pfactory.h

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/*
 * factory.h
 *
 * Abstract Factory Classes
 *
 * Portable Windows Library
 *
 * Copyright (C) 2004 Post Increment
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.0 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 *
 * The Original Code is Portable Windows Library.
 *
 * The Initial Developer of the Original Code is Post Increment
 *
 * Contributor(s): ______________________________________.
 *
 * $Revision: 19008 $
 * $Author: rjongbloed $
 * $Date: 2007-11-29 09:17:41 +0000 (Thu, 29 Nov 2007) $
 */

#ifndef _PFACTORY_H
#define _PFACTORY_H

#ifdef P_USE_PRAGMA
#pragma interface
#endif

#ifndef _PTLIB_H
#include <ptlib.h>
#endif

#include <string>
#include <map>
#include <vector>

#if defined(_MSC_VER)
#pragma warning(disable:4786)
#endif

// this define the default class to be used for keys into PFactories
//typedef PString PDefaultPFactoryKey;
typedef std::string PDefaultPFactoryKey;


class PFactoryBase
{
  protected:
    PFactoryBase()
    { }
  public:
    virtual ~PFactoryBase()
    { }

    class FactoryMap : public std::map<std::string, PFactoryBase *>
    {
      public:
        FactoryMap() { }
        ~FactoryMap();
    };

    static FactoryMap & GetFactories();
    static PMutex & GetFactoriesMutex();

    PMutex mutex;

  private:
    PFactoryBase(const PFactoryBase &) {}
    void operator=(const PFactoryBase &) {}
};


template <class _Abstract_T, typename _Key_T = PDefaultPFactoryKey>
class PFactory : PFactoryBase
{
  public:
    typedef _Key_T      Key_T;
    typedef _Abstract_T Abstract_T;

    class WorkerBase
    {
      protected:
        WorkerBase(bool singleton = false)
          : isDynamic(false),
            isSingleton(singleton),
            singletonInstance(NULL),
            deleteSingleton(false)
        { }
        WorkerBase(Abstract_T * instance)
          : isDynamic(true),
            isSingleton(true),
            singletonInstance(instance),
            deleteSingleton(true)
        { }

        virtual ~WorkerBase()
        {
          if (deleteSingleton)
            delete singletonInstance;
        }

        Abstract_T * CreateInstance(const Key_T & key)
        {
          if (!isSingleton)
            return Create(key);

          if (singletonInstance == NULL)
            singletonInstance = Create(key);
          return singletonInstance;
        }

        virtual Abstract_T * Create(const Key_T & /*key*/) const { return singletonInstance; }

        bool         isDynamic;
        bool         isSingleton;
        Abstract_T * singletonInstance;
        bool         deleteSingleton;

      friend class PFactory<_Abstract_T, _Key_T>;
    };

    template <class _Concrete_T>
    class Worker : WorkerBase
    {
      public:
        Worker(const Key_T & key, bool singleton = false)
          : WorkerBase(singleton)
        {
          PMEMORY_IGNORE_ALLOCATIONS_FOR_SCOPE;
          PFactory<_Abstract_T, _Key_T>::Register(key, this);   // here
        }

      protected:
        virtual Abstract_T * Create(const Key_T & /*key*/) const
        {
#if PMEMORY_HEAP
          // Singletons are never deallocated, so make sure they arenot reported as a leak
          PBoolean previousIgnoreAllocations = PMemoryHeap::SetIgnoreAllocations(isSingleton);
#endif
          Abstract_T * instance = new _Concrete_T;
#if PMEMORY_HEAP
          PMemoryHeap::SetIgnoreAllocations(previousIgnoreAllocations);
#endif
          return instance;
        }
    };

    typedef std::map<_Key_T, WorkerBase *> KeyMap_T;
    typedef std::vector<_Key_T> KeyList_T;

    static void Register(const _Key_T & key, WorkerBase * worker)
    {
      GetInstance().Register_Internal(key, worker);
    }

    static void Register(const _Key_T & key, Abstract_T * instance)
    {
      GetInstance().Register_Internal(key, PNEW WorkerBase(instance));
    }

    static PBoolean RegisterAs(const _Key_T & newKey, const _Key_T & oldKey)
    {
      return GetInstance().RegisterAs_Internal(newKey, oldKey);
    }

    static void Unregister(const _Key_T & key)
    {
      GetInstance().Unregister_Internal(key);
    }

    static void UnregisterAll()
    {
      GetInstance().UnregisterAll_Internal();
    }

    static bool IsRegistered(const _Key_T & key)
    {
      return GetInstance().IsRegistered_Internal(key);
    }

    static _Abstract_T * CreateInstance(const _Key_T & key)
    {
      return GetInstance().CreateInstance_Internal(key);
    }

    static PBoolean IsSingleton(const _Key_T & key)
    {
      return GetInstance().IsSingleton_Internal(key);
    }

    static KeyList_T GetKeyList()
    { 
      return GetInstance().GetKeyList_Internal();
    }

    static KeyMap_T & GetKeyMap()
    { 
      return GetInstance().keyMap;
    }

    static PMutex & GetMutex()
    {
      return GetInstance().mutex;
    }

  protected:
    PFactory()
    { }

    ~PFactory()
    {
      typename KeyMap_T::const_iterator entry;
      for (entry = keyMap.begin(); entry != keyMap.end(); ++entry) {
        if (entry->second->isDynamic)
          delete entry->second;
      }
    }

    static PFactory & GetInstance()
    {
      std::string className = typeid(PFactory).name();
      PWaitAndSignal m(GetFactoriesMutex());
      FactoryMap & factories = GetFactories();
      FactoryMap::const_iterator entry = factories.find(className);
      if (entry != factories.end()) {
        PAssert(entry->second != NULL, "Factory map returned NULL for existing key");
        PFactoryBase * b = entry->second;
        // don't use the following dynamic cast, because gcc does not like it
        //PFactory * f = dynamic_cast<PFactory*>(b);
        return *(PFactory *)b;
      }

      PMEMORY_IGNORE_ALLOCATIONS_FOR_SCOPE;
      PFactory * factory = new PFactory;
      factories[className] = factory;
      return *factory;
    }


    void Register_Internal(const _Key_T & key, WorkerBase * worker)
    {
      PWaitAndSignal m(mutex);
      if (keyMap.find(key) == keyMap.end())
        keyMap[key] = worker;
    }

    PBoolean RegisterAs_Internal(const _Key_T & newKey, const _Key_T & oldKey)
    {
      PWaitAndSignal m(mutex);
      if (keyMap.find(oldKey) == keyMap.end())
        return PFalse;
      keyMap[newKey] = keyMap[oldKey];
      return PTrue;
    }

    void Unregister_Internal(const _Key_T & key)
    {
      PWaitAndSignal m(mutex);
      keyMap.erase(key);
    }

    void UnregisterAll_Internal()
    {
      PWaitAndSignal m(mutex);
      keyMap.erase(keyMap.begin(), keyMap.end());
    }

    bool IsRegistered_Internal(const _Key_T & key)
    {
      PWaitAndSignal m(mutex);
      return keyMap.find(key) != keyMap.end();
    }

    _Abstract_T * CreateInstance_Internal(const _Key_T & key)
    {
      PWaitAndSignal m(mutex);
      typename KeyMap_T::const_iterator entry = keyMap.find(key);
      if (entry != keyMap.end())
        return entry->second->CreateInstance(key);
      return NULL;
    }

    bool IsSingleton_Internal(const _Key_T & key)
    {
      PWaitAndSignal m(mutex);
      if (keyMap.find(key) == keyMap.end())
        return false;
      return keyMap[key]->isSingleton;
    }

    KeyList_T GetKeyList_Internal()
    { 
      PWaitAndSignal m(mutex);
      KeyList_T list;
      typename KeyMap_T::const_iterator entry;
      for (entry = keyMap.begin(); entry != keyMap.end(); ++entry)
        list.push_back(entry->first);
      return list;
    }

    KeyMap_T keyMap;

  private:
    PFactory(const PFactory &) {}
    void operator=(const PFactory &) {}
};

//
//  this macro is used to initialise the static member variable used to force factories to instantiate
//
#define PLOAD_FACTORY(AbstractType, KeyType) \
  namespace PWLibFactoryLoader { \
    extern int AbstractType##_##KeyType##_loader; \
    static int AbstractType##_##KeyType##_loader_instance = AbstractType##_##KeyType##_loader; \
  };


//
//  this macro is used to instantiate a static variable that accesses the static member variable 
//  in a factory forcing it to load
//
#define PINSTANTIATE_FACTORY(AbstractType, KeyType) \
  namespace PWLibFactoryLoader { int AbstractType##_##KeyType##_loader; }


#endif // _PFACTORY_H

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