_INCL_COMSTL_UTIL_HPP_OBJECT_FUNCTIONS
# include <comstl/util/object_functions.h>
#endif /* !COMSTL_INCL_COMSTL_UTIL_HPP_OBJECT_FUNCTIONS */
#ifndef STLSOFT_INCL_STLSOFT_SYNCH_HPP_LOCK_SCOPE
# include <stlsoft/synch/lock_scope.hpp>
#endif /* !STLSOFT_INCL_STLSOFT_SYNCH_HPP_LOCK_SCOPE */
/* /////////////////////////////////////////////////////////////////////////
* Namespace
*/
#ifndef _COMSTL_NO_NAMESPACE
# if defined(_STLSOFT_NO_NAMESPACE) || \
defined(STLSOFT_DOCUMENTATION_SKIP_SECTION)
/* There is no stlsoft namespace, so must define ::comstl */
namespace comstl
{
# else
/* Define stlsoft::comstl_project */
namespace stlsoft
{
namespace comstl_project
{
# endif /* _STLSOFT_NO_NAMESPACE */
#endif /* !_COMSTL_NO_NAMESPACE */
/* /////////////////////////////////////////////////////////////////////////
* Classes
*/
/** \brief Interface for acyclic communication.
*/
#ifdef STLSOFT_DOCUMENTATION_SKIP_SECTION
struct IAcyclicSide
: public IUnknown
#else /* ? STLSOFT_DOCUMENTATION_SKIP_SECTION */
DECLARE_INTERFACE_(IAcyclicSide, IUnknown)
#endif /* STLSOFT_DOCUMENTATION_SKIP_SECTION */
{
/** \brief Causes knowledge of the presence of the peer to be discarded
*/
STDMETHOD_(void, Clear)() PURE;
/** \brief Queries for the given interface on the peer.
*
* \param riid The interface identifier of the requested interface.
* \param ppv Address of the interface pointer.
*
* \return A standard HRESULT status code indicating success/failure.
*/
STDMETHOD(QueryPeer)(THIS_ REFIID riid, void **ppv) PURE;
/** \brief returns the IID for the IAcyclicSide interface. */
static REFIID iid()
{
static IID s_iid = { 0x8D5D0B0A, 0x4429, 0x4be1, { 0x8C, 0x00, 0xDE, 0xE0, 0xA8, 0xFF, 0xD0, 0xAF } };
return s_iid;
}
};
/** \brief A component that allows two objects to be connected without
* creating cyclic dependencies.
*
* Reference counting architectures, such as COM, rely on there being no
* dependency cycles. A cyclic dependency is the situation where, say,
* object <b>a</b> holds a reference to object <b>b</b>, and object
* <b>b</b> holds a reference to object <b>a</b>. Since neither will
* release the references it holds (held on its efferent dependents)
* until all references to itself (held by its afferent dependents) the
* circle will never be broken.
*
* COM lore thus proscribes the use of mutual references, or prescribes
* rigid protocols (e.g. Connection Points) for their management.
*
* acyclic_connector is designed to help in the case where two objects
* need to have knowledge of each other, but not hold references on each
* other. It works by acting as an intermediary that each of two objects
* in the relationship keep informed as to their existance.
*
* \param MX The type of the mutex that will be used to provide exclusive
* access to the instance state during the Clear() and QueryPeer() methods.
*/
template <ss_typename_param_k MX>
class acyclic_connector
{
/// \name Member Types
/// @{
public:
typedef MX mutex_type;
private:
typedef acyclic_connector<MX> connector_type;
public:
typedef acyclic_connector<MX> class_type;
private:
class side
: public IAcyclicSide
{
/// \name Member Types
/// @{
public:
typedef side class_type;
/// @}
/// \name Construction
/// @{
public:
ss_explicit_k side(connector_type &connector, LPUNKNOWN peer, IAcyclicSide **side)
: m_connector(connector)
, m_peer(peer)
, m_refCount(1)
{
COMSTL_ASSERT(NULL != side);
*side = this;
}
/// @}
/// \name IUnknown
/// @{
public:
STDMETHOD_(ULONG, AddRef)()
{
return ++m_refCount;
}
STDMETHOD_(ULONG, Release)()
{
class_type &other = (this == &m_connector.m_left) ? m_connector.m_right : m_connector.m_left;
if(0 == --m_refCount)
{
m_peer = NULL;
if(0 == other.m_refCount)
{
delete &m_connector;
return 0;
}
}
return m_refCount;
}
STDMETHOD(QueryInterface)(REFIID riid, void **ppv)
{
if( IID_IUnknown == riid ||
IAcyclicSide::iid() == riid)
{
*ppv = static_cast<LPUNKNOWN>(this);
static_cast<LPUNKNOWN>(*ppv)->AddRef();
return S_OK;
}
return E_NOINTERFACE;
}
/// @}
/// \name IAcyclicSide
/// @{
public:
STDMETHOD_(void, Clear)()
{
stlsoft::lock_scope<mutex_type> lock(m_connector.m_mx);
m_peer = NULL;
}
STDMETHOD(QueryPeer)(THIS_ REFIID riid, void **ppv)
{
COMSTL_ASSERT(NULL != ppv);
stlsoft::lock_scope<mutex_type> lock(m_connector.m_mx);
class_type &other = (this == &m_connector.m_left) ? m_connector.m_right : m_connector.m_left;
if(NULL == other.m_peer)
{
return E_POINTER;
}
else
{
return other.m_peer->QueryInterface(riid, ppv);
}
}
/// @}
/// \name Members
/// @{
private:
connector_type &m_connector;
LPUNKNOWN m_peer;
LONG m_refCount;
/// @}
};
friend class side;
/// @}
/// \name Construction
/// @{
public:
acyclic_connector( LPUNKNOWN leftPeer
, IAcyclicSide **leftSide
, LPUNKNOWN rightPeer
, IAcyclicSide **rightSide);
private:
~acyclic_connector() stlsoft_throw_0();
/// @}
/// \name Implementation
/// @{
private:
class_type& get_this_();
/// @}
/// \name Construction
/// @{
private:
side m_left;
side m_right;
mutex_type m_mx;
/// @}
/// \name Not to be implemented
/// @{
private:
acyclic_connector(class_type const& rhs);
class_type& operator =(class_type const& rhs);
/// @}
};
/* /////////////////////////////////////////////////////////////////////////
* Implementation
*/
#ifndef STLSOFT_DOCUMENTATION_SKIP_SECTION
// acyclic_connector::side
#if 0
template <ss_typename_param_k MX>
inline acyclic_connector<MX>::side::side(connector_type &connector, LPUNKNOWN peer, IAcyclicSide **side)
: m_connector(connector)
, m_peer(peer)
, m_refCount(1)
{
COMSTL_ASSERT(NULL != side);
*side = this;
}
template <ss_typename_param_k MX>
inline STDMETHODIMP_(ULONG) acyclic_connector<MX>::side::AddRef()
{
return ++m_refCount;
}
template <ss_typename_param_k MX>
inline STDMETHODIMP_(ULONG) acyclic_connector<MX>::side::Release()
{
class_type &other = (this == &m_connector.m_left) ? m_connector.m_right : m_connector.m_left;
if( 0 == --m_refCount &&
0 == other.m_refCount)
{
delete &m_connector;
return 0;
}
return m_refCount;
}
template <ss_typename_param_k MX>
inline STDMETHODIMP acyclic_connector<MX>::side::QueryInterface(REFIID riid, void **ppv)
{
if( IID_IUnknown == riid ||
IAcyclicSide::iid() == riid)
{
*ppv = static_cast<LPUNKNOWN>(this);
static_cast<LPUNKNOWN>(*ppv)->AddRef();
return S_OK;
}
return E_INTERFACE;
}
#endif /* 0 */
#if 0
template <ss_typename_param_k MX>
inline STDMETHODIMP_(void) acyclic_connector<MX>::side::Clear()
{
stlsoft::lock_scope<mutex_type> lock(m_mx);
m_peer = NULL;
}
template <ss_typename_param_k MX>
inline STDMETHODIMP acyclic_connector<MX>::side::QueryPeer(THIS_ REFIID riid, void **ppv)
{
COMSTL_ASSERT(NULL != ppv);
stlsoft::lock_scope<mutex_type> lock(m_mx);
if(NULL == m_peer)
{
return E_POINTER;
}
else
{
return m_peer->QueryInterface(riid, ppv);
}
}
#endif /* 0 */
// acyclic_connector
template <ss_typename_param_k MX>
inline acyclic_connector<MX>::acyclic_connector(LPUNKNOWN leftPeer
, IAcyclicSide **leftSide
, LPUNKNOWN rightPeer
, IAcyclicSide **rightSide)
: m_left(get_this_(), leftPeer, leftSide)
, m_right(get_this_(), rightPeer, rightSide)
, m_mx()
{
COMSTL_MESSAGE_ASSERT("Acyclic connector cannot be initialised with null pointers", NULL != leftPeer);
COMSTL_MESSAGE_ASSERT("Acyclic connector cannot be initialised with null pointers", NULL != rightPeer);
COMSTL_MESSAGE_ASSERT("Acyclic connector cannot be initialised with null pointers", NULL != leftSide);
COMSTL_MESSAGE_ASSERT("Acyclic connector cannot be initialised with null pointers", NULL != rightSide);
#if 0
HRESULT hr;
hr = get_object_identity(left, &m_left);
if(FAILED(hr))
{
#ifdef STLSOFT_CF_EXCEPTION_SUPPORT
STLSOFT_THROW_X(com_exception("Could not acquire left-side identity", hr));
#endif /* STLSOFT_CF_EXCEPTION_SUPPORT */
}
else
{
hr = get_object_identity(right, &m_right);
if(FAILED(hr))
{
m_left->Release();
#ifdef STLSOFT_CF_EXCEPTION_SUPPORT
STLSOFT_THROW_X(com_exception("Could not acquire right-side identity", hr));
#else /* ? STLSOFT_CF_EXCEPTION_SUPPORT */
m_left = NULL;
#endif /* STLSOFT_CF_EXCEPTION_SUPPORT */
}
}
#endif /* 0 */
}
template <ss_typename_param_k MX>
inline acyclic_connector<MX>::~acyclic_connector() stlsoft_throw_0()
{}
template <ss_typename_param_k MX>
inline ss_typename_type_ret_k acyclic_connector<MX>::class_type& acyclic_connector<MX>::get_this_()
{
return *this;
}
#endif /* !STLSOFT_DOCUMENTATION_SKIP_SECTION */
/* ////////////////////////////////////////////////////////////////////// */
#ifndef _COMSTL_NO_NAMESPACE
# if defined(_STLSOFT_NO_NAMESPACE) || \
defined(STLSOFT_DOCUMENTATION_SKIP_SECTION)
} // namespace comstl
# else
} // namespace comstl_project
} // namespace stlsoft
# endif /* _STLSOFT_NO_NAMESPACE */
#endif /* !_COMSTL_NO_NAMESPACE */
/* ////////////////////////////////////////////////////////////////////// */
#endif /* !COMSTL_INCL_COMSTL_UTIL_HPP_ACYCLIC_CONNECTOR */
/* ///////////////////////////// end of file //////////////////////////// */