Ichthyostega
685a9b84ee
Benefits - get rid of yet another pervasive Boost dependency - define additional more fine grained policies (move only, clonable)
248 lines
8 KiB
C++
248 lines
8 KiB
C++
/*
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INSTANCEHANDLE.hpp - automatically handling interface lifecycle
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Copyright (C) Lumiera.org
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2008, Hermann Vosseler <Ichthyostega@web.de>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/** @file instancehandle.hpp
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** A handle template for automatically dealing with interface and plugin
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** registration and deregistration. By placing an instance of this template,
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** parametrised with the appropriate interface type, the respective interface
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** and instance is loaded and opened through the Lumiera Interface system.
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** It will be closed and unregistered automatically when the handle goes
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** out of scope. Additionally, access via an (existing) interface proxy
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** may be enabled and disabled alongside with the loading and unloading.
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**
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** @see gui::GuiFacade usage example
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** @see interface.h
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** @see interfaceproxy.hpp (more explanations)
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** @see interfaceproxy.cpp (Implementation of the proxies)
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**
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*/
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#ifndef LUMIERA_INSTANCEHANDLE_H
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#define LUMIERA_INSTANCEHANDLE_H
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#include "include/logging.h"
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#include "lib/error.hpp"
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#include "lib/nocopy.hpp"
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#include "include/interfaceproxy.hpp"
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extern "C" {
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#include "common/interface.h"
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#include "common/interfaceregistry.h"
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}
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#include <string>
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namespace lumiera {
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using std::string;
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template<class I, class FA>
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class InstanceHandle;
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namespace { // implementation details
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void
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throwIfError()
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{
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if (lumiera_error_peek())
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throw lumiera::error::Config("failed to open interface or plugin.",lumiera_error());
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}
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/** takes a (single) instance definitions, as typically created
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* when defining interfaces for external use, and registers it
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* with the InterfaceSystem. Then uses the data found in the
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* \em given instance descriptor to open an instance handle.
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* @throws error::Config when the registration process fails
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*/
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LumieraInterface
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register_and_open (LumieraInterface descriptor)
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{
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if (!descriptor) return NULL;
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lumiera_interfaceregistry_register_interface (descriptor, NULL);
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throwIfError();
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return lumiera_interface_open (descriptor->interface,
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descriptor->version,
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descriptor->size,
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descriptor->name);
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}
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/** do a lookup within the interfaceregistry
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* using the name/version found within the interface
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* handle, to ensure it is still valid and registered */
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bool
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verify_validity (LumieraInterface ifa)
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{
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REQUIRE (ifa);
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return (ifa == lumiera_interfaceregistry_interface_find (ifa->interface,
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ifa->version,
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ifa->name));
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}
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} // (End) impl details
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namespace facade {
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/**
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* @internal Helper/Adapter for establishing a link
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* between an InstanceHandle and a facade interface,
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* which is going to be implemented through the given
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* interface/plugin. This way, creating the InstanceHandle
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* automatically creates a lumiera::facade::Proxy, to route
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* any facade calls through the interface/plugin. Similarly,
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* when destroying the InstanceHandle, the proxy will be closed.
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*/
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template<class I, class FA>
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struct Link
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: util::NonCopyable
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{
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typedef InstanceHandle<I,FA> IH;
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Link (IH const& iha) { facade::openProxy(iha); }
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~Link() { facade::closeProxy<IH>(); }
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FA&
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operator() (IH const&) const
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{
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return facade::Accessor<FA>()();
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}
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};
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/**
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* @internal when the InstanceHandle isn't associated with a
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* facade interface, then this specialisation switches
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* the facade::Link into "NOP" mode.
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*/
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template<class I>
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struct Link<I,I>
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: util::NonCopyable
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{
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typedef InstanceHandle<I,I> IH;
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Link (IH const&) { /* NOP */ }
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~Link() { /* NOP */ }
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I&
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operator() (IH const& handle) const
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{
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return handle.get();
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}
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};
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} // namespace facade (impl details)
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/**
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* Handle tracking the registration of an interface, deregistering it on deletion.
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* Depending on which flavour of the ctor is used, either (bulk) registration of interfaces
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* or plugin loading is triggered. The interface type is defined by type parameter.
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* Additionally, choosing a facade interface as second type parameter causes installation
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* of a proxy, which implements the facade by routing calls through the basic interface
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* represented by this handle. This proxy will be "closed" automatically when this
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* InstanceHandle goes out of scope. Of course, the proxy needs to be implemented
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* somewhere, typically in interfaceproxy.cpp
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*/
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template< class I ///< fully mangled name of the interface type
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, class FA = I ///< facade interface type to be used by clients
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>
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class InstanceHandle
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: util::NonCopyable
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{
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LumieraInterface desc_;
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I* instance_;
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facade::Link<I,FA> facadeLink_;
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public:
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/** Set up an InstanceHandle representing a plugin.
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* Should be placed at the client side.
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* @param iName unmangled name of the interface
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* @param version major version
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* @param minminor minimum acceptable minor version number
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* @param impName unmangled name of the instance (implementation)
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*/
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InstanceHandle (string const& iName, uint version, size_t minminor, string const& impName)
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: desc_(0)
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, instance_(reinterpret_cast<I*>
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(lumiera_interface_open (iName.c_str(), version, minminor, impName.c_str())))
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, facadeLink_(*this)
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{
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throwIfError();
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}
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/** Set up an InstanceHandle managing the
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* registration and deregistration of interface(s).
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* Should be placed at the service providing side.
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* @param a (single) interface descriptor, which can be created with
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* LUMIERA_INTERFACE_INSTANCE and referred to by LUMIERA_INTERFACE_REF
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*/
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InstanceHandle (LumieraInterface descriptor)
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: desc_(descriptor)
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, instance_(reinterpret_cast<I*> (register_and_open (desc_)))
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, facadeLink_(*this)
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{
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throwIfError();
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}
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~InstanceHandle ()
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{
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lumiera_interface_close (&instance_->interface_header_);
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if (desc_)
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lumiera_interfaceregistry_remove_interface (desc_);
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}
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/** act as smart pointer providing access through the facade.
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* @note we don't provide operator* */
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FA * operator-> () const { return &(facadeLink_(*this)); }
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/** directly access the instance via the CL interface */
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I& get () const { ENSURE(instance_); return *instance_; }
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explicit operator bool() const { return isValid(); }
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bool operator! () const { return not isValid();}
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private:
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bool
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isValid() const
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{
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return instance_
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&& verify_validity (&instance_->interface_header_);
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}
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};
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} // namespace lumiera
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#endif
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