PolymorphicPointerReflector.h

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/*
 * Copyright (C) 2012 by
 *   MetraLabs GmbH (MLAB), GERMANY
 * and
 *   Neuroinformatics and Cognitive Robotics Labs (NICR) at TU Ilmenau, GERMANY
 * All rights reserved.
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 * Contact: info@mira-project.org
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 */

#ifndef _MIRA_POLYMORPHICPOINTERREFLECTOR_H_
#define _MIRA_POLYMORPHICPOINTERREFLECTOR_H_

#include <map>
#include <memory>

#include <utils/Foreach.h>
#include <serialization/VoidCast.h>

namespace mira {


MIRA_DEFINE_EXCEPTION(XPolymorphicPointerReflectorNotRegistered, XIO)

namespace serialization {


template <typename Derived>
struct PolymorphicPointerReflectorBase
{
    virtual ~PolymorphicPointerReflectorBase() {}

    virtual void invoke(Derived& serializer, void* pointer) = 0;
};

template <typename T, typename Derived>
struct PolymorphicPointerReflector :
            public PolymorphicPointerReflectorBase<Derived>
{
    virtual void invoke(Derived& reflector, void* pointer)
    {
        // and serialize content recursively
        reflector.invokePointerObject(*serialization::void_downcast<T>(pointer));
    }
};

template <typename Derived>
class PolymorphicPointerReflectorRegistrar :
            public LazySingleton<PolymorphicPointerReflectorRegistrar<Derived> >
{
public:

    typedef PolymorphicPointerReflectorBase<Derived>& ReflectorRef;

    typedef std::unique_ptr<PolymorphicPointerReflectorBase<Derived>> ReflectorPtr;

public:

    ~PolymorphicPointerReflectorRegistrar() {
#ifdef MIRA_WINDOWS
    // If mReflectors is not empty here, some classes were not unregistered
    // before this singleton is destroyed. Their destructors will be called
    // when mReflectors is destroyed with its parent object.
    // However, calling the destructor can be dangerous especially on
    // Windows, since some necessary dynamic libraries were already
    // removed from memory for some reason. Since the destructor does not
    // actually do anything, it is preferable to just omit the deletion
    // and leak some memory at program end. We achieve that by
    // releasing ownership of the managed objects.
    foreach(typename ReflectorMap::value_type& v, mReflectors)
        v.second.release();
#endif
    }

public:

    template<typename Class>
    void registerClass()
    {
        int typeId = Class::CLASS().getTypeId();
        if(mReflectors.count(typeId)!=0)
            return; // we already have registered that class type

        // add a new pointer serializer
        mReflectors.insert(std::make_pair(typeId,
                                          std::make_unique<PolymorphicPointerReflector<Class, Derived>>()));
    }

    template<typename Class>
    void unregisterClass()
    {
        int typeId = Class::CLASS().getTypeId();

        auto it = mReflectors.find(typeId);
        if(it==mReflectors.end())
            return; // we have not registered that class type,
                    // or already unregistered it

        // remove it from our map (will automatically delete the managed object)
        mReflectors.erase(it);
    }

    ReflectorRef getPolymorphicPointerReflector(int typeId)
    {
        auto it = mReflectors.find(typeId);
        if(it==mReflectors.end())
            MIRA_THROW(XPolymorphicPointerReflectorNotRegistered,
                       "Type ID " << typeId << " not registered");

        return *it->second;
    }

private:

    typedef std::map<int, ReflectorPtr> ReflectorMap;

    ReflectorMap mReflectors;

};


} // namespace


} // namespace

#endif