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#ifndef QPID_PLUGIN_H
#define QPID_PLUGIN_H
/*
*
* Copyright (c) 2006 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#include "qpid/shared_ptr.h"
#include <boost/noncopyable.hpp>
#include <vector>
#include <boost/function.hpp>
/**@file Generic plug-in framework. */
namespace qpid {
class Options;
/** Generic base class to allow dynamic casting of generic Plugin objects
* to concrete types.
*/
struct Plugin : private boost::noncopyable {
virtual ~Plugin() {}
};
/** Generic interface for anything that uses plug-ins. */
struct PluginUser : boost::noncopyable {
virtual ~PluginUser() {}
/**
* Called by a PluginProvider to provide a plugin.
*
* A concrete PluginUser will dynamic_pointer_cast plugin to a
* class it knows how to use. A PluginUser should ignore plugins
* it does not recognize.
*
* The user will release its shared_ptr when it is finished using
* plugin.
*/
virtual void use(const shared_ptr<Plugin>& plugin) = 0;
};
/**
* Base for classes that provide plug-ins.
*/
class PluginProvider : boost::noncopyable
{
public:
/**
* Register the provider to appear in getProviders()
*
* A concrete PluginProvider is instantiated as a global or static
* member variable in a library so it is registered during static
* initialization when the library is loaded.
*/
PluginProvider();
virtual ~PluginProvider();
/**
* Returns configuration options for the plugin.
* Then will be updated during option parsing by the host program.
*
* @return An options group or 0 for no options. Default returns 0.
* PluginProvider retains ownership of return value.
*/
virtual Options* getOptions();
/** Provide plugins to a PluginUser.
*
* The provider can dynamic_cast the user if it only provides
* plugins to certain types of user. Providers should ignore
* users they don't recognize.
*/
virtual void provide(PluginUser& user) = 0;
/** Get the list of pointers to the registered providers.
* Caller must not delete the pointers.
*/
static const std::vector<PluginProvider*>& getProviders();
private:
static std::vector<PluginProvider*> providers;
};
/** Load a shared library, registering any PluginProvider it contains.
*
* This is just a convenient portable wrapper for normal shared
* library loading. A global PluginProvider instance loaded or
* linked in any way will get registered.
*/
void dlopen(const char* libname);
} // namespace qpid
#endif /*!QPID_PLUGIN_H*/
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