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): ______________________________________.
 */

#ifndef PTLIB_FACTORY_H
#define PTLIB_FACTORY_H

#ifdef P_USE_PRAGMA
#pragma interface
#endif

#include <ptlib.h>

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

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

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

    virtual void DestroySingletons() = 0;

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

    static FactoryMap & GetFactories();

  protected:
    static PFactoryBase & InternalGetFactory(const std::string & className, PFactoryBase * (*createFactory)());

    template <class TheFactory> static PFactoryBase * CreateFactory() { return new TheFactory; }

    template <class TheFactory> static TheFactory & GetFactoryAs()
    {
      return dynamic_cast<TheFactory&>(InternalGetFactory(typeid(TheFactory).name(), CreateFactory<TheFactory>));
    }

  protected:
    PDECLARE_MUTEX(m_mutex, "PFactoryBase");

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


template <class AbstractClass, typename ParamType, typename KeyType>
class PFactoryTemplate : public PFactoryBase
{
  public:
    class WorkerBase;

    typedef AbstractClass                  Abstract_T;
    typedef ParamType                      Param_T;
    typedef KeyType                        Key_T;
    typedef std::vector<Key_T>             KeyList_T;

    struct WorkerWrap
    {
      WorkerWrap(WorkerBase * worker, bool autoDelete) : m_worker(worker), m_autoDelete(autoDelete) { }
      WorkerBase * m_worker;
      bool         m_autoDelete;
    };
    typedef std::map<Key_T, WorkerWrap>    WorkerMap_T;
    typedef typename WorkerMap_T::iterator WorkerIter_T;

    class WorkerBase
    {
      public:
        enum Types {
          NonSingleton,
          StaticSingleton,
          DynamicSingleton
        };

        WorkerBase(bool singleton = false)
          : m_type(singleton ? DynamicSingleton : NonSingleton)
          , m_singletonInstance(NULL)
        {
        }

        WorkerBase(Abstract_T * instance, bool delSingleton = true)
          : m_type(delSingleton ? DynamicSingleton : StaticSingleton)
          , m_singletonInstance(instance)
        {
        }

        virtual ~WorkerBase()
        {
          DestroySingleton();
        }

        Abstract_T * CreateInstance(Param_T param)
        {
          if (m_type == NonSingleton)
            return Create(param);

          if (m_singletonInstance == NULL)
            m_singletonInstance = Create(param);
          return m_singletonInstance;
        }

        virtual void DestroySingleton()
        {
          if (m_type == DynamicSingleton) {
            delete m_singletonInstance;
            m_singletonInstance = NULL;
          }
        }

        bool IsSingleton() const { return m_type != NonSingleton; }

      protected:
        virtual Abstract_T * Create(Param_T /*param*/) const
        {
          PAssert(this->m_type == StaticSingleton, "Incorrect factory worker descendant");
          return this->m_singletonInstance;
        }

        Types        m_type;
        Abstract_T * m_singletonInstance;

      private:
        WorkerBase(const WorkerBase &) { }
        void operator=(const WorkerBase &) { }

      friend class PFactoryTemplate;
    };

    virtual void DestroySingletons()
    {
      for (WorkerIter_T it = m_workers.begin(); it != m_workers.end(); ++it)
        it->second.m_worker->DestroySingleton();
    }

  protected:
    PFactoryTemplate()
    { }

    ~PFactoryTemplate()
    {
      DestroySingletons();
      InternalUnregisterAll();
    }

    bool InternalRegister(const Key_T & key, WorkerBase * worker, bool autoDeleteWorker)
    {
      PWaitAndSignal mutex(m_mutex);
      typename WorkerMap_T::iterator it = m_workers.find(key);
      if (it != m_workers.end()) {
        return it->second.m_worker == worker;
      }

      PMEMORY_IGNORE_ALLOCATIONS_FOR_SCOPE;
      m_workers.insert(make_pair(key, WorkerWrap(PAssertNULL(worker), autoDeleteWorker)));
      return true;
    }

    bool InternalRegister(const Key_T & key, Abstract_T * instance, bool autoDeleteInstance)
    {
      PWaitAndSignal mutex(m_mutex);
      typename WorkerMap_T::iterator it = m_workers.find(key);
      if (it != m_workers.end())
        return it->second.m_worker->m_singletonInstance == instance;

      PMEMORY_IGNORE_ALLOCATIONS_FOR_SCOPE;
      m_workers.insert(make_pair(key, WorkerWrap(PNEW WorkerBase(instance, autoDeleteInstance), true)));
      return true;
    }

    PBoolean InternalRegisterAs(const Key_T & newKey, const Key_T & oldKey)
    {
      PWaitAndSignal mutex(m_mutex);
      typename WorkerMap_T::iterator itOld = m_workers.find(oldKey);
      if (itOld == m_workers.end())
        return false;

      typename WorkerMap_T::iterator itNew = m_workers.find(newKey);
      if (itNew != m_workers.end())
        return itNew->second.m_worker == itOld->second.m_worker;

      m_workers.insert(make_pair(newKey, WorkerWrap(itOld->second.m_worker, false)));
      return true;
    }

    void InternalUnregister(const Key_T & key)
    {
      m_mutex.Wait();
      typename WorkerMap_T::iterator it = m_workers.find(key);
      if (it != m_workers.end()) {
        if (it->second.m_autoDelete)
          delete it->second.m_worker;
        m_workers.erase(it);
      }
      m_mutex.Signal();
    }

    void InternalUnregister(WorkerBase * instance)
    {
      m_mutex.Wait();
      for (WorkerIter_T it = m_workers.begin(); it != m_workers.end(); ++it) {
        if (it->second == instance) {
          InternalUnregister(it->first);
          break;
        }
      }
      m_mutex.Signal();
    }

    void InternalUnregisterAll()
    {
      m_mutex.Wait();
      for (typename WorkerMap_T::iterator it = m_workers.begin(); it != m_workers.end(); ++it) {
        if (it->second.m_autoDelete)
          delete it->second.m_worker;
      }
      m_workers.clear();
      m_mutex.Signal();
    }

    bool InternalIsRegistered(const Key_T & key)
    {
      PWaitAndSignal mutex(m_mutex);
      return m_workers.find(key) != m_workers.end();
    }

    Abstract_T * InternalCreateInstance(const Key_T & key, Param_T param)
    {
      PWaitAndSignal mutex(m_mutex);
      WorkerIter_T entry = m_workers.find(key);
      return entry == m_workers.end() ? NULL : entry->second.m_worker->CreateInstance(param);
    }

    void InternalDestroy(const Key_T & key, Abstract_T * instance)
    {
      PWaitAndSignal mutex(m_mutex);
      WorkerIter_T entry = m_workers.find(key);
      if (entry != m_workers.end() && !entry->second.m_worker->IsSingleton())
        delete instance;
    }

    bool InternalIsSingleton(const Key_T & key)
    {
      PWaitAndSignal mutex(m_mutex);
      WorkerIter_T entry = m_workers.find(key);
      return entry != m_workers.end() && entry->second.m_worker->IsSingleton();
    }

    KeyList_T InternalGetKeyList()
    { 
      PWaitAndSignal mutex(m_mutex);
      KeyList_T list;
      for (WorkerIter_T entry = m_workers.begin(); entry != m_workers.end(); ++entry)
        list.push_back(entry->first);
      return list;
    }

  protected:
    WorkerMap_T m_workers;

  private:
    PFactoryTemplate(const PFactoryTemplate &) {}
    void operator=(const PFactoryTemplate &) {}

  friend class PFactoryBase;
};


typedef std::string PDefaultPFactoryKey;


#define PFACTORY_STATICS(cls) \
  static cls & GetFactory()                                            { return PFactoryBase::GetFactoryAs<cls>(); } \
  static bool Register(const Key_T & k, WorkerBase_T *w, bool a=false) { return GetFactory().InternalRegister(k, w, a); } \
  static bool Register(const Key_T & k, Abstract_T * i, bool a = true) { return GetFactory().InternalRegister(k, i, a); } \
  static bool RegisterAs(const Key_T & synonym, const Key_T & original){ return GetFactory().InternalRegisterAs(synonym, original); } \
  static void Unregister(const Key_T & k)                              {        GetFactory().InternalUnregister(k); } \
  static void Unregister(WorkerBase_T * a)                             {        GetFactory().InternalUnregister(a); } \
  static void UnregisterAll()                                          {        GetFactory().InternalUnregisterAll(); } \
  static bool IsRegistered(const Key_T & k)                            { return GetFactory().InternalIsRegistered(k); } \
  static bool IsSingleton(const Key_T & k)                             { return GetFactory().InternalIsSingleton(k); } \
  static typename Base_T::KeyList_T GetKeyList()                       { return GetFactory().InternalGetKeyList(); } \
  static PMutex & GetMutex()                                           { return GetFactory().m_mutex; } \


template <class AbstractClass, typename KeyType = PDefaultPFactoryKey>
class PFactory : public PFactoryTemplate<AbstractClass, const KeyType &, KeyType>
{
  public:
    typedef PFactoryTemplate<AbstractClass, const KeyType &, KeyType> Base_T;
    typedef typename Base_T::WorkerBase WorkerBase_T;
    typedef typename Base_T::Abstract_T Abstract_T;
    typedef typename Base_T::Param_T    Param_T;
    typedef typename Base_T::Key_T      Key_T;

    PFACTORY_STATICS(PFactory);

    template <class ConcreteClass>
    class Worker : protected WorkerBase_T
    {
      private:
        Key_T * m_key;
      public:
        Worker(const Key_T & key, bool singleton = false)
          : WorkerBase_T(singleton)
          , m_key(new Key_T(key))
        {
          PAssert(Register(key, this), "Factory Worker already registered");
        }

        ~Worker()
        {
          if (m_key == NULL)
            return;
          Unregister(*m_key);
          delete m_key;
          m_key = NULL;
        }

        const Key_T & GetKey() const { return *m_key; }

      protected:
        virtual Abstract_T * Create(Param_T) const
        {
          return new ConcreteClass();
        }
    };

    static Abstract_T * CreateInstance(const Key_T & key)
    {
      return GetFactory().InternalCreateInstance(key, key);
    }

    template <class Derived_T>
    static Derived_T * CreateInstanceAs(const Key_T & key)
    {
      Abstract_T * instance = GetFactory().InternalCreateInstance(key, key);
      Derived_T * derived = dynamic_cast<Derived_T *>(instance);
      if (derived != NULL)
        return derived;

      GetFactory().InternalDestroy(key, instance);
      return NULL;
    }
};


template <class AbstractClass, typename ParamType, typename KeyType = PDefaultPFactoryKey>
class PParamFactory : public PFactoryTemplate<AbstractClass, ParamType, KeyType>
{
  public:
    typedef PFactoryTemplate<AbstractClass, ParamType, KeyType> Base_T;
    typedef typename Base_T::WorkerBase WorkerBase_T;
    typedef typename Base_T::Abstract_T Abstract_T;
    typedef typename Base_T::Param_T    Param_T;
    typedef typename Base_T::Key_T      Key_T;

    PFACTORY_STATICS(PParamFactory);

    template <class ConcreteClass>
    class Worker : protected WorkerBase_T
    {
      private:
        Key_T * m_key;
      public:
        Worker(const Key_T & key, bool singleton = false)
          : WorkerBase_T(singleton)
          , m_key(new Key_T(key))
        {
          PAssert(Register(key, this), "Factory Worker already registered");
        }

        ~Worker()
        {
          if (m_key == NULL)
            return;
          Unregister(*m_key);
          delete m_key;
          m_key = NULL;
        }

        const Key_T & GetKey() const { return *m_key; }

      protected:
        virtual Abstract_T * Create(Param_T param) const
        {
          return new ConcreteClass(param);
        }
    };

    static Abstract_T * CreateInstance(const Key_T & key, Param_T param)
    {
      return GetFactory().InternalCreateInstance(key, param);
    }

    template <class Derived_T>
    static Derived_T * CreateInstanceAs(const Key_T & key, Param_T param)
    {
      Abstract_T * instance = GetFactory().InternalCreateInstance(key, param);
      Derived_T * derived = dynamic_cast<Derived_T *>(instance);
      if (derived != NULL)
        return derived;
      GetFactory().InternalDestroy(key, instance);
      return NULL;
    }
};


#define PFACTORY_CREATE(factory, ConcreteClass, ...) \
  namespace PFactoryLoader { \
    int ConcreteClass##_link(int const *) { return 0; } \
    factory::Worker<ConcreteClass> ConcreteClass##_instance(__VA_ARGS__); \
  }

#define PFACTORY_SYNONYM(factory, ConcreteClass, name, key) \
  namespace PFactoryLoader { \
    bool ConcreteClass##name##_synonym = factory::RegisterAs(key, ConcreteClass##_instance.GetKey()); \
  }

#define PFACTORY_CREATE_SINGLETON(factory, ConcreteClass) \
        PFACTORY_CREATE(factory, ConcreteClass, typeid(ConcreteClass).name(), true)

#define PFACTORY_GET_SINGLETON(factory, ConcreteClass) \
        static ConcreteClass & GetInstance() { \
          return *factory::CreateInstanceAs<ConcreteClass>(typeid(ConcreteClass).name()); \
        }




/* This macro is used to force linking of factories.
   See PFACTORY_CREATE() for more information
 */
#define PFACTORY_LOAD(ConcreteType) \
  namespace PFactoryLoader { \
    extern int ConcreteType##_link(int const *); \
    static int const ConcreteType##_loader = ConcreteType##_link(&ConcreteType##_loader); \
  }


#endif // PTLIB_FACTORY_H


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