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DoubleDispatcher.hpp

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#ifndef WNS_DOUBLEDISPATCHER_HPP
#define WNS_DOUBLEDISPATCHER_HPP
#include <WNS/TypeInfo.hpp>
#include <WNS/TypeTraits.hpp>
#include <WNS/SmartPtr.hpp>
#include <string>
#include <map>
#include <iostream>

namespace wns
{
    template<typename PlainBaseRhs,
         typename CallbackType>
    class DoubleDispatcherBase
    {
        friend class DoubleDispatcherTest;
    public:
        typedef std::map<TypeInfo, CallbackType> CallbackMap;
        typedef typename CallbackMap::iterator CMI;

        DoubleDispatcherBase()
            : cm(CallbackMap()),
              defaultCallback(0)
        {
        }

        virtual ~DoubleDispatcherBase()
        {}

    protected:
        CallbackType
        getCallback(const TypeInfo& rhs)
        {
            CMI res = cm.find(rhs);
            if(res!=cm.end()) {
                return res->second;
            } else {
                assert(defaultCallback);
                return defaultCallback;
            }
        }

        void
        addCallback(const TypeInfo& rhs, const CallbackType& cb)
        {
            if(rhs == TypeInfo::create<PlainBaseRhs>()) {
                defaultCallback = cb;
            } else {
                assert(!cm.count(rhs));
                cm[rhs] = cb;
            };
        }

        void
        addDefaultCallback(const CallbackType& cb) {
            defaultCallback = cb;
        }

    private:
        CallbackMap cm;
        CallbackType defaultCallback;
    };

    template<class ConcreteLhs,
         class BaseRhs,
         typename ResultType = void,
         int Argument = TypeTraits<BaseRhs>::propNumber>
    class DoubleDispatcher
    {
    };

    template<class ConcreteLhs,
         class BaseRhs,
         typename ResultType>
    class DoubleDispatcher<ConcreteLhs,
                   BaseRhs,
                   ResultType,
                   TypeTraits<NullType>::Reference>
                       : public DoubleDispatcherBase<typename TypeTraits<BaseRhs>::ReferenceType,
                                     ResultType (*)(ConcreteLhs&, BaseRhs)>
    {
    public:
        DoubleDispatcher()
            : DoubleDispatcherBase<typename TypeTraits<BaseRhs>::ReferenceType, ResultType (*)(ConcreteLhs&, BaseRhs)>()
            {
            }
        virtual ~DoubleDispatcher()
            {}

        template <typename ConcreteRhs,
            ResultType (ConcreteLhs::*callback)(ConcreteRhs&)>
            void
            addMemberFunction()
            {
                struct Local
                {
                    static ResultType Trampoline(ConcreteLhs& lhs, BaseRhs rhs)
                    {
                        return ((lhs).*callback)(static_cast<ConcreteRhs&>(rhs));
                    }
                };
                addCallback(TypeInfo::create<ConcreteRhs>(), &Local::Trampoline);
            }

        ResultType dispatch(ConcreteLhs& lhs, BaseRhs rhs)
            {
                return (*getCallback(TypeInfo::create(rhs)))(lhs, rhs);
            }

        ResultType dispatch(ConcreteLhs* lhs, BaseRhs rhs)
            {
                return (*getCallback(TypeInfo::create(rhs)))(*lhs, rhs);
            }
    };

    template<class ConcreteLhs,
         class BaseRhs,
         typename ResultType>
    class DoubleDispatcher<ConcreteLhs,
                   BaseRhs,
                   ResultType,
                   TypeTraits<NullType>::Pointer>
                       : public DoubleDispatcherBase<typename TypeTraits<BaseRhs>::PointeeType,
                                     ResultType (*)(ConcreteLhs&, BaseRhs)>
    {
    public:
        DoubleDispatcher()
            : DoubleDispatcherBase<typename TypeTraits<BaseRhs>::PointeeType, ResultType (*)(ConcreteLhs&, BaseRhs)>()
            {
            }
        virtual ~DoubleDispatcher()
            {}

        template <typename ConcreteRhs,
            ResultType (ConcreteLhs::*callback)(ConcreteRhs*)>
            void
            addMemberFunction()
            {
                struct Local
                {
                    static ResultType Trampoline(ConcreteLhs& lhs, BaseRhs rhs)
                    {
                        return ((lhs).*callback)(staticCast<ConcreteRhs>(rhs));
                    }
                };
                addCallback(TypeInfo::create<ConcreteRhs>(), &Local::Trampoline);
            }

        ResultType dispatch(ConcreteLhs& lhs, BaseRhs rhs)
            {
                return (*getCallback(TypeInfo::create(*rhs)))(lhs, rhs);
            }

        ResultType dispatch(ConcreteLhs* lhs, BaseRhs rhs)
            {
                return (*getCallback(TypeInfo::create(*rhs)))(*lhs, rhs);
            }
    };

    template<class ConcreteLhs,
         class BaseRhs,
         typename ResultType>
    class DoubleDispatcher<ConcreteLhs,
                   BaseRhs,
                   ResultType,
                   TypeTraits<NullType>::ConstReference>
                       : public DoubleDispatcherBase<typename TypeTraits<BaseRhs>::ReferenceType,
                                     ResultType (*)(ConcreteLhs&, BaseRhs)>
    {
    public:
        DoubleDispatcher()
            : DoubleDispatcherBase<typename TypeTraits<BaseRhs>::ReferenceType, ResultType (*)(ConcreteLhs&, BaseRhs)>()
            {
            }
        virtual ~DoubleDispatcher()
            {}

        template <typename ConcreteRhs,
            ResultType (ConcreteLhs::*callback)(const ConcreteRhs&)>
            void
            addMemberFunction()
            {
                struct Local
                {
                    static ResultType Trampoline(ConcreteLhs& lhs, BaseRhs rhs)
                    {
                        return ((lhs).*callback)(static_cast<const ConcreteRhs&>(rhs));
                    }
                };
                addCallback(TypeInfo::create<ConcreteRhs>(), &Local::Trampoline);
            }

        ResultType dispatch(ConcreteLhs& lhs, BaseRhs rhs)
            {
                return (*getCallback(TypeInfo::create(rhs)))(lhs, rhs);
            }

        ResultType dispatch(ConcreteLhs* lhs, BaseRhs rhs)
            {
                return (*getCallback(TypeInfo::create(rhs)))(*lhs, rhs);
            }
    };


    template<class ConcreteLhs,
             class BaseRhs,
             typename ResultType>
    class DoubleDispatcher<ConcreteLhs,
                   const SmartPtr<BaseRhs>&,
                   ResultType,
                   TypeTraits<NullType>::ConstReference>
                       : public DoubleDispatcherBase<BaseRhs,
                                     ResultType (*)(ConcreteLhs&, const SmartPtr<BaseRhs>&)>
    {
    public:
        DoubleDispatcher()
            : DoubleDispatcherBase<BaseRhs, ResultType (*)(ConcreteLhs&, const SmartPtr<BaseRhs>&)>()
            {
            }
        virtual ~DoubleDispatcher()
            {}

        template <typename ConcreteRhs,
            ResultType (ConcreteLhs::*callback)(const SmartPtr<ConcreteRhs>&)>
            void
            addMemberFunction()
            {
                struct Local
                {
                    static ResultType Trampoline(ConcreteLhs& lhs, const SmartPtr<BaseRhs>& rhs)
                        {
                            return ((lhs).*callback)(staticCast<ConcreteRhs>(rhs));
                        }
                };
                addCallback(TypeInfo::create<ConcreteRhs>(), &Local::Trampoline);
            }

        ResultType dispatch(ConcreteLhs& lhs, const SmartPtr<BaseRhs>& rhs)
            {
                return (*getCallback(TypeInfo::create(*rhs)))(lhs, rhs);
            }

        ResultType dispatch(ConcreteLhs* lhs, const SmartPtr<BaseRhs>& rhs)
            {
                return (*getCallback(TypeInfo::create(*rhs)))(*lhs, rhs);
            }
    };
}

#endif // NOT defined WNS_DOUBLEDISPATCHER_HPP

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