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#ifndef QPID_PLUGIN_H
#define QPID_PLUGIN_H
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 <boost/noncopyable.hpp>
#include <boost/function.hpp>
#include <vector>
#include "qpid/CommonImportExport.h"
/**@file Generic plug-in framework. */
namespace qpid {
struct Options;
/**
* Plug-in base class.
*/
class Plugin : private boost::noncopyable {
public:
typedef std::vector<Plugin*> Plugins;
/** Default value returned by initOrder() */
static const int DEFAULT_INIT_ORDER=1000;
/**
* Base interface for targets that can receive plug-ins.
* Also allows plug-ins to attach a a function to be called
* when the target is 'finalized'.
*/
class Target : private boost::noncopyable
{
public:
/** Calls finalize() if not already called. */
QPID_COMMON_EXTERN virtual ~Target();
/** Run all the finalizers */
QPID_COMMON_EXTERN void finalize();
/** Add a function to run when finalize() is called */
QPID_COMMON_EXTERN void addFinalizer(const boost::function<void()>&);
private:
std::vector<boost::function<void()> > finalizers;
};
/**
* Constructor registers the plug-in to appear in getPlugins().
*
* A concrete Plugin is instantiated as a global or static
* member variable in a library so it is registered during
* initialization when the library is loaded.
*/
QPID_COMMON_EXTERN Plugin();
QPID_COMMON_EXTERN virtual ~Plugin();
/**
* 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.
* Plugin retains ownership of return value.
*/
QPID_COMMON_EXTERN virtual Options* getOptions();
/**
* Initialize Plugin functionality on a Target, called before
* initializing the target.
*
* Plugins should ignore targets they don't recognize.
*
* Called before the target itself is initialized.
*/
virtual void earlyInitialize(Target&) = 0;
/**
* Initialize Plugin functionality on a Target. Called after
* initializing the target.
*
* Plugins should ignore targets they don't recognize.
*
* Called after the target is fully initialized.
*/
virtual void initialize(Target&) = 0;
/**
* Initialization order. If a plugin does not override this, it
* returns DEFAULT_INIT_ORDER. Plugins that need to be initialized
* earlier/later than normal can override initOrder to return
* a lower/higher value than DEFAULT_INIT_ORDER.
*/
QPID_COMMON_EXTERN virtual int initOrder() const;
/** List of registered Plugin objects.
* Caller must not delete plugin pointers.
*/
QPID_COMMON_EXTERN static const Plugins& getPlugins();
/** Call earlyInitialize() on all registered plugins */
QPID_COMMON_EXTERN static void earlyInitAll(Target&);
/** Call initialize() on all registered plugins */
QPID_COMMON_EXTERN static void initializeAll(Target&);
/** For each registered plugin, add plugin.getOptions() to opts. */
QPID_COMMON_EXTERN static void addOptions(Options& opts);
};
} // namespace qpid
#endif /*!QPID_PLUGIN_H*/
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